helpdata.c

Go to the documentation of this file.

/***********************************************************************
 Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
***********************************************************************/
 
/***********************************************************************
  This module is for generic handling of help data, independent
  of gui considerations.
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
#include <stdio.h>
#include <string.h>
 
/* utility */
#include "astring.h"
#include "bitvector.h"
#include "fciconv.h"
#include "fcintl.h"
#include "log.h"
#include "mem.h"
#include "registry.h"
#include "string_vector.h"
#include "support.h"
 
/* common */
#include "counters.h"
#include "effects.h"
#include "game.h"
#include "government.h"
#include "map.h"
#include "movement.h"
#include "multipliers.h"
#include "nation.h"
#include "reqtext.h"
#include "research.h"
#include "server_settings.h"
#include "specialist.h"
#include "tilespec.h"
#include "unit.h"
#include "version.h"
 
/* client */
#include "client_main.h"
#include "climisc.h"
#include "gui_main_g.h" /* client_string */
#include "music.h"
 
#include "helpdata.h"
 
/* TRANS: Character appearing in the beginning of each helptext point */
#define BULLET Q_("?bullet:*")
/* TRANS: bullet point with trailing space */
#define BULLET_SPACE Q_("?bullet:* ")
 
/* helper macro for easy conversion from snprintf and cat_snprintf */
#define CATLSTR(_b, _s, _t, ...) cat_snprintf(_b, _s, _t, ## __VA_ARGS__)
 
/* This must be in same order as enum in helpdlg_g.h */
static const char * const help_type_names[] = {
  "(Any)", "(Text)", "Units", "Improvements", "Wonders",
  "Techs", "Terrain", "Extras", "Goods", "Specialists", "Governments",
  "Ruleset", "Tileset", "Musicset", "Nations", "Multipliers", "Counters", NULL
};
 
#define SPECLIST_TAG help
#define SPECLIST_TYPE struct help_item
#include "speclist.h"
 
#define help_list_iterate(helplist, phelp) \
    TYPED_LIST_ITERATE(struct help_item, helplist, phelp)
#define help_list_iterate_end  LIST_ITERATE_END
 
static const struct help_list_link *help_nodes_iterator;
static struct help_list *help_nodes;
static bool help_nodes_init = FALSE;
/* help_nodes_init is not quite the same as booted in boot_help_texts();
   latter can be FALSE even after call, eg if couldn't find helpdata.txt.
*/
 
/************************************************************************/
void helpdata_init(void)
{
  help_nodes = help_list_new();
}
 
/************************************************************************/
void helpdata_done(void)
{
  help_list_destroy(help_nodes);
}
 
/************************************************************************/
static void check_help_nodes_init(void)
{
  if (!help_nodes_init) {
    help_nodes_init = TRUE;    /* before help_iter_start to avoid recursion! */
    help_iter_start();
  }
}
 
/************************************************************************/
void free_help_texts(void)
{
  check_help_nodes_init();
  help_list_iterate(help_nodes, ptmp) {
    free(ptmp->topic);
    free(ptmp->text);
    free(ptmp);
  } help_list_iterate_end;
  help_list_clear(help_nodes);
}
 
/************************************************************************/
static bool show_help_for_nation(const struct nation_type *pnation)
{
  return client_nation_is_in_current_set(pnation);
}
 
/************************************************************************/
static bool insert_veteran_help(char *outbuf, size_t outlen,
                                const struct veteran_system *veteran,
                                const char *intro, const char *nolevels)
{
  /* game.veteran can be NULL in pregame; if so, keep quiet about
   * veteran levels */
  if (!veteran) {
    return FALSE;
  }
 
  fc_assert_ret_val(veteran->levels >= 1, FALSE);
 
  if (veteran->levels == 1) {
    /* Only a single veteran level. Don't bother to name it. */
    if (nolevels) {
      CATLSTR(outbuf, outlen, "%s", nolevels);
      return TRUE;
    } else {
      return FALSE;
    }
  } else {
    int i;
    fc_assert_ret_val(veteran->definitions != NULL, FALSE);
    if (intro) {
      CATLSTR(outbuf, outlen, "%s", intro);
      CATLSTR(outbuf, outlen, "\n\n");
    }
    /* TODO: Report raise_chance and work_raise_chance */
    CATLSTR(outbuf, outlen,
            /* TRANS: Header for fixed-width veteran level table.
             * TRANS: Translators cannot change column widths :(
             * TRANS: "Level name" left-justified, other two right-justified */
            _("Veteran level      Power factor   Move bonus\n"));
    CATLSTR(outbuf, outlen,
            /* TRANS: Part of header for veteran level table. */
            _("--------------------------------------------"));
    for (i = 0; i < veteran->levels; i++) {
      const struct veteran_level *level = &veteran->definitions[i];
      const char *name = name_translation_get(&level->name);
      int slen;
 
      /* Use get_internal_string_length() for correct alignment with
       * multibyte character encodings */
      slen = 25 - (int)get_internal_string_length(name);
      cat_snprintf(outbuf, outlen,
          "\n%s%*s %4d%% %12s",
          name, MAX(0, slen), "",
          level->power_fact,
          /* e.g. "-    ", "+ 1/3", "+ 1    ", "+ 2 2/3" */
          move_points_text_full(level->move_bonus, TRUE, "+ ", "-", TRUE));
    }
    return TRUE;
  }
}
 
/************************************************************************/
static bool insert_generated_text(char *outbuf, size_t outlen, const char *name)
{
  if (!game.client.ruleset_init) {
    return FALSE;
  }
 
  if (0 == strcmp(name, "TerrainAlterations")) {
    int clean_time = -1, pillage_time = -1;
    bool terrain_independent_extras = FALSE;
 
    /* Special handling for transform.
     * Transforming from a land to ocean, or from ocean to land, may require
     * a number of adjacent tiles of the right terrain class. If so,
     * we provide that bit of info.
     * The terrain.ruleset file may include a transform from a land to
     * ocean, or from ocean to land, which then is not possible because
     * the value of land_channel_requirement or ocean_reclaim_requirement
     * prevents it. 101 is the value that prevents it. */
    bool can_transform_water2land =
         (terrain_control.ocean_reclaim_requirement_pct < 101);
    bool can_transform_land2water =
         (terrain_control.land_channel_requirement_pct < 101);
    int num_adj_tiles = wld.map.num_valid_dirs;
    int num_land_tiles_needed =
        ceil((terrain_control.ocean_reclaim_requirement_pct/100.0) *
              num_adj_tiles);
    int num_water_tiles_needed =
        ceil((terrain_control.land_channel_requirement_pct/100.0) *
              num_adj_tiles);
 
    if (can_transform_water2land && num_land_tiles_needed > 0) {
      cat_snprintf(outbuf, outlen,
          PL_("To transform a water tile to a land tile, the water tile "
              "must have %d adjacent land tile.\n",
              "To transform a water tile to a land tile, the water tile "
              "must have %d adjacent land tiles.\n",
              num_land_tiles_needed),
          num_land_tiles_needed);
    }
    if (can_transform_land2water && num_water_tiles_needed > 0) {
      cat_snprintf(outbuf, outlen,
          PL_("To transform a land tile to a water tile, the land tile "
              "must have %d adjacent water tile.\n",
              "To transform a land tile to a water tile, the land tile "
              "must have %d adjacent water tiles.\n",
              num_water_tiles_needed),
          num_water_tiles_needed);
    }
    CATLSTR(outbuf, outlen, "\n");
 
    CATLSTR(outbuf, outlen,
            /* TRANS: Header for fixed-width terrain alteration table.
             * TRANS: Translators cannot change column widths :( */
            _("Terrain       Cultivate        Plant            Transform\n"));
    CATLSTR(outbuf, outlen,
            "----------------------------------------------------------------\n");
    terrain_type_iterate(pterrain) {
      if (0 != strlen(terrain_rule_name(pterrain))) {
        char cultivation_time[4], plant_time[4], transform_time[4];
        const char *terrain, *cultivate_result,
                   *plant_result,*transform_result;
        struct universal for_terr = { .kind = VUT_TERRAIN, .value = { .terrain = pterrain }};
        int cslen, pslen, tslen;
 
        fc_snprintf(cultivation_time, sizeof(cultivation_time),
                    "%d", pterrain->cultivate_time);
        fc_snprintf(plant_time, sizeof(plant_time),
                    "%d", pterrain->plant_time);
        fc_snprintf(transform_time, sizeof(transform_time),
                    "%d", pterrain->transform_time);
        terrain = terrain_name_translation(pterrain);
        cultivate_result =
          (pterrain->cultivate_result == T_NONE
           || !action_id_univs_not_blocking(ACTION_CULTIVATE, NULL, &for_terr))
            ? ""
            : terrain_name_translation(pterrain->cultivate_result);
        plant_result =
          (pterrain->plant_result == T_NONE
           || !action_id_univs_not_blocking(ACTION_PLANT, NULL, &for_terr))
            ? ""
            : terrain_name_translation(pterrain->plant_result);
        transform_result =
          (pterrain->transform_result == pterrain
           || pterrain->transform_result == T_NONE
           || !action_id_univs_not_blocking(ACTION_TRANSFORM_TERRAIN,
                                            NULL, &for_terr)) ? ""
          : terrain_name_translation(pterrain->transform_result);
 
        /* More special handling for transform.
         * Check if it is really possible. */
        if (strcmp(transform_result, "") != 0
            && pterrain->transform_result != T_NONE) {
          enum terrain_class ter_class =
               terrain_type_terrain_class(pterrain);
          enum terrain_class trans_ter_class =
               terrain_type_terrain_class(pterrain->transform_result);
          if (!can_transform_water2land
              && ter_class == TC_OCEAN && trans_ter_class == TC_LAND) {
            transform_result = "";
          }
          if (!can_transform_land2water
              && ter_class == TC_LAND && trans_ter_class == TC_OCEAN) {
            transform_result = "";
          }
        }
 
        /* Use get_internal_string_length() for correct alignment with
         * multibyte character encodings */
        tslen = 12 - (int)get_internal_string_length(terrain);
        cslen = 12 - (int)get_internal_string_length(cultivate_result);
        pslen = 12 - (int)get_internal_string_length(plant_result);
        cat_snprintf(outbuf, outlen,
            "%s%*s %3s %s%*s %3s %s%*s %3s %s\n",
            terrain,
            MAX(0, tslen), "",
            (pterrain->cultivate_result == T_NONE) ? "-" : cultivation_time,
            cultivate_result,
            MAX(0, cslen), "",
            (pterrain->plant_result == T_NONE) ? "-" : plant_time,
            plant_result,
            MAX(0, pslen), "",
            (!strcmp(transform_result, "")) ? "-" : transform_time,
            transform_result);
 
        if (clean_time != 0) {
          extra_type_by_rmcause_iterate(ERM_CLEAN, pextra) {
            int rmtime = pterrain->extra_removal_times[extra_index(pextra)];
 
            if (rmtime != 0) {
              if (clean_time < 0) {
                clean_time = rmtime;
              } else if (clean_time != rmtime) {
                clean_time = 0; /* Give up */
              }
            }
          } extra_type_by_rmcause_iterate_end;
        }
 
        if (pillage_time != 0 && pterrain->pillage_time != 0) {
          if (pillage_time < 0) {
            pillage_time = pterrain->pillage_time;
          } else {
            if (pillage_time != pterrain->pillage_time) {
              pillage_time = 0; /* Give up */
            }
          }
        }
      }
    } terrain_type_iterate_end;
 
    /* Examine extras to see if time of removal activities really is
     * terrain-independent, and take into account removal_time_factor.
     * XXX: this is rather overwrought to handle cases which the ruleset
     *      author could express much more simply for the same result */
    {
      int time = -1, factor = -1;
 
      extra_type_by_rmcause_iterate(ERM_CLEAN, pextra) {
        if (pextra->removal_time == 0) {
          if (factor < 0) {
            factor = pextra->removal_time_factor;
          } else if (factor != pextra->removal_time_factor) {
            factor = 0; /* Give up */
          }
        } else {
          if (time < 0) {
            time = pextra->removal_time;
          } else if (time != pextra->removal_time) {
            time = 0; /* Give up */
          }
        }
      } extra_type_by_rmcause_iterate_end;
 
      if (factor < 0) {
        /* No extra has terrain-dependent clean time; use extra's time */
        if (time >= 0) {
          clean_time = time;
        } else {
          clean_time = 0;
        }
      } else if (clean_time != 0) {
        /* At least one extra's time depends on terrain */
        fc_assert(clean_time > 0);
 
        if (time > 0 && factor > 0 && time != clean_time * factor) {
          clean_time = 0;
        } else if (time >= 0) {
          clean_time = time;
        } else if (factor >= 0) {
          clean_time *= factor;
        } else {
          fc_assert(FALSE);
        }
      }
    }
 
    {
      int time = -1, factor = -1;
 
      extra_type_by_rmcause_iterate(ERM_PILLAGE, pextra) {
        if (pextra->removal_time == 0) {
          if (factor < 0) {
            factor = pextra->removal_time_factor;
          } else if (factor != pextra->removal_time_factor) {
            factor = 0; /* Give up */
          }
        } else {
          if (time < 0) {
            time = pextra->removal_time;
          } else if (time != pextra->removal_time) {
            time = 0; /* Give up */
          }
        }
      } extra_type_by_rmcause_iterate_end;
      if (factor < 0) {
        /* No extra has terrain-dependent pillage time; use extra's time */
        if (time >= 0) {
          pillage_time = time;
        } else {
          pillage_time = 0;
        }
      } else if (pillage_time != 0) {
        /* At least one extra's time depends on terrain */
        fc_assert(pillage_time > 0);
        if (time > 0 && factor > 0 && time != pillage_time * factor) {
          pillage_time = 0;
        } else if (time >= 0) {
          pillage_time = time;
        } else if (factor >= 0) {
          pillage_time = pillage_time * factor;
        } else {
          fc_assert(FALSE);
        }
      }
    }
 
    /* Check whether there are any bases or roads whose build time is
     * independent of terrain */
 
    extra_type_by_cause_iterate(EC_BASE, pextra) {
      if (pextra->buildable && pextra->build_time > 0) {
        terrain_independent_extras = TRUE;
        break;
      }
    } extra_type_by_cause_iterate_end;
    if (!terrain_independent_extras) {
      extra_type_by_cause_iterate(EC_ROAD, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          terrain_independent_extras = TRUE;
          break;
        }
      } extra_type_by_cause_iterate_end;
    }
 
    if (clean_time > 0 || pillage_time > 0
        || terrain_independent_extras) {
      CATLSTR(outbuf, outlen, "\n");
      CATLSTR(outbuf, outlen,
              _("Time taken for the following activities is independent of "
                "terrain:\n"));
      CATLSTR(outbuf, outlen, "\n");
      CATLSTR(outbuf, outlen,
              /* TRANS: Header for fixed-width terrain alteration table.
               * TRANS: Translators cannot change column widths :( */
              _("Activity            Time\n"));
      CATLSTR(outbuf, outlen,
              "---------------------------");
      if (clean_time > 0) {
        cat_snprintf(outbuf, outlen,
                     _("\nClean              %3d"), clean_time);
      }
      if (pillage_time > 0) {
        cat_snprintf(outbuf, outlen,
                     _("\nPillage            %3d"), pillage_time);
      }
 
      extra_type_by_cause_iterate(EC_ROAD, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          const char *rname = extra_name_translation(pextra);
          int slen = 18 - (int)get_internal_string_length(rname);
 
          cat_snprintf(outbuf, outlen,
                       "\n%s%*s %3d",
                       rname,
                       MAX(0, slen), "",
                       pextra->build_time);
        }
      } extra_type_by_cause_iterate_end;
 
      extra_type_by_cause_iterate(EC_BASE, pextra) {
        if (pextra->buildable && pextra->build_time > 0) {
          const char *bname = extra_name_translation(pextra);
          int slen = 18 - (int)get_internal_string_length(bname);
 
          cat_snprintf(outbuf, outlen,
                       "\n%s%*s %3d",
                       bname,
                       MAX(0, slen), "",
                       pextra->build_time);
        }
      } extra_type_by_cause_iterate_end;
    }
 
    return TRUE;
  } else if (0 == strcmp(name, "VeteranLevels")) {
    return insert_veteran_help(outbuf, outlen, game.veteran,
        _("In this ruleset, the following veteran levels are defined:"),
        _("This ruleset has no default veteran levels defined."));
  } else if (0 == strcmp(name, "FreecivVersion")) {
    const char *ver = freeciv_name_version();
 
    cat_snprintf(outbuf, outlen,
                 /* TRANS: First %s is version string, e.g.,
                  * "Freeciv version 3.2.0-beta1 (beta version)" (translated).
                  * Second %s is client_string, e.g., "gui-gtk-4.0". */
                 _("This is %s, %s client."), ver, client_string);
    insert_client_build_info(outbuf, outlen);
 
    return TRUE;
  } else if (0 == strcmp(name, "DefaultMetaserver")) {
    cat_snprintf(outbuf, outlen, "  %s", FREECIV_META_URL);
 
    return TRUE;
  }
  log_error("Unknown directive '$%s' in help", name);
  return FALSE;
}
 
/************************************************************************/
static void insert_allows_single(struct universal *psource,
                                 struct requirement_vector *psubjreqs,
                                 const char *subjstr,
                                 const char *const *strs,
                                 char *buf, size_t bufsz,
                                 const char *prefix)
{
  struct strvec *coreqs = strvec_new();
  struct strvec *conoreqs = strvec_new();
  struct astring coreqstr = ASTRING_INIT;
  struct astring conoreqstr = ASTRING_INIT;
  char buf2[bufsz];
 
  /* FIXME: show other data like range and survives. */
 
  requirement_vector_iterate(psubjreqs, req) {
    if (!req->quiet && are_universals_equal(psource, &req->source)) {
      /* We're definitely going to print _something_. */
      CATLSTR(buf, bufsz, "%s", prefix);
      if (req->present) {
        /* psource enables the subject, but other sources may
         * also be required (or required to be absent). */
        requirement_vector_iterate(psubjreqs, coreq) {
          if (!coreq->quiet && !are_universals_equal(psource, &coreq->source)) {
            universal_name_translation(&coreq->source, buf2, sizeof(buf2));
            strvec_append(coreq->present ? coreqs : conoreqs, buf2);
          }
        } requirement_vector_iterate_end;
 
        if (0 < strvec_size(coreqs)) {
          if (0 < strvec_size(conoreqs)) {
            cat_snprintf(buf, bufsz,
                         Q_(strs[0]), /* "Allows %s (with %s but no %s)." */
                         subjstr,
                         strvec_to_and_list(coreqs, &coreqstr),
                         strvec_to_or_list(conoreqs, &conoreqstr));
          } else {
            cat_snprintf(buf, bufsz,
                         Q_(strs[1]), /* "Allows %s (with %s)." */
                         subjstr,
                         strvec_to_and_list(coreqs, &coreqstr));
          }
        } else {
          if (0 < strvec_size(conoreqs)) {
            cat_snprintf(buf, bufsz,
                         Q_(strs[2]), /* "Allows %s (absent %s)." */
                         subjstr,
                         strvec_to_and_list(conoreqs, &conoreqstr));
          } else {
            cat_snprintf(buf, bufsz,
                         Q_(strs[3]), /* "Allows %s." */
                         subjstr);
          }
        }
      } else {
        /* psource can, on its own, prevent the subject. */
        cat_snprintf(buf, bufsz,
                     Q_(strs[4]), /* "Prevents %s." */
                     subjstr);
      }
      cat_snprintf(buf, bufsz, "\n");
    }
  } requirement_vector_iterate_end;
 
  strvec_destroy(coreqs);
  strvec_destroy(conoreqs);
  astr_free(&coreqstr);
  astr_free(&conoreqstr);
}
 
