unittools.c

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/***********************************************************************
 Freeciv - Copyright (C) 1996 - A Kjeldberg, L Gregersen, P Unold
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
***********************************************************************/
 
#ifdef HAVE_CONFIG_H
#include <fc_config.h>
#endif
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
/* utility */
#include "bitvector.h"
#include "fcintl.h"
#include "log.h"
#include "mem.h"
#include "rand.h"
#include "shared.h"
#include "support.h"
 
/* common */
#include "base.h"
#include "city.h"
#include "combat.h"
#include "events.h"
#include "game.h"
#include "government.h"
#include "idex.h"
#include "map.h"
#include "movement.h"
#include "packets.h"
#include "player.h"
#include "research.h"
#include "terrain.h"
#include "unit.h"
#include "unitlist.h"
#include "unittype.h"
 
/* common/scriptcore */
#include "luascript_signal.h"
#include "luascript_types.h"
 
/* aicore */
#include "path_finding.h"
#include "pf_tools.h"
 
/* server/scripting */
#include "script_server.h"
 
/* server */
#include "actiontools.h"
#include "aiiface.h"
#include "barbarian.h"
#include "citytools.h"
#include "cityturn.h"
#include "diplhand.h"
#include "gamehand.h"
#include "maphand.h"
#include "notify.h"
#include "plrhand.h"
#include "sanitycheck.h"
#include "sernet.h"
#include "srv_main.h"
#include "techtools.h"
#include "unithand.h"
 
/* server/advisors */
#include "advgoto.h"
#include "autoexplorer.h"
#include "autoworkers.h"
 
/* ai */
#include "handicaps.h"
 
#include "unittools.h"
 
 
/* Tools for controlling the client vision of every unit when a unit
 * moves + script effects. See unit_move(). You can access this data with
 * punit->server.moving; it may be nullptr if the unit is not moving). */
struct unit_move_data {
  int ref_count;
  struct unit *punit; /* nullptr for invalidating. */
  struct player *powner;
  bv_player can_see_unit;
  bv_player can_see_move;
  struct vision *old_vision;
};
 
#define SPECLIST_TAG unit_move_data
#include "speclist.h"
#define unit_move_data_list_iterate(_plist, _pdata)                         \
  TYPED_LIST_ITERATE(struct unit_move_data, _plist, _pdata)
#define unit_move_data_list_iterate_end LIST_ITERATE_END
#define unit_move_data_list_iterate_rev(_plist, _pdata)                     \
  TYPED_LIST_ITERATE_REV(struct unit_move_data, _plist, _pdata)
#define unit_move_data_list_iterate_rev_end LIST_ITERATE_REV_END
 
/* This data structure lets the auto attack code cache each potential
 * attacker unit's probability of success against the target unit during
 * the checks if the unit can do autoattack. It is then reused when the
 * list of potential attackers is sorted by probability of success. */
struct autoattack_prob {
  int unit_id;
  struct act_prob prob;
};
 
#define SPECLIST_TAG autoattack_prob
#define SPECLIST_TYPE struct autoattack_prob
#include "speclist.h"
 
#define autoattack_prob_list_iterate_safe(autoattack_prob_list, _aap_,     \
                                          _unit_)                          \
  TYPED_LIST_ITERATE(struct autoattack_prob, autoattack_prob_list, _aap_)  \
  struct unit *_unit_ = game_unit_by_number(_aap_->unit_id);               \
                                                                           \
  if (_unit_ == nullptr) {                                                 \
    continue;                                                              \
  }
 
#define autoattack_prob_list_iterate_safe_end  LIST_ITERATE_END
 
static void unit_restore_hitpoints(struct unit *punit);
static void unit_restore_movepoints(struct player *pplayer, struct unit *punit);
static void update_unit_activity(struct unit *punit);
static bool try_to_save_unit(struct unit *punit, const struct unit_type *pttype,
                             bool helpless, bool teleporting,
                             const struct city *pexclcity);
static void wakeup_neighbor_sentries(struct unit *punit);
static void do_upgrade_effects(struct player *pplayer);
 
static bool maybe_cancel_patrol_due_to_enemy(struct unit *punit);
 
static bool maybe_become_veteran_real(struct unit *punit, int base_chance,
                                      bool worker);
 
static void unit_transport_load_tp_status(struct unit *punit,
                                               struct unit *ptrans,
                                               bool force);
 
static void wipe_unit_full(struct unit *punit, bool transported,
                           enum unit_loss_reason reason,
                           struct player *killer);
 
static int get_unit_vision_base(const struct unit *punit,
                                enum vision_layer vlayer,
                                const int base);
static int unit_vision_range_modifiers(const struct unit *punit,
                                       const struct tile *ptile);
 
