reqtext.c

Go to the documentation of this file.

/****************************************************************************
 Freeciv - Copyright (C) 2004 - The Freeciv Team
   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.
****************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
/* utility */
#include "astring.h"
#include "fcintl.h"
 
/* common */
#include "achievements.h"
#include "actions.h"
#include "calendar.h"
#include "counters.h"
#include "extras.h"
#include "government.h"
#include "map.h"
#include "movement.h"
#include "nation.h"
#include "player.h"
#include "requirements.h"
#include "server_settings.h"
#include "specialist.h"
#include "terrain.h"
#include "tiledef.h"
 
#include "reqtext.h"
 
 
/*************************************************************/
static bool req_text_counter(char *buf, size_t bufsz,
                             struct player *pplayer,
                             const struct requirement *preq,
                             const char *prefix)
{
  if (preq->present) {
     fc_strlcat(buf, prefix, bufsz);
    cat_snprintf(buf, bufsz,
               _("Requires counter %s to achieve at minimum %d value."),
               counter_rule_name(preq->source.value.counter),
               preq->source.value.counter->checkpoint);
  } else {
    fc_strlcat(buf, prefix, bufsz);
    cat_snprintf(buf, bufsz,
                 _("Requires counter %s to be less than %d value."),
                 counter_rule_name(preq->source.value.counter),
                 preq->source.value.counter->checkpoint - 1);
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_advance(char *buf, size_t bufsz,
                             struct player *pplayer,
                             const struct requirement *preq,
                             const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires knowledge of the technology %s."),
                   advance_name_translation(preq->source.value.advance));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented by knowledge of the technology %s."),
                   advance_name_translation(preq->source.value.advance));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that a player on your team knows the "
                     "technology %s."),
                   advance_name_translation(preq->source.value.advance));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented if any player on your team knows the "
                     "technology %s."),
                   advance_name_translation(preq->source.value.advance));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that a player allied to you knows the "
                     "technology %s."),
                   advance_name_translation(preq->source.value.advance));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented if any player allied to you knows the "
                     "technology %s."),
                   advance_name_translation(preq->source.value.advance));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->survives) {
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that someone has discovered the "
                       "technology %s."),
                     advance_name_translation(preq->source.value.advance));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that no-one has yet discovered the "
                      "technology %s."),
                     advance_name_translation(preq->source.value.advance));
      }
    } else {
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that some player knows the "
                       "technology %s."),
                     advance_name_translation(preq->source.value.advance));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that no player knows the "
                       "technology %s."),
                     advance_name_translation(preq->source.value.advance));
      }
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_techflag(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Requires knowledge of a technology with the "
                     "\"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Prevented by knowledge of any technology with the "
                     "\"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Requires that a player on your team knows "
                     "a technology with the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Prevented if any player on your team knows "
                     "any technology with the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Requires that a player allied to you knows "
                     "a technology with the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Prevented if any player allied to you knows "
                     "any technology with the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Requires that some player knows a technology "
                     "with the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) tech flag. */
                   _("Requires that no player knows any technology with "
                     "the \"%s\" flag."),
                   tech_flag_id_translated_name(preq->source.value.techflag));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
    }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_government(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  if (preq->range != REQ_RANGE_PLAYER) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz, _("Requires the %s government."),
                 government_name_translation(preq->source.value.govern));
  } else {
    cat_snprintf(buf, bufsz, _("Not available under the %s government."),
                 government_name_translation(preq->source.value.govern));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_government_flag(char *buf, size_t bufsz,
                                     struct player *pplayer,
                                     const struct requirement *preq,
                                     const char *prefix)
{
  if (preq->range != REQ_RANGE_PLAYER) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz, _("Requires a %s government."),
                 gov_flag_id_translated_name(preq->source.value.govflag));
  } else {
    cat_snprintf(buf, bufsz, _("Not available under a %s government."),
                 gov_flag_id_translated_name(preq->source.value.govflag));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_achievement(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Requires you to have achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    } else {
      cat_snprintf(buf, bufsz, _("Not available once you have achieved "
                                 "\"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Requires that at least one of your "
                                 "team-mates has achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    } else {
      cat_snprintf(buf, bufsz, _("Not available if any of your team-mates "
                                 "has achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Requires that at least one of your allies "
                                 "has achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    } else {
      cat_snprintf(buf, bufsz, _("Not available if any of your allies has "
                                 "achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Requires that at least one player "
                                 "has achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    } else {
      cat_snprintf(buf, bufsz, _("Not available if any player has "
                                 "achieved \"%s\"."),
                   achievement_name_translation(preq->source.value.achievement));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
 