/************************************************************************/
static void insert_allows(struct universal *psource,
                          char *buf, size_t bufsz, const char *prefix)
{
  buf[0] = '\0';
 
  governments_iterate(pgov) {
    static const char *const govstrs[] = {
      /* TRANS: First %s is a government name. */
      N_("?gov:Allows %s (with %s but no %s)."),
      /* TRANS: First %s is a government name. */
      N_("?gov:Allows %s (with %s)."),
      /* TRANS: First %s is a government name. */
      N_("?gov:Allows %s (absent %s)."),
      /* TRANS: %s is a government name. */
      N_("?gov:Allows %s."),
      /* TRANS: %s is a government name. */
      N_("?gov:Prevents %s.")
    };
    insert_allows_single(psource, &pgov->reqs,
                         government_name_translation(pgov), govstrs,
                         buf, bufsz, prefix);
  } governments_iterate_end;
 
  improvement_iterate(pimprove) {
    if (valid_improvement(pimprove)) {
      static const char *const imprstrs[] = {
        /* TRANS: First %s is a building name. */
        N_("?improvement:Allows %s (with %s but no %s)."),
        /* TRANS: First %s is a building name. */
        N_("?improvement:Allows %s (with %s)."),
        /* TRANS: First %s is a building name. */
        N_("?improvement:Allows %s (absent %s)."),
        /* TRANS: %s is a building name. */
        N_("?improvement:Allows %s."),
        /* TRANS: %s is a building name. */
        N_("?improvement:Prevents %s.")
      };
      insert_allows_single(psource, &pimprove->reqs,
                           improvement_name_translation(pimprove), imprstrs,
                           buf, bufsz, prefix);
    }
  } improvement_iterate_end;
 
  unit_type_iterate(putype) {
    static const char *const utstrs[] = {
      /* TRANS: First %s is a unit type name. */
      N_("?unittype:Allows %s (with %s but no %s)."),
      /* TRANS: First %s is a unit type name. */
      N_("?unittype:Allows %s (with %s)."),
      /* TRANS: First %s is a unit type name. */
      N_("?unittype:Allows %s (absent %s)."),
      /* TRANS: %s is a unit type name. */
      N_("?unittype:Allows %s."),
      /* TRANS: %s is a unit type name. */
      N_("?unittype:Prevents %s.")
    };
    insert_allows_single(psource, &putype->build_reqs,
                         utype_name_translation(putype), utstrs,
                         buf, bufsz, prefix);
  } unit_type_iterate_end;
 
  extra_type_iterate(pextra) {
    static const char *const estrs[] = {
      /* TRANS: First %s is an extra name. */
      N_("?extra:Allows %s (with %s but no %s)."),
      /* TRANS: First %s is an extra name. */
      N_("?extra:Allows %s (with %s)."),
      /* TRANS: First %s is an extra name. */
      N_("?extra:Allows %s (absent %s)."),
      /* TRANS: %s is an extra name. */
      N_("?extra:Allows %s."),
      /* TRANS: %s is an extra name. */
      N_("?extra:Prevents %s.")
    };
    insert_allows_single(psource, &pextra->reqs,
                         extra_name_translation(pextra), estrs,
                         buf, bufsz, prefix);
  } extra_type_iterate_end;
 
  goods_type_iterate(pgood) {
    static const char *const gstrs[] = {
      /* TRANS: First %s is a good name. */
      N_("?good:Allows %s (with %s but no %s)."),
      /* TRANS: First %s is a good name. */
      N_("?good:Allows %s (with %s)."),
      /* TRANS: First %s is a good name. */
      N_("?good:Allows %s (absent %s)."),
      /* TRANS: %s is a good name. */
      N_("?good:Allows %s."),
      /* TRANS: %s is a good name. */
      N_("?good:Prevents %s.")
    };
    insert_allows_single(psource, &pgood->reqs,
                         goods_name_translation(pgood), gstrs,
                         buf, bufsz, prefix);
  } goods_type_iterate_end;
}
 
/************************************************************************/
static struct help_item *new_help_item(int type)
{
  struct help_item *pitem;
 
  pitem = fc_malloc(sizeof(struct help_item));
  pitem->topic = NULL;
  pitem->text = NULL;
  pitem->type = type;
 
  return pitem;
}
 
/************************************************************************/
static int help_item_compar(const struct help_item *const *ppa,
                            const struct help_item *const *ppb)
{
  const struct help_item *ha, *hb;
  char *ta, *tb;
  ha = *ppa;
  hb = *ppb;
  for (ta = ha->topic, tb = hb->topic; *ta != '\0' && *tb != '\0'; ta++, tb++) {
    if (*ta != ' ') {
      if (*tb == ' ') return -1;
      break;
    } else if (*tb != ' ') {
      if (*ta == ' ') return 1;
      break;
    }
  }
  return compare_strings(ta, tb);
}
 
/************************************************************************/
void boot_help_texts(void)
{
  static bool booted = FALSE;
 
  struct section_file *sf;
  const char *filename;
  struct help_item *pitem;
  int i;
  struct section_list *sec;
  const char **paras;
  size_t npara;
  char long_buffer[64000]; /* HACK: this may be overrun. */
 
  check_help_nodes_init();
 
  /* need to do something like this or bad things happen */
  popdown_help_dialog();
 
  if (!booted) {
    log_verbose("Booting help texts");
  } else {
    /* free memory allocated last time booted */
    free_help_texts();
    log_verbose("Rebooting help texts");
  }
 
  filename = fileinfoname(get_data_dirs(), "helpdata.txt");
  if (!filename) {
    log_error("Did not read help texts");
    return;
  }
  /* after following call filename may be clobbered; use sf->filename instead */
  if (!(sf = secfile_load(filename, FALSE))) {
    /* this is now unlikely to happen */
    log_error("failed reading help-texts from '%s':\n%s", filename,
              secfile_error());
    return;
  }
 
  sec = secfile_sections_by_name_prefix(sf, "help_");
 
  if (NULL != sec) {
    section_list_iterate(sec, psection) {
      char help_text_buffer[MAX_LEN_PACKET];
      const char *sec_name = section_name(psection);
      const char *gen_str = secfile_lookup_str(sf, "%s.generate", sec_name);
 
      if (gen_str) {
        enum help_page_type current_type = HELP_ANY;
        int level = strspn(gen_str, " ");
 
        gen_str += level;
 
        for (i = 2; help_type_names[i]; i++) {
          if (strcmp(gen_str, help_type_names[i]) == 0) {
            current_type = i;
            break;
          }
        }
        if (current_type == HELP_ANY) {
          log_error("bad help-generate category \"%s\"", gen_str);
          continue;
        }
 
        if (!booted) {
          if (current_type == HELP_EXTRA) {
            size_t ncats;
 
            /* Avoid warnings about entries unused on this round,
             * when the entries in question are valid once help system has been booted */
            (void) secfile_lookup_str_vec(sf, &ncats,
                                          "%s.categories", sec_name);
          }
          continue; /* on initial boot data tables are empty */
        }
 
        {
          /* Note these should really fill in pitem->text from auto-gen
             data instead of doing it later on the fly, but I don't want
             to change that now.  --dwp
          */
          char name[2048];
          struct help_list *category_nodes = help_list_new();
 
          switch (current_type) {
          case HELP_UNIT:
            unit_type_iterate(punittype) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          utype_name_translation(punittype));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } unit_type_iterate_end;
            break;
          case HELP_TECH:
            advance_index_iterate(A_FIRST, advi) {
              if (valid_advance_by_number(advi)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            advance_name_translation(advance_by_number(advi)));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } advance_index_iterate_end;
            break;
          case HELP_TERRAIN:
            terrain_type_iterate(pterrain) {
              if (0 != strlen(terrain_rule_name(pterrain))) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            terrain_name_translation(pterrain));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } terrain_type_iterate_end;
            break;
          case HELP_EXTRA:
            {
              const char **cats;
              size_t ncats;
              cats = secfile_lookup_str_vec(sf, &ncats,
                                            "%s.categories", sec_name);
              extra_type_iterate(pextra) {
                /* If categories not specified, don't filter */
                if (cats) {
                  bool include = FALSE;
                  const char *cat = extra_category_name(pextra->category);
                  int ci;
 
                  for (ci = 0; ci < ncats; ci++) {
                    if (fc_strcasecmp(cats[ci], cat) == 0) {
                      include = TRUE;
                      break;
                    }
                  }
                  if (!include) {
                    continue;
                  }
                }
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            extra_name_translation(pextra));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              } extra_type_iterate_end;
              FC_FREE(cats);
            }
            break;
          case HELP_GOODS:
            goods_type_iterate(pgood) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          goods_name_translation(pgood));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } goods_type_iterate_end;
            break;
          case HELP_SPECIALIST:
            specialist_type_iterate(sp) {
              struct specialist *pspec = specialist_by_number(sp);
 
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          specialist_plural_translation(pspec));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } specialist_type_iterate_end;
            break;
          case HELP_GOVERNMENT:
            governments_iterate(gov) {
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          government_name_translation(gov));
              pitem->topic = fc_strdup(name);
              pitem->text = fc_strdup("");
              help_list_append(category_nodes, pitem);
            } governments_iterate_end;
            break;
          case HELP_IMPROVEMENT:
            improvement_iterate(pimprove) {
              if (valid_improvement(pimprove) && !is_great_wonder(pimprove)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            improvement_name_translation(pimprove));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } improvement_iterate_end;
            break;
          case HELP_WONDER:
            improvement_iterate(pimprove) {
              if (valid_improvement(pimprove) && is_great_wonder(pimprove)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            improvement_name_translation(pimprove));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } improvement_iterate_end;
            break;
          case HELP_RULESET:
            {
              int desc_len;
              int len;
 
              pitem = new_help_item(HELP_RULESET);
              /*           pitem->topic = fc_strdup(_(game.control.name)); */
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          Q_(HELP_RULESET_ITEM));
              pitem->topic = fc_strdup(name);
              if (game.ruleset_description != NULL) {
                desc_len = strlen("\n\n") + strlen(game.ruleset_description);
              } else {
                desc_len = 0;
              }
              if (game.ruleset_summary != NULL) {
                if (game.control.version[0] != '\0') {
                  len = strlen(_(game.control.name))
                    + strlen(" ")
                    + strlen(game.control.version)
                    + strlen("\n\n")
                    + strlen(_(game.ruleset_summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(game.control.name), game.control.version,
                              _(game.ruleset_summary));
                } else {
                  len = strlen(_(game.control.name))
                    + strlen("\n\n")
                    + strlen(_(game.ruleset_summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(game.control.name), _(game.ruleset_summary));
                }
              } else {
                const char *nodesc = _("Current ruleset contains no summary.");
 
                if (game.control.version[0] != '\0') {
                  len = strlen(_(game.control.name))
                    + strlen(" ")
                    + strlen(game.control.version)
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(game.control.name), game.control.version,
                              nodesc);
                } else {
                  len = strlen(_(game.control.name))
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(game.control.name),
                              nodesc);
                }
              }
              if (game.ruleset_description != NULL) {
                fc_strlcat(pitem->text, "\n\n", len + desc_len);
                fc_strlcat(pitem->text, game.ruleset_description, len + desc_len);
              }
              help_list_append(help_nodes, pitem);
            }
            break;
          case HELP_TILESET:
            {
              int desc_len;
              int len;
              const char *ts_name = tileset_name_get(tileset);
              const char *version = tileset_version(tileset);
              const char *summary = tileset_summary(tileset);
              const char *description = tileset_description(tileset);
 
              pitem = new_help_item(HELP_TILESET);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          Q_(HELP_TILESET_ITEM));
              pitem->topic = fc_strdup(name);
              if (description != NULL) {
                desc_len = strlen("\n\n") + strlen(description);
              } else {
                desc_len = 0;
              }
              if (summary != NULL) {
                if (version[0] != '\0') {
                  len = strlen(_(ts_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ts_name), version, _(summary));
                } else {
                  len = strlen(_(ts_name))
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ts_name), _(summary));
                }
              } else {
                const char *nodesc = _("Current tileset contains no summary.");
 
                if (version[0] != '\0') {
                  len = strlen(_(ts_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ts_name), version,
                              nodesc);
                } else {
                  len = strlen(_(ts_name))
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ts_name),
                              nodesc);
                }
              }
              if (description != NULL) {
                fc_strlcat(pitem->text, "\n\n", len + desc_len);
                fc_strlcat(pitem->text, description, len + desc_len);
              }
              help_list_append(help_nodes, pitem);
            }
            break;
          case HELP_MUSICSET:
            {
              int desc_len;
              int len;
              const char *ms_name = current_musicset_name();
              const char *version = current_musicset_version();
              const char *summary = current_musicset_summary();
              const char *description = current_musicset_description();
 
              pitem = new_help_item(HELP_MUSICSET);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          Q_(HELP_MUSICSET_ITEM));
              pitem->topic = fc_strdup(name);
              if (description != NULL) {
                desc_len = strlen("\n\n") + strlen(description);
              } else {
                desc_len = 0;
              }
              if (summary != NULL) {
                if (version != NULL && version[0] != '\0') {
                  len = strlen(_(ms_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ms_name), version, _(summary));
                } else {
                  len = strlen(_(ms_name))
                    + strlen("\n\n")
                    + strlen(_(summary))
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ms_name), _(summary));
                }
              } else {
                const char *nodesc = _("Current musicset contains no summary.");
 
                if (version != NULL && version[0] != '\0') {
                  len = strlen(_(ms_name))
                    + strlen(" ")
                    + strlen(version)
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s %s\n\n%s",
                              _(ms_name), version,
                              nodesc);
                } else {
                  len = strlen(_(ms_name))
                    + strlen("\n\n")
                    + strlen(nodesc)
                    + 1;
 
                  pitem->text = fc_malloc(len + desc_len);
                  fc_snprintf(pitem->text, len, "%s\n\n%s",
                              _(ms_name),
                              nodesc);
                }
              }
              if (description != NULL) {
                fc_strlcat(pitem->text, "\n\n", len + desc_len);
                fc_strlcat(pitem->text, description, len + desc_len);
              }
              help_list_append(help_nodes, pitem);
            }
            break;
          case HELP_NATIONS:
            nations_iterate(pnation) {
              if (client_state() < C_S_RUNNING
                  || show_help_for_nation(pnation)) {
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            nation_plural_translation(pnation));
                pitem->topic = fc_strdup(name);
                pitem->text = fc_strdup("");
                help_list_append(category_nodes, pitem);
              }
            } nations_iterate_end;
            break;
          case HELP_MULTIPLIER:
            multipliers_iterate(pmul) {
              help_text_buffer[0] = '\0';
              pitem = new_help_item(current_type);
              fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                          name_translation_get(&pmul->name));
              pitem->topic = fc_strdup(name);
              if (pmul->helptext) {
                const char *sep = "";
                strvec_iterate(pmul->helptext, text) {
                  cat_snprintf(help_text_buffer, sizeof(help_text_buffer),
                               "%s%s", sep, text);
                  sep = "\n\n";
                } strvec_iterate_end;
              }
              pitem->text = fc_strdup(help_text_buffer);
              help_list_append(help_nodes, pitem);
            } multipliers_iterate_end;
            break;
          case HELP_COUNTER:
            {
              int j;
              for (j = 0; j < game.control.num_counters; j++) {
                struct counter *pcount = counter_by_id(j);
 
                help_text_buffer[0] = '\0';
                pitem = new_help_item(current_type);
                fc_snprintf(name, sizeof(name), "%*s%s", level, "",
                            counter_name_translation(pcount));
                pitem->topic = fc_strdup(name);
                if (pcount->helptext) {
                  strvec_iterate(pcount->helptext, text) {
                    cat_snprintf(help_text_buffer, sizeof(help_text_buffer),
                               "%s%s", "\n\n", text);
                  } strvec_iterate_end;
                }
                pitem->text = fc_strdup(help_text_buffer);
                help_list_append(help_nodes, pitem);
              }
            }
            break;
          default:
            log_error("Bad current_type: %d.", current_type);
            break;
          }
          help_list_sort(category_nodes, help_item_compar);
          help_list_iterate(category_nodes, ptmp) {
            help_list_append(help_nodes, ptmp);
          } help_list_iterate_end;
          help_list_destroy(category_nodes);
          continue;
        }
      }
 
      /* It wasn't a "generate" node: */
 
      pitem = new_help_item(HELP_TEXT);
      pitem->topic = fc_strdup(Q_(secfile_lookup_str(sf, "%s.name",
                                                     sec_name)));
 
      paras = secfile_lookup_str_vec(sf, &npara, "%s.text", sec_name);
 
      long_buffer[0] = '\0';
      for (i = 0; i < npara; i++) {
        bool inserted;
        const char *para = paras[i];
 
        if (!fc_strncmp(para, "$", 1)) {
          inserted
            = insert_generated_text(long_buffer, sizeof(long_buffer), para+1);
        } else {
          sz_strlcat(long_buffer, _(para));
          inserted = TRUE;
        }
        if (inserted && i != npara - 1) {
          sz_strlcat(long_buffer, "\n\n");
        }
      }
      free(paras);
      paras = NULL;
      pitem->text = fc_strdup(long_buffer);
      help_list_append(help_nodes, pitem);
    } section_list_iterate_end;
 
    section_list_destroy(sec);
  }
 
  secfile_check_unused(sf);
  secfile_destroy(sf);
  booted = TRUE;
  log_verbose("Booted help texts ok");
}
 
/****************************************************************************
  The following few functions are essentially wrappers for the
  help_nodes help_list. This allows us to avoid exporting the
  help_list, and instead only access it through a controlled
  interface.
****************************************************************************/
 
/************************************************************************/
int num_help_items(void)
{
  check_help_nodes_init();
  return help_list_size(help_nodes);
}
 
/************************************************************************/
const struct help_item *get_help_item(int pos)
{
  int size;
 
  check_help_nodes_init();
  size = help_list_size(help_nodes);
  if (pos < 0 || pos > size) {
    log_error("Bad index %d to get_help_item (size %d)", pos, size);
    return NULL;
  }
  if (pos == size) {
    return NULL;
  }
  return help_list_get(help_nodes, pos);
}
 
/************************************************************************/
const struct help_item*
get_help_item_spec(const char *name, enum help_page_type htype, int *pos)
{
  int idx;
  const struct help_item *pitem = NULL;
  static struct help_item vitem; /* v = virtual */
  static char vtopic[128];
  static char vtext[256];
 
  check_help_nodes_init();
  idx = 0;
  help_list_iterate(help_nodes, ptmp) {
    char *p = ptmp->topic;
 
    while (*p == ' ') {
      p++;
    }
    if (strcmp(name, p) == 0 && (htype == HELP_ANY || htype == ptmp->type)) {
      pitem = ptmp;
      break;
    }
    idx++;
  }
  help_list_iterate_end;
 
  if (!pitem) {
    idx = -1;
    vitem.topic = vtopic;
    sz_strlcpy(vtopic, name);
    vitem.text = vtext;
    if (htype == HELP_ANY || htype == HELP_TEXT) {
      fc_snprintf(vtext, sizeof(vtext),
                  _("Sorry, no help topic for %s.\n"), vitem.topic);
      vitem.type = HELP_TEXT;
    } else {
      fc_snprintf(vtext, sizeof(vtext),
                  _("Sorry, no help topic for %s.\n"
                    "This page was auto-generated.\n\n"),
                  vitem.topic);
      vitem.type = htype;
    }
    pitem = &vitem;
  }
  *pos = idx;
  return pitem;
}
 
/************************************************************************/
void help_iter_start(void)
{
  check_help_nodes_init();
  help_nodes_iterator = help_list_head(help_nodes);
}
 
/************************************************************************/
const struct help_item *help_iter_next(void)
{
  const struct help_item *pitem;
 
  check_help_nodes_init();
  pitem = help_list_link_data(help_nodes_iterator);
  if (pitem) {
    help_nodes_iterator = help_list_link_next(help_nodes_iterator);
  }
 
  return pitem;
}
 
/****************************************************************************
  FIXME:
  Also, in principle these could be auto-generated once, inserted
  into pitem->text, and then don't need to keep re-generating them.
  Only thing to be careful of would be changeable data, but don't
  have that here (for ruleset change or spacerace change must
  re-boot helptexts anyway).  Eg, genuinely dynamic information
  which could be useful would be if help system said which wonders
  have been built (or are being built and by who/where?)
****************************************************************************/
 
/************************************************************************/
char *helptext_building(char *buf, size_t bufsz, struct player *pplayer,
                        const char *user_text, const struct impr_type *pimprove)
{
  bool reqs = FALSE;
  struct universal source = {
    .kind = VUT_IMPROVEMENT,
    .value = {.building = pimprove}
  };
 
  fc_assert_ret_val(NULL != buf && 0 < bufsz, NULL);
  buf[0] = '\0';
 
  if (NULL == pimprove) {
    return buf;
  }
 
  if (NULL != pimprove->helptext) {
    strvec_iterate(pimprove->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
 