/**********************************************************************/
struct unit_type *find_a_unit_type(enum unit_role_id role,
                                   enum unit_role_id role_tech)
{
  struct unit_type *which[U_LAST];
  int i, num = 0;
 
  if (role_tech != -1) {
    for (i = 0; i < num_role_units(role_tech); i++) {
      struct unit_type *iunit = get_role_unit(role_tech, i);
      const int minplayers = 2;
      int players = 0;
 
      /* Note, if there's only one player in the game this check will always
       * fail. */
      players_iterate(pplayer) {
        if (!is_barbarian(pplayer)
            && can_player_build_unit_direct(pplayer, iunit,
                                            RPT_CERTAIN, TRUE)) {
          players++;
        }
      } players_iterate_end;
 
      if (players > minplayers) {
        which[num++] = iunit;
      }
    }
  }
  if (num == 0) {
    for (i = 0; i < num_role_units(role); i++) {
      which[num++] = get_role_unit(role, i);
    }
  }
 
  /* Ruleset code should ensure there is at least one unit for each
   * possibly-required role, or check before calling this function. */
  fc_assert_exit_msg(0 < num, "No unit types in find_a_unit_type(%d, %d)!",
                     role, role_tech);
 
  return which[fc_rand(num)];
}
 
/**********************************************************************/
bool maybe_make_veteran(struct unit *punit, int base_chance)
{
  return maybe_become_veteran_real(punit, base_chance, FALSE);
}
 
/**********************************************************************/
static bool maybe_become_veteran_real(struct unit *punit, int base_chance,
                                      bool worker)
{
  const struct veteran_system *vsystem;
  const struct veteran_level *vlevel;
  int chance;
  const struct civ_map *nmap = &(wld.map);
 
  fc_assert_ret_val(punit != nullptr, FALSE);
 
  vsystem = utype_veteran_system(unit_type_get(punit));
  fc_assert_ret_val(vsystem != nullptr, FALSE);
  fc_assert_ret_val(vsystem->levels > punit->veteran, FALSE);
 
  vlevel = vsystem_veteran_level(vsystem, punit->veteran);
  fc_assert_ret_val(vlevel != nullptr, FALSE);
 
  if (punit->veteran + 1 >= vsystem->levels
      || !is_action_enabled_unit_on_self(nmap, ACTION_GAIN_VETERANCY, punit)) {
    return FALSE;
  } else if (!worker) {
    int mod = base_chance + get_unit_bonus(punit, EFT_VETERAN_COMBAT);
 
    /* The modification is tacked on as a multiplier to the base chance.
     * For example with a base chance of 50% for green units and a modifier
     * of +50% the end chance is 75%. */
    chance = vlevel->base_raise_chance * mod / 100;
  } else if (worker && unit_has_type_flag(punit, UTYF_WORKERS)) {
    int mod = base_chance + get_unit_bonus(punit, EFT_VETERAN_WORK);
 
    chance = vlevel->work_raise_chance * mod / 100;
  } else {
    /* No battle and no work done. */
    return FALSE;
  }
 
  if (fc_rand(100) < chance) {
    punit->veteran++;
    return TRUE;
  }
 
  return FALSE;
}
 
/**********************************************************************/
bool unit_versus_unit(struct unit *attacker, struct unit *defender,
                      int *att_hp, int *def_hp, int *att_vet, int *def_vet,
                      const struct action *paction)
{
  int attackpower = get_total_attack_power(attacker, defender, paction);
  int defensepower = get_total_defense_power(attacker, defender);
  int attack_firepower, defense_firepower;
  struct player *plr1 = unit_owner(attacker);
  struct player *plr2 = unit_owner(defender);
  struct civ_map *nmap = &(wld.map);
  int max_rounds;
  int rounds;
  int att_strength;
  int def_strength;
 
  *att_hp = attacker->hp;
  *def_hp = defender->hp;
  get_modified_firepower(nmap, attacker, defender,
                         &attack_firepower, &defense_firepower);
 
  log_verbose("attack:%d, defense:%d, attack firepower:%d, "
              "defense firepower:%d", attackpower, defensepower,
              attack_firepower, defense_firepower);
 
  player_update_last_war_action(plr1);
  player_update_last_war_action(plr2);
 
  att_strength = attackpower * attacker->hp * attack_firepower;
  def_strength = defensepower * defender->hp * defense_firepower;
 