  return TRUE;
}
 
/*************************************************************/
static bool req_text_action(char *buf, size_t bufsz,
                            struct player *pplayer,
                            const struct requirement *preq,
                            const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Applies to the \"%s\" action."),
                   action_name_translation(preq->source.value.action));
    } else {
      cat_snprintf(buf, bufsz, _("Doesn't apply to the \"%s\""
                                 " action."),
                   action_name_translation(preq->source.value.action));
    }
    return TRUE;
  default:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_impr_genus(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Applies to \"%s\" buildings."),
                   impr_genus_id_translated_name(
                     preq->source.value.impr_genus));
    } else {
      cat_snprintf(buf, bufsz, _("Doesn't apply to \"%s\" buildings."),
                   impr_genus_id_translated_name(
                     preq->source.value.impr_genus));
    }
    return TRUE;
  default:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_impr_flag(char *buf, size_t bufsz,
                               struct player *pplayer,
                               const struct requirement *preq,
                               const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Applies to \"%s\" buildings."),
                   impr_flag_id_translated_name(
                     preq->source.value.impr_flag));
    } else {
      cat_snprintf(buf, bufsz, _("Doesn't apply to \"%s\" buildings."),
                   impr_flag_id_translated_name(
                     preq->source.value.impr_flag));
    }
    return TRUE;
  default:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_player_flag(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Applies to players with \"%s\" flag."),
                   plr_flag_id_translated_name(
                     preq->source.value.plr_flag));
    } else {
      cat_snprintf(buf, bufsz, _("Doesn't apply to players with \"%s\" flag."),
                   plr_flag_id_translated_name(
                     preq->source.value.plr_flag));
    }
    return TRUE;
  default:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_player_state(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, _("Applies to \"%s\" players."),
                   plrstate_type_translated_name(preq->source.value.plrstate));
    } else {
      cat_snprintf(buf, bufsz, _("Doesn't apply to \"%s\" players."),
                   plrstate_type_translated_name(preq->source.value.plrstate));
    }
    return TRUE;
  default:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_improvement(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_WORLD:
    if (is_great_wonder(preq->source.value.building)) {
      fc_strlcat(buf, prefix, bufsz);
      if (preq->survives) {
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires that %s was built at some point, "
                           "and that it has not yet been rendered "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires that %s was built at some point."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if %s has ever been built, "
                           "unless it would be obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if %s has ever been built."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      } else {
        /* Non-surviving requirement */
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires %s to be owned by any player "
                           "and not yet obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires %s to be owned by any player."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if %s is currently owned by "
                           "any player, unless it is obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if %s is currently owned by "
                           "any player."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      }
      return TRUE;
    }
    /* Non-great-wonder world-ranged requirements not supported */
    return FALSE;
  case REQ_RANGE_ALLIANCE:
    if (is_wonder(preq->source.value.building)) {
      fc_strlcat(buf, prefix, bufsz);
      if (preq->survives) {
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone who is currently allied to "
                           "you to have built %s at some point, and for "
                           "it not to have been rendered obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone who is currently allied to "
                           "you to have built %s at some point."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone currently allied to you "
                           "has ever built %s, unless it would be "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone currently allied to you "
                           "has ever built %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      } else {
        /* Non-surviving requirement */
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone allied to you to own %s, "
                           "and for it not to have been rendered "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone allied to you to own %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone allied to you owns %s, "
                           "unless it is obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone allied to you owns %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      }
      return TRUE;
    }
    /* Non-wonder alliance-ranged requirements not supported */
    return FALSE;
  case REQ_RANGE_TEAM:
    if (is_wonder(preq->source.value.building)) {
      fc_strlcat(buf, prefix, bufsz);
      if (preq->survives) {
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone on your team to have "
                           "built %s at some point, and for it not "
                           "to have been rendered obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone on your team to have "
                           "built %s at some point."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone on your team has ever "
                           "built %s, unless it would be obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone on your team has ever "
                           "built %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      } else {
        /* Non-surviving requirement */
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone on your team to own %s, "
                           "and for it not to have been rendered "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires someone on your team to own %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone on your team owns %s, "
                           "unless it is obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if someone on your team owns %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      }
      return TRUE;
    }
    /* Non-wonder team-ranged requirements not supported */
    return FALSE;
  case REQ_RANGE_PLAYER:
    if (is_wonder(preq->source.value.building)) {
      fc_strlcat(buf, prefix, bufsz);
      if (preq->survives) {
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires you to have built %s at some point, "
                           "and for it not to have been rendered "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires you to have built %s at some point."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if you have ever built %s, "
                           "unless it would be obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if you have ever built %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      } else {
        /* Non-surviving requirement */
        if (preq->present) {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires you to own %s, which must not "
                           "be obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Requires you to own %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        } else {
          if (preq->source.kind == VUT_IMPROVEMENT
              && can_improvement_go_obsolete(preq->source.value.building)) {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if you own %s, unless it is "
                           "obsolete."),
                         improvement_name_translation
                         (preq->source.value.building));
          } else {
            cat_snprintf(buf, bufsz,
                         /* TRANS: %s is a wonder */
                         _("Prevented if you own %s."),
                         improvement_name_translation
                         (preq->source.value.building));
          }
        }
      }
      return TRUE;
    }
    /* Non-wonder player-ranged requirements not supported */
    return FALSE;
  case REQ_RANGE_CONTINENT:
    if (is_wonder(preq->source.value.building)) {
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        if (preq->source.kind == VUT_IMPROVEMENT
            && can_improvement_go_obsolete(preq->source.value.building)) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is a wonder */
                       _("Requires %s in one of your cities on the same "
                         "continent, and not yet obsolete."),
                       improvement_name_translation
                       (preq->source.value.building));
        } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is a wonder */
                       _("Requires %s in one of your cities on the same "
                         "continent."),
                       improvement_name_translation
                       (preq->source.value.building));
        }
      } else {
        if (preq->source.kind == VUT_IMPROVEMENT
            && can_improvement_go_obsolete(preq->source.value.building)) {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is a wonder */
                       _("Prevented if %s is in one of your cities on the "
                         "same continent, unless it is obsolete."),
                       improvement_name_translation
                       (preq->source.value.building));
        } else {
          cat_snprintf(buf, bufsz,
                       /* TRANS: %s is a wonder */
                       _("Prevented if %s is in one of your cities on the "
                         "same continent."),
                       improvement_name_translation
                       (preq->source.value.building));
        }
      }
      return TRUE;
    }
    /* Surviving or non-wonder continent-ranged requirements not supported */
    return FALSE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      if (preq->source.kind == VUT_IMPROVEMENT
          && can_improvement_go_obsolete(preq->source.value.building)) {
        /* Should only apply to wonders */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Requires %s in the city or a trade partner "
                       "(and not yet obsolete)."),
                     improvement_name_translation
                     (preq->source.value.building));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Requires %s in the city or a trade partner."),
                     improvement_name_translation
                     (preq->source.value.building));
      }
    } else {
      if (preq->source.kind == VUT_IMPROVEMENT
          && can_improvement_go_obsolete(preq->source.value.building)) {
        /* Should only apply to wonders */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Prevented by %s in the city or a trade partner "
                       "(unless it is obsolete)."),
                     improvement_name_translation
                     (preq->source.value.building));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Prevented by %s in the city or a trade partner."),
                     improvement_name_translation
                     (preq->source.value.building));
      }
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      if (preq->source.kind == VUT_IMPROVEMENT
          && can_improvement_go_obsolete(preq->source.value.building)) {
        /* Should only apply to wonders */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Requires %s in the city (and not yet obsolete)."),
                     improvement_name_translation
                     (preq->source.value.building));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Requires %s in the city."),
                     improvement_name_translation
                     (preq->source.value.building));
      }
    } else {
      if (preq->source.kind == VUT_IMPROVEMENT
          && can_improvement_go_obsolete(preq->source.value.building)) {
        /* Should only apply to wonders */
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Prevented by %s in the city (unless it is "
                       "obsolete)."),
                     improvement_name_translation
                     (preq->source.value.building));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: %s is a building or wonder */
                     _("Prevented by %s in the city."),
                     improvement_name_translation
                     (preq->source.value.building));
      }
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Only applies to \"%s\" buildings."),
                   improvement_name_translation
                   (preq->source.value.building));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Does not apply to \"%s\" buildings."),
                   improvement_name_translation
                   (preq->source.value.building));
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires \"%s\" building in a city on the tile."),
                   improvement_name_translation
                   (preq->source.value.building));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented by \"%s\" building in a city on the tile."),
                   improvement_name_translation
                   (preq->source.value.building));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_extra(char *buf, size_t bufsz,
                           struct player *pplayer,
                           const struct requirement *preq,
                           const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Only applies to \"%s\" extras."),
                   extra_name_translation(preq->source.value.extra));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Does not apply to \"%s\" extras."),
                   extra_name_translation(preq->source.value.extra));
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Requires %s on the tile."),
                   extra_name_translation(preq->source.value.extra));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Prevented by %s on the tile."),
                   extra_name_translation(preq->source.value.extra));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Requires %s on the tile or a cardinally "
                      "adjacent tile."),
                   extra_name_translation(preq->source.value.extra));
      } else {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Prevented by %s on the tile or any cardinally "
                      "adjacent tile."),
                   extra_name_translation(preq->source.value.extra));
      }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Requires %s on the tile or an adjacent "
                      "tile."),
                   extra_name_translation(preq->source.value.extra));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Prevented by %s on the tile or any adjacent "
                      "tile."),
                   extra_name_translation(preq->source.value.extra));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Requires %s on a tile within the city "
                      "radius."),
                   extra_name_translation(preq->source.value.extra));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Prevented by %s on any tile within the city "
                      "radius."),
                   extra_name_translation(preq->source.value.extra));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Requires %s on a tile within the city "
                      "radius, or the city radius of a trade partner."),
                   extra_name_translation(preq->source.value.extra));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?extra:Prevented by %s on any tile within the city "
                      "radius or the city radius of a trade partner."),
                   extra_name_translation(preq->source.value.extra));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
    }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_good(char *buf, size_t bufsz,
                          struct player *pplayer,
                          const struct requirement *preq,
                          const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, Q_("?good:Requires import of %s."),
                   goods_name_translation(preq->source.value.good));
    } else {
      cat_snprintf(buf, bufsz, Q_("?goods:Prevented by import of %s."),
                   goods_name_translation(preq->source.value.good));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_tiledef(char *buf, size_t bufsz,
                             struct player *pplayer,
                             const struct requirement *preq,
                             const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Only applies to \"%s\" tiledef."),
                   tiledef_name_translation(preq->source.value.tiledef));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Does not apply to \"%s\" tiledef."),
                   tiledef_name_translation(preq->source.value.tiledef));
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Requires %s on the tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Prevented by %s on the tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Requires %s on the tile or a cardinally "
                      "adjacent tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
      } else {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Prevented by %s on the tile or any cardinally "
                      "adjacent tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
      }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Requires %s on the tile or an adjacent "
                      "tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Prevented by %s on the tile or any adjacent "
                      "tile."),
                   tiledef_name_translation(preq->source.value.tiledef));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Requires %s on a tile within the city "
                      "radius."),
                   tiledef_name_translation(preq->source.value.tiledef));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Prevented by %s on any tile within the city "
                      "radius."),
                   tiledef_name_translation(preq->source.value.tiledef));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Requires %s on a tile within the city "
                      "radius, or the city radius of a trade partner."),
                   tiledef_name_translation(preq->source.value.tiledef));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?tiledef:Prevented by %s on any tile within the city "
                      "radius or the city radius of a trade partner."),
                   tiledef_name_translation(preq->source.value.tiledef));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_terrain(char *buf, size_t bufsz,
                             struct player *pplayer,
                             const struct requirement *preq,
                             const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz, Q_("?terrain:Requires %s on the tile."),
                   terrain_name_translation(preq->source.value.terrain));
    } else {
      cat_snprintf(buf, bufsz, Q_("?terrain:Prevented by %s on the tile."),
                   terrain_name_translation(preq->source.value.terrain));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Requires %s on the tile or a cardinally "
                      "adjacent tile."),
                   terrain_name_translation(preq->source.value.terrain));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Prevented by %s on the tile or any "
                      "cardinally adjacent tile."),
                   terrain_name_translation(preq->source.value.terrain));
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Requires %s on the tile or an adjacent "
                      "tile."),
                   terrain_name_translation(preq->source.value.terrain));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Prevented by %s on the tile or any "
                      "adjacent tile."),
                   terrain_name_translation(preq->source.value.terrain));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Requires %s on a tile within the city "
                      "radius."),
                   terrain_name_translation(preq->source.value.terrain));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Prevented by %s on any tile within the city "
                      "radius."),
                   terrain_name_translation(preq->source.value.terrain));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Requires %s on a tile within the city "
                      "radius, or the city radius of a trade partner."),
                   terrain_name_translation(preq->source.value.terrain));
    } else {
      cat_snprintf(buf, bufsz,
                   Q_("?terrain:Prevented by %s on any tile within the city "
                      "radius or the city radius of a trade partner."),
                   terrain_name_translation(preq->source.value.terrain));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
return TRUE;
}
 