  /* Add requirement text for improvement itself */
  requirement_vector_iterate(&pimprove->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT, "")) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }
 
  requirement_vector_iterate(&pimprove->obsolete_by, pobs) {
    if (VUT_ADVANCE == pobs->source.kind
        && pobs->present && !pobs->quiet) {
      cat_snprintf(buf, bufsz,
                   _("%s The discovery of %s will make %s obsolete.\n"),
                   BULLET,
                   advance_name_translation(pobs->source.value.advance),
                   improvement_name_translation(pimprove));
    }
    if (VUT_IMPROVEMENT == pobs->source.kind
        && pobs->present && !pobs->quiet) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: both %s are improvement names */
                   _("%s The presence of %s in the city will make %s "
                     "obsolete.\n"),
                   BULLET,
                   improvement_name_translation(pobs->source.value.building),
                   improvement_name_translation(pimprove));
    }
  } requirement_vector_iterate_end;
 
  if (is_small_wonder(pimprove)) {
    cat_snprintf(buf, bufsz,
                 _("%s A 'small wonder': at most one of your cities may "
                   "possess this improvement.\n"), BULLET);
  }
  /* (Great wonders are in their own help section explaining their
   * uniqueness, so we don't mention it here.) */
 
  if (building_has_effect(pimprove, EFT_ENABLE_NUKE)) {
    action_id nuke_actions[MAX_NUM_ACTIONS];
    struct unit_type *u = NULL;
 
    {
      /* Find Manhattan dependent nuke actions */
      int i = 0;
 
      action_array_add_all_by_result(nuke_actions, &i, ACTRES_NUKE);
      action_array_add_all_by_result(nuke_actions, &i, ACTRES_NUKE_UNITS);
 
      action_array_end(nuke_actions, i);
    }
 
    action_array_iterate(nuke_actions, act_id) {
      if (num_role_units(action_id_get_role(act_id)) > 0) {
        u = get_role_unit(action_id_get_role(act_id), 0);
        break;
      }
    } action_array_iterate_end;
 
    if (u) {
      struct advance *req = NULL;
      int count = 0;
 
      unit_tech_reqs_iterate(u, preq) {
        req = preq;
        count++;
      } unit_tech_reqs_iterate_end;
 
      if (req != NULL) {
        if (count == 1) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: 'Allows all players with knowledge of atomic
                        * power to build nuclear units.' */
                       _("%s Allows all players with knowledge of %s "
                         "to build %s units.\n"), BULLET,
                       advance_name_translation(req),
                       utype_name_translation(u));
        } else {
          /* Multiple tech requirements */
          cat_snprintf(buf, bufsz,
                       /* TRANS: 'Allows all players with knowledge of required
                        * techs to build nuclear units.' */
                       _("%s Allows all players with knowledge of required "
                         "techs to build %s units.\n"), BULLET,
                       utype_name_translation(u));
        }
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: 'Allows all players to build nuclear units.' */
                     _("%s Allows all players to build %s units.\n"), BULLET,
                     utype_name_translation(u));
      }
    }
  }
 
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf),
               BULLET_SPACE);
 
  /* Actions that requires the building to target a city. */
  action_iterate(act) {
    /* Nothing is found yet. */
    bool demanded = FALSE;
    enum req_range max_range = REQ_RANGE_LOCAL;
 
    if (action_id_get_target_kind(act) != ATK_CITY) {
      /* Not relevant */
      continue;
    }
 
    if (action_by_number(act)->quiet) {
      /* The ruleset it self documents this action. */
      continue;
    }
 
    action_enabler_list_iterate(action_enablers_for_action(act), enabler) {
      if (universal_fulfills_requirements(TRUE, &(enabler->target_reqs),
                                          &source)) {
        /* The building is needed by this action enabler. */
        demanded = TRUE;
 
        /* See if this enabler gives the building a wider range. */
        requirement_vector_iterate(&(enabler->target_reqs), preq) {
          if (!universal_is_relevant_to_requirement(preq, &source)) {
            /* Not relevant. */
            continue;
          }
 
          if (!preq->present) {
            /* A !present larger range requirement would make the present
             * lower range illegal. */
            continue;
          }
 
          if (preq->range > max_range) {
            /* Found a larger range. */
            max_range = preq->range;
            /* Intentionally not breaking here. The requirement vector may
             * contain other requirements with a larger range.
             * Example: Building a GreatWonder in a city with a Palace. */
          }
        } requirement_vector_iterate_end;
      }
    } action_enabler_list_iterate_end;
 
    if (demanded) {
      switch (max_range) {
      case REQ_RANGE_LOCAL:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target the city building it "
                       "with the action \'%s\'.\n"), BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_CITY:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target its city with the "
                       "action \'%s\'.\n"), BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TRADE_ROUTE:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target its city and its "
                       "trade partners with the action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_CONTINENT:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target all cities with its "
                       "owner on its continent with the action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_PLAYER:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target all cities with its "
                       "owner with the action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TEAM:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target all cities on the "
                       "same team with the action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_ALLIANCE:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target all cities owned by "
                       "or allied to its owner with the action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_WORLD:
        /* At least one action enabler needed the building in its target
         * requirements. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Help build Wonder */
                     _("%s Makes it possible to target all cities with the "
                       "action \'%s\'.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TILE:
      case REQ_RANGE_CADJACENT:
      case REQ_RANGE_ADJACENT:
      case REQ_RANGE_COUNT:
        log_error("The range %s is invalid for buildings.",
                  req_range_name(max_range));
        break;
      }
    }
  } action_iterate_end;
 
  /* Building protects against action. */
  action_iterate(act) {
    struct action *paction = action_by_number(act);
    /* Nothing is found yet. */
    bool vulnerable = FALSE;
    enum req_range min_range = REQ_RANGE_COUNT;
 
    if (action_id_get_target_kind(act) != ATK_CITY) {
      /* Not relevant */
      continue;
    }
 
    if (!action_is_in_use(paction)) {
      /* This action isn't enabled at all. */
      continue;
    }
 
    if (action_by_number(act)->quiet) {
      /* The ruleset it self documents this action. */
      continue;
    }
 
    /* Must be immune in all cases. */
    action_enabler_list_iterate(action_enablers_for_action(act), enabler) {
      if (requirement_fulfilled_by_improvement(pimprove,
                                               &(enabler->target_reqs))) {
        vulnerable = TRUE;
        break;
      } else {
        enum req_range vector_max_range = REQ_RANGE_LOCAL;
 
        requirement_vector_iterate(&(enabler->target_reqs), preq) {
          if (!universal_is_relevant_to_requirement(preq, &source)) {
            /* Not relevant. */
            continue;
          }
 
          if (preq->present) {
            /* Not what is looked for. */
            continue;
          }
 
          if (preq->range > vector_max_range) {
            /* Found a larger range. */
            vector_max_range = preq->range;
          }
        } requirement_vector_iterate_end;
 
        if (vector_max_range < min_range) {
          /* Found a smaller range. */
          min_range = vector_max_range;
        }
      }
    } action_enabler_list_iterate_end;
 
    if (!vulnerable) {
      switch (min_range) {
      case REQ_RANGE_LOCAL:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "the city building it.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_CITY:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "its city.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TRADE_ROUTE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "its city or to its city's trade partners.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_CONTINENT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "any city with its owner on its continent.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_PLAYER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "any city with its owner.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TEAM:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "any city on the same team.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_ALLIANCE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "any city allied to or owned by its owner.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_WORLD:
        cat_snprintf(buf, bufsz,
                     /* TRANS: Incite City */
                     _("%s Makes it impossible to do the action \'%s\' to "
                       "any city in the game.\n"),
                     BULLET,
                     action_id_name_translation(act));
        break;
      case REQ_RANGE_TILE:
      case REQ_RANGE_CADJACENT:
      case REQ_RANGE_ADJACENT:
      case REQ_RANGE_COUNT:
        log_error("The range %s is invalid for buildings.",
                  req_range_name(min_range));
        break;
      }
    }
  } action_iterate_end;
 
  {
    int i;
 
    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      Impr_type_id n = game.rgame.global_init_buildings[i];
      if (n == B_LAST) {
        break;
      } else if (improvement_by_number(n) == pimprove) {
        cat_snprintf(buf, bufsz,
                     _("%s All players start with this improvement in their "
                       "first city.\n"), BULLET);
        break;
      }
    }
  }
 
  /* Assume no-one will set the same building in both global and nation
   * init_buildings... */
  nations_iterate(pnation) {
    int i;
 
    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      Impr_type_id n = pnation->init_buildings[i];
      if (n == B_LAST) {
        break;
      } else if (improvement_by_number(n) == pimprove) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a nation plural */
                     _("%s The %s start with this improvement in their "
                       "first city.\n"), BULLET,
                     nation_plural_translation(pnation));
        break;
      }
    }
  } nations_iterate_end;
 
  if (improvement_has_flag(pimprove, IF_SAVE_SMALL_WONDER)) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: don't translate 'savepalace' */
                 _("%s If you lose the city containing this improvement, "
                   "it will be rebuilt for free in another of your cities "
                   "(if the 'savepalace' server setting is enabled).\n"),
                 BULLET);
  }
 
  if (user_text && user_text[0] != '\0') {
    cat_snprintf(buf, bufsz, "\n\n%s", user_text);
  }
  return buf;
}
 
/************************************************************************/
static bool utype_may_do_escape_action(const struct unit_type *utype)
{
  action_iterate(act_id) {
    struct action *paction = action_by_number(act_id);
 
    if (action_get_actor_kind(paction) != AAK_UNIT) {
      /* Not relevant. */
      continue;
    }
 
    if (!utype_can_do_action(utype, paction->id)) {
      /* Can't do it. */
      continue;
    }
 
    if (utype_is_consumed_by_action(paction, utype)) {
      /* No escape when dead. */
      continue;
    }
 
    if (paction->actor.is_unit.moves_actor == MAK_ESCAPE) {
      /* Survives and escapes. */
      return TRUE;
    }
  } action_iterate_end;
 
  return FALSE;
}
 
/************************************************************************/
void helptext_unitclass(struct unit_class *pclass, char *buf, size_t bufsz)
{
  int flagid;
 
  if (pclass->helptext != NULL) {
    strvec_iterate(pclass->helptext, text) {
      cat_snprintf(buf, bufsz, "\n%s\n", _(text));
    } strvec_iterate_end;
  } else {
    CATLSTR(buf, bufsz, "\n");
  }
 
  if (!uclass_has_flag(pclass, UCF_TERRAIN_SPEED)) {
    /* TRANS: indented unit class property, preserve leading spaces */
    CATLSTR(buf, bufsz, _("  %s Speed is not affected by terrain.\n"),
            BULLET);
  }
  if (!uclass_has_flag(pclass, UCF_TERRAIN_DEFENSE)) {
    /* TRANS: indented unit class property, preserve leading spaces */
    CATLSTR(buf, bufsz, _("  %s Does not get defense bonuses from terrain.\n"),
            BULLET);
  }
 
  if (!uclass_has_flag(pclass, UCF_ZOC)) {
    /* TRANS: indented unit class property, preserve leading spaces */
    CATLSTR(buf, bufsz, _("  %s Not subject to zones of control.\n"),
            BULLET);
  }
 
  if (uclass_has_flag(pclass, UCF_DAMAGE_SLOWS)) {
    /* TRANS: indented unit class property, preserve leading spaces */
    CATLSTR(buf, bufsz, _("  %s Slowed down while damaged.\n"), BULLET);
  }
 
  if (uclass_has_flag(pclass, UCF_UNREACHABLE)) {
    CATLSTR(buf, bufsz,
            /* TRANS: indented unit class property, preserve leading spaces */
            _("  %s Is unreachable. Most units cannot attack this one.\n"),
            BULLET);
  }
 
  if (uclass_has_flag(pclass, UCF_DOESNT_OCCUPY_TILE)) {
    CATLSTR(buf, bufsz,
            /* TRANS: Indented unit class property, preserve leading spaces */
            _("  %s Doesn't prevent enemy cities from working the tile it's on.\n"),
            BULLET);
  }
 
  for (flagid = UCF_USER_FLAG_1; flagid <= UCF_LAST_USER_FLAG; flagid++) {
    if (uclass_has_flag(pclass, flagid)) {
      const char *helptxt = unit_class_flag_helptxt(flagid);
 
      if (helptxt != NULL) {
        /* TRANS: Indented unit class property, preserve leading spaces */
        CATLSTR(buf, bufsz, "  %s %s\n", BULLET, _(helptxt));
      }
    }
  }
}
 
/************************************************************************/
char *helptext_unit(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, const struct unit_type *utype,
                    bool class_help)
{
  bool has_vet_levels;
  int flagid;
  struct unit_class *pclass;
  int fuel;
 
  fc_assert_ret_val(NULL != buf && 0 < bufsz && NULL != user_text, NULL);
 
  if (!utype) {
    log_error("Unknown unit!");
    fc_strlcpy(buf, user_text, bufsz);
    return buf;
  }
 
  has_vet_levels = utype_veteran_levels(utype) > 1;
 
  buf[0] = '\0';
 
  pclass = utype_class(utype);
  cat_snprintf(buf, bufsz,
               _("%s Belongs to %s unit class."),
               BULLET,
               uclass_name_translation(pclass));
 
  if (class_help) {
    helptext_unitclass(pclass, buf, bufsz);
  } else {
    cat_snprintf(buf, bufsz, "\n");
  }
 
  if (uclass_has_flag(pclass, UCF_ZOC)
      && !utype_has_flag(utype, UTYF_IGZOC)) {
    /* TRANS: Indented unit class property, preserve leading spaces */
    CATLSTR(buf, bufsz, _("  %s Subject to zones of control.\n"),
            BULLET);
  }
 
  if (utype->defense_strength > 0) {
    struct universal unit_is_in_city[] = {
      { .kind = VUT_UTYPE, .value = { .utype = utype }},
      { .kind = VUT_CITYTILE, .value = { .citytile = CITYT_CENTER }},
    };
    int bonus = effect_value_from_universals(
          EFT_FORTIFY_DEFENSE_BONUS,
          unit_is_in_city, ARRAY_SIZE(unit_is_in_city));
 
    if (bonus > 0) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: Indented unit class property, preserve leading
                    * spaces */
                   _("  %s Gets a %d%% defensive bonus while in cities.\n"),
                   BULLET, bonus);
    }
  }
  if (uclass_has_flag(pclass, UCF_UNREACHABLE)
      && utype_has_flag(utype, UTYF_NEVER_PROTECTS)) {
    CATLSTR(buf, bufsz,
            /* TRANS: Indented twice; preserve leading spaces */
            _("    %s Doesn't prevent enemy units from attacking other "
              "units on its tile.\n"), BULLET);
  }
 
  if (can_attack_non_native(utype)) {
    CATLSTR(buf, bufsz,
            /* TRANS: Indented unit class property, preserve leading spaces */
            _("  %s Can attack units on non-native tiles.\n"), BULLET);
  }
 
  /* The unit's combat bonuses. Won't mention that another unit type has a
   * combat bonus against this unit type. Doesn't handle complex cases like
   * when a unit type has multiple combat bonuses of the same kind. */
  combat_bonus_list_iterate(utype->bonuses, cbonus) {
    const char *against[utype_count()];
    int targets = 0;
 
    if (cbonus->quiet) {
      /* Handled in the help text of the ruleset. */
      continue;
    }
 
    /* Find the unit types of the bonus targets. */
    unit_type_iterate(utype2) {
      if (utype_has_flag(utype2, cbonus->flag)) {
        against[targets++] = utype_name_translation(utype2);
      }
    } unit_type_iterate_end;
 
    if (targets > 0) {
      struct astring list = ASTRING_INIT;
 
      switch (cbonus->type) {
      case CBONUS_DEFENSE_MULTIPLIER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: percentage ... or-list of unit types */
                     _("%s %d%% defense bonus if attacked by %s.\n"),
                     BULLET,
                     cbonus->value * 100,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_DEFENSE_DIVIDER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: defense divider ... or-list of unit types */
                     _("%s Reduces target's defense to 1 / %d when "
                       "attacking %s.\n"), BULLET,
                     cbonus->value + 1,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_LOW_FIREPOWER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: or-list of unit types */
                     _("%s Reduces target's firepower to 1 when "
                       "attacking %s.\n"), BULLET,
                     astr_build_and_list(&list, against, targets));
        break;
      case CBONUS_DEFENSE_MULTIPLIER_PCT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: percentage ... or-list of unit types */
                     _("%s %d%% defense bonus if attacked by %s.\n"),
                     BULLET, cbonus->value,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_DEFENSE_DIVIDER_PCT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: defense divider ... or-list of unit types */
                     _("%s Reduces target's defense to 1 / %.2f when "
                       "attacking %s.\n"), BULLET,
                     ((float) cbonus->value + 100.0f) / 100.0f,
                     astr_build_or_list(&list, against, targets));
        break;
      case CBONUS_SCRAMBLES_PCT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: percentage ... or-list of unit types */
                     _("%s %d%% defense bonus "
                       "instead of any bonuses from city improvements "
                       "if attacked by %s in a city.\n"),
                     BULLET, cbonus->value,
                     astr_build_or_list(&list, against, targets));
        break;
      }
 
      astr_free(&list);
    }
  } combat_bonus_list_iterate_end;
 
  /* Add requirement text for the unit type itself */
  requirement_vector_iterate(&utype->build_reqs, preq) {
    req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT,
                       BULLET_SPACE);
  } requirement_vector_iterate_end;
 
  if (utype_has_flag(utype, UTYF_CANKILLESCAPING)) {
    CATLSTR(buf, bufsz, _("%s Can pursue escaping units and kill them.\n"),
            BULLET);
  }
 
  if (utype_has_flag(utype, UTYF_NOBUILD)) {
    CATLSTR(buf, bufsz, _("%s May not be built in cities.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_BARBARIAN_ONLY)) {
    CATLSTR(buf, bufsz, _("%s Only barbarians may build this.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_NEWCITY_GAMES_ONLY)) {
    CATLSTR(buf, bufsz, _("%s Can only be built in games where new cities "
                          "are allowed.\n"), BULLET);
    if (game.scenario.prevent_new_cities) {
      /* TRANS: indented; preserve leading spaces */
      CATLSTR(buf, bufsz, _("  %s New cities are not allowed in the current "
                            "game.\n"), BULLET);
    } else {
      /* TRANS: indented; preserve leading spaces */
      CATLSTR(buf, bufsz, _("  %s New cities are allowed in the current "
                            "game.\n"), BULLET);
    }
  }
  nations_iterate(pnation) {
    int i, count = 0;
 
    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (i = 0; i < MAX_NUM_UNIT_LIST; i++) {
      if (!pnation->init_units[i]) {
        break;
      } else if (pnation->init_units[i] == utype) {
        count++;
      }
    }
    if (count > 0) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a nation plural */
                   PL_("%s The %s start the game with %d of these units.\n",
                       "%s The %s start the game with %d of these units.\n",
                       count), BULLET,
                   nation_plural_translation(pnation), count);
    }
  } nations_iterate_end;
  {
    const char *types[utype_count()];
    int i = 0;
 
    unit_type_iterate(utype2) {
      if (utype2->converted_to == utype
          && utype_can_do_action_result(utype2, ACTRES_CONVERT)) {
        types[i++] = utype_name_translation(utype2);
      }
    } unit_type_iterate_end;
    if (i > 0) {
      struct astring list = ASTRING_INIT;
 
      astr_build_or_list(&list, types, i);
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a list of unit types separated by "or". */
                   _("%s May be obtained by conversion of %s.\n"),
                   BULLET, astr_str(&list));
      astr_free(&list);
    }
  }
  if (utype_has_flag(utype, UTYF_NOHOME)) {
    if (utype_can_do_action_result(utype, ACTRES_HOME_CITY)) {
      CATLSTR(buf, bufsz, _("%s Built without a home city.\n"), BULLET);
    } else {
      CATLSTR(buf, bufsz, _("%s Never has a home city.\n"), BULLET);
    }
  }
  if (utype_has_flag(utype, UTYF_GAMELOSS)) {
    CATLSTR(buf, bufsz, _("%s Losing this unit will lose you the game!\n"),
            BULLET);
  }
  if (utype_has_flag(utype, UTYF_UNIQUE)) {
    CATLSTR(buf, bufsz,
            _("%s Each player may only have one of this type of unit.\n"),
            BULLET);
  }
  for (flagid = UTYF_USER_FLAG_1 ; flagid <= UTYF_LAST_USER_FLAG; flagid++) {
    if (utype_has_flag(utype, flagid)) {
      const char *helptxt = unit_type_flag_helptxt(flagid);
 
