actiontools.c

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/***********************************************************************
 Freeciv - Copyright (C) 1996-2015 - Freeciv Development 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 "rand.h"
 
/* common */
#include "actions.h"
 
/* server */
#include "aiiface.h"
#include "nation.h"
#include "notify.h"
#include "plrhand.h"
#include "unithand.h"
#include "unittools.h"
 
#include "actiontools.h"
 
typedef void (*action_notify)(struct player *,
                              const struct action *,
                              struct player *,
                              struct player *,
                              const struct tile *,
                              const char *);
 
/**********************************************************************/
static void action_success_actor_consume(struct action *paction,
                                         int actor_id, struct unit *actor)
{
  if (unit_is_alive(actor_id)
      && utype_is_consumed_by_action(paction, unit_type_get(actor))) {
    if (action_has_result(paction, ACTRES_DISBAND_UNIT)
        || action_has_result(paction, ACTRES_DISBAND_UNIT_RECOVER)) {
      wipe_unit(actor, ULR_DISBANDED, NULL);
    } else if (action_has_result(paction, ACTRES_NUKE)
               || action_has_result(paction, ACTRES_NUKE_UNITS)) {
      wipe_unit(actor, ULR_DETONATED, NULL);
    } else if (action_has_result(paction, ACTRES_ATTACK)
               || action_has_result(paction, ACTRES_WIPE_UNITS)) {
      wipe_unit(actor, ULR_MISSILE, NULL);
    } else {
      wipe_unit(actor, ULR_USED, NULL);
    }
  }
}
 
/**********************************************************************/
static void action_success_pay_mp(struct action *paction,
                                  int actor_id, struct unit *actor)
{
  if (unit_is_alive(actor_id)) {
    int spent_mp = unit_pays_mp_for_action(paction, actor);
    actor->moves_left = MAX(0, actor->moves_left - spent_mp);
    send_unit_info(NULL, actor);
  }
}
 
/**********************************************************************/
void action_success_target_pay_mp(struct action *paction,
                                  int target_id, struct unit *target)
{
  if (unit_is_alive(target_id)) {
    int spent_mp = get_target_bonus_effects(
        NULL,
        &(const struct req_context) {
          .player = unit_owner(target),
          .city = unit_tile(target) ? tile_city(unit_tile(target)) : NULL,
          .tile = unit_tile(target),
          .unit = target,
          .unittype = unit_type_get(target),
          .action = paction,
        },
        NULL,
        EFT_ACTION_SUCCESS_TARGET_MOVE_COST);
 
    target->moves_left = MAX(0, target->moves_left - spent_mp);
    send_unit_info(NULL, target);
  }
}
 
/**********************************************************************/
void action_success_actor_price(struct action *paction,
                                int actor_id, struct unit *actor)
{
  action_success_actor_consume(paction, actor_id, actor);
  action_success_pay_mp(paction, actor_id, actor);
}
 
/**********************************************************************/
static void action_give_casus_belli(struct player *offender,
                                    struct player *victim_player,
                                    const bool int_outrage)
{
  if (int_outrage) {
    /* This action is seen as a reason for any other player, no matter who
     * the victim was, to declare war on the actor. It could be used to
     * label certain actions atrocities in rule sets where international
     * outrage over an action fits the setting. */
 
    players_iterate(oplayer) {
      if (oplayer != offender) {
        player_diplstate_get(oplayer, offender)->has_reason_to_cancel = 2;
        player_update_last_war_action(oplayer);
      }
    } players_iterate_end;
  } else if (victim_player && offender != victim_player) {
    /* If an unclaimed tile is nuked there is no victim to give casus
     * belli. If an actor nukes their own tile, they are more than willing
     * to forgive themself. */
 
    /* Give the victim player a casus belli. */
    player_diplstate_get(victim_player, offender)->has_reason_to_cancel =
        2;
    player_update_last_war_action(victim_player);
  }
  player_update_last_war_action(offender);
}
 