/*************************************************************/
static bool req_text_nation(char *buf, size_t bufsz,
                            struct player *pplayer,
                            const struct requirement *preq,
                            const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... playing as the Swedes." */
                   _("Requires that you are playing as the %s."),
                   nation_plural_translation(preq->source.value.nation));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... playing as the Turks." */
                   _("Requires that you are not playing as the %s."),
                   nation_plural_translation(preq->source.value.nation));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... same team as the Indonesians." */
                   _("Requires that you are on the same team as "
                     "the %s."),
                   nation_plural_translation(preq->source.value.nation));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... same team as the Greeks." */
                   _("Requires that you are not on the same team as "
                     "the %s."),
                   nation_plural_translation(preq->source.value.nation));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... allied with the Koreans." */
                   _("Requires that you are allied with the %s."),
                   nation_plural_translation(preq->source.value.nation));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... allied with the Danes." */
                   _("Requires that you are not allied with the %s."),
                   nation_plural_translation(preq->source.value.nation));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->survives) {
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: "Requires the Apaches to have ..." */
                     _("Requires the %s to have been in the game."),
                     nation_plural_translation(preq->source.value.nation));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: "Requires the Celts never to have ..." */
                     _("Requires the %s never to have been in the "
                       "game."),
                     nation_plural_translation(preq->source.value.nation));
      }
    } else {
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: "Requires the Belgians in the game." */
                     _("Requires the %s in the game."),
                     nation_plural_translation(preq->source.value.nation));
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: "Requires that the Russians are not ... */
                     _("Requires that the %s are not in the game."),
                     nation_plural_translation(preq->source.value.nation));
      }
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_nation_group(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "... playing African nation." */
                   _("Requires that you are playing %s nation."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "... playing Imaginary nation." */
                   _("Prevented if you are playing %s nation."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Requires Medieval nation ..." */
                   _("Requires %s nation on your team."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Prevented by Medieval nation ..." */
                   _("Prevented by %s nation on your team."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Requires Modern nation ..." */
                   _("Requires %s nation in alliance with you."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Prevented by Modern nation ..." */
                   _("Prevented if %s nation is in alliance with you."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Requires Asian nation ..." */
                   _("Requires %s nation in the game."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: nation group: "Prevented by Asian nation ..." */
                   _("Prevented by %s nation in the game."),
                   nation_group_name_translation(preq->source.value.nationgroup));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_style(char *buf, size_t bufsz,
                           struct player *pplayer,
                           const struct requirement *preq,
                           const char *prefix)
{
  if (preq->range != REQ_RANGE_PLAYER) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: "Requires that you are playing Asian style
                  * nation." */
                 _("Requires that you are playing %s style nation."),
                 style_name_translation(preq->source.value.style));
  } else {
    cat_snprintf(buf, bufsz,
                 /* TRANS: "Requires that you are not playing Classical
                  * style nation." */
                 _("Requires that you are not playing %s style nation."),
                 style_name_translation(preq->source.value.style));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_nationality(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "Requires at least one Barbarian citizen ..." */
                   _("Requires at least one %s citizen in the city or a "
                     "trade partner."),
                   nation_adjective_translation(preq->source.value.nationality));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... no Pirate citizens ..." */
                   _("Requires that there are no %s citizens in "
                     "the city or any trade partners."),
                   nation_adjective_translation(preq->source.value.nationality));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "Requires at least one Barbarian citizen ..." */
                   _("Requires at least one %s citizen in the city."),
                   nation_adjective_translation(preq->source.value.nationality));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: "... no Pirate citizens ..." */
                   _("Requires that there are no %s citizens in "
                     "the city."),
                   nation_adjective_translation(preq->source.value.nationality));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_original_owner(char *buf, size_t bufsz,
                                    struct player *pplayer,
                                    const struct requirement *preq,
                                    const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires city to be founded by %s."),
                   nation_adjective_translation(preq->source.value.origowner));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that city was not originally owned by %s."),
                   nation_adjective_translation(preq->source.value.origowner));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_diplrel(char *buf, size_t bufsz,
                             struct player *pplayer,
                             const struct requirement *preq,
                             const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: in this and following strings, '%s' can be one
                    * of a wide range of relationships; e.g., 'Peace',
                    * 'Never met', 'Foreign', 'Hosts embassy',
                    * 'Provided Casus Belli' */
                   _("Requires that you have the relationship '%s' with at "
                     "least one other living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that you do not have the relationship '%s' "
                     "with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that somebody on your team has the "
                     "relationship '%s' with at least one other living "
                     "player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that nobody on your team has the "
                     "relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that somebody in your alliance has the "
                     "relationship '%s' with at least one other living "
                     "player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that nobody in your alliance has the "
                     "relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires the relationship '%s' between two living "
                     "players."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that no two living players have the "
                     "relationship '%s'."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that you have the relationship '%s' with the "
                     "other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that you do not have the relationship '%s' "
                     "with the other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_diplrel_tile(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: in this and following strings, '%s' can be one
                    * of a wide range of relationships; e.g., 'Peace',
                    * 'Never met', 'Foreign', 'Hosts embassy',
                    * 'Provided Casus Belli' */
                   _("Requires that the tile owner has the relationship"
                     " '%s' with at least one other living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile owner does not have the"
                     " relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that somebody on the tile owner's team"
                     " has the relationship '%s' with at least one other"
                     " living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that nobody on the tile owner's team has"
                     " the relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that somebody in the tile owner's alliance"
                     " has the relationship '%s' with at least one other "
                     "living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that nobody in the tile owner's alliance "
                     "has the relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that you have the relationship '%s' with"
                     " the tile owner."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that you do not have the relationship '%s'"
                     " with the tile owner."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_diplrel_tile_o(char *buf, size_t bufsz,
                                    struct player *pplayer,
                                    const struct requirement *preq,
                                    const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile owner has the relationship"
                     " '%s' with the other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile owner does not have the"
                     " relationship '%s' with the other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_diplrel_unit_any(char *buf, size_t bufsz,
                                      struct player *pplayer,
                                      const struct requirement *preq,
                                      const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: in this and following strings, '%s' can be one
                    * of a wide range of relationships; e.g., 'Peace',
                    * 'Never met', 'Foreign', 'Hosts embassy',
                    * 'Provided Casus Belli' */
                   _("Requires that the tile has at least one unit whose "
                     "owner has the relationship "
                     "'%s' with at least one other living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that no unit at the tile is owned by a player "
                     "who has the relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile has at least one unit whose "
                     "owner is on a team where a member "
                     "has the relationship '%s' with at least one other "
                     "living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that no unit at the tile is owned by a player "
                     "who is on a team where a member "
                     "has the relationship '%s' with at least one other "
                     "living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile has at least one unit whose "
                     "owner is allied to someone that "
                     "has the relationship '%s' with at least one other "
                     "living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that no unit at the tile is owned by a player "
                     "allied to someone that "
                     "has the relationship '%s' with any living player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that you have the relationship '%s' with "
                     "the owner of at least one unit at the tile."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that you do not have the relationship '%s' "
                     "with the owner of any unit at the tile."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_diplrel_unit_any_o(char *buf, size_t bufsz,
                                        struct player *pplayer,
                                        const struct requirement *preq,
                                        const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that the tile has at least one unit whose "
                     "owner has the relationship '%s' with the other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that no unit at the tile is owned by a player "
                     "who has the relationship '%s' with the other player."),
                   diplrel_name_translation(preq->source.value.diplrel));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_utype(char *buf, size_t bufsz,
                           struct player *pplayer,
                           const struct requirement *preq,
                           const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      /* TRANS: %s is a single kind of unit (e.g., "Settlers"). */
      cat_snprintf(buf, bufsz, Q_("?unit:Requires %s."),
                   utype_name_translation(preq->source.value.utype));
    } else {
      /* TRANS: %s is a single kind of unit (e.g., "Settlers"). */
      cat_snprintf(buf, bufsz, Q_("?unit:Does not apply to %s."),
                   utype_name_translation(preq->source.value.utype));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_unitflag(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    {
      struct astring astr = ASTRING_INIT;
 
