effects.c

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/***********************************************************************
 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
 
#include <ctype.h>
#include <string.h>
 
/* utility */
#include "astring.h"
#include "fcintl.h"
#include "log.h"
#include "mem.h"
#include "support.h"
#include "shared.h" /* ARRAY_SIZE */
#include "string_vector.h"
 
/* common */
#include "city.h"
#include "game.h"
#include "government.h"
#include "improvement.h"
#include "map.h"
#include "packets.h"
#include "player.h"
#include "tech.h"
 
#include "effects.h"
 
 
static bool initialized = FALSE;
 
struct user_effect {
  enum effect_type ai_value_as;
};
 
struct user_effect ueffects[EFT_USER_EFFECT_LAST + 1 - EFT_USER_EFFECT_1];
 
/**************************************************************************
  The code creates a ruleset cache on ruleset load. This constant cache
  is used to speed up effects queries. After the cache is created it is
  not modified again (though it may later be freed).
 
  Since the cache is constant, the server only needs to send effects data to
  the client upon connect. It also means that an AI can do fast searches in
  the effects space by trying the possible combinations of addition or
  removal of buildings with the effects it cares about.
 
 
  To know how much a target is being affected, simply use the convenience
  functions:
 
  * get_world_bonus()
  * get_player_bonus()
  * get_player_output_bonus()
  * get_city_bonus()
  * get_city_output_bonus()
  * get_city_tile_output_bonus()
  * get_city_specialist_output_bonus()
  * get_tile_bonus()
  * get_tile_output_bonus()
  * get_building_bonus()
  * get_unittype_bonus()
  * get_unit_bonus()
  * get_unit_vs_tile_bonus()
 
  These functions require as arguments the target and the effect type to be
  queried.
 
  Effect sources are unique and at a well known place in the
  data structures. This allows the above queries to be fast:
    - Look up the possible sources for the effect (O(1) lookup)
    - For each source, find out if it is present (O(1) lookup per source).
  The first is commonly called the "ruleset cache" and is stored statically
  in this file. The second is the "sources cache" and is stored all over.
 
  Any type of effect range and "survives" is possible if we have a sources
  cache for that combination. For instance
    - There is a sources cache of all existing buildings in a city; thus any
      building effect in a city can have city range.
    - There is a sources cache of all wonders in the world; thus any wonder
      effect can have world range.
    - There is a sources cache of all wonders for each player; thus any
      wonder effect can have player range.
    - There is a sources cache of all wonders ever built; thus any wonder
      effect that survives can have world range.
  However there is no sources cache for many of the possible sources. For
  instance non-unique buildings do not have a world-range sources cache, so
  you can't have a non-wonder building have a world-ranged effect.
 
  The sources caches could easily be extended by generalizing it to a set
  of arrays
    game.buildings[], pplayer->buildings[],
    pisland->buildings[], pcity->buildings[]
  which would store the number of buildings of that type present by game,
  player, island (continent) or city. This would allow non-surviving effects
  to come from any building at any range. However to allow surviving effects
  a second set of arrays would be needed. This should enable basic support
  for small wonders and satellites.
 
  No matter which sources caches are present, we should always know where
  to look for a source and so the lookups will always be fast even as the
  number of possible sources increases.
**************************************************************************/
 
/**************************************************************************
  Ruleset cache. The cache is created during ruleset loading and the data
  is organized to enable fast queries.
**************************************************************************/
static struct {
  /* A single list containing every effect. */
  struct effect_list *tracker;
 
  /* This array provides a full list of the effects of this type
   * (It's not really a cache, it's the real data.) */
  struct effect_list *effects[EFT_COUNT];
 
  struct {
    /* This cache shows for each building, which effects it provides. */
    struct effect_list *buildings[B_LAST];
    /* Same for governments */
    struct effect_list *govs[G_LAST];
    /* ...advances... */
    struct effect_list *advances[A_LAST];
  } reqs;
} ruleset_cache;
 
 
/**********************************************************************/
struct effect_list *get_effects(enum effect_type effect_type)
{
  return ruleset_cache.effects[effect_type];
}
 