/**********************************************************************/
static void action_consequence_common(const struct action *paction,
                                      struct player *offender,
                                      const struct unit_type *offender_utype,
                                      struct player *victim_player,
                                      const struct tile *victim_tile,
                                      const char *victim_link,
                                      const action_notify notify_actor,
                                      const action_notify notify_victim,
                                      const action_notify notify_global,
                                      const enum effect_type eft)
{
  enum casus_belli_range cbr;
 
  cbr = casus_belli_range_for(offender, offender_utype, victim_player,
                              eft, paction, victim_tile);
 
  if (cbr >= CBR_VICTIM_ONLY) {
    /* In this situation the specified action provides a casus belli
     * against the actor. */
 
    /* International outrage: This isn't just between the offender and the
     * victim. */
    const bool int_outrage = (cbr == CBR_INTERNATIONAL_OUTRAGE);
 
    /* Notify the involved players by sending them a message. */
    notify_actor(offender, paction, offender, victim_player,
                 victim_tile, victim_link);
    notify_victim(victim_player, paction, offender, victim_player,
                  victim_tile, victim_link);
 
    if (int_outrage) {
      /* Every other player gets a casus belli against the actor. Tell each
       * players about it. */
      players_iterate(oplayer) {
        notify_global(oplayer, paction, offender,
                      victim_player, victim_tile, victim_link);
      } players_iterate_end;
    }
 
    /* Give casus belli. */
    action_give_casus_belli(offender, victim_player, int_outrage);
 
    /* Notify players controlled by the built in AI. */
    call_incident(INCIDENT_ACTION, cbr, paction, offender, victim_player);
 
    /* Update the clients. */
    send_player_all_c(offender, NULL);
 
    if (victim_player != NULL && victim_player != offender) {
      /* The actor player was just sent. */
      /* An action against an ownerless tile is victimless. */
      send_player_all_c(victim_player, NULL);
    }
  }
}
 
/**********************************************************************/
static void notify_actor_caught(struct player *receiver,
                                const struct action *paction,
                                struct player *offender,
                                struct player *victim_player,
                                const struct tile *victim_tile,
                                const char *victim_link)
{
  if (!victim_player || offender == victim_player) {
    /* There is no victim or the actor did this to themself. */
    return;
  }
 
  /* Custom message based on action type. */
  switch (action_get_target_kind(paction)) {
  case ATK_CITY:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke ... San Francisco */
                  _("You have caused an diplomatic incident getting caught"
                    " trying to do %s to %s."),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_UNIT:
  case ATK_STACK:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Bribe Enemy Unit ... American ... Partisan */
                  _("You have caused an diplomatic incident getting caught"
                    " trying to do %s to %s %s."),
                  action_name_translation(paction),
                  nation_adjective_for_player(victim_player),
                  victim_link);
    break;
  case ATK_TILE:
  case ATK_EXTRAS:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Explode Nuclear ... (54, 26) */
                  _("You have caused an diplomatic incident getting caught"
                    " trying to do %s at %s."),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_SELF:
    /* Special actor notice not needed. Actor is victim. */
    break;
  case ATK_COUNT:
    fc_assert(ATK_COUNT != ATK_COUNT);
    break;
  }
}
 
/**********************************************************************/
static void notify_victim_caught(struct player *receiver,
                                 const struct action *paction,
                                 struct player *offender,
                                 struct player *victim_player,
                                 const struct tile *victim_tile,
                                 const char *victim_link)
{
  if (!victim_player || offender == victim_player) {
    /* There is no victim or the actor did this to themself. */
    return;
  }
 