       /* Unit type flags mean nothing to users. Explicitly list the unit
       * types with those flags. */
      if (role_units_translations(&astr, preq->source.value.unitflag,
                                  TRUE)) {
        fc_strlcat(buf, prefix, bufsz);
        if (preq->present) {
          /* TRANS: %s is a list of unit types separated by "or". */
          cat_snprintf(buf, bufsz, Q_("?ulist:Requires %s."),
                       astr_str(&astr));
        } else {
          /* TRANS: %s is a list of unit types separated by "or". */
          cat_snprintf(buf, bufsz, Q_("?ulist:Does not apply to %s."),
                       astr_str(&astr));
        }
        astr_free(&astr);
        return TRUE;
      }
    }
    break;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_uclass(char *buf, size_t bufsz,
                            struct player *pplayer,
                            const struct requirement *preq,
                            const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      /* TRANS: %s is a single unit class (e.g., "Air"). */
      cat_snprintf(buf, bufsz, Q_("?uclass:Requires %s units."),
                   uclass_name_translation(preq->source.value.uclass));
    } else {
      /* TRANS: %s is a single unit class (e.g., "Air"). */
      cat_snprintf(buf, bufsz, Q_("?uclass:Does not apply to %s units."),
                   uclass_name_translation(preq->source.value.uclass));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_ucflag(char *buf, size_t bufsz,
                            struct player *pplayer,
                            const struct requirement *preq,
                            const char *prefix)
{
  const char *classes[uclass_count()];
  int i = 0;
  bool done = FALSE;
  struct astring list = ASTRING_INIT;
 
  unit_class_iterate(uclass) {
    if (uclass_has_flag(uclass, preq->source.value.unitclassflag)) {
      classes[i++] = uclass_name_translation(uclass);
    }
  } unit_class_iterate_end;
  astr_build_or_list(&list, classes, i);
 
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      /* TRANS: %s is a list of unit classes separated by "or". */
      cat_snprintf(buf, bufsz, Q_("?uclasslist:Requires %s units."),
                   astr_str(&list));
    } else {
      /* TRANS: %s is a list of unit classes separated by "or". */
      cat_snprintf(buf, bufsz, Q_("?uclasslist:Does not apply to "
                                  "%s units."),
                   astr_str(&list));
    }
    done = TRUE;
    break;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    break;
  }
  astr_free(&list);
 
  return done;
}
 
/*************************************************************/
static bool req_text_unit_state(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    switch (preq->source.value.unit_state) {
    case USP_TRANSPORTED:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit is transported."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit isn't transported."));
      }
      return TRUE;
    case USP_LIVABLE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit is on livable tile."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit isn't on livable tile."));
      }
      return TRUE;
    case USP_TRANSPORTING:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit does transport one or "
                       "more cargo units."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit doesn't transport "
                       "any cargo units."));
      }
      return TRUE;
    case USP_HAS_HOME_CITY:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit has a home city."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit is homeless."));
      }
      return TRUE;
    case USP_NATIVE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit is on native tile."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit isn't on native tile."));
      }
      return TRUE;
    case USP_NATIVE_EXTRA:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit is in a native extra."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit isn't in a native extra."));
      }
      return TRUE;
    case USP_MOVED_THIS_TURN:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit has moved this turn."));
      } else {
        cat_snprintf(buf, bufsz,
                     _("Requires that the unit hasn't moved this turn."));
      }
      return TRUE;
    case USP_COUNT:
      fc_assert_msg(preq->source.value.unit_state != USP_COUNT,
                    "Invalid unit state property.");
    }
    break;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_activity(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires that the unit is performing activity %s."),
                   Q_(unit_activity_name(preq->source.value.activity)));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Requires that the unit is not performing activity %s."),
                   Q_(unit_activity_name(preq->source.value.activity)));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_moves(char *buf, size_t bufsz,
                               struct player *pplayer,
                               const struct requirement *preq,
                               const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is numeric move points; it may have a
                    * fractional part ("1 1/3 MP"). */
                   _("Requires that the unit has at least %s MP left."),
                   move_points_text(preq->source.value.minmoves, TRUE));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is numeric move points; it may have a
                    * fractional part ("1 1/3 MP"). */
                   _("Requires that the unit has less than %s MP left."),
                   move_points_text(preq->source.value.minmoves, TRUE));
    }
    return TRUE;
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_veteran(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  if (preq->range != REQ_RANGE_LOCAL) {
    return FALSE;
  }
  /* FIXME: this would be better with veteran level names, but that's
   * potentially unit type dependent. */
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 PL_("Requires a unit with at least %d veteran level.",
                     "Requires a unit with at least %d veteran levels.",
                     preq->source.value.minveteran),
                 preq->source.value.minveteran);
  } else {
    cat_snprintf(buf, bufsz,
                 PL_("Requires a unit with fewer than %d veteran level.",
                     "Requires a unit with fewer than %d veteran levels.",
                     preq->source.value.minveteran),
                 preq->source.value.minveteran);
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_hp(char *buf, size_t bufsz,
                            struct player *pplayer,
                            const struct requirement *preq,
                            const char *prefix)
{
  if (preq->range != REQ_RANGE_LOCAL) {
    return FALSE;
  }
 