/**********************************************************************/
struct effect_list *get_req_source_effects(const struct universal *psource)
{
  int type, value;
 
  universal_extraction(psource, &type, &value);
 
  switch (type) {
  case VUT_GOVERNMENT:
    if (value >= 0 && value < government_count()) {
      return ruleset_cache.reqs.govs[value];
    } else {
      return NULL;
    }
  case VUT_IMPROVEMENT:
    if (value >= 0 && value < improvement_count()) {
      return ruleset_cache.reqs.buildings[value];
    } else {
      return NULL;
    }
  case VUT_ADVANCE:
    if (value >= 0 && value < advance_count()) {
      return ruleset_cache.reqs.advances[value];
    } else {
      return NULL;
    }
  default:
    return NULL;
  }
}
 
/**********************************************************************/
struct effect *effect_new(enum effect_type type, int value,
                          struct multiplier *pmul)
{
  struct effect *peffect;
 
  /* Create the effect. */
  peffect = fc_malloc(sizeof(*peffect));
  peffect->type = type;
  peffect->value = value;
  peffect->multiplier = pmul;
 
  requirement_vector_init(&peffect->reqs);
 
  /* Now add the effect to the ruleset cache. */
  effect_list_append(ruleset_cache.tracker, peffect);
  effect_list_append(get_effects(type), peffect);
 
  /* Only relevant for ruledit and other rulesave users. */
  peffect->rulesave.do_not_save = FALSE;
  peffect->rulesave.comment = NULL;
 
  return peffect;
}
 
/**********************************************************************/
void effect_free(struct effect *peffect)
{
  requirement_vector_free(&peffect->reqs);
  if (peffect->rulesave.comment != NULL) {
    free(peffect->rulesave.comment);
  }
  free(peffect);
}
 
/**********************************************************************/
void effect_remove(struct effect *peffect)
{
  effect_list_remove(ruleset_cache.tracker, peffect);
  effect_list_remove(get_effects(peffect->type), peffect);
}
 
/**********************************************************************/
struct effect *effect_copy(struct effect *old,
                           enum effect_type override_type)
{
  struct effect *new_eff;
  enum effect_type type = (effect_type_is_valid(override_type)
                           ? override_type
                           : old->type);
 
  new_eff = effect_new(type, old->value, old->multiplier);
 
  requirement_vector_iterate(&old->reqs, preq) {
    effect_req_append(new_eff, *preq);
  } requirement_vector_iterate_end;
 
  return new_eff;
}
 
/**********************************************************************/
void effect_req_append(struct effect *peffect, struct requirement req)
{
  struct effect_list *eff_list = get_req_source_effects(&req.source);
 
  requirement_vector_append(&peffect->reqs, req);
 
  if (eff_list != NULL) {
    effect_list_append(eff_list, peffect);
  }
 
  if (req.source.kind == VUT_IMPR_FLAG) {
    improvement_iterate(impr) {
      if (improvement_has_flag(impr, req.source.value.impr_flag)) {
        eff_list = get_req_source_effects(&(const struct universal) {
                                            .kind = VUT_IMPROVEMENT,
                                            .value.building = impr
                                          });
 
        if (eff_list != NULL) {
          effect_list_append(eff_list, peffect);
        }
      }
    } improvement_iterate_end;
  }
}
 
/**********************************************************************/
void ruleset_cache_init(void)
{
  int i;
 
  initialized = TRUE;
 
  ruleset_cache.tracker = effect_list_new();
 
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.effects); i++) {
    ruleset_cache.effects[i] = effect_list_new();
  }
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.buildings); i++) {
    ruleset_cache.reqs.buildings[i] = effect_list_new();
  }
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.govs); i++) {
    ruleset_cache.reqs.govs[i] = effect_list_new();
  }
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.advances); i++) {
    ruleset_cache.reqs.advances[i] = effect_list_new();
  }
 
  /* By default, user effects are valued as themselves
   * (currently meaning that they get no value at all) */
  for (i = EFT_USER_EFFECT_1 ; i <= EFT_USER_EFFECT_LAST; i++) {
    ueffects[USER_EFFECT_NUMBER(i)].ai_value_as = i;
  }
}
 