  /* Custom message based on action type. */
  switch (action_get_target_kind(paction)) {
  case ATK_CITY:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke ... San Francisco */
                  _("The %s have caused an diplomatic incident getting caught"
                    " trying to do %s to %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_UNIT:
  case ATK_STACK:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Bribe Enemy Unit ... Partisan */
                  _("The %s have caused an diplomatic incident getting caught"
                    " trying to do %s to your %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_TILE:
  case ATK_EXTRAS:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Explode Nuclear ... (54, 26) */
                  _("The %s have caused an diplomatic incident getting caught"
                    " trying to do %s at %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_SELF:
    /* Special victim notice not needed. Actor is victim. */
    break;
  case ATK_COUNT:
    fc_assert(ATK_COUNT != ATK_COUNT);
    break;
  }
}
 
/**********************************************************************/
static void notify_global_caught(struct player *receiver,
                                 const struct action *paction,
                                 struct player *offender,
                                 struct player *victim_player,
                                 const struct tile *victim_tile,
                                 const char *victim_link)
{
  if (receiver == offender) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke */
                  _("Getting caught while trying to do %s gives "
                    "everyone a casus belli against you."),
                  action_name_translation(paction));
  } else if (receiver == victim_player) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke ... Europeans */
                  _("Getting caught while trying to do %s to you gives "
                    "everyone a casus belli against the %s."),
                  action_name_translation(paction),
                  nation_plural_for_player(offender));
  } else if (victim_player == NULL) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke */
                  _("You now have a casus belli against the %s. "
                    "They got caught trying to do %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction));
  } else {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke ... Americans */
                  _("You now have a casus belli against the %s. "
                    "They got caught trying to do %s to the %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  nation_plural_for_player(victim_player));
  }
}
 
/**********************************************************************/
void action_consequence_caught(const struct action *paction,
                               struct player *offender,
                               const struct unit_type *offender_utype,
                               struct player *victim_player,
                               const struct tile *victim_tile,
                               const char *victim_link)
{
  action_consequence_common(paction, offender, offender_utype,
                            victim_player, victim_tile, victim_link,
                            notify_actor_caught,
                            notify_victim_caught,
                            notify_global_caught,
                            EFT_CASUS_BELLI_CAUGHT);
}
 
/**********************************************************************/
static void notify_actor_success(struct player *receiver,
                                 const struct action *paction,
                                 struct player *offender,
                                 struct player *victim_player,
                                 const struct tile *victim_tile,
                                 const char *victim_link)
{
  if (!victim_player || offender == victim_player) {
    /* There is no victim or the actor did this to themself. */
    return;
  }
 
  /* Custom message based on action type. */
  switch (action_get_target_kind(paction)) {
  case ATK_CITY:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke ... San Francisco */
                  _("You have caused an diplomatic incident doing %s to %s."),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_UNIT:
  case ATK_STACK:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRAND: Bribe Enemy Unit ... American ... Partisan */
                  _("You have caused an diplomatic incident doing %s to %s %s."),
                  action_name_translation(paction),
                  nation_adjective_for_player(victim_player),
                  victim_link);
    break;
  case ATK_TILE:
  case ATK_EXTRAS:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Explode Nuclear ... (54, 26) */
                  _("You have caused an diplomatic incident doing %s at %s."),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_SELF:
    /* Special actor notice not needed. Actor is victim. */
    break;
  case ATK_COUNT:
    fc_assert(ATK_COUNT != ATK_COUNT);
    break;
  }
}
 
/**********************************************************************/
static void notify_victim_success(struct player *receiver,
                                  const struct action *paction,
                                  struct player *offender,
                                  struct player *victim_player,
                                  const struct tile *victim_tile,
                                  const char *victim_link)
{
  if (!victim_player || offender == victim_player) {
    /* There is no victim or the actor did this to themself. */
    return;
  }
 
  /* Custom message based on action type. */
  switch (action_get_target_kind(paction)) {
  case ATK_CITY:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke ... San Francisco */
                  _("The %s have caused an diplomatic incident doing %s to %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_UNIT:
  case ATK_STACK:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Bribe Enemy Unit ... Partisan */
                  _("The %s have caused an diplomatic incident doing "
                    "%s to your %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_TILE:
  case ATK_EXTRAS:
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Explode Nuclear ... (54, 26) */
                  _("The %s have caused an diplomatic incident doing %s at %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  victim_link);
    break;
  case ATK_SELF:
    /* Special victim notice not needed. Actor is victim. */
    break;
  case ATK_COUNT:
    fc_assert(ATK_COUNT != ATK_COUNT);
    break;
  }
}
 