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 PL_("Requires a unit with at least %d hit point left.",
                     "Requires a unit with at least %d hit points left.",
                     preq->source.value.min_hit_points),
                 preq->source.value.min_hit_points);
  } else {
    cat_snprintf(buf, bufsz,
                 PL_("Requires a unit with fewer than %d hit point "
                     "left.",
                     "Requires a unit with fewer than %d hit points "
                     "left.",
                     preq->source.value.min_hit_points),
                 preq->source.value.min_hit_points);
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_otype(char *buf, size_t bufsz,
                           struct player *pplayer,
                           const struct requirement *preq,
                           const char *prefix)
{
  if (preq->range != REQ_RANGE_LOCAL) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    /* TRANS: "Applies only to Food." */
    cat_snprintf(buf, bufsz, Q_("?output:Applies only to %s."),
                 get_output_name(preq->source.value.outputtype));
  } else {
    /* TRANS: "Does not apply to Food." */
    cat_snprintf(buf, bufsz, Q_("?output:Does not apply to %s."),
                 get_output_name(preq->source.value.outputtype));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_specialist(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  if (preq->range != REQ_RANGE_LOCAL) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    /* TRANS: "Applies only to Scientists." */
    cat_snprintf(buf, bufsz, Q_("?specialist:Applies only to %s."),
                 specialist_plural_translation(preq->source.value.specialist));
  } else {
    /* TRANS: "Does not apply to Scientists." */
    cat_snprintf(buf, bufsz, Q_("?specialist:Does not apply to %s."),
                 specialist_plural_translation(preq->source.value.specialist));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_size(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires a minimum city size of %d for this "
                       "city or a trade partner.",
                       "Requires a minimum city size of %d for this "
                       "city or a trade partner.",
                       preq->source.value.minsize),
                   preq->source.value.minsize);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Requires the city size to be less than %d "
                       "for this city and all trade partners.",
                       "Requires the city size to be less than %d "
                       "for this city and all trade partners.",
                       preq->source.value.minsize),
                   preq->source.value.minsize);
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires a minimum city size of %d.",
                       "Requires a minimum city size of %d.",
                       preq->source.value.minsize),
                   preq->source.value.minsize);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Requires the city size to be less than %d.",
                       "Requires the city size to be less than %d.",
                       preq->source.value.minsize),
                 preq->source.value.minsize);
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_culture(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires a minimum culture of %d in the city.",
                       "Requires a minimum culture of %d in the city.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Requires the culture in the city to be less "
                       "than %d.",
                       "Requires the culture in the city to be less "
                       "than %d.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires a minimum culture of %d in this city or "
                       "a trade partner.",
                       "Requires a minimum culture of %d in this city or "
                       "a trade partner.",
                       preq->source.value.minculture),
                    preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Requires the culture in this city and all trade "
                       "partners to be less than %d.",
                       "Requires the culture in this city and all trade "
                       "partners to be less than %d.",
                       preq->source.value.minculture),
                    preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires your nation to have culture "
                       "of at least %d.",
                       "Requires your nation to have culture "
                       "of at least %d.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Prevented if your nation has culture of "
                       "%d or more.",
                       "Prevented if your nation has culture of "
                       "%d or more.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_TEAM:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires someone on your team to have culture of "
                       "at least %d.",
                       "Requires someone on your team to have culture of "
                       "at least %d.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Prevented if anyone on your team has culture of "
                       "%d or more.",
                       "Prevented if anyone on your team has culture of "
                       "%d or more.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_ALLIANCE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires someone in your current alliance to "
                       "have culture of at least %d.",
                       "Requires someone in your current alliance to "
                       "have culture of at least %d.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Prevented if anyone in your current alliance has "
                       "culture of %d or more.",
                       "Prevented if anyone in your current alliance has "
                       "culture of %d or more.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("Requires that some player has culture of at "
                       "least %d.",
                       "Requires that some player has culture of at "
                       "least %d.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("Requires that no player has culture of %d "
                       "or more.",
                       "Requires that no player has culture of %d "
                       "or more.",
                       preq->source.value.minculture),
                   preq->source.value.minculture);
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_foreign_pct(char *buf, size_t bufsz,
                                     struct player *pplayer,
                                     const struct requirement *preq,
                                     const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("At least %d%% of the citizens of the city "
                     "must be foreign."),
                   preq->source.value.minforeignpct);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Less than %d%% of the citizens of the city "
                     "must be foreign."),
                   preq->source.value.minforeignpct);
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("At least %d%% of the citizens of the city "
                     "or some trade partner must be foreign."),
                   preq->source.value.minforeignpct);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Less than %d%% of the citizens of the city "
                     "and each trade partner must be foreign."),
                    preq->source.value.minforeignpct);
    }
    return TRUE;
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_COUNT:
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_max_tile_total_units(char *buf, size_t bufsz,
                                          struct player *pplayer,
                                          const struct requirement *preq,
                                          const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("At most %d total unit may be present on the tile.",
                       "At most %d total units may be present on the tile.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("There must be more than %d total unit present on "
                       "the tile.",
                       "There must be more than %d total units present on "
                       "the tile.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("The tile or at least one cardinally adjacent tile "
                       "must have %d total unit or fewer.",
                       "The tile or at least one cardinally adjacent tile "
                       "must have %d total units or fewer.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("The tile and all cardinally adjacent tiles must "
                       "have more than %d total unit each.",
                       "The tile and all cardinally adjacent tiles must "
                       "have more than %d total units each.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("The tile or at least one adjacent tile must have "
                       "%d total unit or fewer.",
                       "The tile or at least one adjacent tile must have "
                       "%d total units or fewer.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("The tile and all adjacent tiles must have more "
                       "than %d total unit each.",
                       "The tile and all adjacent tiles must have more "
                       "than %d total units each.",
                       preq->source.value.max_tile_total_units),
                   preq->source.value.max_tile_total_units);
    }
    return TRUE;
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_max_tile_top_units(char *buf, size_t bufsz,
                                        struct player *pplayer,
                                        const struct requirement *preq,
                                        const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("At most %d untransported unit may be present on the tile.",
                       "At most %d untransported units may be present on the tile.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("There must be more than %d untransported unit present on "
                       "the tile.",
                       "There must be more than %d untransported units present on "
                       "the tile.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("The tile or at least one cardinally adjacent tile "
                       "must have %d untransporte unit or fewer.",
                       "The tile or at least one cardinally adjacent tile "
                       "must have %d untransporte units or fewer.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("The tile and all cardinally adjacent tiles must "
                       "have more than %d untransported unit each.",
                       "The tile and all cardinally adjacent tiles must "
                       "have more than %d untransported units each.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   PL_("The tile or at least one adjacent tile must have "
                       "%d untransported unit or fewer.",
                       "The tile or at least one adjacent tile must have "
                       "%d untransported units or fewer.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    } else {
      cat_snprintf(buf, bufsz,
                   PL_("The tile and all adjacent tiles must have "
                       "more than %d untransported unit each.",
                       "The tile and all adjacent tiles must have "
                       "more than %d untransported units each.",
                       preq->source.value.max_tile_top_units),
                   preq->source.value.max_tile_top_units);
    }
    return TRUE;
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_ai_level(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  if (preq->range != REQ_RANGE_PLAYER) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: AI level (e.g., "Handicapped") */
                 _("Applies to %s AI players."),
                 ai_level_translated_name(preq->source.value.ai_level));
  } else {
    cat_snprintf(buf, bufsz,
                 /* TRANS: AI level (e.g., "Cheating") */
                 _("Does not apply to %s AI players."),
                 ai_level_translated_name(preq->source.value.ai_level));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_terrain_class(char *buf, size_t bufsz,
                                   struct player *pplayer,
                                   const struct requirement *preq,
                                   const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Requires %s terrain on the tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Prevented by %s terrain on the tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Requires %s terrain on the tile or a "
                      "cardinally adjacent tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Prevented by %s terrain on the tile or "
                      "any cardinally adjacent tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Requires %s terrain on the tile or an "
                      "adjacent tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Prevented by %s terrain on the tile or "
                      "any adjacent tile."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Requires %s terrain on a tile within "
                      "the city radius."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Prevented by %s terrain on any tile "
                      "within the city radius."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Requires %s terrain on a tile within "
                      "the city radius or the city radius of a trade "
                      "partner."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a terrain class */
                   Q_("?terrainclass:Prevented by %s terrain on any tile "
                      "within the city radius or the city radius of a trade "
                      "partner."),
                   terrain_class_name_translation
                   (preq->source.value.terrainclass));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_terrain_flag(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Requires terrain with the \"%s\" flag on the tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Prevented by terrain with the \"%s\" flag on the "
                     "tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Requires terrain with the \"%s\" flag on the "
                     "tile or a cardinally adjacent tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Prevented by terrain with the \"%s\" flag on "
                     "the tile or any cardinally adjacent tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Requires terrain with the \"%s\" flag on the "
                     "tile or an adjacent tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Prevented by terrain with the \"%s\" flag on "
                     "the tile or any adjacent tile."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Requires terrain with the \"%s\" flag on a tile "
                     "within the city radius."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Prevented by terrain with the \"%s\" flag on any tile "
                     "within the city radius."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Requires terrain with the \"%s\" flag on a tile "
                     "within the city radius or the city radius of "
                     "a trade partner."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) terrain flag. */
                   _("Prevented by terrain with the \"%s\" flag on any tile "
                     "within the city radius or the city radius of "
                     "a trade partner."),
                   terrain_flag_id_translated_name(preq->source.value.terrainflag));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_road_flag(char *buf, size_t bufsz,
                               struct player *pplayer,
                               const struct requirement *preq,
                               const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Only applies to roads with the \"%s\" flag."),
                   road_flag_id_translated_name
                   (preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Does not apply to roads with the \"%s\" flag."),
                   road_flag_id_translated_name
                   (preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Requires a road with the \"%s\" flag on the tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Prevented by a road with the \"%s\" flag on the "
                     "tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Requires a road with the \"%s\" flag on the "
                     "tile or a cardinally adjacent tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Prevented by a road with the \"%s\" flag on "
                     "the tile or any cardinally adjacent tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Requires a road with the \"%s\" flag on the "
                     "tile or an adjacent tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Prevented by a road with the \"%s\" flag on "
                     "the tile or any adjacent tile."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Requires a road with the \"%s\" flag on a tile "
                     "within the city radius."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Prevented by a road with the \"%s\" flag on any tile "
                     "within the city radius."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Requires a road with the \"%s\" flag on a tile "
                     "within the city radius or the city radius of a "
                     "trade partner."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) road flag. */
                   _("Prevented by a road with the \"%s\" flag on any tile "
                     "within the city radius or the city radius of a "
                     "trade partner."),
                   road_flag_id_translated_name(preq->source.value.roadflag));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_extra_flag(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_LOCAL:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Only applies to extras with the \"%s\" flag."),
                   extra_flag_id_translated_name
                   (preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Does not apply to extras with the \"%s\" flag."),
                   extra_flag_id_translated_name
                   (preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Requires an extra with the \"%s\" flag on the tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Prevented by an extra with the \"%s\" flag on the "
                     "tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Requires an extra with the \"%s\" flag on the "
                     "tile or a cardinally adjacent tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Prevented by an extra with the \"%s\" flag on "
                     "the tile or any cardinally adjacent tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Requires an extra with the \"%s\" flag on the "
                     "tile or an adjacent tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Prevented by an extra with the \"%s\" flag on "
                     "the tile or any adjacent tile."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_CITY:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Requires an extra with the \"%s\" flag on a tile "
                     "within the city radius."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Prevented by an extra with the \"%s\" flag on any tile "
                     "within the city radius."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_TRADE_ROUTE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Requires an extra with the \"%s\" flag on a tile "
                     "within the city radius or the city radius of a "
                     "trade partner."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    } else {
      cat_snprintf(buf, bufsz,
                   /* TRANS: %s is a (translatable) extra flag. */
                   _("Prevented by an extra with the \"%s\" flag on any tile "
                     "within the city radius or the city radius of a "
                     "trade partner."),
                   extra_flag_id_translated_name(preq->source.value.extraflag));
    }
    return TRUE;
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_year(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  if (preq->range != REQ_RANGE_WORLD) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 _("Requires the game to have reached the year %s."),
                 textyear(preq->source.value.minyear));
  } else {
    cat_snprintf(buf, bufsz,
                 _("Requires that the game has not yet reached the "
                   "year %s."),
                 textyear(preq->source.value.minyear));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_cal_frag(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  if (preq->range != REQ_RANGE_WORLD) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: %s is a representation of a calendar fragment,
                  * from the ruleset. May be a bare number. */
                 _("Requires the game to have reached %s."),
                 textcalfrag(preq->source.value.mincalfrag));
  } else {
    cat_snprintf(buf, bufsz,
                 /* TRANS: %s is a representation of a calendar fragment,
                  * from the ruleset. May be a bare number. */
                 _("Requires that the game has not yet reached %s."),
                 textcalfrag(preq->source.value.mincalfrag));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_topo_property(char *buf, size_t bufsz,
                                   struct player *pplayer,
                                   const struct requirement *preq,
                                   const char *prefix)
{
  if (preq->range != REQ_RANGE_WORLD) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: topology flag name ("Hex", "ISO") */
                 _("Requires %s map."),
                 _(topo_flag_name(preq->source.value.topo_property)));
  } else {
    cat_snprintf(buf, bufsz,
                 /* TRANS: topology flag name ("Hex", "ISO") */
                 _("Prevented on %s map."),
                 _(topo_flag_name(preq->source.value.topo_property)));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_wrap_property(char *buf, size_t bufsz,
                                   struct player *pplayer,
                                   const struct requirement *preq,
                                   const char *prefix)
{
  if (preq->range != REQ_RANGE_WORLD) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 /* TRANS: wrap flag name ("WrapX", "WrapY") */
                 _("Requires %s map."),
                 _(wrap_flag_name(preq->source.value.wrap_property)));
  } else {
    cat_snprintf(buf, bufsz,
                 /* TRANS: wrap flag name ("WrapX", "WrapY") */
                 _("Prevented on %s map."),
                 _(wrap_flag_name(preq->source.value.wrap_property)));
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_server_setting(char *buf, size_t bufsz,
                                    struct player *pplayer,
                                    const struct requirement *preq,
                                    const char *prefix)
{
  if (preq->range != REQ_RANGE_WORLD) {
    return FALSE;
  }
  fc_strlcat(buf, prefix, bufsz);
  cat_snprintf(buf, bufsz,
               /* TRANS: %s is a server setting, its value and if it is
                * required to be present or absent. The string's format
                * is specified in ssetv_human_readable().
                * Example: "killstack is enabled". */
               _("Requires that the server setting %s."),
               ssetv_human_readable(preq->source.value.ssetval,
                                    preq->present));
  return TRUE;
}
 