  /* In a combat between equal strength units the values are 50% / 50%.
   * -> scaling that to 100% by doubling, to match scale of chances
   *    in existing rulesets, and in !combat_odds_scaled_veterancy case. */
  *att_vet = 100 * def_strength * 2 / (att_strength + def_strength);
  *def_vet = 100 * att_strength * 2 / (att_strength + def_strength);
 
  if (attackpower == 0) {
    *att_hp = 0;
  } else if (defensepower == 0) {
    *def_hp = 0;
  }
  max_rounds = get_unit_bonus(attacker, EFT_COMBAT_ROUNDS);
  for (rounds = 0;
       *att_hp > 0 && *def_hp > 0
         && (max_rounds <= 0 || max_rounds > rounds);
       rounds++) {
    if (fc_rand(attackpower + defensepower) >= defensepower) {
      *def_hp -= attack_firepower;
    } else {
      *att_hp -= defense_firepower;
    }
  }
  if (*att_hp < 0) {
    *att_hp = 0;
  }
  if (*def_hp < 0) {
    *def_hp = 0;
  }
 
  return attackpower <= 0 || defensepower <= 0;
}
 
/**********************************************************************/
void unit_bombs_unit(struct unit *attacker, struct unit *defender,
                     int *att_hp, int *def_hp,
                     const struct action *paction)
{
  int i;
  int rate = unit_bombard_rate(attacker);
  int attackpower = get_total_attack_power(attacker, defender, paction);
  int defensepower = get_total_defense_power(attacker, defender);
  int attack_firepower, defense_firepower;
  struct player *plr1 = unit_owner(attacker);
  struct player *plr2 = unit_owner(defender);
  struct civ_map *nmap = &(wld.map);
 
  *att_hp = attacker->hp;
  *def_hp = defender->hp;
  get_modified_firepower(nmap, attacker, defender,
                         &attack_firepower, &defense_firepower);
 
  log_verbose("attack:%d, defense:%d, attack firepower:%d, "
              "defense firepower:%d", attackpower, defensepower,
              attack_firepower, defense_firepower);
 
  player_update_last_war_action(plr1);
  player_update_last_war_action(plr2);
 
  for (i = 0; i < rate; i++) {
    if (fc_rand(attackpower + defensepower) >= defensepower) {
      *def_hp -= attack_firepower;
    }
  }
 
  if (*def_hp <= 0) {
    if (BV_ISSET(paction->sub_results, ACT_SUB_RES_NON_LETHAL)) {
      /* Don't kill the target. */
      *def_hp = 1;
    } else {
      *def_hp = 0;
    }
  }
}
 
/**********************************************************************/
void combat_veterans(struct unit *attacker, struct unit *defender,
                     bool powerless, int att_vet, int def_vet)
{
  if (!powerless || !game.info.only_real_fight_makes_veteran) {
    if (attacker->hp <= 0 || defender->hp <= 0
        || !game.info.only_killing_makes_veteran) {
      if (!game.info.combat_odds_scaled_veterancy) {
        att_vet = 100;
        def_vet = 100;
      }
      if (attacker->hp > 0) {
        maybe_make_veteran(attacker, att_vet);
      }
      if (defender->hp > 0) {
        maybe_make_veteran(defender, def_vet);
      }
    }
  }
}
 
/**********************************************************************/
static void do_upgrade_effects(struct player *pplayer)
{
  int upgrades = get_player_bonus(pplayer, EFT_UPGRADE_UNIT);
  struct unit_list *candidates;
 
  if (upgrades <= 0) {
    return;
  }
  candidates = unit_list_new();
 
  unit_list_iterate(pplayer->units, punit) {
    /* We have to be careful not to strand units at sea, for example by
     * upgrading a frigate to an ironclad while it was carrying a unit. */
    if (UU_OK == unit_upgrade_test(&(wld.map), punit, TRUE)) {
      unit_list_prepend(candidates, punit);     /* Potential candidate :) */
    }
  } unit_list_iterate_end;
 
  while (upgrades > 0 && unit_list_size(candidates) > 0) {
    /* Upgrade one unit.  The unit is chosen at random from the list of
     * available candidates. */
    int candidate_to_upgrade = fc_rand(unit_list_size(candidates));
    struct unit *punit = unit_list_get(candidates, candidate_to_upgrade);
    const struct unit_type *type_from = unit_type_get(punit);
    const struct unit_type *type_to = can_upgrade_unittype(pplayer, type_from);
 
    transform_unit(punit, type_to, game.server.autoupgrade_veteran_loss);
    notify_player(pplayer, unit_tile(punit), E_UNIT_UPGRADED, ftc_server,
                  _("%s was upgraded for free to %s."),
                  utype_name_translation(type_from),
                  unit_link(punit));
    unit_list_remove(candidates, punit);
    upgrades--;
  }
 
  unit_list_destroy(candidates);
}
 
/**********************************************************************/
void player_restore_units(struct player *pplayer)
{
  const struct civ_map *nmap = &(wld.map);
 