/**********************************************************************/
static void notify_global_success(struct player *receiver,
                                  const struct action *paction,
                                  struct player *offender,
                                  struct player *victim_player,
                                  const struct tile *victim_tile,
                                  const char *victim_link)
{
  if (receiver == offender) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke */
                  _("Doing %s gives everyone a casus belli against you."),
                  action_name_translation(paction));
  } else if (receiver == victim_player) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Suitcase Nuke ... Europeans */
                  _("Doing %s to you gives everyone a casus belli against "
                    "the %s."),
                  action_name_translation(paction),
                  nation_plural_for_player(offender));
  } else if (victim_player == NULL) {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke */
                  _("You now have a casus belli against the %s. "
                    "They did %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction));
  } else {
    notify_player(receiver, victim_tile,
                  E_DIPLOMATIC_INCIDENT, ftc_server,
                  /* TRANS: Europeans ... Suitcase Nuke ... Americans */
                  _("You now have a casus belli against the %s. "
                    "They did %s to the %s."),
                  nation_plural_for_player(offender),
                  action_name_translation(paction),
                  nation_plural_for_player(victim_player));
  }
}
 
/**********************************************************************/
void action_consequence_success(const struct action *paction,
                                struct player *offender,
                                const struct unit_type *offender_utype,
                                struct player *victim_player,
                                const struct tile *victim_tile,
                                const char *victim_link)
{
  action_consequence_common(paction, offender, offender_utype,
                            victim_player, victim_tile, victim_link,
                            notify_actor_success,
                            notify_victim_success,
                            notify_global_success,
                            EFT_CASUS_BELLI_SUCCESS);
}
 
/**************************************************************************
  Take care of any consequences (like casus belli) of successfully
  completing the given action.
 
  victim_player can be NULL
**************************************************************************/
void action_consequence_complete(const struct action *paction,
                                 struct player *offender,
                                 const struct unit_type *offender_utype,
                                 struct player *victim_player,
                                 const struct tile *victim_tile,
                                 const char *victim_link)
{
  action_consequence_common(paction, offender, offender_utype,
                            victim_player, victim_tile, victim_link,
                            notify_actor_success,
                            notify_victim_success,
                            notify_global_success,
                            EFT_CASUS_BELLI_COMPLETE);
}
 
/**********************************************************************/
static bool may_unit_act_vs_city(struct unit *actor, struct city *target,
                                 bool accept_all_actions)
{
  const struct civ_map *nmap = &(wld.map);
 
  if (actor == NULL || target == NULL) {
    /* Can't do any actions if actor or target are missing. */
    return FALSE;
  }
 
  action_iterate(act) {
    if (!(action_id_get_actor_kind(act) == AAK_UNIT
        && action_id_get_target_kind(act) == ATK_CITY)) {
      /* Not a relevant action. */
      continue;
    }
 
    if (action_id_is_rare_pop_up(act) && !accept_all_actions) {
      /* Not relevant since not accepted here. */
      continue;
    }
 
    if (action_prob_possible(action_prob_vs_city(nmap, actor, act, target))) {
      /* The actor unit may be able to do this action to the target
       * city. */
      return TRUE;
    }
  } action_iterate_end;
 
  return FALSE;
}
 
/**********************************************************************/
struct city *action_tgt_city(struct unit *actor, struct tile *target_tile,
                             bool accept_all_actions)
{
  struct city *target = tile_city(target_tile);
 
  if (target && may_unit_act_vs_city(actor, target, accept_all_actions)) {
    /* It may be possible to act against this city. */
    return target;
  }
 