/*************************************************************/
static bool req_text_age(char *buf, size_t bufsz,
                         struct player *pplayer,
                         const struct requirement *preq,
                         const char *prefix)
{
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 _("Requires age of %d turns."),
                 preq->source.value.age);
  } else {
    cat_snprintf(buf, bufsz,
                 _("Prevented if age is over %d turns."),
                 preq->source.value.age);
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_form_age(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  fc_strlcat(buf, prefix, bufsz);
  if (preq->present) {
    cat_snprintf(buf, bufsz,
                 _("Requires form age of %d turns."),
                 preq->source.value.form_age);
  } else {
    cat_snprintf(buf, bufsz,
                 _("Prevented if form age is over %d turns."),
                 preq->source.value.form_age);
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_techs(char *buf, size_t bufsz,
                               struct player *pplayer,
                               const struct requirement *preq,
                               const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires %d techs to be known in the world."),
                   preq->source.value.min_techs);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented when %d techs are known in the world."),
                   preq->source.value.min_techs);
    }
    return TRUE;
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires player to know %d techs."),
                   preq->source.value.min_techs);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented when player knows %d techs."),
                   preq->source.value.min_techs);
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_future_techs(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires %d future techs to be known in the world."),
                   preq->source.value.future_techs);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented when %d future techs are known in the world."),
                   preq->source.value.future_techs);
    }
    return TRUE;
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires player to know %d future techs."),
                   preq->source.value.future_techs);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented when player knows %d future techs."),
                   preq->source.value.future_techs);
    }
    return TRUE;
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_cities(char *buf, size_t bufsz,
                                struct player *pplayer,
                                const struct requirement *preq,
                                const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_PLAYER:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires player to have at least %d cities."),
                   preq->source.value.min_cities);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented when player has at least %d cities."),
                   preq->source.value.min_cities);
    }
    return TRUE;
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_terrain_alter(char *buf, size_t bufsz,
                                   struct player *pplayer,
                                   const struct requirement *preq,
                                   const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Requires terrain on which alteration %s is "
                     "possible."),
                   Q_(terrain_alteration_name(preq->source.value.terrainalter)));
    } else {
      cat_snprintf(buf, bufsz,
                   _("Prevented by terrain on which alteration %s "
                     "can be made."),
                   Q_(terrain_alteration_name(preq->source.value.terrainalter)));
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_city_tile(char *buf, size_t bufsz,
                               struct player *pplayer,
                               const struct requirement *preq,
                               const char *prefix)
{
  if (preq->source.value.citytile == CITYT_LAST) {
    return FALSE;
  } else {
    static char *tile_property = nullptr;
 
    switch (preq->source.value.citytile) {
    case CITYT_CENTER:
      tile_property = _("city centers");
      break;
    case CITYT_CLAIMED:
      tile_property = _("claimed tiles");
      break;
    case CITYT_EXTRAS_OWNED:
      tile_property = _("owned extras");
      break;
    case CITYT_WORKED:
      tile_property = _("worked tiles");
      break;
    case CITYT_SAME_CONTINENT:
      /* TRANS: a specific city for each use case */
      tile_property = _("tiles on the same continent as the city");
      break;
    case CITYT_BORDERING_TCLASS_REGION:
      {
        bool oceanic_cities = FALSE; /* FIXME: maybe cache globally? */
 
        terrain_type_iterate(tt) {
          if (terrain_type_terrain_class(tt) == TC_OCEAN
              && !terrain_has_flag(tt, TER_NO_CITIES)) {
            oceanic_cities = TRUE;
            /* TRANS: a specific city for each use case */
            tile_property = _("tiles of a mass of a different "
                              "terrain class next to the city");
            break;
          }
        } terrain_type_iterate_end;
        if (oceanic_cities) {
          break;
        }
        /* TRANS: a specific city for each use case */
        tile_property = _("tiles of a body of water next to the city");
      }
      break;
    case CITYT_LAST:
      fc_assert(preq->source.value.citytile != CITYT_LAST);
      break;
    }
 