      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, "%s %s\n", BULLET, _(helptxt));
      }
    }
  }
  if (utype->pop_cost > 0) {
    cat_snprintf(buf, bufsz,
                 PL_("%s Costs %d population to build.\n",
                     "%s Costs %d population to build.\n", utype->pop_cost),
                 BULLET, utype->pop_cost);
  }
  if (0 < utype->transport_capacity) {
    const char *classes[uclass_count()];
    int i = 0;
    struct astring list = ASTRING_INIT;
 
    unit_class_iterate(uclass) {
      if (can_unit_type_transport(utype, uclass)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;
    astr_build_or_list(&list, classes, i);
 
    cat_snprintf(buf, bufsz,
                 /* TRANS: %s is a list of unit classes separated by "or". */
                 PL_("%s Can carry and refuel %d %s unit.\n",
                     "%s Can carry and refuel up to %d %s units.\n",
                     utype->transport_capacity),
                 BULLET, utype->transport_capacity, astr_str(&list));
    astr_free(&list);
    if (uclass_has_flag(utype_class(utype), UCF_UNREACHABLE)) {
      /* Document restrictions on when units can load/unload */
      bool has_restricted_load = FALSE, has_unrestricted_load = FALSE,
           has_restricted_unload = FALSE, has_unrestricted_unload = FALSE;
      unit_type_iterate(pcargo) {
        if (can_unit_type_transport(utype, utype_class(pcargo))) {
          if (utype_can_freely_load(pcargo, utype)) {
            has_unrestricted_load = TRUE;
          } else {
            has_restricted_load = TRUE;
          }
          if (utype_can_freely_unload(pcargo, utype)) {
            has_unrestricted_unload = TRUE;
          } else {
            has_restricted_unload = TRUE;
          }
        }
      } unit_type_iterate_end;
      if (has_restricted_load) {
        if (has_unrestricted_load) {
          /* At least one type of cargo can load onto us freely.
           * The specific exceptions will be documented in cargo help. */
          CATLSTR(buf, bufsz,
                  /* TRANS: indented; preserve leading spaces */
                  _("  %s Some cargo cannot be loaded except in a city or a "
                    "base native to this transport.\n"), BULLET);
        } else {
          /* No exceptions */
          CATLSTR(buf, bufsz,
                  /* TRANS: indented; preserve leading spaces */
                  _("  %s Cargo cannot be loaded except in a city or a "
                    "base native to this transport.\n"), BULLET);
        }
      } /* else, no restricted cargo exists; keep quiet */
      if (has_restricted_unload) {
        if (has_unrestricted_unload) {
          /* At least one type of cargo can unload from us freely. */
          CATLSTR(buf, bufsz,
                  /* TRANS: indented; preserve leading spaces */
                  _("  %s Some cargo cannot be unloaded except in a city or a "
                    "base native to this transport.\n"), BULLET);
        } else {
          /* No exceptions */
          CATLSTR(buf, bufsz,
                  /* TRANS: indented; preserve leading spaces */
                  _("  %s Cargo cannot be unloaded except in a city or a "
                    "base native to this transport.\n"), BULLET);
        }
      } /* else, no restricted cargo exists; keep quiet */
    }
  }
  if (utype_has_flag(utype, UTYF_COAST_STRICT)) {
    CATLSTR(buf, bufsz, _("%s Must stay next to safe coast.\n"), BULLET);
  }
  {
    /* Document exceptions to embark/disembark restrictions that we
     * have as cargo. */
    bv_unit_classes embarks, disembarks;
    BV_CLR_ALL(embarks);
    BV_CLR_ALL(disembarks);
    /* Determine which of our transport classes have restrictions in the first
     * place (that is, contain at least one transport which carries at least
     * one type of cargo which is restricted).
     * We'll suppress output for classes not in this set, since this cargo
     * type is not behaving exceptionally in such cases. */
    unit_type_iterate(utrans) {
      const Unit_Class_id trans_class = uclass_index(utype_class(utrans));
      /* Don't waste time repeating checks on classes we've already checked,
       * or weren't under consideration in the first place */
      if (!BV_ISSET(embarks, trans_class)
          && BV_ISSET(utype->embarks, trans_class)) {
        unit_type_iterate(other_cargo) {
          if (can_unit_type_transport(utrans, utype_class(other_cargo))
              && !utype_can_freely_load(other_cargo, utrans)) {
            /* At least one load restriction in transport class, which
             * we aren't subject to */
            BV_SET(embarks, trans_class);
          }
        } unit_type_iterate_end; /* cargo */
      }
      if (!BV_ISSET(disembarks, trans_class)
          && BV_ISSET(utype->disembarks, trans_class)) {
        unit_type_iterate(other_cargo) {
          if (can_unit_type_transport(utrans, utype_class(other_cargo))
              && !utype_can_freely_unload(other_cargo, utrans)) {
            /* At least one load restriction in transport class, which
             * we aren't subject to */
            BV_SET(disembarks, trans_class);
          }
        } unit_type_iterate_end; /* cargo */
      }
    } unit_class_iterate_end; /* transports */
 
    if (BV_ISSET_ANY(embarks)) {
      /* Build list of embark exceptions */
      const char *eclasses[uclass_count()];
      int i = 0;
      struct astring elist = ASTRING_INIT;
 
      unit_class_iterate(uclass) {
        if (BV_ISSET(embarks, uclass_index(uclass))) {
          eclasses[i++] = uclass_name_translation(uclass);
        }
      } unit_class_iterate_end;
      astr_build_or_list(&elist, eclasses, i);
      if (BV_ARE_EQUAL(embarks, disembarks)) {
        /* A common case: the list of disembark exceptions is identical */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit classes separated
                      * by "or". */
                     _("%s May load onto and unload from %s transports even "
                       "when underway.\n"),
                     BULLET, astr_str(&elist));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit classes separated
                      * by "or". */
                     _("%s May load onto %s transports even when underway.\n"),
                     BULLET, astr_str(&elist));
      }
      astr_free(&elist);
    }
    if (BV_ISSET_ANY(disembarks) && !BV_ARE_EQUAL(embarks, disembarks)) {
      /* Build list of disembark exceptions (if different from embarking) */
      const char *dclasses[uclass_count()];
      int i = 0;
      struct astring dlist = ASTRING_INIT;
 
      unit_class_iterate(uclass) {
        if (BV_ISSET(disembarks, uclass_index(uclass))) {
          dclasses[i++] = uclass_name_translation(uclass);
        }
      } unit_class_iterate_end;
      astr_build_or_list(&dlist, dclasses, i);
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a list of unit classes separated
                    * by "or". */
                   _("%s May unload from %s transports even when underway.\n"),
                   BULLET, astr_str(&dlist));
      astr_free(&dlist);
    }
  }
 
  if (utype_has_flag(utype, UTYF_SPY)) {
    CATLSTR(buf, bufsz, _("%s Strong in diplomatic battles.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_DIPLOMAT)
      || utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("%s Defends cities against diplomatic actions.\n"),
            BULLET);
  }
  if (utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("%s Will never lose a diplomat-versus-diplomat fight.\n"),
            BULLET);
  }
  if (utype_may_do_escape_action(utype)
      && utype_has_flag(utype, UTYF_SUPERSPY)) {
    CATLSTR(buf, bufsz, _("%s Will always survive a spy mission.\n"), BULLET);
  }
  if (utype->vlayer == V_INVIS) {
    CATLSTR(buf, bufsz,
            _("%s Is invisible except when next to an enemy unit or city.\n"),
            BULLET);
  }
  if (utype_has_flag(utype, UTYF_ONLY_NATIVE_ATTACK)) {
    CATLSTR(buf, bufsz,
            _("%s Can only attack units on native tiles.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_CITYBUSTER)) {
    CATLSTR(buf, bufsz,
            _("%s Gets double firepower when attacking cities.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_IGTER)) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: "MP" = movement points. %s may have a
                  * fractional part. */
                 _("%s Ignores terrain effects (moving costs at most %s MP "
                   "per tile).\n"), BULLET,
                 move_points_text(terrain_control.igter_cost, TRUE));
  }
  if (utype_has_flag(utype, UTYF_NOZOC)) {
    CATLSTR(buf, bufsz, _("%s Never imposes a zone of control.\n"), BULLET);
  } else {
    CATLSTR(buf, bufsz, _("%s May impose a zone of control on its adjacent "
                          "tiles.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_IGZOC)) {
    CATLSTR(buf, bufsz, _("%s Not subject to zones of control imposed "
                          "by other units.\n"), BULLET);
  }
  if (utype_has_flag(utype, UTYF_CIVILIAN)) {
    CATLSTR(buf, bufsz,
            _("%s A non-military unit:\n"), BULLET);
    CATLSTR(buf, bufsz,
            /* TRANS: indented; preserve leading spaces */
            _("  %s Cannot attack.\n"), BULLET);
    CATLSTR(buf, bufsz,
            /* TRANS: indented; preserve leading spaces */
            _("  %s Doesn't impose martial law.\n"), BULLET);
    CATLSTR(buf, bufsz,
            /* TRANS: indented; preserve leading spaces */
            _("  %s Can enter foreign territory regardless of peace treaty.\n"),
            BULLET);
    CATLSTR(buf, bufsz,
            /* TRANS: indented; preserve leading spaces */
            _("  %s Doesn't prevent enemy cities from working the tile it's on.\n"),
            BULLET);
  }
  if (utype_has_flag(utype, UTYF_FIELDUNIT)) {
    CATLSTR(buf, bufsz,
            _("%s A field unit: one unhappiness applies even when non-aggressive.\n"),
            BULLET);
  }
  if (utype_has_flag(utype, UTYF_PROVOKING)
      && server_setting_value_bool_get(
        server_setting_by_name("autoattack"))) {
    CATLSTR(buf, bufsz,
            _("%s An enemy unit considering to auto attack this unit will "
              "choose to do so even if it has better odds when defending "
              "against it than when attacking it.\n"), BULLET);
  }
 
  unit_class_iterate(target) {
    if (uclass_has_flag(target, UCF_UNREACHABLE)
        && BV_ISSET(utype->targets, uclass_index(target))) {
      cat_snprintf(buf, bufsz,
                   _("%s Can attack against %s units, which are usually not "
                     "reachable.\n"), BULLET,
                   uclass_name_translation(target));
    }
  } unit_class_iterate_end;
 
  fuel = utype_fuel(utype);
  if (fuel > 0) {
    const char *types[utype_count()];
    int i = 0;
 
    unit_type_iterate(transport) {
      if (can_unit_type_transport(transport, utype_class(utype))) {
        types[i++] = utype_name_translation(transport);
      }
    } unit_type_iterate_end;
 
    if (0 == i) {
      if (utype_has_flag(utype, UTYF_COAST)) {
        if (fuel == 1) {
          cat_snprintf(buf, bufsz,
                       _("%s Unit has to end each turn next to safe coast or"
                         " in a city or a base.\n"), BULLET);
        } else {
          cat_snprintf(buf, bufsz,
                       /* Pluralization for the benefit of languages with
                        * duals etc */
                       /* TRANS: Never called for 'turns = 1' case */
                       PL_("%s Unit has to be next to safe coast, in a city or a base"
                           " after %d turn.\n",
                           "%s Unit has to be next to safe coast, in a city or a base"
                           " after %d turns.\n",
                           fuel),
                       BULLET, fuel);
        }
      } else {
        cat_snprintf(buf, bufsz,
                     PL_("%s Unit has to be in a city or a base"
                         " after %d turn.\n",
                         "%s Unit has to be in a city or a base"
                         " after %d turns.\n",
                         fuel),
                     BULLET, fuel);
      }
    } else {
      struct astring list = ASTRING_INIT;
 
      if (utype_has_flag(utype, UTYF_COAST)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit types separated by "or" */
                     PL_("%s Unit has to be next to safe coast, in a city, a base, or on a %s"
                         " after %d turn.\n",
                         "%s Unit has to be next to safe coast, in a city, a base, or on a %s"
                         " after %d turns.\n",
                         fuel),
                     BULLET, astr_build_or_list(&list, types, i), fuel);
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of unit types separated by "or" */
                     PL_("%s Unit has to be in a city, a base, or on a %s"
                         " after %d turn.\n",
                         "%s Unit has to be in a city, a base, or on a %s"
                         " after %d turns.\n",
                         fuel),
                     BULLET, astr_build_or_list(&list, types, i), fuel);
      }
      astr_free(&list);
    }
  }
 
  /* Auto attack immunity. (auto_attack.if_attacker ruleset setting) */
  if (server_setting_value_bool_get(
        server_setting_by_name("autoattack"))) {
    bool not_an_auto_attacker = TRUE;
 
    action_auto_perf_iterate(auto_action) {
      if (auto_action->cause != AAPC_UNIT_MOVED_ADJ) {
        /* Not relevant for auto attack. */
        continue;
      }
 
      if (requirement_fulfilled_by_unit_type(utype, &auto_action->reqs)) {
        /* Can be forced to auto attack. */
        not_an_auto_attacker = FALSE;
        break;
      }
    } action_auto_perf_iterate_end;
 
    if (not_an_auto_attacker) {
      CATLSTR(buf, bufsz,
              _("%s Will never be forced (by the autoattack server setting)"
                " to attack units moving to an adjacent tile.\n"), BULLET);
    }
  }
 
  action_iterate(act) {
    struct action *paction = action_by_number(act);
 
    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }
 
    if (utype_can_do_action(utype, act)) {
      const char *target_adjective;
      char sub_target_text[100];
      const char *blockers[MAX_NUM_ACTIONS];
      int i = 0;
 
      /* Generic action information. */
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is the action's ruleset defined ui name */
                   _("%s Can do the action \'%s\'.\n"),
                   BULLET, action_id_name_translation(act));
 
      switch (action_id_get_target_kind(act)) {
      case ATK_SELF:
        /* No target. */
        break;
      default:
        if (!can_utype_do_act_if_tgt_diplrel(utype, act,
                                             DRO_FOREIGN, TRUE)) {
          /* TRANS: describes the target of an action. */
          target_adjective = _("domestic ");
        } else if (!can_utype_do_act_if_tgt_diplrel(utype, act,
                                                    DRO_FOREIGN, FALSE)) {
          /* TRANS: describes the target of an action. */
          target_adjective = _("foreign ");
        } else {
          /* Both foreign and domestic targets are acceptable. */
          target_adjective = "";
        }
 
        sub_target_text[0] = '\0';
        if (action_get_sub_target_kind(paction) != ASTK_NONE) {
          if (action_get_target_kind(paction) == ATK_EXTRAS
              && action_get_sub_target_kind(paction) == ASTK_EXTRA) {
            cat_snprintf(sub_target_text, sizeof(sub_target_text),
                         /* TRANS: action sub target extras with tile
                          * extras target. */
                         _("extras among "));
          } else {
            cat_snprintf(sub_target_text, sizeof(sub_target_text),
                         /* TRANS: action sub target kind. */
                         _("%s "),
                         _(action_sub_target_kind_name(
                             action_get_sub_target_kind(paction))));
          }
        }
 
        cat_snprintf(buf, bufsz,
                     /* TRANS: First %s in %s%s%s is the sub target kind.
                      * The next may be an adjective (that includes a space).
                      * The next is the name of the target kind.
                      * Example: "* is done to extras on foreign tiles." */
                     _("  %s is done to %s%s%s.\n"), BULLET,
                     sub_target_text,
                     target_adjective,
                     action_target_kind_help(action_id_get_target_kind(act)));
      }
 
      if (utype_is_consumed_by_action(paction, utype)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: said about an action. %s is a unit type
                      * name. */
                     _("  %s uses up the %s.\n"), BULLET,
                     utype_name_translation(utype));
      }
 
      if (actres_get_battle_kind(paction->result) != ABK_NONE) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: The %s is a kind of battle defined in
                      * actions.h. Example: "diplomatic battle". */
                     _("  %s can lead to a %s against a defender.\n"),
                     BULLET,
                     action_battle_kind_translated_name(
                       actres_get_battle_kind(paction->result)));
      }
 
      {
        struct universal req_pattern[] = {
          { .kind = VUT_ACTION, .value.action = paction },
          { .kind = VUT_UTYPE,  .value.utype = utype },
        };
        int odds = action_dice_roll_initial_odds(paction);
 
        if (odds != ACTION_ODDS_PCT_DICE_ROLL_NA
            && !effect_universals_value_never_below(EFT_ACTION_ODDS_PCT,
                                                    req_pattern,
                                                    ARRAY_SIZE(req_pattern),
                                                    ((100 - odds) * 100
                                                     / odds))) {
          cat_snprintf(buf, bufsz,
                       _("  %s may fail because of a dice throw.\n"),
                       BULLET);
        }
      }
 
      if (!utype_is_consumed_by_action(paction, utype)
          && paction->actor.is_unit.moves_actor == MAK_ESCAPE) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: said about an action. %s is a unit type
                      * name. */
                     _("  %s the %s may be captured while trying to"
                       " escape after completing the mission.\n"),
                     BULLET,
                     utype_name_translation(utype));
      }
 
      if (utype_is_consumed_by_action(paction, utype)) {
        /* The dead don't care about movement loss. */
      } else if (utype_action_takes_all_mp(utype, paction)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: Indented unit action property, preserve
                      * leading spaces. */
                     _("  %s ends this unit's turn.\n"),
                     BULLET);
      } else if (utype_action_takes_all_mp_if_ustate_is(utype, paction,
                                                        USP_NATIVE_TILE)) {
        /* Used in the implementation of slow_invasion in many of the
         * bundled rulesets and in rulesets upgraded with rscompat from 3.0
         * to 3.1. */
        cat_snprintf(buf, bufsz,
                     /* TRANS: Indented unit action property, preserve
                      * leading spaces. */
                     _("  %s ending up on a native tile"
                       " after this action has been performed"
                       " ends this unit's turn.\n"), BULLET);
      }
 
      if (action_id_get_target_kind(act) != ATK_SELF) {
        /* Distance to target is relevant. */
 
        /* FIXME: move paratroopers_range to the action and remove this
         * variable once actions are generalized. */
        int relative_max = (action_has_result(paction, ACTRES_PARADROP)
                            || action_has_result(paction,
                                                 ACTRES_PARADROP_CONQUER)) ?
              MIN(paction->max_distance, utype->paratroopers_range) :
              paction->max_distance;
 
        if (paction->min_distance == relative_max) {
          /* Only one distance to target is acceptable */
 
          if (paction->min_distance == 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: distance between an actor unit and its
                          * target when performing a specific action. */
                         _("  %s target must be at the same tile.\n"),
                         BULLET);
          } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  %s target must be exactly %d tile away.\n",
                           "  %s target must be exactly %d tiles away.\n",
                           paction->min_distance),
                       BULLET, paction->min_distance);
          }
        } else if (relative_max == ACTION_DISTANCE_UNLIMITED) {
          /* No max distance */
 
          if (paction->min_distance == 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: distance between an actor unit and its
                          * target when performing a specific action. */
                         _("  %s target can be anywhere.\n"), BULLET);
          } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  %s target must be at least %d tile away.\n",
                           "  %s target must be at least %d tiles away.\n",
                           paction->min_distance),
                       BULLET, paction->min_distance);
          }
        } else if (paction->min_distance == 0) {
          /* No min distance */
 
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  %s target can be max %d tile away.\n",
                           "  %s target can be max %d tiles away.\n",
                           relative_max),
                       BULLET, relative_max);
        } else {
          /* Full range. */
 
          cat_snprintf(buf, bufsz,
                       /* TRANS: distance between an actor unit and its
                        * target when performing a specific action. */
                       PL_("  %s target must be between %d and %d tile away.\n",
                           "  %s target must be between %d and %d tiles away.\n",
                           relative_max),
                       BULLET, paction->min_distance, relative_max);
        }
      }
 