  return NULL;
}
 
/**********************************************************************/
static bool may_unit_act_vs_unit(struct unit *actor, struct unit *target,
                                 bool accept_all_actions)
{
  const struct civ_map *nmap = &(wld.map);
 
  if (actor == NULL || target == NULL) {
    /* Can't do any actions if actor or target are missing. */
    return FALSE;
  }
 
  action_iterate(act) {
    if (!(action_id_get_actor_kind(act) == AAK_UNIT
        && action_id_get_target_kind(act) == ATK_UNIT)) {
      /* Not a relevant action. */
      continue;
    }
 
    if (action_id_is_rare_pop_up(act) && !accept_all_actions) {
      /* Not relevant since not accepted here. */
      continue;
    }
 
    if (action_prob_possible(action_prob_vs_unit(nmap, actor, act, target))) {
      /* The actor unit may be able to do this action to the target
       * unit. */
      return TRUE;
    }
  } action_iterate_end;
 
  return FALSE;
}
 
/**********************************************************************/
struct unit *action_tgt_unit(struct unit *actor, struct tile *target_tile,
                             bool accept_all_actions)
{
  unit_list_iterate(target_tile->units, target) {
    if (may_unit_act_vs_unit(actor, target, accept_all_actions)) {
      return target;
    }
  } unit_list_iterate_end;
 
  return NULL;
}
 
/**********************************************************************/
struct tile *action_tgt_tile(struct unit *actor,
                             struct tile *target,
                             const struct extra_type *target_extra,
                             bool accept_all_actions)
{
  const struct civ_map *nmap = &(wld.map);
 
  if (actor == NULL || target == NULL) {
    /* Can't do any actions if actor or target are missing. */
    return NULL;
  }
 
  action_iterate(act) {
    struct act_prob prob;
 
    if (action_id_get_actor_kind(act) != AAK_UNIT) {
      /* Not a relevant action. */
      continue;
    }
 
    if (action_id_is_rare_pop_up(act) && !accept_all_actions) {
      /* Not relevant since not accepted here. */
      continue;
    }
 
    switch (action_id_get_target_kind(act)) {
    case ATK_TILE:
      prob = action_prob_vs_tile(nmap, actor, act, target, target_extra);
      break;
    case ATK_EXTRAS:
      prob = action_prob_vs_extras(nmap, actor, act, target, target_extra);
      break;
    case ATK_STACK:
      prob = action_prob_vs_stack(nmap, actor, act, target);
      break;
    case ATK_CITY:
    case ATK_UNIT:
    case ATK_SELF:
      /* Target not specified by tile. */
      continue;
    case ATK_COUNT:
      /* Invalid target kind */
      fc_assert(action_id_get_target_kind(act) != ATK_COUNT);
      continue;
    }
 
    if (action_prob_possible(prob)) {
      /* The actor unit may be able to do this action to the target
       * tile. */
      return target;
    }
  } action_iterate_end;
 
  return NULL;
}
 
/**********************************************************************/
static bool may_unit_act_vs_tile_extra(const struct unit *actor,
                                       const struct tile *tgt_tile,
                                       const struct extra_type *tgt_extra,
                                       bool accept_all_actions)
{
  const struct civ_map *nmap = &(wld.map);
 
  if (actor == NULL || tgt_tile == NULL || tgt_extra == NULL) {
    /* Can't do any actions if actor or target are missing. */
    return FALSE;
  }
 
  action_iterate(act) {
    if (!(action_id_get_actor_kind(act) == AAK_UNIT
          && (action_id_get_target_kind(act) == ATK_TILE
              || action_id_get_target_kind(act) == ATK_EXTRAS)
          && action_id_has_complex_target(act))) {
      /* Not a relevant action. */
      continue;
    }
 
    if (action_id_is_rare_pop_up(act) && !accept_all_actions) {
      /* Not relevant since not accepted here. */
      continue;
    }
 