    switch (preq->range) {
    case REQ_RANGE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                     /* TRANS: tile property ("city centers", etc) */
                     Q_("?tileprop:Applies only to %s."), tile_property);
      } else {
        cat_snprintf(buf, bufsz,
                     /* TRANS: tile property ("city centers", etc) */
                     Q_("?tileprop:Does not apply to %s."), tile_property);
      }
      return TRUE;
    case REQ_RANGE_CADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        /* TRANS: tile property ("city centers", etc) */
        cat_snprintf(buf, bufsz, Q_("?tileprop:Applies only to %s and "
                                    "cardinally adjacent tiles."),
                     tile_property);
      } else {
        /* TRANS: tile property ("city centers", etc) */
        cat_snprintf(buf, bufsz, Q_("?tileprop:Does not apply to %s or "
                                    "cardinally adjacent tiles."),
                     tile_property);
      }
      return TRUE;
    case REQ_RANGE_ADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        /* TRANS: tile property ("city centers", etc) */
        cat_snprintf(buf, bufsz, Q_("?tileprop:Applies only to %s and "
                                    "adjacent tiles."), tile_property);
      } else {
        /* TRANS: tile property ("city centers", etc) */
        cat_snprintf(buf, bufsz, Q_("?tileprop:Does not apply to %s or "
                                    "adjacent tiles."), tile_property);
      }
      return TRUE;
    case REQ_RANGE_CITY:
    case REQ_RANGE_TRADE_ROUTE:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_city_status(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  if (preq->source.value.citystatus != CITYS_LAST) {
    static char *city_property = nullptr;
 
    switch (preq->source.value.citystatus) {
    case CITYS_OWNED_BY_ORIGINAL:
      city_property = _("owned by original");
      break;
    case CITYS_STARVED:
      city_property = _("starved");
      break;
    case CITYS_DISORDER:
      city_property = _("disorder");
      break;
    case CITYS_CELEBRATION:
      city_property = _("celebration");
      break;
    case CITYS_TRANSFERRED:
      city_property = _("transferred");
      break;
    case CITYS_CAPITALCONNECTED:
      city_property = _("capitalconnected");
      break;
    case CITYS_LAST:
      fc_assert(preq->source.value.citystatus != CITYS_LAST);
      break;
    }
 
    switch (preq->range) {
    case REQ_RANGE_CITY:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        /* TRANS: city property ("owned by original", etc) */
        cat_snprintf(buf, bufsz, Q_("?cityprop:Applies only to %s cities."),
                     city_property);
      } else {
        /* TRANS: city property ("owned by original", etc) */
        cat_snprintf(buf, bufsz, Q_("?cityprop:Does not apply to %s cities."),
                     city_property);
      }
      return TRUE;
    case REQ_RANGE_TRADE_ROUTE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        /* TRANS: city property ("owned by original", etc) */
        cat_snprintf(buf, bufsz, Q_("?cityprop:Applies only to %s cities or "
                                    "their trade partners."), city_property);
      } else {
        /* TRANS: city property ("owned by original", etc) */
        cat_snprintf(buf, bufsz, Q_("?cityprop:Does not apply to %s cities or "
                                    "their trade partners."), city_property);
      }
      return TRUE;
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_TILE:
    case REQ_RANGE_ADJACENT:
    case REQ_RANGE_CADJACENT:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_min_latitude(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Some part of the world must be at latitude %d or "
                     "further north."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("The entire world must be at latitude %d or "
                     "further south."),
                   preq->source.value.latitude - 1);
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Tile must be at latitude %d or further north."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Tile must be at latitude %d or further south."),
                   preq->source.value.latitude - 1);
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("A cardinally adjacent tile must be at latitude "
                     "%d or further north."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("All cardinally adjacent tiles must be at latitude "
                     "%d or further south."),
                   preq->source.value.latitude - 1);
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("An adjacent tile must be at latitude %d or "
                     "further north."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("All adjacent tiles must be at latitude %d or "
                     "further south."),
                   preq->source.value.latitude - 1);
    }
    return TRUE;
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_max_latitude(char *buf, size_t bufsz,
                                  struct player *pplayer,
                                  const struct requirement *preq,
                                  const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_WORLD:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Some part of the world must be at latitude %d or "
                     "further south."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("The entire world must be at latitude %d or "
                     "further north."),
                   preq->source.value.latitude + 1);
    }
    return TRUE;
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("Tile must be at latitude %d or further south."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("Tile must be at latitude %d or further north."),
                   preq->source.value.latitude + 1);
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("A cardinally adjacent tile must be at latitude "
                     "%d or further south."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("All cardinally adjacent tiles must be at latitude "
                     "%d or further north."),
                   preq->source.value.latitude + 1);
    }
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                   _("An adjacent tile must be at latitude %d or "
                     "further south."),
                   preq->source.value.latitude);
    } else {
      cat_snprintf(buf, bufsz,
                   _("All adjacent tiles must be at latitude %d or "
                     "further north."),
                   preq->source.value.latitude + 1);
    }
    return TRUE;
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_distance_sq(char *buf, size_t bufsz,
                                 struct player *pplayer,
                                 const struct requirement *preq,
                                 const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_TILE:
    fc_strlcat(buf, prefix, bufsz);
    /* Test some special cases */
    switch (preq->source.value.distance_sq)
    {
    case 0:
      if (preq->present) {
        fc_strlcat(buf, _("Must be the same tile."), bufsz);
      } else {
        fc_strlcat(buf, _("Must not be the same tile."), bufsz);
      }
      break;
    case 1:
      if (preq->present) {
        fc_strlcat(buf, _("Must be cardinally adjacent."), bufsz);
      } else {
        fc_strlcat(buf, _("Must not be cardinally adjacent."), bufsz);
      }
      break;
    case 2:
    case 3:
      if (preq->present) {
        fc_strlcat(buf, _("Must be adjacent."), bufsz);
      } else {
        fc_strlcat(buf, _("Must not be adjacent."), bufsz);
      }
      break;
 
    default:
      if (preq->present) {
        cat_snprintf(buf, bufsz,
                    _("The squared distance between the tiles "
                      "must be at most %d."),
                    preq->source.value.distance_sq);
      } else {
        cat_snprintf(buf, bufsz,
                    _("The squared distance between the tiles "
                      "must be at least %d."),
                    preq->source.value.distance_sq + 1);
      }
      break;
    }
    return TRUE;
  case REQ_RANGE_CADJACENT:
  case REQ_RANGE_ADJACENT:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_CONTINENT:
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_max_region_tiles(char *buf, size_t bufsz,
                                      struct player *pplayer,
                                      const struct requirement *preq,
                                      const char *prefix)
{
  switch (preq->range) {
  case REQ_RANGE_CADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    /* Off-by-one: The requirement counts the tile itself, we're phrasing
     * the helptext in terms of *other* tiles only. */
    if (preq->present) {
      if (preq->source.value.region_tiles == 1) {
        /* Special case for zero */
        fc_strlcat(buf,
                   _("No other cardinally adjacent tile may be part of "
                     "the same continent or ocean."),
                   bufsz);
      } else {
        cat_snprintf(buf, bufsz,
                    PL_("No more than %d other cardinally adjacent tile "
                        "may be part of the same continent or ocean.",
                        "No more than %d other cardinally adjacent tiles "
                        "may be part of the same continent or ocean.",
                        preq->source.value.region_tiles - 1),
                    preq->source.value.region_tiles - 1);
      }
    } else {
      cat_snprintf(buf, bufsz,
                  PL_("Requires at least %d other cardinally adjacent "
                      "tile of the same continent or ocean.",
                      "Requires at least %d other cardinally adjacent "
                      "tiles of the same continent or ocean.",
                      preq->source.value.region_tiles),
                  preq->source.value.region_tiles);
    }
 
    return TRUE;
  case REQ_RANGE_ADJACENT:
    fc_strlcat(buf, prefix, bufsz);
    /* Off-by-one: The requirement counts the tile itself, we're phrasing
     * the helptext in terms of *other* tiles only. */
    if (preq->present) {
      if (preq->source.value.region_tiles == 1) {
        /* Special case for zero */
        fc_strlcat(buf,
                   _("No other adjacent tile may be part of the same "
                     "continent or ocean."),
                   bufsz);
      } else {
        cat_snprintf(buf, bufsz,
                    PL_("No more than %d other adjacent tile may be "
                        "part of the same continent or ocean.",
                        "No more than %d other adjacent tiles may be "
                        "part of the same continent or ocean.",
                        preq->source.value.region_tiles - 1),
                    preq->source.value.region_tiles - 1);
      }
    } else {
      cat_snprintf(buf, bufsz,
                  PL_("Requires at least %d other adjacent tile of the "
                      "same continent or ocean.",
                      "Requires at least %d other adjacent tiles of the "
                      "same continent or ocean.",
                      preq->source.value.region_tiles),
                  preq->source.value.region_tiles);
    }
 