/**********************************************************************/
void ruleset_cache_free(void)
{
  int i;
  struct effect_list *tracker_list = ruleset_cache.tracker;
 
  if (tracker_list) {
    effect_list_iterate(tracker_list, peffect) {
      effect_free(peffect);
    } effect_list_iterate_end;
    effect_list_destroy(tracker_list);
    ruleset_cache.tracker = NULL;
  }
 
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.effects); i++) {
    struct effect_list *plist = ruleset_cache.effects[i];
 
    if (plist) {
      effect_list_destroy(plist);
      ruleset_cache.effects[i] = NULL;
    }
  }
 
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.buildings); i++) {
    struct effect_list *plist = ruleset_cache.reqs.buildings[i];
 
    if (plist) {
      effect_list_destroy(plist);
      ruleset_cache.reqs.buildings[i] = NULL;
    }
  }
 
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.govs); i++) {
    struct effect_list *plist = ruleset_cache.reqs.govs[i];
 
    if (plist) {
      effect_list_destroy(plist);
      ruleset_cache.reqs.govs[i] = NULL;
    }
  }
 
  for (i = 0; i < ARRAY_SIZE(ruleset_cache.reqs.advances); i++) {
    struct effect_list *plist = ruleset_cache.reqs.advances[i];
 
    if (plist) {
      effect_list_destroy(plist);
      ruleset_cache.reqs.advances[i] = NULL;
    }
  }
 
  initialized = FALSE;
}
 
/**********************************************************************/
int effect_cumulative_max(enum effect_type type, struct universal *unis,
                          size_t n_unis)
{
  struct effect_list *plist = ruleset_cache.tracker;
  int value = 0;
 
  fc_assert_ret_val(((unis == NULL && n_unis == 0)
                     || (unis != NULL && n_unis > 0)),
                    0);
 
  if (plist) {
    effect_list_iterate(plist, peffect) {
      if (peffect->type == type) {
        if (peffect->value > 0) {
          if (unis == NULL
              || !universals_mean_unfulfilled(&(peffect->reqs), unis, n_unis)) {
            value += peffect->value;
          }
        } else if (requirement_vector_size(&peffect->reqs) == 0) {
          /* Always active negative effect */
          value += peffect->value;
        }
      }
    } effect_list_iterate_end;
  }
 
  return value;
}
 
/**********************************************************************/
int effect_cumulative_min(enum effect_type type, struct universal *for_uni)
{
  struct effect_list *plist = ruleset_cache.tracker;
  int value = 0;
 
  if (plist) {
    effect_list_iterate(plist, peffect) {
      if (peffect->type == type) {
        if (peffect->value < 0) {
          if (for_uni == NULL
              || universal_fulfills_requirements(FALSE, &(peffect->reqs),
                                                 for_uni)) {
            value += peffect->value;
          }
        } else if (requirement_vector_size(&peffect->reqs) == 0) {
          /* Always active positive effect */
          value += peffect->value;
        }
      }
    } effect_list_iterate_end;
  }
 
  return value;
}
 
/**********************************************************************/
int effect_value_from_universals(enum effect_type type,
                                 struct universal *unis, size_t n_unis)
{
  int value = 0;
  struct effect_list *el = get_effects(type);
 
  effect_list_iterate(el, peffect) {
    bool effect_applies = TRUE;
    bool first_source_mentioned = FALSE;
 
    if (peffect->multiplier) {
      /* Discount any effects with multipliers; we are looking for constant
       * effects */
      continue;
    }
 
    requirement_vector_iterate(&(peffect->reqs), preq) {
      int i;
      bool req_mentioned_a_source = FALSE;
 
      for (i = 0; effect_applies && i < n_unis; i++) {
        switch (universal_fulfills_requirement(preq, &(unis[i]))) {
        case ITF_NOT_APPLICABLE:
          /* This req not applicable to this source (but might be relevant
           * to another source in our template). Keep looking. */
          break;
        case ITF_NO:
          req_mentioned_a_source = TRUE; /* this req matched this source */
          if (preq->present) {
            /* Requirement contradicts template. Effect doesn't apply. */
            effect_applies = FALSE;
          } /* but negative req doesn't count for first_source_mentioned */
          break;
        case ITF_YES:
          req_mentioned_a_source = TRUE; /* this req matched this source */
          if (preq->present) {
            if (i == 0) {
              first_source_mentioned = TRUE;
            }
            /* keep looking */
          } else /* !present */ {
            /* Requirement contradicts template. Effect doesn't apply. */
            effect_applies = FALSE;
          }
          break;
        }
      }
      if (!req_mentioned_a_source) {
        /* This requirement isn't relevant to any source in our template,
         * so it's an extra condition and the effect should be ignored. */
        effect_applies = FALSE;
      }
      if (!effect_applies) {
        /* Already known to be irrelevant, bail out early */
        break;
      }
    } requirement_vector_iterate_end;
 