    switch (action_id_get_target_kind(act)) {
    case ATK_TILE:
      if (action_prob_possible(action_prob_vs_tile(nmap, actor, act,
                                                   tgt_tile, tgt_extra))) {
        /* The actor unit may be able to do this action to the target
         * extra. */
        return TRUE;
      }
      break;
    case ATK_EXTRAS:
      if (action_prob_possible(action_prob_vs_extras(nmap, actor, act,
                                                     tgt_tile,
                                                     tgt_extra))) {
        /* The actor unit may be able to do this action to the target
         * extra. */
        return TRUE;
      }
      break;
    case ATK_CITY:
    case ATK_UNIT:
    case ATK_STACK:
    case ATK_SELF:
      /* Not supported. */
      break;
    case ATK_COUNT:
      fc_assert(action_id_get_target_kind(act) != ATK_COUNT);
      break;
    }
  } action_iterate_end;
 
  return FALSE;
}
 
/**********************************************************************/
struct extra_type *action_tgt_tile_extra(const struct unit *actor,
                                         const struct tile *target_tile,
                                         bool accept_all_actions)
{
  extra_type_re_active_iterate(target) {
    if (may_unit_act_vs_tile_extra(actor, target_tile, target,
                                   accept_all_actions)) {
      return target;
    }
  } extra_type_re_active_iterate_end;
 
  return NULL;
}
 
/**********************************************************************/
int action_sub_target_id_for_action(const struct action *paction,
                                    struct unit *actor_unit)
{
  const struct tile *tgt_tile = unit_tile(actor_unit);
  const struct civ_map *nmap = &(wld.map);
 
  fc_assert_ret_val(paction->target_complexity == ACT_TGT_COMPL_FLEXIBLE,
                    NO_TARGET);
 
  switch (action_get_sub_target_kind(paction)) {
  case ASTK_NONE:
    /* Should not be reached */
    fc_assert_ret_val(action_get_sub_target_kind(paction) != ASTK_NONE,
                      NO_TARGET);
    break;
  case ASTK_BUILDING:
    /* Implement if a building sub targeted action becomes flexible */
    fc_assert_ret_val(paction->target_complexity == ACT_TGT_COMPL_FLEXIBLE,
                      NO_TARGET);
    break;
  case ASTK_TECH:
    /* Implement if a tech sub targeted action becomes flexible */
    fc_assert_ret_val(paction->target_complexity == ACT_TGT_COMPL_FLEXIBLE,
                      NO_TARGET);
    break;
  case ASTK_EXTRA:
  case ASTK_EXTRA_NOT_THERE:
    if (action_has_result(paction, ACTRES_PILLAGE)) {
      /* Special treatment for "Pillage" */
      struct extra_type *pextra = NULL;
      enum unit_activity activity = action_get_activity(paction);
 
      unit_assign_specific_activity_target(actor_unit, &activity,
                                           action_number(paction), &pextra);
 
      if (pextra != NULL) {
        return extra_number(pextra);
      }
    }
    extra_type_re_active_iterate(tgt_extra) {
      if (action_prob_possible(action_prob_vs_tile(nmap, actor_unit, paction->id,
                                                   tgt_tile, tgt_extra))) {
        /* The actor unit may be able to do this action to the target
         * extra. */
        return extra_number(tgt_extra);
      }
    } extra_type_re_active_iterate_end;
    break;
  case ASTK_COUNT:
    /* Should not exist. */
    fc_assert_ret_val(action_get_sub_target_kind(paction) != ASTK_COUNT,
                      NO_TARGET);
    break;
  }
 
  return NO_TARGET;
}
 
/**********************************************************************/
const struct action_auto_perf *
action_auto_perf_unit_sel(const enum action_auto_perf_cause cause,
                          const struct unit *actor,
                          const struct player *other_player,
                          const struct output_type *eval_output,
                          const struct action *eval_action)
{
  const struct req_context actor_ctxt = {
    .player = unit_owner(actor),
    .tile = unit_tile(actor),
    .unit = actor,
    .unittype = unit_type_get(actor),
    .output = eval_output,
    .action = eval_action,
  };
 
  action_auto_perf_by_cause_iterate(cause, autoperformer) {
    if (are_reqs_active(&actor_ctxt,
                        &(const struct req_context) {
                          .player = other_player,
                        },
                        &autoperformer->reqs, RPT_CERTAIN)) {
      /* Select this action auto performer. */
      return autoperformer;
    }
  } action_auto_perf_by_cause_iterate_end;
 