  /* 1) get Leonardo out of the way first: */
  do_upgrade_effects(pplayer);
 
  unit_list_iterate_safe(pplayer->units, punit) {
 
    /* 2) Modify unit hitpoints. Helicopters can even lose them. */
    unit_restore_hitpoints(punit);
 
    /* 3) Check that unit has hitpoints */
    if (punit->hp <= 0) {
      /* This should usually only happen for heli units, but if any other
       * units get 0 hp somehow, catch them too.  --dwp  */
      /* if 'game.server.killunhomed' is activated unhomed units are slowly
       * killed; notify player here */
      if (!punit->homecity && 0 < game.server.killunhomed) {
        notify_player(pplayer, unit_tile(punit), E_UNIT_LOST_MISC,
                      ftc_server, _("Your %s has run out of hit points "
                                    "because it was not supported by a city."),
                      unit_tile_link(punit));
      } else {
        notify_player(pplayer, unit_tile(punit), E_UNIT_LOST_MISC, ftc_server,
                      _("Your %s has run out of hit points."),
                      unit_tile_link(punit));
      }
 
      wipe_unit(punit, ULR_HP_LOSS, nullptr);
      continue; /* Continue iterating... */
    }
 
    /* 4) Rescue planes if needed */
    if (utype_fuel(unit_type_get(punit))) {
      /* Shall we emergency return home on the last vapors? */
 
      /* I think this is strongly against the spirit of client goto.
       * The problem is (again) that here we know too much. -- Zamar */
 
      if (punit->fuel <= 1
          && !is_unit_being_refueled(punit)) {
        struct unit *carrier;
 
        carrier = transporter_for_unit(punit);
        if (carrier) {
          unit_transport_load_tp_status(punit, carrier, FALSE);
        } else {
          struct pf_map *pfm;
          struct pf_parameter parameter;
          bool alive = TRUE;
 
          pft_fill_unit_parameter(&parameter, nmap, punit);
          parameter.omniscience = !has_handicap(pplayer, H_MAP);
          pfm = pf_map_new(&parameter);
 
          pf_map_move_costs_iterate(pfm, ptile, move_cost, TRUE) {
            if (move_cost > punit->moves_left) {
              /* Too far */
              break;
            }
 
            if (is_refuel_point(ptile, pplayer, punit)) {
              struct pf_path *path;
              int id = punit->id;
 
              /* Client orders may be running for this unit - if so
               * we free them before engaging goto. */
              free_unit_orders(punit);
 
              path = pf_map_path(pfm, ptile);
 
              alive = adv_follow_path(punit, path, ptile);
 
              if (!alive) {
                log_error("rescue plane: unit %d died enroute!", id);
              } else if (!same_pos(unit_tile(punit), ptile)) {
                /* Enemy units probably blocked our route
                 * FIXME: We should try find alternative route around
                 * the enemy unit instead of just giving up and crashing. */
                log_debug("rescue plane: unit %d could not move to "
                          "refuel point!", punit->id);
              }
 
              if (alive) {
                /* Clear activity. Unit info will be sent in the end of
                 * the function. */
                unit_activity_handling(punit, ACTIVITY_IDLE, ACTION_NONE);
                adv_unit_new_task(punit, AUT_NONE, nullptr);
                punit->goto_tile = nullptr;
 
                if (!is_unit_being_refueled(punit)) {
                  carrier = transporter_for_unit(punit);
                  if (carrier) {
                    unit_transport_load_tp_status(punit, carrier, FALSE);
                  }
                }
 
                notify_player(pplayer, unit_tile(punit),
                              E_UNIT_ORDERS, ftc_server,
                              _("Your %s has returned to refuel."),
                              unit_link(punit));
              }
              pf_path_destroy(path);
              break;
            }
          } pf_map_move_costs_iterate_end;
          pf_map_destroy(pfm);
 
          if (!alive) {
            /* Unit died trying to move to refuel point. */
            return;
          }
        }
      }
 
      /* 5) Update fuel */
      punit->fuel--;
 
      /* 6) Automatically refuel air units in cities, airbases, and
       *    transporters (carriers). */
      if (is_unit_being_refueled(punit)) {
        punit->fuel = utype_fuel(unit_type_get(punit));
      }
    }
  } unit_list_iterate_safe_end;
 
  /* 7) Check if there are air units without fuel */
  unit_list_iterate_safe(pplayer->units, punit) {
    const struct unit_type *utype = unit_type_get(punit);
 
    if (punit->fuel <= 0 && utype_fuel(utype)) {
      /* Notifications sent from the lua script when unit wiped. */
      wipe_unit(punit, ULR_FUEL, nullptr);
    }
  } unit_list_iterate_safe_end;
 