      /* The action may be a Casus Belli. */
      {
        const struct {
          const enum effect_type eft;
          const char *hlp_text;
        } casus_belli[] = {
          /* TRANS: ...performing this action ... Casus Belli */
          { EFT_CASUS_BELLI_SUCCESS, N_("successfully") },
          /* TRANS: ...performing this action ... Casus Belli */
          { EFT_CASUS_BELLI_CAUGHT, N_("getting caught before") },
        };
 
        struct universal req_pattern[] = {
          { .kind = VUT_ACTION,  .value.action = paction },
          { .kind = VUT_DIPLREL, /* value filled in later */ },
        };
 
        /* First group by effect (currently getting caught and successfully
         * performing the action) */
        for (i = 0; i < ARRAY_SIZE(casus_belli); i++) {
          int diplrel;
 
          /* DiplRel list of each Casus Belli size. */
          const char *victim_diplrel_names[DRO_LAST];
          const char *outrage_diplrel_names[DRO_LAST];
          int victim_diplrel_count = 0;
          int outrage_diplrel_count = 0;
 
          /* Ignore Team and everything in diplrel_other. */
          for (diplrel = 0; diplrel < DS_NO_CONTACT; diplrel++) {
            int casus_belli_amount;
 
            if (!can_utype_do_act_if_tgt_diplrel(utype, act,
                                                 diplrel, TRUE)) {
              /* Can't do the action. Can't give Casus Belli. */
              continue;
            }
 
            req_pattern[1].value.diplrel = diplrel;
            casus_belli_amount = effect_value_from_universals(
                casus_belli[i].eft,
                req_pattern, ARRAY_SIZE(req_pattern));
 
            if (CASUS_BELLI_OUTRAGE <= casus_belli_amount) {
              outrage_diplrel_names[outrage_diplrel_count++] =
                  diplrel_name_translation(diplrel);
            } else if (CASUS_BELLI_VICTIM <= casus_belli_amount) {
              victim_diplrel_names[victim_diplrel_count++] =
                  diplrel_name_translation(diplrel);
            }
          }
 
          /* Then group by Casus Belli size (currently victim and
           * international outrage) */
          if (outrage_diplrel_count > 0) {
            struct astring list = ASTRING_INIT;
            cat_snprintf(buf, bufsz,
                         /* TRANS: successfully ... Peace, or Alliance  */
                         _("  %s %s performing this action during %s causes"
                           " international outrage: the whole world gets "
                           "Casus Belli against you.\n"), BULLET,
                         _(casus_belli[i].hlp_text),
                         astr_build_or_list(&list, outrage_diplrel_names,
                                            outrage_diplrel_count));
            astr_free(&list);
          }
          if (victim_diplrel_count > 0) {
            struct astring list = ASTRING_INIT;
            cat_snprintf(buf, bufsz,
                         /* TRANS: successfully ... Peace, or Alliance  */
                         _("  %s %s performing this action during %s gives"
                           " the victim Casus Belli against you.\n"),
                         BULLET,
                         _(casus_belli[i].hlp_text),
                         astr_build_or_list(&list, victim_diplrel_names,
                                            victim_diplrel_count));
            astr_free(&list);
          }
        }
      }
 
      /* Custom action result specific information. */
      switch (paction->result) {
      case ACTRES_HELP_WONDER:
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is the number of shields the unit can
                      * contribute. */
                     _("  %s adds %d production.\n"), BULLET,
                     utype_build_shield_cost_base(utype));
        break;
      case ACTRES_HEAL_UNIT:
        {
          struct universal req_pattern[] = {
            { .kind = VUT_ACTION, .value.action = paction },
            { .kind = VUT_UTYPE,  .value.utype = utype },
          };
 
          cat_snprintf(buf, bufsz,
                       _("  %s restores up to %d%% of the target unit's"
                         " hit points.\n"), BULLET,
                       effect_value_from_universals(
                         EFT_HEAL_UNIT_PCT,
                         req_pattern, ARRAY_SIZE(req_pattern))
                       + 100);
        }
        break;
      case ACTRES_FOUND_CITY:
        if (game.scenario.prevent_new_cities) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: is talking about an action. */
                       _("  %s is disabled in the current game.\n"),
                       BULLET);
        }
        cat_snprintf(buf, bufsz,
                     /* TRANS: the %d is initial population. */
                     PL_("  %s initial population: %d.\n",
                         "  %s initial population: %d.\n",
                         utype->city_size),
                     BULLET, utype->city_size);
        if (is_super_specialist(utype->spec_type)) {
          cat_snprintf(buf, bufsz,
                       /* FIXME: Here we'd better have a singular specialist
                        * but the translated name is plural by definition. */
                       /* TRANS: * ... Great Artist(s) ... */
                       _("  %s the city starts with a %s superspecialist.\n"),
                       BULLET, specialist_plural_translation(utype->spec_type));
        }
        break;
      case ACTRES_JOIN_CITY:
        if (utype->pop_cost > 0 ){
          cat_snprintf(buf, bufsz,
                       /* TRANS: the %d is population. */
                       PL_("  %s max target size: %d.\n",
                           "  %s max target size: %d.\n",
                           game.info.add_to_size_limit - utype->pop_cost),
                       BULLET, game.info.add_to_size_limit - utype->pop_cost);
          cat_snprintf(buf, bufsz,
                       /* TRANS: the %d is the population added. */
                       PL_("  %s adds %d population.\n",
                           "  %s adds %d population.\n",
                           utype->pop_cost),
                       BULLET, utype->pop_cost);
        }
        if (is_super_specialist(utype->spec_type)) {
          cat_snprintf(buf, bufsz,
                       /* FIXME: Here we'd better have a singular specialist
                        * but the translated name is plural by definition. */
                       /* TRANS: * ... Great Artist(s) ... */
                       _("  %s adds a %s superspecialist to the city.\n"),
                       BULLET, specialist_plural_translation(utype->spec_type));
        } else if (DEFAULT_SPECIALIST != specialist_index(utype->spec_type)) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: * ... Scientists */
                       _("  %s adds to cities as %s.\n"),
                       BULLET, specialist_plural_translation(utype->spec_type));
        }
        break;
      case ACTRES_BOMBARD:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %d is bombard rate. */
                     _("  %s %d per turn.\n"), BULLET,
                     utype->bombard_rate);
        cat_snprintf(buf, bufsz,
                     /* TRANS: talking about bombard */
                     _("  %s Will damage all"
                       " defenders on a tile, and have no risk for the"
                       " attacker.\n"), BULLET);
        break;
      case ACTRES_UPGRADE_UNIT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a unit type. */
                     _("  %s upgraded to %s or, when possible, to the unit "
                       "type it upgrades to.\n"), BULLET,
                     utype_name_translation(utype->obsoleted_by));
        break;
      case ACTRES_ATTACK:
        if (game.info.tired_attack) {
          cat_snprintf(buf, bufsz,
                       _("  %s weaker when tired. If performed with less "
                         "than a single move point left the attack power "
                         "is reduced accordingly.\n"), BULLET);
        }
        break;
      case ACTRES_WIPE_UNITS:
        cat_snprintf(buf, bufsz,
                     _("  %s can wipe stack of units with zero defense.\n"),
                     BULLET);
        break;
      case ACTRES_CONVERT:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a unit type. "MP" = movement points. */
                     PL_("  %s is converted into %s (takes %d MP).\n",
                         "  %s is converted into %s (takes %d MP).\n",
                         utype->convert_time),
                     BULLET,
                     utype_name_translation(utype->converted_to),
                     utype->convert_time);
        break;
      case ACTRES_SPY_NUKE:
      case ACTRES_NUKE:
      case ACTRES_NUKE_UNITS:
        if (game.info.nuke_pop_loss_pct > 0) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: percentage */
                       _("  %s %d%% of the population of each city inside"
                         " the nuclear blast dies.\n"), BULLET,
                         game.info.nuke_pop_loss_pct);
          if (game.info.nuke_pop_loss_pct < 50) {
            cat_snprintf(buf, bufsz,
                         _("  %s can never destroy city completely "
                           "(%d%% of size 1 rounds down to 0).\n"), BULLET,
                         game.info.nuke_pop_loss_pct);
          } else {
            cat_snprintf(buf, bufsz,
                         _("  %s can even destroy city completely "
                           "(%d%% of size 1 rounds up to 1).\n"), BULLET,
                         game.info.nuke_pop_loss_pct);
          }
        }
        if (game.info.nuke_defender_survival_chance_pct > 0) {
          cat_snprintf(buf, bufsz,
                       _("  %s all units caught in the open by the nuclear"
                         " blast die.\n"), BULLET);
          cat_snprintf(buf, bufsz,
                       /* TRANS: percentage */
                       _("  %s a unit caught in the nuclear blast while"
                         " inside a city has a %d%% chance of survival.\n"),
                       BULLET,
                       game.info.nuke_defender_survival_chance_pct);
        } else {
          cat_snprintf(buf, bufsz,
                       _("  %s all units caught in the nuclear blast"
                         " die.\n"), BULLET);
        }
        {
          struct universal req_pattern[] = {
            { .kind = VUT_ACTION, .value.action = paction },
            { .kind = VUT_UTYPE,  .value.utype = utype },
          };
 
          int blast_radius_1 =
              effect_value_from_universals(EFT_NUKE_BLAST_RADIUS_1_SQ,
                                           req_pattern,
                                           ARRAY_SIZE(req_pattern));
 
          cat_snprintf(buf, bufsz,
                       _("  %s has a squared blast radius of %d.\n"),
                       BULLET, blast_radius_1);
        }
 
        break;
      case ACTRES_PLANT:
      case ACTRES_CULTIVATE:
      case ACTRES_TRANSFORM_TERRAIN:
        cat_snprintf(buf, bufsz,
                     _("  %s converts target tile terrain to another"
                       " type.\n"), BULLET);
        break;
      case ACTRES_ROAD:
      case ACTRES_MINE:
      case ACTRES_IRRIGATE:
      case ACTRES_BASE:
        {
          struct astring extras_and = ASTRING_INIT;
          struct strvec *extras_vec = strvec_new();
 
          extra_type_iterate(pextra) {
            if (actres_creates_extra(paction->result, pextra)) {
              strvec_append(extras_vec, extra_name_translation(pextra));
            }
          } extra_type_iterate_end;
 
          if (strvec_size(extras_vec) > 0) {
            strvec_to_and_list(extras_vec, &extras_and);
            /* TRANS: %s is list of extra types separated by ',' and 'and' */
            cat_snprintf(buf, bufsz, _("  %s builds %s on tiles.\n"),
                         BULLET, astr_str(&extras_and));
            strvec_clear(extras_vec);
          }
 
          strvec_destroy(extras_vec);
        }
        break;
      case ACTRES_CLEAN:
        {
          struct astring extras_and = ASTRING_INIT;
          struct strvec *extras_vec = strvec_new();
 
          extra_type_iterate(pextra) {
            if (actres_removes_extra(paction->result, pextra)) {
              strvec_append(extras_vec, extra_name_translation(pextra));
            }
          } extra_type_iterate_end;
 
          if (strvec_size(extras_vec) > 0) {
            strvec_to_and_list(extras_vec, &extras_and);
            /* TRANS: list of extras separated by "and" */
            cat_snprintf(buf, bufsz, _("  %s cleans %s from tiles.\n"),
                         BULLET, astr_str(&extras_and));
            strvec_clear(extras_vec);
          }
 
          strvec_destroy(extras_vec);
        }
        break;
      case ACTRES_PILLAGE:
        {
          struct astring extras_and = ASTRING_INIT;
          struct strvec *extras_vec = strvec_new();
 
          extra_type_iterate(pextra) {
            if (actres_removes_extra(paction->result, pextra)) {
              strvec_append(extras_vec, extra_name_translation(pextra));
            }
          } extra_type_iterate_end;
 
          if (strvec_size(extras_vec) > 0) {
            strvec_to_and_list(extras_vec, &extras_and);
            /* TRANS: list of extras separated by "and" */
            cat_snprintf(buf, bufsz, _("  %s pillages %s from tiles.\n"),
                         BULLET, astr_str(&extras_and));
            strvec_clear(extras_vec);
          }
 
          strvec_destroy(extras_vec);
        }
        break;
      case ACTRES_FORTIFY:
        {
          struct universal unit_is_fortified[] = {
            { .kind = VUT_ACTIVITY,
              .value = { .activity = ACTIVITY_FORTIFIED }},
            { .kind = VUT_UTYPE, .value = { .utype = utype }},
          };
          int bonus = effect_value_from_universals(
                EFT_FORTIFY_DEFENSE_BONUS,
                unit_is_fortified, ARRAY_SIZE(unit_is_fortified));
 
          if (utype->defense_strength <= 0
              || (effect_cumulative_max(EFT_FORTIFY_DEFENSE_BONUS,
                                        &(struct universal){
                                          .kind = VUT_UTYPE,
                                          .value = { .utype = utype }},
                                        1)
                  <= 0)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: indented unit action property, preserve
                          * leading spaces */
                         _("  %s to stay put. No defensive bonus.\n"),
                         BULLET);
          } else if (bonus > 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: indented unit action property, preserve
                          * leading spaces */
                         _("  %s granting a %d%% defensive bonus.\n"),
                         BULLET, bonus);
          }
        }
        break;
      case ACTRES_CONQUER_EXTRAS:
        {
          const char *targets[extra_count()];
          int j = 0;
 
          /* Extra being native one is a hard requirement
           * Not using unit class native_bases cache here.
           * Sometimes it's not initialized when we run this,
           * and as this is not performance critical, no point
           * in using it conditionally and having this only as
           * fallback implementation. */
          extra_type_by_cause_iterate(EC_BASE, pextra) {
            if (!is_native_extra_to_uclass(pextra, pclass)) {
              continue;
            }
 
            if (!territory_claiming_base(pextra->data.base)) {
              continue;
            }
 
            targets[j++] = extra_name_translation(pextra);
          } extra_type_by_cause_iterate_end;
 
          if (j > 0) {
            struct astring list = ASTRING_INIT;
            /* TRANS: indented unit action property, preserve
             * leading spaces.
             * %s is a list of extra types separated by "and". */
            cat_snprintf(buf, bufsz, _("  %s done to %s.\n"),
                         BULLET,
                         astr_build_and_list(&list, targets, j));
            astr_free(&list);
          }
        }
        break;
      default:
        /* No action specific details. */
        break;
      }
 
      /* Custom action sub result specific information. */
      if (BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_ENTER)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: indented unit action property, preserve
                      * leading spaces. */
                     _("  %s if a suitable hut is at the targetet tile it"
                       " will be entered.\n"), BULLET);
      }
      if (BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_FRIGHTEN)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: indented unit action property, preserve
                      * leading spaces. */
                     _("  %s if a suitable hut is at the targetet tile it"
                       " will be frightened.\n"), BULLET);
      }
      if (BV_ISSET(paction->sub_results, ACT_SUB_RES_MAY_EMBARK)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: indented unit action property, preserve
                      * leading spaces.
                      * The %s is the unit type name */
                     _("  %s the %s may end up loaded into a transport if it"
                       " can't survive on its own at the target tile.\n"),
                     BULLET, utype_name_translation(utype));
      }
      if (BV_ISSET(paction->sub_results, ACT_SUB_RES_NON_LETHAL)) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: talking about non lethal attacks */
                     _("  %s These attacks will only damage (never kill)"
                       " defenders.\n"), BULLET);
      }
 
      i = 0;
      action_iterate(blocker_id) {
        const struct action *blocker = action_by_number(blocker_id);
 
        if (!utype_can_do_action(utype, blocker->id)) {
          /* Can't block since never legal. */
          continue;
        }
 
        if (action_would_be_blocked_by(paction, blocker)) {
          /* action name alone can be MAX_LEN_NAME, leave space for extra
           * characters */
          int maxlen = MAX_LEN_NAME + 16;
          char *quoted = fc_malloc(maxlen);
 
          fc_snprintf(quoted, maxlen,
                      /* TRANS: %s is an action that can block another. */
                      _("\'%s\'"), action_name_translation(blocker));
          blockers[i] = quoted;
 
          i++;
        }
      } action_iterate_end;
 
      if (i > 0) {
        struct astring blist = ASTRING_INIT;
 
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a list of actions separated by "or". */
                     _("  %s can't be done if %s is legal.\n"), BULLET,
                     astr_build_or_list(&blist, blockers, i));
 
        astr_free(&blist);
 
        for (; i > 0; i--) {
          /* The text was copied above. */
          free((char *)(blockers[i - 1]));
        }
      }
    }
  } action_iterate_end;
  action_iterate(act) {
    struct action *paction = action_by_number(act);
    bool vulnerable;
 
    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }
 
    /* Not relevant */
    if (action_id_get_target_kind(act) != ATK_UNIT
        && action_id_get_target_kind(act) != ATK_STACK
        && action_id_get_target_kind(act) != ATK_SELF) {
      continue;
    }
 
    /* All units are immune to this since its not enabled */
    if (!action_is_in_use(paction)) {
      continue;
    }
 
    /* Must be immune in all cases */
    vulnerable = FALSE;
    action_enabler_list_iterate(action_enablers_for_action(act), enabler) {
      if (requirement_fulfilled_by_unit_type(utype,
                                             &(enabler->target_reqs))) {
        vulnerable = TRUE;
        break;
      }
    } action_enabler_list_iterate_end;
 
    if (!vulnerable) {
      cat_snprintf(buf, bufsz,
                   _("%s Doing the action \'%s\' to this unit"
                     " is impossible.\n"), BULLET,
                   action_id_name_translation(act));
    }
  } action_iterate_end;
  if (!has_vet_levels) {
    /* Only mention this if the game generally does have veteran levels. */
    if (game.veteran->levels > 1) {
      CATLSTR(buf, bufsz, _("%s Will never achieve veteran status.\n"), BULLET);
    }
  } else {
    /* Not useful currently: */
#if 0
    /* Some units can never become veteran through combat in practice. */
    bool veteran_through_combat =
      !(!utype_can_do_action(utype, ACTION_ATTACK)
        && utype->defense_strength == 0);
#endif
    /* FIXME: if we knew the raise chances on the client, we could be
     * more specific here about whether veteran status can be acquired
     * through combat/missions/work. */
    CATLSTR(buf, bufsz, _("%s May acquire veteran status.\n"), BULLET);
    if (utype_veteran_has_power_bonus(utype)) {
      if (utype_can_do_action(utype, ACTION_ATTACK)
          || utype->defense_strength > 0) {
        CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                _("  %s Veterans have increased strength in combat.\n"),
                BULLET);
      }
      /* SUPERSPY always wins/escapes */
      if (utype_has_flag(utype, UTYF_DIPLOMAT)
          && !utype_has_flag(utype, UTYF_SUPERSPY)) {
        CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                _("  %s Veterans have improved chances in diplomatic "
                  "contests.\n"), BULLET);
        if (utype_may_do_escape_action(utype)) {
          CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                  _("  %s Veterans are more likely to survive missions.\n"),
                  BULLET);
        }
      }
      if (utype_has_flag(utype, UTYF_WORKERS)) {
        CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                _("  %s Veterans work faster.\n"), BULLET);
      }
    }
  }
  if (strlen(buf) > 0) {
    CATLSTR(buf, bufsz, "\n");
  }
  if (has_vet_levels && utype->veteran) {
    /* The case where the unit has only a single veteran level has already
     * been handled above, so keep quiet here if that happens */
    if (insert_veteran_help(buf, bufsz, utype->veteran,
            _("This type of unit has its own veteran levels:"), NULL)) {
      CATLSTR(buf, bufsz, "\n\n");
    }
  }
  if (NULL != utype->helptext) {
    strvec_iterate(utype->helptext, text) {
      CATLSTR(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
  CATLSTR(buf, bufsz, "%s", user_text);
 
  return buf;
}
 
/************************************************************************/
void helptext_advance(char *buf, size_t bufsz, struct player *pplayer,
                      const char *user_text, int i)
{
  struct astring astr = ASTRING_INIT;
  struct advance *vap = valid_advance_by_number(i);
  struct universal source = {
    .kind = VUT_ADVANCE,
    .value = {.advance = vap}
  };
  int flagid;
 
  fc_assert_ret(NULL != buf && 0 < bufsz && NULL != user_text);
  fc_strlcpy(buf, user_text, bufsz);
 
  if (NULL == vap) {
    log_error("Unknown tech %d.", i);
    return;
  }
 
  if (game.control.num_tech_classes > 0) {
    if (vap->tclass == NULL) {
      cat_snprintf(buf, bufsz, _("Belongs to the default tech class.\n\n"));
    } else {
      cat_snprintf(buf, bufsz, _("Belongs to tech class %s.\n\n"),
                   tech_class_name_translation(vap->tclass));
    }
  }
 
  if (NULL != pplayer) {
    const struct research *presearch = research_get(pplayer);
 
    if (research_invention_state(presearch, i) != TECH_KNOWN) {
      if (research_invention_state(presearch, i) == TECH_PREREQS_KNOWN) {
        int bulbs = research_total_bulbs_required(presearch, i, FALSE);
 
        cat_snprintf(buf, bufsz,
                     PL_("Starting now, researching %s would need %d bulb.",
                         "Starting now, researching %s would need %d bulbs.",
                         bulbs),
                     advance_name_translation(vap), bulbs);
      } else if (research_invention_reachable(presearch, i)) {
        /* Split string into two to allow localization of two pluralizations. */
        char buf2[MAX_LEN_MSG];
        int bulbs = research_goal_bulbs_required(presearch, i);
 
        fc_snprintf(buf2, ARRAY_SIZE(buf2),
                    /* TRANS: appended to another sentence. Preserve the
                     * leading space. */
                    PL_(" The whole project will require %d bulb to complete.",
                        " The whole project will require %d bulbs to complete.",
                        bulbs),
                    bulbs);
        cat_snprintf(buf, bufsz,
                     /* TRANS: last %s is a sentence pluralized separately. */
                     PL_("To research %s you need to research %d other"
                         " technology first.%s",
                         "To research %s you need to research %d other"
                         " technologies first.%s",
                         research_goal_unknown_techs(presearch, i) - 1),
                     advance_name_translation(vap),
                     research_goal_unknown_techs(presearch, i) - 1, buf2);
      } else {
        CATLSTR(buf, bufsz,
                _("You cannot research this technology."));
      }
      if (!techs_have_fixed_costs()
          && research_invention_reachable(presearch, i)) {
        CATLSTR(buf, bufsz,
                /* TRANS: preserve leading space */
                _(" This number may vary depending on what "
                  "other players research.\n"));
      } else {
        CATLSTR(buf, bufsz, "\n");
      }
    }
 