    if (!first_source_mentioned) {
      /* First source not positively mentioned anywhere in requirements,
       * so ignore this effect */
      continue;
    }
    if (effect_applies) {
      value += peffect->value;
    }
  } effect_list_iterate_end;
 
  return value;
}
 
/**********************************************************************/
bool effect_universals_value_never_below(enum effect_type type,
                                         struct universal *unis,
                                         size_t n_unis,
                                         int min_value)
{
  int guaranteed_min_effect_value = 0;
 
  effect_list_iterate(get_effects(type), peffect) {
    if (universals_mean_unfulfilled(&peffect->reqs, unis, n_unis)) {
      /* Not relevant. */
      continue;
    }
 
    if (peffect->multiplier) {
      /* Multipliers may change during the game. */
      return FALSE;
    }
 
    if (universals_say_everything(&peffect->reqs, unis, n_unis)) {
      /* This value is guaranteed to be there since the universals alone
       * fulfill all the requirements in the vector. */
      guaranteed_min_effect_value += peffect->value;
    } else if (peffect->value < 0) {
      /* Can't be ignored. It may apply. It subtracts. */
      guaranteed_min_effect_value += peffect->value;
    }
  } effect_list_iterate_end;
 
  /* The value of this effect type is never below the guaranteed
   * minimum. */
  return guaranteed_min_effect_value >= min_value;
}
 
/**********************************************************************/
int effect_value_will_make_positive(enum effect_type type)
{
  return 1 + (effect_cumulative_min(type, NULL) * -1);
}
 
/**********************************************************************/
void recv_ruleset_effect(const struct packet_ruleset_effect *packet)
{
  struct effect *peffect;
  struct multiplier *pmul;
  int i;
 
  pmul = packet->has_multiplier ? multiplier_by_number(packet->multiplier)
                                : NULL;
  peffect = effect_new(packet->effect_type, packet->effect_value, pmul);
 
  for (i = 0; i < packet->reqs_count; i++) {
    effect_req_append(peffect, packet->reqs[i]);
  }
  fc_assert(peffect->reqs.size == packet->reqs_count);
}
 
/**********************************************************************/
void send_ruleset_cache(struct conn_list *dest)
{
  effect_list_iterate(ruleset_cache.tracker, peffect) {
    struct packet_ruleset_effect effect_packet;
    int counter;
 
    effect_packet.effect_type = peffect->type;
    effect_packet.effect_value = peffect->value;
    if (peffect->multiplier) {
      effect_packet.has_multiplier = TRUE;
      effect_packet.multiplier = multiplier_number(peffect->multiplier);
    } else {
      effect_packet.has_multiplier = FALSE;
      effect_packet.multiplier = 0; /* arbitrary */
    }
 
    counter = 0;
    requirement_vector_iterate(&(peffect->reqs), req) {
      effect_packet.reqs[counter++] = *req;
    } requirement_vector_iterate_end;
    effect_packet.reqs_count = counter;
 
    lsend_packet_ruleset_effect(dest, &effect_packet);
  } effect_list_iterate_end;
}
 