  /* Send all updates. */
  unit_list_iterate(pplayer->units, punit) {
    send_unit_info(nullptr, punit);
  } unit_list_iterate_end;
}
 
/**********************************************************************/
static void unit_restore_hitpoints(struct unit *punit)
{
  bool was_lower;
  const struct unit_type *utype = unit_type_get(punit);
 
  was_lower = (punit->hp < utype->hp);
 
  punit->hp += unit_gain_hitpoints(punit);
 
  fc_assert(punit->hp >= 0);
  fc_assert(punit->hp <= utype->hp);
 
  if (punit->hp == utype->hp) {
    if (was_lower && punit->activity == ACTIVITY_SENTRY) {
      set_unit_activity(punit, ACTIVITY_IDLE, ACTION_NONE);
    }
  }
 
  punit->moved = FALSE;
  punit->paradropped = FALSE;
}
 
/**********************************************************************/
static void unit_restore_movepoints(struct player *pplayer, struct unit *punit)
{
  punit->moves_left = unit_move_rate(punit);
  punit->done_moving = FALSE;
}
 
/**********************************************************************/
void update_unit_activities(struct player *pplayer)
{
  unit_list_iterate_safe(pplayer->units, punit) {
    update_unit_activity(punit);
  } unit_list_iterate_safe_end;
}
 
/**********************************************************************/
void execute_unit_orders(struct player *pplayer)
{
  unit_list_iterate_safe(pplayer->units, punit) {
    if (unit_has_orders(punit)) {
      execute_orders(punit, FALSE);
    }
  } unit_list_iterate_safe_end;
}
 
/**********************************************************************/
void unit_tc_effect_refresh(struct player *pplayer)
{
  unit_list_iterate(pplayer->units, punit) {
    unit_refresh_vision(punit);
  } unit_list_iterate_end;
}
 
/**********************************************************************/
void finalize_unit_phase_beginning(struct player *pplayer)
{
  /* Remember activities only after all knock-on effects of unit activities
   * on other units have been resolved */
  unit_list_iterate(pplayer->units, punit) {
    punit->changed_from = punit->activity;
    punit->changed_from_target = punit->activity_target;
    punit->changed_from_count = punit->activity_count;
    send_unit_info(nullptr, punit);
  } unit_list_iterate_end;
}
 
/**********************************************************************/
static int total_activity(struct tile *ptile, enum unit_activity act,
                          struct extra_type *tgt)
{
  int total = 0;
  bool tgt_matters = activity_requires_target(act);
 
  unit_list_iterate(ptile->units, punit) {
    if (punit->activity == act
        && (!tgt_matters || punit->activity_target == tgt)) {
      total += punit->activity_count;
    }
  } unit_list_iterate_end;
 
  return total;
}
 
/**********************************************************************/
static bool total_activity_done(struct tile *ptile, enum unit_activity act,
                                struct extra_type *tgt)
{
  return total_activity(ptile, act, tgt) >= tile_activity_time(act, ptile, tgt);
}
 
/**********************************************************************/
void notify_unit_experience(struct unit *punit)
{
  const struct veteran_level *vlevel;
  const struct veteran_system *vsystem;
 
  if (!punit) {
    return;
  }
 
  vsystem = utype_veteran_system(unit_type_get(punit));
  fc_assert_ret(vsystem != nullptr);
  fc_assert_ret(vsystem->levels > punit->veteran);
 
  vlevel = vsystem_veteran_level(vsystem, punit->veteran);
  fc_assert_ret(vlevel != nullptr);
 
  notify_player(unit_owner(punit), unit_tile(punit),
                E_UNIT_BECAME_VET, ftc_server,
                /* TRANS: Your <unit> became ... rank of <veteran level>. */
                _("Your %s became more experienced and achieved the rank "
                  "of %s."),
                unit_link(punit), name_translation_get(&vlevel->name));
}
 
/**********************************************************************/
static void unit_convert(struct unit *punit)
{
  const struct unit_type *to_type;
  const struct unit_type *from_type;
 
  from_type = unit_type_get(punit);
  to_type = from_type->converted_to;
 
  if (unit_can_convert(&(wld.map), punit)) {
    transform_unit(punit, to_type, 0);
    notify_player(unit_owner(punit), unit_tile(punit),
                  E_UNIT_UPGRADED, ftc_server,
                  _("%s converted to %s."),
                  utype_name_translation(from_type),
                  utype_name_translation(to_type));
  } else {
    notify_player(unit_owner(punit), unit_tile(punit),
                  E_UNIT_UPGRADED, ftc_server,
                  _("%s cannot be converted."),
                  utype_name_translation(from_type));
  }
}
 