    CATLSTR(buf, bufsz, "\n");
  }
 
  if (requirement_vector_size(&vap->research_reqs) > 0) {
    CATLSTR(buf, bufsz, _("Requirements to research:\n"));
    requirement_vector_iterate(&vap->research_reqs, preq) {
      (void) req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT, "");
    } requirement_vector_iterate_end;
    CATLSTR(buf, bufsz, "\n");
  }
 
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf),
                BULLET_SPACE);
 
  {
    int j;
 
    for (j = 0; j < MAX_NUM_TECH_LIST; j++) {
      if (game.rgame.global_init_techs[j] == A_LAST) {
        break;
      } else if (game.rgame.global_init_techs[j] == i) {
        CATLSTR(buf, bufsz,
                _("%s All players start the game with knowledge of this "
                  "technology.\n"), BULLET);
        break;
      }
    }
  }
 
  /* Assume no-one will set the same tech in both global and nation
   * init_tech... */
  nations_iterate(pnation) {
    int j;
 
    /* Avoid mentioning nations not in current set. */
    if (!show_help_for_nation(pnation)) {
      continue;
    }
    for (j = 0; j < MAX_NUM_TECH_LIST; j++) {
      if (pnation->init_techs[j] == A_LAST) {
        break;
      } else if (pnation->init_techs[j] == i) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a nation plural */
                     _("%s The %s start the game with knowledge of this "
                       "technology.\n"), BULLET,
                     nation_plural_translation(pnation));
        break;
      }
    }
  } nations_iterate_end;
 
  /* Explain the effects of root_reqs. */
  {
    bv_techs roots, rootsofroots;
 
    BV_CLR_ALL(roots);
    BV_CLR_ALL(rootsofroots);
    advance_root_req_iterate(vap, proot) {
      if (proot == vap) {
        /* Don't say anything at all if this tech is a self-root-req one;
         * assume that the ruleset help will explain how to get it. */
        BV_CLR_ALL(roots);
        break;
      }
      BV_SET(roots, advance_number(proot));
      if (advance_requires(proot, AR_ROOT) != proot) {
        /* Now find out what roots each of this tech's root_req has, so that
         * we can suppress them. If tech A has roots B/C, and B has root C,
         * it's not worth saying that A needs C, and can lead to overwhelming
         * lists. */
        /* (Special case: don't do this if the root is a self-root-req tech,
         * since it would appear in its own root iteration; in the scenario
         * where S is a self-root tech that is root for T, this would prevent
         * S appearing in T's help.) */
        /* FIXME this is quite inefficient */
        advance_root_req_iterate(proot, prootroot) {
          BV_SET(rootsofroots, advance_number(prootroot));
        } advance_root_req_iterate_end;
      }
    } advance_root_req_iterate_end;
 
    /* Filter out all but the direct root reqs. */
    BV_CLR_ALL_FROM(roots, rootsofroots);
 
    if (BV_ISSET_ANY(roots)) {
      const char *root_techs[A_LAST];
      size_t n_roots = 0;
      struct astring root_list = ASTRING_INIT;
 
      advance_index_iterate(A_FIRST, root) {
        if (BV_ISSET(roots, root)) {
          root_techs[n_roots++]
            = advance_name_translation(advance_by_number(root));
        }
      } advance_index_iterate_end;
      fc_assert(n_roots > 0);
      cat_snprintf(buf, bufsz,
                   /* TRANS: 'and'-separated list of techs */
                   _("%s Only those who know %s can acquire this "
                     "technology (by any means).\n"),
                   BULLET,
                   astr_build_and_list(&root_list, root_techs, n_roots));
      astr_free(&root_list);
    }
  }
 
  if (advance_has_flag(i, TF_BONUS_TECH)) {
    cat_snprintf(buf, bufsz,
                 _("%s The first player to learn %s gets"
                   " an immediate advance.\n"), BULLET,
                 advance_name_translation(vap));
  }
 
  for (flagid = TECH_USER_1 ; flagid <= TECH_USER_LAST; flagid++) {
    if (advance_has_flag(i, flagid)) {
      const char *helptxt = tech_flag_helptxt(flagid);
 
      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, "%s %s\n", BULLET, _(helptxt));
      }
    }
  }
 
  if (game.info.tech_upkeep_style != TECH_UPKEEP_NONE) {
    CATLSTR(buf, bufsz,
            _("%s To preserve this technology for our nation some bulbs "
              "are needed each turn.\n"), BULLET);
  }
 
  if (NULL != vap->helptext) {
    if (strlen(buf) > 0) {
      CATLSTR(buf, bufsz, "\n");
    }
    strvec_iterate(vap->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
 
  astr_free(&astr);
}
 
/************************************************************************/
void helptext_terrain(char *buf, size_t bufsz, struct player *pplayer,
                      const char *user_text, struct terrain *pterrain)
{
  struct universal source = {
    .kind = VUT_TERRAIN,
    .value = {.terrain = pterrain}
  };
  int flagid;
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (!pterrain) {
    log_error("Unknown terrain!");
    return;
  }
 
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf),
                BULLET_SPACE);
  if (terrain_has_flag(pterrain, TER_NO_CITIES)) {
    CATLSTR(buf, bufsz,
            _("%s You cannot build cities on this terrain.\n"),
            BULLET);
  }
  if (!action_id_univs_not_blocking(ACTION_ROAD, NULL, &source)) {
    /* Can't build roads; only mention if ruleset has buildable roads */
    extra_type_by_cause_iterate(EC_ROAD, pextra) {
      if (pextra->buildable) {
        CATLSTR(buf, bufsz,
                _("%s Paths cannot be built on this terrain.\n"),
                BULLET);
        break;
      }
    } extra_type_by_cause_iterate_end;
  }
  if (!action_id_univs_not_blocking(ACTION_BASE, NULL, &source)) {
    /* Can't build bases; only mention if ruleset has buildable bases */
    extra_type_by_cause_iterate(EC_BASE, pextra) {
      if (pextra->buildable) {
        CATLSTR(buf, bufsz,
                _("%s Bases cannot be built on this terrain.\n"),
                BULLET);
        break;
      }
    } extra_type_by_cause_iterate_end;
  }
  if (terrain_has_flag(pterrain, TER_UNSAFE_COAST)
      && terrain_type_terrain_class(pterrain) != TC_OCEAN) {
    CATLSTR(buf, bufsz,
            _("%s The coastline of this terrain is unsafe.\n"),
            BULLET);
  }
  {
    const char *classes[uclass_count()];
    int i = 0;
 
    unit_class_iterate(uclass) {
      if (is_native_to_class(uclass, pterrain, NULL)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;
 
    if (0 < i) {
      struct astring list = ASTRING_INIT;
 
      /* TRANS: %s is a list of unit classes separated by "and". */
      cat_snprintf(buf, bufsz, _("%s Can be traveled by %s units.\n"),
                   BULLET, astr_build_and_list(&list, classes, i));
      astr_free(&list);
    }
  }
  if (terrain_has_flag(pterrain, TER_NO_ZOC)) {
    CATLSTR(buf, bufsz,
            _("%s Units on this terrain neither impose zones of control "
              "nor are restricted by them.\n"), BULLET);
  } else {
    CATLSTR(buf, bufsz,
            _("%s Units on this terrain may impose a zone of control, or "
              "be restricted by one.\n"), BULLET);
  }
  for (flagid = TER_USER_1 ; flagid <= TER_USER_LAST; flagid++) {
    if (terrain_has_flag(pterrain, flagid)) {
      const char *helptxt = terrain_flag_helptxt(flagid);
 
      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, "%s %s\n", BULLET, _(helptxt));
      }
    }
  }
 
  if (NULL != pterrain->helptext) {
    if (buf[0] != '\0') {
      CATLSTR(buf, bufsz, "\n");
    }
    strvec_iterate(pterrain->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
  if (user_text && user_text[0] != '\0') {
    CATLSTR(buf, bufsz, "\n\n%s", user_text);
  }
}
 
/************************************************************************/
const char *helptext_road_bonus_str(const struct terrain *pterrain,
                                    const struct road_type *proad)
{
  static char str[64];
  bool has_effect = FALSE;
 
  str[0] = '\0';
  output_type_iterate(o) {
    switch (o) {
    case O_FOOD:
    case O_SHIELD:
    case O_TRADE:
      {
        int bonus = proad->tile_bonus[o];
        int incr = proad->tile_incr_const[o];
 
        if (pterrain) {
          incr +=
            proad->tile_incr[o] * pterrain->road_output_incr_pct[o] / 100;
        }
        if (str[0] != '\0') {
          CATLSTR(str, sizeof(str), "/");
        }
        if (incr == 0 && bonus == 0) {
          cat_snprintf(str, sizeof(str), "%d", incr);
        } else {
          has_effect = TRUE;
          if (incr != 0) {
            cat_snprintf(str, sizeof(str), "%+d", incr);
          }
          if (bonus != 0) {
            cat_snprintf(str, sizeof(str), "%+d%%", bonus);
          }
        }
      }
      break;
    default:
      /* FIXME: there's nothing actually stopping roads having gold, etc
       * bonuses */
      fc_assert(proad->tile_incr_const[o] == 0
                && proad->tile_incr[o] == 0
                && proad->tile_bonus[o] == 0);
      break;
    }
  } output_type_iterate_end;
 
  return has_effect ? str : NULL;
}
 
/**********************************************************************/
static void extra_bonus_for_terrain(struct extra_type *pextra,
                                    struct terrain *pterrain,
                                    int *bonus)
{
  struct universal req_pattern[] = {
    { .kind = VUT_EXTRA,   .value.extra = pextra },
    { .kind = VUT_TERRAIN, .value.terrain = pterrain },
    { .kind = VUT_OTYPE    /* value filled in later */ }
  };
 
  fc_assert_ret(bonus != NULL);
 
  /* Irrigation-like food bonuses */
  bonus[0] = (pterrain->irrigation_food_incr
              * effect_value_from_universals(EFT_IRRIGATION_PCT, req_pattern,
                                             2 /* just extra+terrain */)) / 100;
 
  /* Mining-like shield bonuses */
  bonus[1] = (pterrain->mining_shield_incr
              * effect_value_from_universals(EFT_MINING_PCT, req_pattern,
                                             2 /* just extra+terrain */)) / 100;
 
  bonus[2] = 0; /* no trade bonuses so far */
 
  /* Now add fixed bonuses from roads (but not percentage bonus) */
  if (extra_road_get(pextra)) {
    const struct road_type *proad = extra_road_get(pextra);
 
    output_type_iterate(o) {
      switch (o) {
      case O_FOOD:
      case O_SHIELD:
      case O_TRADE:
        bonus[o] += proad->tile_incr_const[o]
          + proad->tile_incr[o] * pterrain->road_output_incr_pct[o] / 100;
        break;
      default:
        /* not dealing with other output types here */
        break;
      }
    } output_type_iterate_end;
  }
 
  /* Fixed bonuses for extra, possibly unrelated to terrain type */
 
  output_type_iterate(o) {
    /* Fill in rest of requirement template */
    req_pattern[2].value.outputtype = o;
    switch (o) {
    case O_FOOD:
    case O_SHIELD:
    case O_TRADE:
      bonus[o] += effect_value_from_universals(EFT_OUTPUT_ADD_TILE,
                                               req_pattern,
                                               ARRAY_SIZE(req_pattern));
      /* Any of the above bonuses is sufficient to trigger
       * Output_Inc_Tile, if underlying terrain does not */
      if (bonus[o] > 0 || pterrain->output[o] > 0) {
        bonus[o] += effect_value_from_universals(EFT_OUTPUT_INC_TILE,
                                                 req_pattern,
                                                 ARRAY_SIZE(req_pattern));
      }
      break;
    default:
      break;
    }
  } output_type_iterate_end;
}
 
/**********************************************************************/
const char *helptext_extra_for_terrain_str(struct extra_type *pextra,
                                           struct terrain *pterrain,
                                           enum unit_activity act)
{
  static char buffer[256];
  int btime;
  int bonus[3];
 
  btime = terrain_extra_build_time(pterrain, act, pextra);
  fc_snprintf(buffer, sizeof(buffer), PL_("%d turn", "%d turns", btime),
              btime);
  extra_bonus_for_terrain(pextra, pterrain, bonus);
  if (bonus[0] > 0) {
    cat_snprintf(buffer, sizeof(buffer),
                 PL_(", +%d food", ", +%d food", bonus[0]), bonus[0]);
  }
  if (bonus[1] > 0) {
    cat_snprintf(buffer, sizeof(buffer),
                 PL_(", +%d shield", ", +%d shields", bonus[1]), bonus[1]);
  }
  if (bonus[2] > 0) {
    cat_snprintf(buffer, sizeof(buffer),
                 PL_(", +%d trade", ", +%d trade", bonus[2]), bonus[2]);
  }
 
  return buffer;
}
 
/************************************************************************/
void helptext_extra(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, struct extra_type *pextra)
{
  size_t group_start;
  struct base_type *pbase;
  struct road_type *proad;
  struct universal source = {
    .kind = VUT_EXTRA,
    .value = {.extra = pextra}
  };
 
  int flagid;
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (!pextra) {
    log_error("Unknown extra!");
    return;
  }
 
  if (is_extra_caused_by(pextra, EC_BASE)) {
    pbase = pextra->data.base;
  } else {
    pbase = NULL;
  }
 
  if (is_extra_caused_by(pextra, EC_ROAD)) {
    proad = pextra->data.road;
  } else {
    proad = NULL;
  }
 
  if (pextra->helptext != NULL) {
    strvec_iterate(pextra->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
 
  /* Describe how extra is created and destroyed */
 
  group_start = strlen(buf);
 
  if (pextra->buildable) {
    if (is_extra_caused_by(pextra, EC_IRRIGATION)) {
      CATLSTR(buf, bufsz,
              _("Build by issuing an \"irrigate\" order.\n"));
    }
    if (is_extra_caused_by(pextra, EC_MINE)) {
      CATLSTR(buf, bufsz,
              _("Build by issuing a \"mine\" order.\n"));
    }
    if (is_extra_caused_by(pextra, EC_ROAD)) {
      CATLSTR(buf, bufsz,
              _("Build by issuing a \"road\" order.\n"));
    }
    if (is_extra_caused_by(pextra, EC_BASE)) {
      fc_assert(pbase != NULL);
 
      if (pbase->gui_type == BASE_GUI_OTHER) {
        cat_snprintf(buf, bufsz,
                _("Build by issuing a \"build base\" order.\n"));
      } else {
        const char *order = "";
 
        switch (pbase->gui_type) {
        case BASE_GUI_FORTRESS:
          order = Q_(terrain_control.gui_type_base0);
          break;
        case BASE_GUI_AIRBASE:
          order = Q_(terrain_control.gui_type_base1);
          break;
        default:
          fc_assert(FALSE);
          break;
        }
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a gui_type base string from a ruleset */
                     _("Build by issuing a \"%s\" order.\n"), order);
      }
    }
  }
 
  if (is_extra_caused_by(pextra, EC_POLLUTION)) {
    CATLSTR(buf, bufsz,
            _("May randomly appear around polluting city.\n"));
  }
 
  if (is_extra_caused_by(pextra, EC_FALLOUT)) {
    CATLSTR(buf, bufsz,
            _("May randomly appear around nuclear blast.\n"));
  }
 
  if (pextra->generated
      && (is_extra_caused_by(pextra, EC_HUT)
          || is_extra_caused_by(pextra, EC_RESOURCE)
          || (proad != NULL && road_has_flag(proad, RF_RIVER)))) {
    CATLSTR(buf, bufsz,
            _("Placed by map generator.\n"));
  }
 
  if (is_extra_removed_by(pextra, ERM_ENTER)) {
    CATLSTR(buf, bufsz,
            _("Can be explored by certain units.\n"));
  }
 
  if (is_extra_caused_by(pextra, EC_APPEARANCE)) {
    CATLSTR(buf, bufsz,
            _("May appear spontaneously.\n"));
  }
 
  if (requirement_vector_size(&pextra->reqs) > 0) {
    char reqsbuf[8192] = "";
    bool buildable = pextra->buildable
      && is_extra_caused_by_worker_action(pextra);
 
    requirement_vector_iterate(&pextra->reqs, preq) {
      (void) req_text_insert_nl(reqsbuf, sizeof(reqsbuf), pplayer, preq,
                                VERB_DEFAULT,
                                buildable ? BULLET_SPACE : "");
    } requirement_vector_iterate_end;
    if (reqsbuf[0] != '\0') {
      if (buildable) {
        CATLSTR(buf, bufsz, _("Requirements to build:\n"));
      }
      CATLSTR(buf, bufsz, "%s", reqsbuf);
    }
  }
 
  if (pextra->infracost > 0) {
    cat_snprintf(buf, bufsz, _("Cost: %d\n"), pextra->infracost);
  }
 
  if (buf[group_start] != '\0') {
    CATLSTR(buf, bufsz, "\n"); /* group separator */
  }
 
  group_start = strlen(buf);
 
  if (is_extra_removed_by(pextra, ERM_PILLAGE)) {
    int pillage_time = -1;
 
    if (pextra->removal_time != 0) {
      pillage_time = pextra->removal_time;
    } else {
      terrain_type_iterate(pterrain) {
        int terr_pillage_time = pterrain->pillage_time
                                * pextra->removal_time_factor;
 
        if (terr_pillage_time != 0) {
          if (pillage_time < 0) {
            pillage_time = terr_pillage_time;
          } else if (pillage_time != terr_pillage_time) {
            /* Give up */
            pillage_time = -1;
            break;
          }
        }
      } terrain_type_iterate_end;
    }
    if (pillage_time < 0) {
      CATLSTR(buf, bufsz,
              _("Can be pillaged by units (time is terrain-dependent).\n"));
    } else if (pillage_time > 0) {
      cat_snprintf(buf, bufsz,
                   PL_("Can be pillaged by units (takes %d turn).\n",
                       "Can be pillaged by units (takes %d turns).\n",
                       pillage_time), pillage_time);
    }
  }
  if (is_extra_removed_by(pextra, ERM_CLEAN)) {
    int clean_time = -1;
 
    if (pextra->removal_time != 0) {
      clean_time = pextra->removal_time;
    } else {
      terrain_type_iterate(pterrain) {
        int terr_clean_time = -1;
        int rmtime = pterrain->extra_removal_times[extra_index(pextra)];
 
        if (rmtime != 0) {
          terr_clean_time = rmtime * pextra->removal_time_factor;
        }
 
        if (clean_time < 0) {
          clean_time = terr_clean_time;
        } else if (clean_time != terr_clean_time) {
          /* Give up */
          clean_time = -1;
          break;
        }
      } terrain_type_iterate_end;
    }
 
    if (clean_time < 0) {
      CATLSTR(buf, bufsz,
              _("Can be cleaned by units (time is terrain-dependent).\n"));
    } else if (clean_time > 0) {
      cat_snprintf(buf, bufsz,
                   PL_("Can be cleaned by units (takes %d turn).\n",
                       "Can be cleaned by units (takes %d turns).\n",
                       clean_time), clean_time);
    }
  }
 
  if (requirement_vector_size(&pextra->rmreqs) > 0) {
    char reqsbuf[8192] = "";
 
    requirement_vector_iterate(&pextra->rmreqs, preq) {
      (void) req_text_insert_nl(reqsbuf, sizeof(reqsbuf), pplayer, preq,
                                VERB_DEFAULT, BULLET_SPACE);
    } requirement_vector_iterate_end;
    if (reqsbuf[0] != '\0') {
      CATLSTR(buf, bufsz, _("Requirements to remove:\n"));
      CATLSTR(buf, bufsz, "%s", reqsbuf);
    }
  }
 
  if (buf[group_start] != '\0') {
    CATLSTR(buf, bufsz, "\n"); /* group separator */
  }
 