/**********************************************************************/
bool building_has_effect(const struct impr_type *pimprove,
                         enum effect_type effect_type)
{
  struct universal source = {
    .kind = VUT_IMPROVEMENT,
    /* just to bamboozle the annoying compiler warning */
    .value = {.building = improvement_by_number(improvement_number(pimprove))}
  };
  struct effect_list *plist = get_req_source_effects(&source);
 
  if (!plist) {
    return FALSE;
  }
 
  effect_list_iterate(plist, peffect) {
    if (peffect->type == effect_type) {
      return TRUE;
    }
  } effect_list_iterate_end;
 
  return FALSE;
}
 
/**********************************************************************/
static bool is_effect_prevented(const struct req_context *context,
                                const struct player *other_player,
                                const struct effect *peffect,
                                const enum   req_problem_type prob_type)
{
  requirement_vector_iterate(&peffect->reqs, preq) {
    /* Only check present=FALSE requirements; these will return _FALSE_
     * from is_req_active() if met, and need reversed prob_type */
    if (!preq->present
        && !is_req_active(context, other_player,
                          preq, REVERSED_RPT(prob_type))) {
      return TRUE;
    }
  } requirement_vector_iterate_end;
 
  return FALSE;
}
 
/**********************************************************************/
bool is_building_replaced(const struct city *pcity,
                          const struct impr_type *pimprove,
                          const enum req_problem_type prob_type)
{
  struct effect_list *plist;
  struct universal source = {
    .kind = VUT_IMPROVEMENT,
    .value = {.building = pimprove}
  };
 
  plist = get_req_source_effects(&source);
 
  /* A building with no effects and no flags is always redundant! */
  if (!plist) {
    return TRUE;
  }
 
  effect_list_iterate(plist, peffect) {
    /* We use TARGET_BUILDING as the lowest common denominator.  Note that
     * the building is its own target - but whether this is actually
     * checked depends on the range of the effect. */
    /* Prob_type is not reversed here. disabled is equal to replaced, not
     * reverse */
    if (!is_effect_prevented(&(const struct req_context) {
                               .player = city_owner(pcity),
                               .city = pcity,
                               .building = pimprove,
                             },
                             NULL,
                             peffect, prob_type)) {
      return FALSE;
    }
  } effect_list_iterate_end;
 
  return TRUE;
}
 
/**********************************************************************/
int get_target_bonus_effects(struct effect_list *plist,
                             const struct req_context *context,
                             const struct player *other_player,
                             enum effect_type effect_type)
{
  int bonus = 0;
 
  if (context == NULL) {
    context = req_context_empty();
  }
 
  /* Loop over all effects of this type. */
  effect_list_iterate(get_effects(effect_type), peffect) {
    /* For each effect, see if it is active. */
    if (are_reqs_active(context, other_player,
                        &peffect->reqs, RPT_CERTAIN)) {
      /* This code will add value of effect. If there's multiplier for 
       * effect and target_player aren't null, then value is multiplied
       * by player's multiplier factor. */
      if (peffect->multiplier) {
        if (context->player) {
          bonus += (peffect->value
            * player_multiplier_effect_value(context->player,
                                             peffect->multiplier)) / 100;
        }
      } else {
        bonus += peffect->value;
      }
 
      if (plist) {
        effect_list_append(plist, peffect);
      }
    }
  } effect_list_iterate_end;
 
  return bonus;
}
 
/**********************************************************************/
double get_effect_expected_value(const struct req_context *context,
                                 const struct player *other_player,
                                 enum effect_type effect_type,
                                 eft_value_filter_cb weighter,
                                 void *data, int n_data)
{
  double sum = 0.;
 
  if (context == NULL) {
    context = req_context_empty();
  }
 
  /* Loop over all effects of this type. */
  effect_list_iterate(get_effects(effect_type), peffect) {
    sum += weighter(peffect, context, other_player, data, n_data);
  } effect_list_iterate_end;
 
  return sum;
}
 
/**********************************************************************/
int get_world_bonus(enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  return get_target_bonus_effects(NULL, NULL, NULL, effect_type);
}
 
/**********************************************************************/
int get_player_bonus(const struct player *pplayer,
                     enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_city_bonus(const struct city *pcity, enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .tile = city_tile(pcity),
                                  },
                                  NULL, effect_type);
}
 