  /* Can't even try to force an action. */
  return NULL;
}
 
#define action_auto_perf_acquire_targets(_target_extra_)                   \
  tgt_city = (target_city ? target_city                                    \
                          : action_tgt_city(actor, unit_tile(actor),       \
                                            TRUE));                        \
  tgt_tile = (target_tile ? target_tile                                    \
                          : action_tgt_tile(actor, unit_tile(actor),       \
                                            _target_extra_,                \
                                            TRUE));                        \
  tgt_unit = (target_unit ? target_unit                                    \
                          : action_tgt_unit(actor, unit_tile(actor),       \
                                            TRUE));
 
/**********************************************************************/
const struct action *
action_auto_perf_unit_do(const enum action_auto_perf_cause cause,
                         struct unit *actor,
                         const struct player *other_player,
                         const struct output_type *eval_output,
                         const struct action *eval_action,
                         const struct tile *target_tile,
                         const struct city *target_city,
                         const struct unit *target_unit,
                         const struct extra_type *target_extra)
{
  int actor_id;
 
  const struct city *tgt_city;
  const struct tile *tgt_tile;
  const struct unit *tgt_unit;
  const struct civ_map *nmap = &(wld.map);
 
  const struct action_auto_perf *autoperf
    = action_auto_perf_unit_sel(cause, actor, other_player,
                                eval_output, eval_action);
 
  if (!autoperf) {
    /* No matching Action Auto Performer. */
    return NULL;
  }
 
  actor_id = actor->id;
 
  /* Acquire the targets. */
  action_auto_perf_acquire_targets(target_extra);
 
  action_auto_perf_actions_iterate(autoperf, act) {
    if (action_id_get_actor_kind(act) == AAK_UNIT) {
      /* This action can be done by units. */
 
#define perform_action_to(act, actor, tgtid, tgt_extra)                   \
  if (unit_perform_action(unit_owner(actor),                              \
                          actor->id, tgtid, tgt_extra,                    \
                          NULL, act, ACT_REQ_RULES)) {                    \
    return action_by_number(act);                                         \
  }
 
      switch (action_id_get_target_kind(act)) {
      case ATK_STACK:
        if (tgt_tile
            && is_action_enabled_unit_on_stack(nmap, act, actor, tgt_tile)) {
          perform_action_to(act, actor, tgt_tile->index, EXTRA_NONE);
        }
        break;
      case ATK_TILE:
        if (tgt_tile
            && is_action_enabled_unit_on_tile(nmap, act, actor,
                                              tgt_tile, target_extra)) {
          perform_action_to(act, actor, tgt_tile->index,
                            target_extra ? extra_number(target_extra) : -1);
        }
        break;
      case ATK_EXTRAS:
        if (tgt_tile
            && is_action_enabled_unit_on_extras(nmap, act, actor,
                                                tgt_tile, target_extra)) {
          perform_action_to(act, actor, tgt_tile->index,
                            target_extra ? extra_number(target_extra) : -1);
        }
        break;
      case ATK_CITY:
        if (tgt_city
            && is_action_enabled_unit_on_city(nmap, act, actor, tgt_city)) {
          perform_action_to(act, actor, tgt_city->id, EXTRA_NONE)
        }
        break;
      case ATK_UNIT:
        if (tgt_unit
            && is_action_enabled_unit_on_unit(nmap, act, actor, tgt_unit)) {
          perform_action_to(act, actor, tgt_unit->id, EXTRA_NONE);
        }
        break;
      case ATK_SELF:
        if (actor
            && is_action_enabled_unit_on_self(nmap, act, actor)) {
          perform_action_to(act, actor, actor->id, EXTRA_NONE);
        }
        break;
      case ATK_COUNT:
        fc_assert(action_id_get_target_kind(act) != ATK_COUNT);
      }
 