  /* Describe what other elements are enabled by extra */
 
  group_start = strlen(buf);
 
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf), "");
 
  if (buf[group_start] != '\0') {
    CATLSTR(buf, bufsz, "\n"); /* group separator */
  }
 
  /* Describe other properties of extras */
 
  if (pextra->visibility_req != A_NONE) {
    char vrbuf[1024];
 
    fc_snprintf(vrbuf, sizeof(vrbuf),
                _("%s Visible only if %s known.\n"), BULLET,
                advance_name_translation(advance_by_number(pextra->visibility_req)));
    CATLSTR(buf, bufsz, "%s", vrbuf);
  }
 
  if (pextra->eus == EUS_HIDDEN) {
    CATLSTR(buf, bufsz,
            _("%s Units inside are hidden from non-allied players.\n"),
            BULLET);
  }
 
  {
    const char *classes[uclass_count()];
    int i = 0;
 
    unit_class_iterate(uclass) {
      if (is_native_extra_to_uclass(pextra, uclass)) {
        classes[i++] = uclass_name_translation(uclass);
      }
    } unit_class_iterate_end;
 
    if (0 < i) {
      struct astring list = ASTRING_INIT;
 
      if (proad != NULL) {
        /* TRANS: %s is a list of unit classes separated by "and". */
        cat_snprintf(buf, bufsz, _("%s Can be traveled by %s units.\n"),
                     BULLET,
                     astr_build_and_list(&list, classes, i));
      } else {
        /* TRANS: %s is a list of unit classes separated by "and". */
        cat_snprintf(buf, bufsz, _("%s Native to %s units.\n"),
                     BULLET,
                     astr_build_and_list(&list, classes, i));
      }
      astr_free(&list);
 
      if (extra_has_flag(pextra, EF_NATIVE_TILE)) {
        CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                _("  %s Such units can move onto this tile even if it would "
                  "not normally be suitable terrain.\n"), BULLET);
      }
 
      if (pextra->no_aggr_near_city >= 0) {
        CATLSTR(buf, bufsz,
                /* TRANS: indented; preserve leading spaces */
                PL_("  %s Such units situated here are not considered aggressive "
                    "if this tile is within %d tile of a friendly city.\n",
                    "  %s Such units situated here are not considered aggressive "
                    "if this tile is within %d tiles of a friendly city.\n",
                    pextra->no_aggr_near_city),
                BULLET, pextra->no_aggr_near_city);
      }
 
      if (pextra->defense_bonus) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: indented; preserve leading spaces */
                     _("  %s Such units get a %d%% defense bonus on this "
                       "tile.\n"), BULLET,
                     pextra->defense_bonus);
      }
    }
  }
 
  if (pbase != NULL && territory_claiming_base(pbase)) {
    const char *conquerors[utype_count()];
    int i = 0;
 
    unit_type_iterate(ut) {
      if (utype_can_do_action_result(ut, ACTRES_CONQUER_EXTRAS)
          && is_native_extra_to_uclass(pextra, utype_class(ut))) {
        conquerors[i++] = utype_name_translation(ut);
      }
    } unit_type_iterate_end;
 
    if (i > 0) {
      struct astring list = ASTRING_INIT;
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a list of unit types separated by "and". */
                   _("%s Can be conquered by %s.\n"), BULLET,
                   astr_build_and_list(&list, conquerors, i));
      astr_free(&list);
    }
  }
 
  if (proad != NULL && road_provides_move_bonus(proad)) {
    if (proad->move_cost == 0) {
      CATLSTR(buf, bufsz, _("%s Allows infinite movement.\n"), BULLET);
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "MP" = movement points. Second %s may have a
                    * fractional part. */
                   _("%s Movement cost along %s is %s MP.\n"),
                   BULLET,
                   extra_name_translation(pextra),
                   move_points_text(proad->move_cost, TRUE));
    }
  }
 
  if (game.info.killstack
      && extra_has_flag(pextra, EF_NO_STACK_DEATH)) {
    CATLSTR(buf, bufsz,
            _("%s Defeat of one unit does not cause death of all other units "
              "on this tile.\n"), BULLET);
  }
  if (pbase != NULL) {
    if (territory_claiming_base(pbase)) {
      CATLSTR(buf, bufsz,
              _("%s Extends national borders of the building nation.\n"),
              BULLET);
    }
    if (pbase->vision_main_sq >= 0) {
      CATLSTR(buf, bufsz,
              _("%s Grants permanent vision of an area around the tile to "
                "its owner.\n"), BULLET);
    }
    if (pbase->vision_invis_sq >= 0) {
      CATLSTR(buf, bufsz,
              _("%s Allows the owner to see normally invisible stealth units "
                "in an area around the tile.\n"), BULLET);
    }
    if (pbase->vision_subs_sq >= 0) {
      CATLSTR(buf, bufsz,
              _("%s Allows the owner to see normally invisible subsurface units "
                "in an area around the tile.\n"), BULLET);
    }
  }
  for (flagid = EF_USER_FLAG_1; flagid <= EF_LAST_USER_FLAG; flagid++) {
    if (extra_has_flag(pextra, flagid)) {
      const char *helptxt = extra_flag_helptxt(flagid);
 
      if (helptxt != NULL) {
        CATLSTR(buf, bufsz, "%s %s\n", BULLET, _(helptxt));
      }
    }
  }
 
  /* Table of terrain-specific attributes, if needed */
  if (proad != NULL || pbase != NULL) {
    bool road, do_time, do_bonus;
 
    road = (proad != NULL);
    /* Terrain-dependent build time? */
    do_time = pextra->buildable && pextra->build_time == 0;
    if (road) {
      /* Terrain-dependent output bonus? */
      do_bonus = FALSE;
      output_type_iterate(o) {
        if (proad->tile_incr[o] > 0) {
          do_bonus = TRUE;
          fc_assert(o == O_FOOD || o == O_SHIELD || o == O_TRADE);
        }
      } output_type_iterate_end;
    } else {
      /* Bases don't have output bonuses */
      do_bonus = FALSE;
    }
 
    if (do_time || do_bonus) {
      if (do_time && do_bonus) {
        CATLSTR(buf, bufsz,
                _("\nTime to build and output bonus depends on terrain:\n\n"));
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width road properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("Terrain       Time     Bonus F/P/T\n"
                  "----------------------------------\n"));
      } else if (do_time) {
        CATLSTR(buf, bufsz,
                _("\nTime to build depends on terrain:\n\n"));
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width extra properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("Terrain       Time\n"
                  "------------------\n"));
      } else {
        fc_assert(do_bonus);
        CATLSTR(buf, bufsz,
                /* TRANS: Header for fixed-width road properties table.
                 * TRANS: Translators cannot change column widths :( */
                _("\nYields an output bonus with some terrains:\n\n"));
        CATLSTR(buf, bufsz,
                _("Terrain       Bonus F/P/T\n"
                  "-------------------------\n"));
      }
      terrain_type_iterate(t) {
        int turns = road ? terrain_extra_build_time(t, ACTIVITY_GEN_ROAD, pextra)
                           : terrain_extra_build_time(t, ACTIVITY_BASE, pextra);
        const char *bonus_text
          = road ? helptext_road_bonus_str(t, proad) : NULL;
        if (turns > 0 || bonus_text) {
          const char *terrain = terrain_name_translation(t);
          int slen = 12 - (int)get_internal_string_length(terrain);
 
          cat_snprintf(buf, bufsz,
                       "%s%*s ", terrain,
                       MAX(0, slen),
                       "");
          if (do_time) {
            if (turns > 0) {
              cat_snprintf(buf, bufsz, "%3d      ", turns);
            } else {
              CATLSTR(buf, bufsz, "  -      ");
            }
          }
          if (do_bonus) {
            fc_assert(proad != NULL);
            cat_snprintf(buf, bufsz, " %s", bonus_text ? bonus_text : "-");
          }
          CATLSTR(buf, bufsz, "\n");
        }
      } terrain_type_iterate_end;
    } /* else rely on client-specific display */
  }
 
  if (user_text && user_text[0] != '\0') {
    CATLSTR(buf, bufsz, "\n\n%s", user_text);
  }
}
 
/************************************************************************/
void helptext_goods(char *buf, size_t bufsz, struct player *pplayer,
                    const char *user_text, struct goods_type *pgood)
{
  bool reqs = FALSE;
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (NULL != pgood->helptext) {
    strvec_iterate(pgood->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
 
  if (pgood->onetime_pct == 0) {
    cat_snprintf(buf, bufsz,
                 _("There's no bonuses paid when trade route gets established.\n\n"));
  } else if (pgood->onetime_pct != 100) {
    cat_snprintf(buf, bufsz,
                 _("When trade route gets established, %d%% of the normal bonus is paid.\n"),
                 pgood->onetime_pct);
  }
  cat_snprintf(buf, bufsz, _("Sending city enjoys %d%% income from the route.\n"),
               pgood->from_pct);
  cat_snprintf(buf, bufsz, _("Receiving city enjoys %d%% income from the route.\n\n"),
               pgood->to_pct);
 
  /* Requirements for this good. */
  requirement_vector_iterate(&pgood->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT, "")) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }
 
  CATLSTR(buf, bufsz, "%s", user_text);
}
 
/************************************************************************/
void helptext_specialist(char *buf, size_t bufsz, struct player *pplayer,
                         const char *user_text, struct specialist *pspec)
{
  bool reqs = FALSE;
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (NULL != pspec->helptext) {
    strvec_iterate(pspec->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
  if (is_super_specialist(pspec)) {
    cat_snprintf(buf, bufsz,
                 _("Superspecialist: is not counted within city population,"
                   "\ncan not be assigned to or from another occupation.\n"));
  }
 
  /* Requirements for this specialist. */
  requirement_vector_iterate(&pspec->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT, "")) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }
 
  CATLSTR(buf, bufsz, "%s", user_text);
}
 
/************************************************************************/
void helptext_government(char *buf, size_t bufsz, struct player *pplayer,
                         const char *user_text, struct government *gov)
{
  bool reqs = FALSE;
  struct universal source = {
    .kind = VUT_GOVERNMENT,
    .value = {.govern = gov}
  };
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (NULL != gov->helptext) {
    strvec_iterate(gov->helptext, text) {
      cat_snprintf(buf, bufsz, "%s\n\n", _(text));
    } strvec_iterate_end;
  }
 
  /* Add requirement text for government itself */
  requirement_vector_iterate(&gov->reqs, preq) {
    if (req_text_insert_nl(buf, bufsz, pplayer, preq, VERB_DEFAULT, "")) {
      reqs = TRUE;
    }
  } requirement_vector_iterate_end;
  if (reqs) {
    fc_strlcat(buf, "\n", bufsz);
  }
 
  /* Effects */
  CATLSTR(buf, bufsz, _("Features:\n"));
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf),
                BULLET_SPACE);
  effect_list_iterate(get_req_source_effects(&source), peffect) {
    Output_type_id output_type = O_LAST;
    struct unit_class *unitclass = NULL;
    const struct unit_type *unittype = NULL;
    enum unit_type_flag_id unitflag = unit_type_flag_id_invalid();
    struct strvec *outputs = strvec_new();
    struct astring outputs_or = ASTRING_INIT;
    struct astring outputs_and = ASTRING_INIT;
    bool too_complex = FALSE;
    bool world_value_valid = TRUE;
 
    /* Grab output type, if there is one */
    requirement_vector_iterate(&peffect->reqs, preq) {
      /* Treat an effect with any negated requirements as too complex for
       * us to explain here.
       * Also don't try to explain an effect with any requirements explicitly
       * marked as 'quiet' by ruleset author. */
      if (!preq->present || preq->quiet) {
        too_complex = TRUE;
        continue;
      }
      switch (preq->source.kind) {
       case VUT_OTYPE:
         /* We should never have multiple outputtype requirements
          * in one list in the first place (it simply makes no sense,
          * output cannot be of multiple types)
          * Ruleset loading code should check against that. */
         fc_assert(output_type == O_LAST);
         output_type = preq->source.value.outputtype;
         strvec_append(outputs, get_output_name(output_type));
         break;
       case VUT_UCLASS:
         fc_assert(unitclass == NULL);
         unitclass = preq->source.value.uclass;
         /* FIXME: can't easily get world bonus for unit class */
         world_value_valid = FALSE;
         break;
       case VUT_UTYPE:
         fc_assert(unittype == NULL);
         unittype = preq->source.value.utype;
         break;
       case VUT_UTFLAG:
         if (!unit_type_flag_id_is_valid(unitflag)) {
           unitflag = preq->source.value.unitflag;
           /* FIXME: can't easily get world bonus for unit type flag */
           world_value_valid = FALSE;
         } else {
           /* Already have a unit flag requirement. More than one is too
            * complex for us to explain, so say nothing. */
           /* FIXME: we could handle this */
           too_complex = TRUE;
         }
         break;
       case VUT_GOVERNMENT:
         /* This is government we are generating helptext for.
          * ...or if not, it's ruleset bug that should never make it
          * this far. Fix ruleset loading code. */
         fc_assert(preq->source.value.govern == gov);
         break;
       default:
         too_complex = TRUE;
         world_value_valid = FALSE;
         break;
      };
    } requirement_vector_iterate_end;
 
    if (!too_complex) {
      /* Only list effects that don't have extra requirements too complex
       * for us to handle.
       * Anything more complicated will have to be documented by hand by the
       * ruleset author. */
 
      /* Guard condition for simple player-wide effects descriptions.
       * (FIXME: in many cases, e.g. EFT_MAKE_CONTENT, additional requirements
       * like unittype will be ignored for gameplay, but will affect our
       * help here.) */
      const bool playerwide
        = world_value_valid && !unittype && (output_type == O_LAST);
      /* In some cases we give absolute values (world bonus + gov bonus).
       * We assume the fact that there's an effect with a gov requirement
       * is sufficient reason to list it in that gov's help.
       * Guard accesses to these with 'playerwide' or 'world_value_valid'. */
      int world_value = -999, net_value = -999;
 
      if (world_value_valid) {
        /* Get government-independent world value of effect if the extra
         * requirements were simple enough. */
        struct output_type *potype =
          output_type != O_LAST ? get_output_type(output_type) : NULL;
 
        world_value =
          get_target_bonus_effects(NULL,
                                   &(const struct req_context) {
                                     .unittype = unittype,
                                     .output = potype,
                                   },
                                   NULL,
                                   peffect->type);
        net_value = peffect->value + world_value;
      }
 
      if (output_type == O_LAST) {
        /* There was no outputtype requirement. Effect is active for all
         * output types. Generate lists for that. */
        bool harvested_only = TRUE; /* Consider only output types from fields */
 
        if (peffect->type == EFT_UPKEEP_PCT
            || peffect->type == EFT_UNIT_UPKEEP_FREE_PER_CITY
            || peffect->type == EFT_OUTPUT_BONUS
            || peffect->type == EFT_OUTPUT_BONUS_2) {
          /* Effect can use or require any kind of output */
          harvested_only = FALSE;
        }
 
        output_type_iterate(ot) {
          struct output_type *pot = get_output_type(ot);
 
          if (!harvested_only || pot->harvested) {
            strvec_append(outputs, _(pot->name));
          }
        } output_type_iterate_end;
      }
 
      if (0 == strvec_size(outputs)) {
         /* TRANS: Empty output type list, should never happen. */
        astr_set(&outputs_or, "%s", Q_("?outputlist: Nothing "));
        astr_set(&outputs_and, "%s", Q_("?outputlist: Nothing "));
      } else {
        strvec_to_or_list(outputs, &outputs_or);
        strvec_to_and_list(outputs, &outputs_and);
      }
 
      switch (peffect->type) {
      case EFT_UNHAPPY_FACTOR:
        if (playerwide) {
          /* FIXME: EFT_MAKE_CONTENT_MIL_PER would cancel this out. We assume
           * no-one will set both, so we don't bother handling it. */
          cat_snprintf(buf, bufsz,
                       PL_("%s Military units away from home and field units"
                           " will each cause %d citizen to become unhappy.\n",
                           "%s Military units away from home and field units"
                           " will each cause %d citizens to become unhappy.\n",
                           net_value),
                       BULLET, net_value);
        } /* else too complicated or silly ruleset */
        break;
      case EFT_ENEMY_CITIZEN_UNHAPPY_PCT:
        if (playerwide && net_value != world_value) {
          if (world_value > 0) {
            if (net_value > 0) {
              cat_snprintf(buf, bufsz,
                           _("%s Unhappiness from foreign citizens due to "
                             "war with their home state is %d%% the usual "
                             "value.\n"), BULLET,
                           (net_value * 100) / world_value);
            } else {
              CATLSTR(buf, bufsz,
                      _("%s No unhappiness from foreign citizens even when "
                        "at war with their home state.\n"), BULLET);
            }
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: not pluralised as gettext doesn't support
                          * fractional numbers, which this might be */
                         _("%s Each foreign citizen causes %.2g unhappiness "
                           "in their city while you are at war with their "
                           "home state.\n"), BULLET,
                         (double)net_value / 100);
          }
        }
        break;
      case EFT_MAKE_CONTENT_MIL:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s Each of your cities will avoid %d unhappiness"
                           " caused by units.\n",
                           "%s Each of your cities will avoid %d unhappiness"
                           " caused by units.\n",
                           peffect->value),
                       BULLET, peffect->value);
        }
        break;
      case EFT_MAKE_CONTENT:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s Each of your cities will avoid %d unhappiness,"
                           " not including that caused by aggression.\n",
                           "%s Each of your cities will avoid %d unhappiness,"
                           " not including that caused by aggression.\n",
                           peffect->value),
                       BULLET, peffect->value);
        }
        break;
      case EFT_FORCE_CONTENT:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s Each of your cities will avoid %d unhappiness,"
                           " including that caused by aggression.\n",
                           "%s Each of your cities will avoid %d unhappiness,"
                           " including that caused by aggression.\n",
                           peffect->value),
                       BULLET, peffect->value);
        }
        break;
      case EFT_UPKEEP_PCT:
        if (world_value_valid && !unittype) {
          if (net_value == 0) {
            if (output_type != O_LAST) {
              cat_snprintf(buf, bufsz,
                           /* TRANS: %s is the output type, like 'shield'
                            * or 'gold'. */
                           _("%s You pay no %s upkeep for your units.\n"),
                           BULLET, astr_str(&outputs_or));
            } else {
              CATLSTR(buf, bufsz,
                      _("%s You pay no upkeep for your units.\n"),
                      BULLET);
            }
          } else if (net_value != world_value) {
            double ratio = (double)net_value / world_value;
 