/**********************************************************************/
int get_tile_bonus(const struct tile *ptile, enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = tile_owner(ptile),
                                    .city = tile_city(ptile),
                                    .tile = ptile,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_city_specialist_output_bonus(const struct city *pcity,
                                     const struct specialist *pspecialist,
                                     const struct output_type *poutput,
                                     enum effect_type effect_type)
{
  fc_assert_ret_val(pcity != NULL, 0);
  fc_assert_ret_val(pspecialist != NULL, 0);
  fc_assert_ret_val(poutput != NULL, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .output = poutput,
                                    .specialist = pspecialist,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_city_tile_output_bonus(const struct city *pcity,
                               const struct tile *ptile,
                               const struct output_type *poutput,
                               enum effect_type effect_type)
{
  fc_assert_ret_val(pcity != NULL, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .tile = ptile,
                                    .output = poutput,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_tile_output_bonus(const struct city *pcity,
                          const struct tile *ptile,
                          const struct output_type *poutput,
                          enum effect_type effect_type)
{
  const struct player *pplayer = pcity ? city_owner(pcity) : NULL;
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                    .city = pcity,
                                    .tile = ptile,
                                    .output = poutput,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_player_output_bonus(const struct player *pplayer,
                            const struct output_type *poutput,
                            enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(pplayer != NULL, 0);
  fc_assert_ret_val(poutput != NULL, 0);
  fc_assert_ret_val(effect_type != EFT_COUNT, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                    .output= poutput,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_city_output_bonus(const struct city *pcity,
                          const struct output_type *poutput,
                          enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(pcity != NULL, 0);
  fc_assert_ret_val(poutput != NULL, 0);
  fc_assert_ret_val(effect_type != EFT_COUNT, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .output = poutput,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_building_bonus(const struct city *pcity,
                       const struct impr_type *building,
                       enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(NULL != pcity && NULL != building, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .building = building,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_unittype_bonus(const struct player *pplayer,
                       const struct tile *ptile,
                       const struct unit_type *punittype,
                       const struct action *paction,
                       enum effect_type effect_type)
{
  struct city *pcity;
 
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(pplayer != NULL && punittype != NULL, 0);
 
  if (ptile != NULL) {
    pcity = tile_city(ptile);
  } else {
    pcity = NULL;
  }
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                    .city = pcity,
                                    .tile = ptile,
                                    .unittype = punittype,
                                    .action = paction,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_unit_bonus(const struct unit *punit, enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(punit != NULL, 0);
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = unit_owner(punit),
                                    .city = unit_tile(punit)
                                            ? tile_city(unit_tile(punit))
                                            : NULL,
                                    .tile = unit_tile(punit),
                                    .unit = punit,
                                    .unittype = unit_type_get(punit),
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_unit_vs_tile_bonus(const struct tile *ptile,
                           const struct unit *punit,
                           enum effect_type etype)
{
  struct player *pplayer = NULL;
  const struct unit_type *utype = NULL;
 
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(ptile != NULL, 0);
 
  if (punit != NULL) {
    pplayer = unit_owner(punit);
    utype = unit_type_get(punit);
  }
 
  return get_target_bonus_effects(NULL,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                    .city = tile_city(ptile),
                                    .tile = ptile,
                                    .unit = punit,
                                    .unittype = utype,
                                  },
                                  tile_owner(ptile),
                                  etype);
}
 
/**********************************************************************/
int get_player_bonus_effects(struct effect_list *plist,
                             const struct player *pplayer,
                             enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(pplayer != NULL, 0);
  return get_target_bonus_effects(plist,
                                  &(const struct req_context) {
                                    .player = pplayer,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_city_bonus_effects(struct effect_list *plist,
                           const struct city *pcity,
                           const struct output_type *poutput,
                           enum effect_type effect_type)
{
  if (!initialized) {
    return 0;
  }
 
  fc_assert_ret_val(pcity != NULL, 0);
  return get_target_bonus_effects(plist,
                                  &(const struct req_context) {
                                    .player = city_owner(pcity),
                                    .city = pcity,
                                    .output = poutput,
                                  },
                                  NULL,
                                  effect_type);
}
 