/**********************************************************************/
void unit_activities_cancel(struct unit *punit)
{
  if (unit_has_orders(punit)) {
    notify_player(unit_owner(punit), unit_tile(punit),
                  E_UNIT_ORDERS, ftc_server,
                  _("Orders for %s aborted because activity "
                    "is no longer available."),
                  unit_link(punit));
    free_unit_orders(punit);
  }
 
  set_unit_activity(punit, ACTIVITY_IDLE, ACTION_NONE);
  send_unit_info(nullptr, punit);
}
 
/**********************************************************************/
void unit_activities_cancel_all_illegal_plr(const struct player *pplayer)
{
  unit_list_iterate(pplayer->units, punit) {
    if (!can_unit_continue_current_activity(&(wld.map), punit)) {
      unit_activities_cancel(punit);
    }
  } unit_list_iterate_end;
}
 
/**********************************************************************/
void unit_activities_cancel_all_illegal_tile(const struct tile *ptile)
{
  unit_list_iterate(ptile->units, punit) {
    if (!can_unit_continue_current_activity(&(wld.map), punit)) {
      unit_activities_cancel(punit);
    }
  } unit_list_iterate_end;
}
 
/**********************************************************************/
void unit_activities_cancel_all_illegal_area(const struct tile *ptile)
{
  unit_activities_cancel_all_illegal_tile(ptile);
 
  adjc_iterate(&(wld.map), ptile, ptile2) {
    unit_activities_cancel_all_illegal_tile(ptile2);
  } adjc_iterate_end;
}
 
/**********************************************************************/
static void update_unit_activity(struct unit *punit)
{
  struct player *pplayer = unit_owner(punit);
  bool unit_activity_done = FALSE;
  enum unit_activity activity = punit->activity;
  struct tile *ptile = unit_tile(punit);
  const struct unit_type *act_utype = unit_type_get(punit);
 
  switch (activity) {
  case ACTIVITY_IDLE:
  case ACTIVITY_EXPLORE:
  case ACTIVITY_FORTIFIED:
  case ACTIVITY_SENTRY:
  case ACTIVITY_GOTO:
  case ACTIVITY_LAST:
    /* We don't need the activity_count for the above */
    break;
 
  case ACTIVITY_FORTIFYING:
  case ACTIVITY_CONVERT:
    punit->activity_count += get_activity_rate_this_turn(punit);
    break;
 
  case ACTIVITY_CLEAN:
  case ACTIVITY_MINE:
  case ACTIVITY_IRRIGATE:
  case ACTIVITY_PILLAGE:
  case ACTIVITY_CULTIVATE:
  case ACTIVITY_PLANT:
  case ACTIVITY_TRANSFORM:
  case ACTIVITY_BASE:
  case ACTIVITY_GEN_ROAD:
    punit->activity_count += get_activity_rate_this_turn(punit);
 
    /* Worker may become veteran when doing something useful */
    if (maybe_become_veteran_real(punit, 100, TRUE)) {
      notify_unit_experience(punit);
    }
    break;
  };
 
  unit_restore_movepoints(pplayer, punit);
 
  switch (activity) {
  case ACTIVITY_EXPLORE:
    /* Not accumulating activity - will be handled more like movement
     * after the TC */
    fc__fallthrough;
  case ACTIVITY_IDLE:
  case ACTIVITY_FORTIFIED:
  case ACTIVITY_SENTRY:
  case ACTIVITY_GOTO:
  case ACTIVITY_FORTIFYING:
  case ACTIVITY_CONVERT:
  case ACTIVITY_LAST:
    /* No default, ensure all handled */
    break;
 
  case ACTIVITY_PILLAGE:
    if (total_activity_done(ptile, ACTIVITY_PILLAGE,
                            punit->activity_target)) {
      destroy_extra(ptile, punit->activity_target);
      unit_activity_done = TRUE;
 
      bounce_units_on_terrain_change(ptile);
 
      /* Change vision if effects have changed. */
      unit_list_refresh_vision(ptile->units);
    }
    break;
 
  case ACTIVITY_CLEAN:
    /* TODO: Remove this fallback target setting when target always correctly
     *       set */
    {
      struct extra_type *pextra;
 
      if (punit->activity_target == nullptr) {
        pextra = prev_extra_in_tile(ptile, ERM_CLEAN,
                                    nullptr, punit);
        if (pextra != nullptr) {
          punit->activity_target = pextra;
        }
      } else {
        if (is_extra_removed_by(punit->activity_target, ERM_CLEAN)) {
          pextra = punit->activity_target;
        } else {
          pextra = nullptr;
        }
      }
 