      if (!unit_is_alive(actor_id)) {
        /* The unit is gone. Maybe it was killed in Lua? */
        return NULL;
      }
    }
  } action_auto_perf_actions_iterate_end;
 
  return NULL;
}
 
/**********************************************************************/
struct act_prob
action_auto_perf_unit_prob(const enum action_auto_perf_cause cause,
                           struct unit *actor,
                           const struct player *other_player,
                           const struct output_type *eval_output,
                           const struct action *eval_action,
                           const struct tile *target_tile,
                           const struct city *target_city,
                           const struct unit *target_unit,
                           const struct extra_type *target_extra)
{
  struct act_prob out;
 
  const struct city *tgt_city;
  const struct tile *tgt_tile;
  const struct unit *tgt_unit;
  const struct civ_map *nmap = &(wld.map);
 
  const struct action_auto_perf *autoperf
    = action_auto_perf_unit_sel(cause, actor, other_player,
                                eval_output, eval_action);
 
  if (!autoperf) {
    /* No matching Action Auto Performer. */
    return ACTPROB_IMPOSSIBLE;
  }
 
  out = ACTPROB_IMPOSSIBLE;
 
  /* Acquire the targets. */
  action_auto_perf_acquire_targets(target_extra);
 
  action_auto_perf_actions_iterate(autoperf, act) {
    struct act_prob current = ACTPROB_IMPOSSIBLE;
 
    if (action_id_get_actor_kind(act) == AAK_UNIT) {
      /* This action can be done by units. */
 
      switch (action_id_get_target_kind(act)) {
      case ATK_STACK:
        if (tgt_tile
            && is_action_enabled_unit_on_stack(nmap, act, actor, tgt_tile)) {
          current = action_prob_vs_stack(nmap, actor, act, tgt_tile);
        }
        break;
      case ATK_TILE:
        if (tgt_tile
            && is_action_enabled_unit_on_tile(nmap, act, actor,
                                              tgt_tile, target_extra)) {
          current = action_prob_vs_tile(nmap, actor, act, tgt_tile, target_extra);
        }
        break;
      case ATK_EXTRAS:
        if (tgt_tile
            && is_action_enabled_unit_on_extras(nmap, act, actor,
                                                tgt_tile, target_extra)) {
          current = action_prob_vs_extras(nmap, actor, act,
                                          tgt_tile, target_extra);
        }
        break;
      case ATK_CITY:
        if (tgt_city
            && is_action_enabled_unit_on_city(nmap, act, actor, tgt_city)) {
          current = action_prob_vs_city(nmap, actor, act, tgt_city);
        }
        break;
      case ATK_UNIT:
        if (tgt_unit
            && is_action_enabled_unit_on_unit(nmap, act, actor, tgt_unit)) {
          current = action_prob_vs_unit(nmap, actor, act, tgt_unit);
        }
        break;
      case ATK_SELF:
        if (actor
            && is_action_enabled_unit_on_self(nmap, act, actor)) {
          current = action_prob_self(nmap, actor, act);
        }
        break;
      case ATK_COUNT:
        fc_assert(action_id_get_target_kind(act) != ATK_COUNT);
      }
    }
 
    out = action_prob_fall_back(&out, &current);
  } action_auto_perf_actions_iterate_end;
 
  return out;
}
 
/************************************************************************/
bool action_failed_dice_roll(const struct player *act_player,
                             const struct unit *act_unit,
                             const struct city *tgt_city,
                             const struct player *tgt_player,
                             const struct action *paction)
{
  int odds = action_dice_roll_odds(act_player, act_unit,
                                   tgt_city, tgt_player,
                                   paction);
 
  /* Roll the dice. */
  return fc_rand(100) >= odds;
}