/**********************************************************************/
int get_current_construction_bonus(const struct city *pcity,
                                   enum effect_type effect_type,
                                   const enum req_problem_type prob_type)
{
  if (!initialized) {
    return 0;
  }
 
  if (VUT_IMPROVEMENT == pcity->production.kind) {
    return get_potential_improvement_bonus(pcity->production.value.building,
                                           pcity, effect_type, prob_type, TRUE);
  }
 
  return 0;
}
 
/**********************************************************************/
int get_potential_improvement_bonus(const struct impr_type *pimprove,
                                    const struct city *pcity,
                                    enum effect_type effect_type,
                                    const enum req_problem_type prob_type,
                                    bool consider_multipliers)
{
  struct universal source = { .kind = VUT_IMPROVEMENT,
                              .value = {.building = pimprove}};
  struct effect_list *plist = get_req_source_effects(&source);
  struct player *owner = NULL;
 
  if (pcity != NULL) {
    owner = city_owner(pcity);
  }
 
  if (plist) {
    int power = 0;
    const struct req_context context = {
      .player = owner,
      .city = pcity,
      .building = pimprove,
    };
 
    effect_list_iterate(plist, peffect) {
      bool present = TRUE;
      bool useful = TRUE;
 
      if (peffect->type != effect_type) {
        continue;
      }
 
      requirement_vector_iterate(&peffect->reqs, preq) {
        if (VUT_IMPROVEMENT == preq->source.kind
            && preq->source.value.building == pimprove) {
          present = preq->present;
          continue;
        }
 
        if (!is_req_active(&context, NULL, preq, prob_type)) {
          useful = FALSE;
          break;
        }
      } requirement_vector_iterate_end;
 
      if (useful) {
        int val;
 
        if (present) {
          val = peffect->value;
        } else {
          val = -peffect->value;
        }
 
        if (consider_multipliers && peffect->multiplier) {
          val = val * player_multiplier_effect_value(owner, peffect->multiplier) / 100;
        }
 
        power += val;
      }
    } effect_list_iterate_end;
 
    return power;
  }
 
  return 0;
}
 
/**********************************************************************/
void get_effect_req_text(const struct effect *peffect,
                         char *buf, size_t buf_len)
{
  buf[0] = '\0';
 
  if (peffect->multiplier) {
    fc_strlcat(buf, multiplier_name_translation(peffect->multiplier), buf_len);
  }
 
  /* FIXME: should we do something for present FALSE reqs?
   * Currently we just ignore them. */
  requirement_vector_iterate(&peffect->reqs, preq) {
    if (!preq->present) {
      continue;
    }
    if (buf[0] != '\0') {
      fc_strlcat(buf, Q_("?req-list-separator:+"), buf_len);
    }
 
    universal_name_translation(&preq->source,
                               buf + strlen(buf), buf_len - strlen(buf));
  } requirement_vector_iterate_end;
}
 
/**********************************************************************/
void get_effect_list_req_text(const struct effect_list *plist,
                              struct astring *astr)
{
  struct strvec *psv = strvec_new();
  char req_text[512];
 
  effect_list_iterate(plist, peffect) {
    get_effect_req_text(peffect, req_text, sizeof(req_text));
    strvec_append(psv, req_text);
  } effect_list_iterate_end;
 
  strvec_to_and_list(psv, astr);
  strvec_destroy(psv);
}
 
/**********************************************************************/
bool iterate_effect_cache(iec_cb cb, void *data)
{
  fc_assert_ret_val(cb != NULL, FALSE);
 
  effect_list_iterate(ruleset_cache.tracker, peffect) {
    if (!cb(peffect, data)) {
      return FALSE;
    }
  } effect_list_iterate_end;
 
  return TRUE;
}
 
/**********************************************************************/
bool is_user_effect(enum effect_type eff)
{
  return eff >= EFT_USER_EFFECT_1 && eff <= EFT_USER_EFFECT_LAST;
}
 
/**********************************************************************/
void user_effect_ai_valued_set(enum effect_type tgt, enum effect_type valued_as)
{
  fc_assert(is_user_effect(tgt));
 
  ueffects[USER_EFFECT_NUMBER(tgt)].ai_value_as = valued_as;
}
 
/**********************************************************************/
enum effect_type user_effect_ai_valued_as(enum effect_type real)
{
  /* Client doesn't know these. */
  fc_assert(is_server());
 
  if (!is_user_effect(real)) {
    return real;
  }
 
  if (!is_user_effect(ueffects[USER_EFFECT_NUMBER(real)].ai_value_as)) {
    return ueffects[USER_EFFECT_NUMBER(real)].ai_value_as;
  }
 
  return real;
}