      if (pextra != nullptr) {
        if (total_activity_done(ptile, ACTIVITY_CLEAN, pextra)) {
          destroy_extra(ptile, pextra);
          unit_activity_done = TRUE;
        }
      }
    }
    break;
 
  case ACTIVITY_BASE:
    {
      if (total_activity(ptile, ACTIVITY_BASE, punit->activity_target)
          >= tile_activity_time(ACTIVITY_BASE, ptile, punit->activity_target)) {
        create_extra(ptile, punit->activity_target, unit_owner(punit));
        unit_activity_done = TRUE;
      }
    }
    break;
 
  case ACTIVITY_GEN_ROAD:
    {
      if (total_activity(ptile, ACTIVITY_GEN_ROAD, punit->activity_target)
          >= tile_activity_time(ACTIVITY_GEN_ROAD, ptile, punit->activity_target)) {
        create_extra(ptile, punit->activity_target, unit_owner(punit));
        unit_activity_done = TRUE;
      }
    }
    break;
 
  case ACTIVITY_IRRIGATE:
  case ACTIVITY_MINE:
  case ACTIVITY_CULTIVATE:
  case ACTIVITY_PLANT:
  case ACTIVITY_TRANSFORM:
    if (total_activity_done(ptile, activity, punit->activity_target)) {
      struct terrain *old = tile_terrain(ptile);
 
      /* The function below could change the terrain. Therefore, we have to
       * check the terrain (which will also do a sanity check for the tile). */
      tile_apply_activity(ptile, activity, punit->activity_target);
      check_terrain_change(ptile, old);
      unit_activity_done = TRUE;
    }
    break;
  }
 
  if (unit_activity_done) {
    struct extra_type *act_tgt = punit->activity_target;
 
    update_tile_knowledge(ptile);
 
    unit_list_iterate(ptile->units, punit2) {
      if (punit2->activity == activity
          && punit2->activity_target == act_tgt) {
        /* This unit was helping with the work just finished.
         * Mark it idle (already finished) so its "current"
         * activity is not considered illegal
         * in tile_change_side_effects() . */
        set_unit_activity(punit2, ACTIVITY_IDLE, ACTION_NONE);
      }
    } unit_list_iterate_end;
 
    tile_change_side_effects(ptile, FALSE);
  }
 
  if (activity == ACTIVITY_FORTIFYING) {
    if (punit->activity_count
        >= action_id_get_act_time(ACTION_FORTIFY,
                                  punit, ptile, punit->activity_target)) {
      set_unit_activity(punit, ACTIVITY_FORTIFIED, punit->action);
      unit_activity_done = TRUE;
    }
  }
 
  if (activity == ACTIVITY_CONVERT) {
    if (punit->activity_count
        >= action_id_get_act_time(ACTION_CONVERT,
                                  punit, ptile, punit->activity_target)) {
      unit_convert(punit);
      set_unit_activity(punit, ACTIVITY_IDLE, ACTION_NONE);
      unit_activity_done = TRUE;
    }
  }
 
  if (unit_activity_done) {
    if (activity == ACTIVITY_PILLAGE) {
      /* Casus Belli for when the action is completed. */
      /* TODO: is it more logical to put Casus_Belli_Success here, change
       * Casus_Belli_Complete to Casus_Belli_Successful_Beginning and
       * trigger it when an activity successfully has began? */
      action_consequence_complete(action_by_number(punit->action),
                                  unit_owner(punit),
                                  act_utype,
                                  tile_owner(unit_tile(punit)),
                                  unit_tile(punit),
                                  tile_link(unit_tile(punit)));
    }
  }
}
 
/**********************************************************************/
void unit_forget_last_activity(struct unit *punit)
{
  punit->changed_from = ACTIVITY_IDLE;
}
 
/**********************************************************************/
bool unit_activity_needs_target_from_client(enum unit_activity activity)
{
  switch (activity) {
  case ACTIVITY_PILLAGE:
    /* Can be set server side. */
    return FALSE;
  default:
    return activity_requires_target(activity);
  }
}
 
/**********************************************************************/
void unit_assign_specific_activity_target(struct unit *punit,
                                          enum unit_activity *activity,
                                          enum gen_action action,
                                          struct extra_type **target)
{
  const struct civ_map *nmap = &(wld.map);
 
  if (*activity == ACTIVITY_PILLAGE
      && *target == nullptr) {
    struct tile *ptile = unit_tile(punit);
    struct extra_type *tgt;
    bv_extras extras = *tile_extras(ptile);
 
    while ((tgt = get_preferred_pillage(extras))) {
 
      BV_CLR(extras, extra_index(tgt));
 
      if (can_unit_do_activity_targeted(nmap, punit, *activity, action,
                                        tgt)) {
        *target = tgt;
        return;
      }
    }
 