            if (output_type != O_LAST) {
              cat_snprintf(buf, bufsz,
                           /* TRANS: %s is the output type, like 'shield'
                            * or 'gold'. */
                           _("%s You pay %.2g times normal %s upkeep for your "
                             "units.\n"), BULLET,
                           ratio, astr_str(&outputs_and));
            } else {
              cat_snprintf(buf, bufsz,
                           _("%s You pay %.2g times normal upkeep for your "
                             "units.\n"), BULLET,
                           ratio);
            }
          } /* else this effect somehow has no effect; keep quiet */
        } /* else there was some extra condition making it complicated */
        break;
      case EFT_UNIT_UPKEEP_FREE_PER_CITY:
        if (!unittype) {
          if (output_type != O_LAST) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is the output type, like 'shield' or
                          * 'gold'; pluralised in %d but there is currently
                          * no way to control the singular/plural name of the
                          * output type; sorry */
                         PL_("%s Each of your cities will avoid paying %d %s"
                             " upkeep for your units.\n",
                             "%s Each of your cities will avoid paying %d %s"
                             " upkeep for your units.\n", peffect->value),
                         BULLET,
                         peffect->value, astr_str(&outputs_and));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Amount is subtracted from upkeep cost
                          * for each upkeep type. */
                         PL_("%s Each of your cities will avoid paying %d"
                             " upkeep for your units.\n",
                             "%s Each of your cities will avoid paying %d"
                             " upkeep for your units.\n", peffect->value),
                         BULLET, peffect->value);
          }
        } /* else too complicated */
        break;
      case EFT_CIVIL_WAR_CHANCE:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       _("%s If you lose your capital,"
                         " the base chance of civil war is %d%%.\n"),
                       BULLET, net_value);
        }
        break;
      case EFT_EMPIRE_SIZE_BASE:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s You can have %d city before an "
                           "additional unhappy citizen appears in each city "
                           "due to civilization size.\n",
                           "%s You can have up to %d cities before an "
                           "additional unhappy citizen appears in each city "
                           "due to civilization size.\n", net_value),
                       BULLET, net_value);
        }
        break;
      case EFT_EMPIRE_SIZE_STEP:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s After the first unhappy citizen due to"
                           " civilization size, for each %d additional city"
                           " another unhappy citizen will appear.\n",
                           "%s After the first unhappy citizen due to"
                           " civilization size, for each %d additional cities"
                           " another unhappy citizen will appear.\n",
                           net_value),
                       BULLET, net_value);
        }
        break;
      case EFT_MAX_RATES:
        if (playerwide && game.info.changable_tax) {
          if (net_value < 100) {
            cat_snprintf(buf, bufsz,
                         _("%s The maximum rate you can set for science,"
                            " gold, or luxuries is %d%%.\n"),
                         BULLET, net_value);
          } else {
            CATLSTR(buf, bufsz,
                    _("%s Has unlimited science/gold/luxuries rates.\n"),
                    BULLET);
          }
        }
        break;
      case EFT_MARTIAL_LAW_BY_UNIT:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s Your units may impose martial law."
                           " Each military unit inside a city will force %d"
                           " unhappy citizen to become content.\n",
                           "%s Your units may impose martial law."
                           " Each military unit inside a city will force %d"
                           " unhappy citizens to become content.\n",
                           peffect->value),
                       BULLET, peffect->value);
        }
        break;
      case EFT_MARTIAL_LAW_MAX:
        if (playerwide && net_value < 100) {
          cat_snprintf(buf, bufsz,
                       PL_("%s A maximum of %d unit in each city can enforce"
                           " martial law.\n",
                           "%s A maximum of %d units in each city can enforce"
                           " martial law.\n",
                           net_value),
                       BULLET, net_value);
        }
        break;
      case EFT_RAPTURE_GROW:
        if (playerwide && net_value > 0) {
          cat_snprintf(buf, bufsz,
                       _("%s You may grow your cities by means of "
                         "celebrations."), BULLET);
          if (game.info.celebratesize > 1) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Preserve leading space. %d should always be
                          * 2 or greater. */
                         _(" (Cities below size %d cannot grow in this way.)"),
                         game.info.celebratesize);
          }
          cat_snprintf(buf, bufsz, "\n");
        }
        break;
      case EFT_REVOLUTION_UNHAPPINESS:
        if (playerwide) {
          cat_snprintf(buf, bufsz,
                       PL_("%s If a city is in disorder for more than %d turn "
                           "in a row, government will fall into anarchy.\n",
                           "%s If a city is in disorder for more than %d turns "
                           "in a row, government will fall into anarchy.\n",
                           net_value),
                       BULLET, net_value);
        }
        break;
      case EFT_HAS_SENATE:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("%s Has a senate that may prevent declaration of war.\n"),
                  BULLET);
        }
        break;
      case EFT_INSPIRE_PARTISANS:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("%s Allows partisans when cities are taken by the "
                    "enemy.\n"), BULLET);
        }
        break;
      case EFT_HAPPINESS_TO_GOLD:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz,
                  _("%s Buildings that normally confer bonuses against"
                    " unhappiness will instead give gold.\n"), BULLET);
        }
        break;
      case EFT_FANATICS:
        if (playerwide && net_value > 0) {
          struct strvec *fanatics = strvec_new();
          struct astring fanaticstr = ASTRING_INIT;
 
          unit_type_iterate(putype) {
            if (utype_has_flag(putype, UTYF_FANATIC)) {
              strvec_append(fanatics, utype_name_translation(putype));
            }
          } unit_type_iterate_end;
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is list of unit types separated by 'or' */
                       _("%s Pays no upkeep for %s.\n"), BULLET,
                       strvec_to_or_list(fanatics, &fanaticstr));
          strvec_destroy(fanatics);
          astr_free(&fanaticstr);
        }
        break;
      case EFT_NO_UNHAPPY:
        if (playerwide && net_value > 0) {
          CATLSTR(buf, bufsz, _("%s Has no unhappy citizens.\n"), BULLET);
        }
        break;
      case EFT_VETERAN_BUILD:
        {
          int conditions = 0;
          if (unitclass) {
            conditions++;
          }
          if (unittype) {
            conditions++;
          }
          if (unit_type_flag_id_is_valid(unitflag)) {
            conditions++;
          }
          if (conditions > 1) {
            /* More than one requirement on units, too complicated for us
             * to describe. */
            break;
          }
          if (unitclass) {
            /* FIXME: account for multiple veteran levels, or negative
             * values. This might lie for complicated rulesets! */
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a unit class */
                         Q_("?unitclass:* New %s units will be veteran.\n"),
                         uclass_name_translation(unitclass));
          } else if (unit_type_flag_id_is_valid(unitflag)) {
            /* FIXME: same problems as unitclass */
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a (translatable) unit type flag */
                         Q_("?unitflag:* New %s units will be veteran.\n"),
                         unit_type_flag_id_translated_name(unitflag));
          } else if (unittype != NULL) {
            if (world_value_valid && net_value > 0) {
              /* Here we can be specific about veteran level, and get
               * net value correct. */
              int maxlvl = utype_veteran_system(unittype)->levels - 1;
              const struct veteran_level *vlevel =
                utype_veteran_level(unittype, MIN(net_value, maxlvl));
              cat_snprintf(buf, bufsz,
                           /* TRANS: "* New Partisan units will have the rank
                            * of elite." */
                           Q_("?unittype:%s New %s units will have the rank "
                              "of %s.\n"), BULLET,
                           utype_name_translation(unittype),
                           name_translation_get(&vlevel->name));
            } /* else complicated */
          } else {
            /* No extra criteria. */
            /* FIXME: same problems as above */
            cat_snprintf(buf, bufsz,
                         _("%s New units will be veteran.\n"), BULLET);
          }
        }
        break;
      case EFT_OUTPUT_PENALTY_TILE:
        if (world_value_valid) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is list of output types, with 'or';
                        * pluralised in %d but of course the output types
                        * can't be pluralised; sorry */
                       PL_("%s Each worked tile that gives more than %d %s will"
                           " suffer a -1 penalty, unless the city working it"
                           " is celebrating.",
                           "%s Each worked tile that gives more than %d %s will"
                           " suffer a -1 penalty, unless the city working it"
                           " is celebrating.", net_value),
                       BULLET, net_value, astr_str(&outputs_or));
          if (game.info.celebratesize > 1) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: Preserve leading space. %d should always be
                          * 2 or greater. */
                         _(" (Cities below size %d will not celebrate.)"),
                         game.info.celebratesize);
          }
          cat_snprintf(buf, bufsz, "\n");
        }
        break;
      case EFT_OUTPUT_INC_TILE_CELEBRATE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'or' */
                     PL_("%s Each worked tile with at least 1 %s will yield"
                         " %d more of it while the city working it is"
                         " celebrating.",
                         "%s Each worked tile with at least 1 %s will yield"
                         " %d more of it while the city working it is"
                         " celebrating.", peffect->value),
                     BULLET, astr_str(&outputs_or), peffect->value);
        if (game.info.celebratesize > 1) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: Preserve leading space. %d should always be
                        * 2 or greater. */
                       _(" (Cities below size %d will not celebrate.)"),
                       game.info.celebratesize);
        }
        cat_snprintf(buf, bufsz, "\n");
        break;
      case EFT_OUTPUT_INC_TILE:
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'or' */
                     PL_("%s Each worked tile with at least 1 %s will yield"
                         " %d more of it.\n",
                         "%s Each worked tile with at least 1 %s will yield"
                         " %d more of it.\n", peffect->value),
                     BULLET, astr_str(&outputs_or), peffect->value);
        break;
      case EFT_OUTPUT_BONUS:
      case EFT_OUTPUT_BONUS_2:
        /* FIXME: makes most sense iff world_value == 0 */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is list of output types, with 'and' */
                     _("%s %s production is increased %d%%.\n"),
                     BULLET, astr_str(&outputs_and), peffect->value);
        break;
      case EFT_OUTPUT_WASTE:
        if (world_value_valid) {
          if (net_value > 30) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s production will suffer massive losses.\n"),
                         BULLET, astr_str(&outputs_and));
          } else if (net_value >= 15) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s production will suffer some losses.\n"),
                         BULLET, astr_str(&outputs_and));
          } else if (net_value > 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s production will suffer a small amount "
                           "of losses.\n"),
                         BULLET, astr_str(&outputs_and));
          }
        }
        break;
      case EFT_HEALTH_PCT:
        if (playerwide) {
          if (peffect->value > 0) {
            CATLSTR(buf, bufsz, _("%s Increases the chance of plague"
                                  " within your cities.\n"), BULLET);
          } else if (peffect->value < 0) {
            CATLSTR(buf, bufsz, _("%s Decreases the chance of plague"
                                  " within your cities.\n"), BULLET);
          }
        }
        break;
      case EFT_OUTPUT_WASTE_BY_REL_DISTANCE:
        /* Semi-arbitrary scaling to get likely ruleset values in roughly
         * the same range as WASTE_BY_DISTANCE */
        /* FIXME: use different wording? */
        net_value = (net_value + 39) / 40; /* round up */
        fc__fallthrough; /* fall through to: */
      case EFT_OUTPUT_WASTE_BY_DISTANCE:
        if (world_value_valid) {
          if (net_value >= 300) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s losses will increase quickly"
                           " with distance from capital.\n"),
                         BULLET, astr_str(&outputs_and));
          } else if (net_value >= 200) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s losses will increase"
                           " with distance from capital.\n"),
                         BULLET, astr_str(&outputs_and));
          } else if (net_value > 0) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is list of output types, with 'and' */
                         _("%s %s losses will increase slowly"
                           " with distance from capital.\n"),
                         BULLET, astr_str(&outputs_and));
          }
        }
        break;
      case EFT_MIGRATION_PCT:
        if (playerwide) {
          if (peffect->value > 0) {
            CATLSTR(buf, bufsz, _("%s Increases the chance of migration"
                                  " into your cities.\n"), BULLET);
          } else if (peffect->value < 0) {
            CATLSTR(buf, bufsz, _("%s Decreases the chance of migration"
                                  " into your cities.\n"), BULLET);
          }
        }
        break;
      case EFT_BORDER_VISION:
        if (game.info.borders == BORDERS_ENABLED
            && playerwide && net_value > 0) {
          CATLSTR(buf, bufsz, _("%s All tiles inside your borders are"
                                " monitored.\n"), BULLET);
        }
        break;
      default:
        break;
      };
    }
 
    strvec_destroy(outputs);
    astr_free(&outputs_or);
    astr_free(&outputs_and);
 
  } effect_list_iterate_end;
 
  /* Action immunity */
  action_iterate(act) {
    if (action_by_number(act)->quiet) {
      /* The ruleset documents this action it self. */
      continue;
    }
 
    if (action_immune_government(gov, act)) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: action name ... action target
                    * ("individual units", etc) */
                   _("%s Makes it impossible to do the action \'%s\'"
                     " to your %s.\n"), BULLET,
                   action_id_name_translation(act),
                   action_target_kind_help(action_id_get_target_kind(act)));
    }
  } action_iterate_end;
 
  if (user_text && user_text[0] != '\0') {
    cat_snprintf(buf, bufsz, "\n%s", user_text);
  }
}
 
/************************************************************************/
char *helptext_unit_upkeep_str(const struct unit_type *utype)
{
  static char buf[128];
  int any = 0;
 
  if (!utype) {
    log_error("Unknown unit!");
    return "";
  }
 
  buf[0] = '\0';
  output_type_iterate(o) {
    if (utype->upkeep[o] > 0) {
      /* TRANS: "2 Food" or ", 1 Shield" */
      cat_snprintf(buf, sizeof(buf), _("%s%d %s"),
                   (any > 0 ? Q_("?blistmore:, ") : ""), utype->upkeep[o],
                   get_output_name(o));
      any++;
    }
  } output_type_iterate_end;
  if (utype->happy_cost > 0) {
    /* TRANS: "2 Unhappy" or ", 1 Unhappy" */
    cat_snprintf(buf, sizeof(buf), _("%s%d Unhappy"),
                 (any > 0 ? Q_("?blistmore:, ") : ""), utype->happy_cost);
    any++;
  }
 
  if (any == 0) {
    /* strcpy(buf, _("None")); */
    fc_snprintf(buf, sizeof(buf), "%d", 0);
  }
  return buf;
}
 
/************************************************************************/
void helptext_nation(char *buf, size_t bufsz, struct nation_type *pnation,
                     const char *user_text)
{
  struct universal source = {
    .kind = VUT_NATION,
    .value = {.nation = pnation}
  };
  bool print_break = TRUE;
 
#define PRINT_BREAK() do {                      \
    if (print_break) { \
      if (buf[0] != '\0') { \
        CATLSTR(buf, bufsz, "\n\n"); \
      } \
      print_break = FALSE; \
    } \
  } while (FALSE)
 
  fc_assert_ret(NULL != buf && 0 < bufsz);
  buf[0] = '\0';
 
  if (pnation->legend[0] != '\0') {
    /* Client side legend is stored already translated */
    cat_snprintf(buf, bufsz, "%s", pnation->legend);
  }
 
  if (pnation->init_government) {
    PRINT_BREAK();
    cat_snprintf(buf, bufsz,
                 _("Initial government is %s.\n"),
                 government_name_translation(pnation->init_government));
  }
  if (pnation->init_techs[0] != A_LAST) {
    const char *tech_names[MAX_NUM_TECH_LIST];
    int i;
    struct astring list = ASTRING_INIT;
 
    for (i = 0; i < MAX_NUM_TECH_LIST; i++) {
      if (pnation->init_techs[i] == A_LAST) {
        break;
      }
      tech_names[i] =
        advance_name_translation(advance_by_number(pnation->init_techs[i]));
    }
    astr_build_and_list(&list, tech_names, i);
    PRINT_BREAK();
    if (game.rgame.global_init_techs[0] != A_LAST) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of techs */
                   _("Starts with knowledge of %s in addition to the standard "
                     "starting technologies.\n"), astr_str(&list));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of techs */
                   _("Starts with knowledge of %s.\n"), astr_str(&list));
    }
    astr_free(&list);
  }
  if (pnation->init_units[0]) {
    const struct unit_type *utypes[MAX_NUM_UNIT_LIST];
    int count[MAX_NUM_UNIT_LIST];
    int i, j, n = 0, total = 0;
 
    /* Count how many of each type there is. */
    for (i = 0; i < MAX_NUM_UNIT_LIST; i++) {
      if (!pnation->init_units[i]) {
        break;
      }
      for (j = 0; j < n; j++) {
        if (pnation->init_units[i] == utypes[j]) {
          count[j]++;
          total++;
          break;
        }
      }
      if (j == n) {
        utypes[n] = pnation->init_units[i];
        count[n] = 1;
        total++;
        n++;
      }
    }
    {
      /* Construct the list of unit types and counts. */
      struct astring utype_names[MAX_NUM_UNIT_LIST];
      struct astring list = ASTRING_INIT;
 
      for (i = 0; i < n; i++) {
        astr_init(&utype_names[i]);
        if (count[i] > 1) {
          /* TRANS: a unit type followed by a count. For instance,
           * "Fighter (2)" means two Fighters. Count is never 1.
           * Used in a list. */
          astr_set(&utype_names[i], _("%s (%d)"),
                   utype_name_translation(utypes[i]), count[i]);
        } else {
          astr_set(&utype_names[i], "%s", utype_name_translation(utypes[i]));
        }
      }
      {
        const char *utype_name_strs[MAX_NUM_UNIT_LIST];
 
        for (i = 0; i < n; i++) {
          utype_name_strs[i] = astr_str(&utype_names[i]);
        }
        astr_build_and_list(&list, utype_name_strs, n);
      }
      for (i = 0; i < n; i++) {
        astr_free(&utype_names[i]);
      }
      PRINT_BREAK();
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of unit types
                    * possibly with counts. Plurality is in total number of
                    * units represented. */
                   PL_("Starts with the following additional unit: %s.\n",
                       "Starts with the following additional units: %s.\n",
                      total), astr_str(&list));
      astr_free(&list);
    }
  }
  if (pnation->init_buildings[0] != B_LAST) {
    const char *impr_names[MAX_NUM_BUILDING_LIST];
    int i;
    struct astring list = ASTRING_INIT;
 
    for (i = 0; i < MAX_NUM_BUILDING_LIST; i++) {
      if (pnation->init_buildings[i] == B_LAST) {
        break;
      }
      impr_names[i] =
        improvement_name_translation(
          improvement_by_number(pnation->init_buildings[i]));
    }
    astr_build_and_list(&list, impr_names, i);
    PRINT_BREAK();
    if (game.rgame.global_init_buildings[0] != B_LAST) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of improvements */
                   _("First city will get %s for free in addition to the "
                     "standard improvements.\n"), astr_str(&list));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is an and-separated list of improvements */
                   _("First city will get %s for free.\n"), astr_str(&list));
    }
    astr_free(&list);
  }
 
  if (buf[0] != '\0') {
    CATLSTR(buf, bufsz, "\n");
  }
  insert_allows(&source, buf + strlen(buf), bufsz - strlen(buf), "");
 
  if (user_text && user_text[0] != '\0') {
    if (buf[0] != '\0') {
      CATLSTR(buf, bufsz, "\n");
    }
    CATLSTR(buf, bufsz, "%s", user_text);
  }
#undef PRINT_BREAK
}
 
/************************************************************************/
enum help_page_type help_type_by_requirement(const struct requirement *req)
{
  if (req == NULL) {
    return HELP_LAST;
  }
 
  if (req->source.kind == VUT_UTYPE) {
    return HELP_UNIT;
  }
  if (req->source.kind == VUT_IMPROVEMENT) {
    if (is_great_wonder(req->source.value.building)) {
      return HELP_WONDER;
    }
    return HELP_IMPROVEMENT;
  }
  if (req->source.kind == VUT_ADVANCE) {
    return HELP_TECH;
  }
  if (req->source.kind == VUT_TERRAIN) {
    return HELP_TERRAIN;
  }
  if (req->source.kind == VUT_EXTRA) {
    return HELP_EXTRA;
  }
  if (req->source.kind == VUT_GOOD) {
    return HELP_GOODS;
  }
  if (req->source.kind == VUT_SPECIALIST) {
    return HELP_SPECIALIST;
  }
  if (req->source.kind == VUT_GOVERNMENT) {
    return HELP_GOVERNMENT;
  }
 
  if (req->source.kind == VUT_NATION) {
    return HELP_NATIONS;
  }
 
  return HELP_LAST;
}