    return TRUE;
  case REQ_RANGE_CONTINENT:
    fc_strlcat(buf, prefix, bufsz);
    if (preq->present) {
      cat_snprintf(buf, bufsz,
                  _("Requires a continent or ocean size of at most %d."),
                  preq->source.value.region_tiles);
    } else {
      cat_snprintf(buf, bufsz,
                  _("Requires a continent or ocean size of at least %d."),
                  preq->source.value.region_tiles + 1);
    }
 
    return TRUE;
  case REQ_RANGE_PLAYER:
  case REQ_RANGE_TEAM:
  case REQ_RANGE_ALLIANCE:
  case REQ_RANGE_WORLD:
  case REQ_RANGE_LOCAL:
  case REQ_RANGE_TILE:
  case REQ_RANGE_CITY:
  case REQ_RANGE_TRADE_ROUTE:
  case REQ_RANGE_COUNT:
    /* Not supported. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
static bool req_text_tile_rel(char *buf, size_t bufsz,
                              struct player *pplayer,
                              const struct requirement *preq,
                              const char *prefix)
{
  switch (preq->source.value.tilerel) {
  case TREL_SAME_TCLASS:
    switch (preq->range) {
    case REQ_RANGE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be on the same terrain class."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must be on a different terrain class."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be cardinally adjacent to the same "
                          "terrain class."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be cardinally adjacent to the same "
                          "terrain class."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_ADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be adjacent to the same terrain class."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be adjacent to the same terrain "
                          "class."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CITY:
    case REQ_RANGE_TRADE_ROUTE:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
    break;
  case TREL_SAME_REGION:
    switch (preq->range) {
    case REQ_RANGE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be on the same continent or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must be on a different continent or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be cardinally adjacent to the same "
                          "continent or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be cardinally adjacent to the same "
                          "continent or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_ADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be adjacent to the same continent or "
                          "ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be adjacent to the same continent "
                          "or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CITY:
    case REQ_RANGE_TRADE_ROUTE:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
    break;
  case TREL_ONLY_OTHER_REGION:
    switch (preq->range) {
    case REQ_RANGE_CADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("May only be cardinally adjacent to this "
                          "other continent or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must be cardinally adjacent to more than "
                          "just this other continent or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_ADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("May only be adjacent to this other continent "
                          "or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must be adjacent to more than just this "
                          "other continent or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CITY:
    case REQ_RANGE_TRADE_ROUTE:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_TILE:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
    break;
  case TREL_REGION_SURROUNDED:
    switch (preq->range) {
    case REQ_RANGE_TILE:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be on a lake or island surrounded by "
                          "this continent or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be on a lake or island surrounded "
                          "by this continent or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be on or cardinally adjacent to a lake "
                          "or island surrounded by this continent or "
                          "ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be on nor cardinally adjacent to a "
                          "lake or island surrounded by this continent "
                          "or ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_ADJACENT:
      fc_strlcat(buf, prefix, bufsz);
      if (preq->present) {
        fc_strlcat(buf, _("Must be on or adjacent to a lake or island "
                          "surrounded by this continent or ocean."),
                   bufsz);
      } else {
        fc_strlcat(buf, _("Must not be on nor adjacent to a lake or "
                          "island surrounded by this continent or "
                          "ocean."),
                   bufsz);
      }
      return TRUE;
    case REQ_RANGE_CITY:
    case REQ_RANGE_TRADE_ROUTE:
    case REQ_RANGE_CONTINENT:
    case REQ_RANGE_PLAYER:
    case REQ_RANGE_TEAM:
    case REQ_RANGE_ALLIANCE:
    case REQ_RANGE_WORLD:
    case REQ_RANGE_LOCAL:
    case REQ_RANGE_COUNT:
      /* Not supported. */
      return FALSE;
    }
    break;
 
  case TREL_COUNT:
    /* Invalid. */
    return FALSE;
  }
  return TRUE;
}
 
/*************************************************************/
bool req_text_insert(char *buf, size_t bufsz, struct player *pplayer,
                     const struct requirement *preq,
                     enum rt_verbosity verb, const char *prefix)
{
  if (preq->quiet && verb != VERB_ACTUAL) {
    return FALSE;
  }
 
  switch (preq->source.kind) {
  case VUT_NONE:
    return FALSE;
 
  case VUT_COUNTER:
    return req_text_counter(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ADVANCE:
    return req_text_advance(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TECHFLAG:
    return req_text_techflag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_GOVERNMENT:
    return req_text_government(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_GOVFLAG:
    return req_text_government_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ACHIEVEMENT:
    return req_text_achievement(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ACTION:
    return req_text_action(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_IMPR_GENUS:
    return req_text_impr_genus(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_IMPR_FLAG:
    return req_text_impr_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_PLAYER_FLAG:
    return req_text_player_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_PLAYER_STATE:
    return req_text_player_state(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_IMPROVEMENT:
  case VUT_SITE:
    return req_text_improvement(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_EXTRA:
    return req_text_extra(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TILEDEF:
    return req_text_tiledef(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_GOOD:
    return req_text_good(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TERRAIN:
    return req_text_terrain(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_NATION:
    return req_text_nation(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_NATIONGROUP:
    return req_text_nation_group(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_STYLE:
    return req_text_style(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_NATIONALITY:
    return req_text_nationality(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ORIGINAL_OWNER:
    return req_text_original_owner(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_DIPLREL:
    return req_text_diplrel(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_DIPLREL_TILE:
    return req_text_diplrel_tile(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_DIPLREL_TILE_O:
    return req_text_diplrel_tile_o(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_DIPLREL_UNITANY:
    return req_text_diplrel_unit_any(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_DIPLREL_UNITANY_O:
    return req_text_diplrel_unit_any_o(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_UTYPE:
    return req_text_utype(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_UTFLAG:
    return req_text_unitflag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_UCLASS:
    return req_text_uclass(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_UCFLAG:
    return req_text_ucflag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_UNITSTATE:
    return req_text_unit_state(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ACTIVITY:
    return req_text_activity(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINMOVES:
    return req_text_min_moves(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINVETERAN:
    return req_text_min_veteran(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINHP:
    return req_text_min_hp(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_OTYPE:
    return req_text_otype(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_SPECIALIST:
    return req_text_specialist(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINSIZE:
    return req_text_min_size(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINCULTURE:
    return req_text_min_culture(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINFOREIGNPCT:
    return req_text_min_foreign_pct(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MAXTILETOTALUNITS:
    return req_text_max_tile_total_units(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MAXTILETOPUNITS:
    return req_text_max_tile_top_units(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_AI_LEVEL:
    return req_text_ai_level(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TERRAINCLASS:
    return req_text_terrain_class(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TERRFLAG:
    return req_text_terrain_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_ROADFLAG:
    return req_text_road_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_EXTRAFLAG:
    return req_text_extra_flag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINYEAR:
    return req_text_min_year(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINCALFRAG:
    return req_text_min_cal_frag(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TOPO:
    return req_text_topo_property(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_WRAP:
    return req_text_wrap_property(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_SERVERSETTING:
    return req_text_server_setting(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_AGE:
    return req_text_age(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_FORM_AGE:
    return req_text_form_age(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINTECHS:
    return req_text_min_techs(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_FUTURETECHS:
    return req_text_future_techs(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINCITIES:
    return req_text_min_cities(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TERRAINALTER:
    return req_text_terrain_alter(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_CITYTILE:
    return req_text_city_tile(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_CITYSTATUS:
    return req_text_city_status(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MINLATITUDE:
    return req_text_min_latitude(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MAXLATITUDE:
    return req_text_max_latitude(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MAX_DISTANCE_SQ:
    return req_text_distance_sq(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_MAX_REGION_TILES:
    return req_text_max_region_tiles(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_TILE_REL:
    return req_text_tile_rel(buf, bufsz, pplayer, preq, prefix);
 
  case VUT_COUNT:
    break;
  }
 
  if (verb == VERB_DEFAULT) {
    char text[256];
 
    log_error("%s requirement %s in range %d is not supported in reqtext.c.",
              preq->present ? "Present" : "Absent",
              universal_name_translation(&preq->source, text, sizeof(text)),
              preq->range);
  }
 
  return FALSE;
}
 
/*************************************************************/
bool req_text_insert_nl(char *buf, size_t bufsz, struct player *pplayer,
                        const struct requirement *preq,
                        enum rt_verbosity verb, const char *prefix)
{
  if (req_text_insert(buf, bufsz, pplayer, preq, verb, prefix)) {
    fc_strlcat(buf, "\n", bufsz);
 
    return TRUE;
  }
 
  return FALSE;
}