    /* Nothing we can pillage here. */
    *activity = ACTIVITY_IDLE;
  }
}
 
/**********************************************************************/
static bool find_a_good_partisan_spot(struct tile *pcenter,
                                      struct player *powner,
                                      struct unit_type *u_type,
                                      int sq_radius,
                                      struct tile **dst_tile)
{
  int bestvalue = 0;
  struct civ_map *nmap = &(wld.map);
 
  /* coords of best tile in arg pointers */
  circle_iterate(nmap, pcenter, sq_radius, ptile) {
    int value;
 
    if (!is_native_tile(u_type, ptile)) {
      continue;
    }
 
    if (tile_city(ptile) != nullptr) {
      continue;
    }
 
    if (0 < unit_list_size(ptile->units)) {
      continue;
    }
 
    /* City may not have changed hands yet; see place_partisans(). */
    value = get_virtual_defense_power(nmap, nullptr, u_type, powner,
                                      ptile, FALSE, 0);
    value *= 10;
 
    if (tile_continent(ptile) != tile_continent(pcenter)) {
      value /= 2;
    }
 
    value -= fc_rand(value/3);
 
    if (value > bestvalue) {
      *dst_tile = ptile;
      bestvalue = value;
    }
  } circle_iterate_end;
 
  return bestvalue > 0;
}
 
/**********************************************************************/
void place_partisans(struct tile *pcenter, struct player *powner,
                     int count, int sq_radius)
{
  struct tile *ptile = nullptr;
  struct unit_type *u_type = get_role_unit(L_PARTISAN, 0);
  const struct civ_map *nmap = &(wld.map);
 
  while (count-- > 0
         && find_a_good_partisan_spot(pcenter, powner, u_type,
                                      sq_radius, &ptile)) {
    struct unit *punit;
    enum gen_action action = activity_default_action(ACTIVITY_FORTIFYING);
 
    punit = unit_virtual_prepare(powner, ptile, u_type, 0, 0, -1, -1);
    if (can_unit_do_activity(nmap, punit, ACTIVITY_FORTIFYING, action)) {
      punit->activity = ACTIVITY_FORTIFIED; /* Yes; directly fortified */
      punit->action = action;
    }
 
    (void) place_unit(punit, powner, nullptr, nullptr, FALSE);
  }
}
 
/**********************************************************************/
bool teleport_unit_to_city(struct unit *punit, struct city *pcity,
                           int move_cost, bool verbose)
{
  struct tile *src_tile = unit_tile(punit), *dst_tile = pcity->tile;
 
  if (city_owner(pcity) == unit_owner(punit)) {
    log_verbose("Teleported %s %s from (%d,%d) to %s",
                nation_rule_name(nation_of_unit(punit)),
                unit_rule_name(punit), TILE_XY(src_tile), city_name_get(pcity));
    if (verbose) {
      notify_player(unit_owner(punit), city_tile(pcity),
                    E_UNIT_RELOCATED, ftc_server,
                    _("Teleported your %s to %s."),
                    unit_link(punit),
                    city_link(pcity));
    }
 
    /* Silently free orders since they won't be applicable anymore. */
    free_unit_orders(punit);
 
    if (move_cost == -1) {
      move_cost = punit->moves_left;
    }
    unit_move(punit, dst_tile, move_cost,
              nullptr, FALSE, FALSE, FALSE, FALSE, FALSE);
 
    return TRUE;
  }
  return FALSE;
}
 
/**********************************************************************/
void bounce_unit(struct unit *punit, bool verbose)
{
  struct player *pplayer;
  struct tile *punit_tile;
  int count = 0;
 
  /* I assume that there are no topologies that have more than
   * (2d + 1)^2 tiles in the "square" of "radius" d. */
  const int DIST = 2;
  struct tile *tiles[(2 * DIST + 1) * (2 * DIST + 1)];
 
  if (!punit) {
    return;
  }
 
  pplayer = unit_owner(punit);
  punit_tile = unit_tile(punit);
 
  square_iterate(&(wld.map), punit_tile, DIST, ptile) {
    if (count >= ARRAY_SIZE(tiles)) {
      break;
    }
 
    if (ptile == punit_tile) {
      continue;
    }
 
    if (can_unit_survive_at_tile(&(wld.map), punit, ptile)
        && !is_non_allied_city_tile(ptile, pplayer)
        && !is_non_allied_unit_tile(ptile, pplayer,
                                    unit_has_type_flag(punit, UTYF_FLAGLESS))) {
      tiles[count++] = ptile;
    }
  } square_iterate_end;
 
  if (count > 0) {
    struct tile *ptile = tiles[fc_rand(count)];
 
    if (verbose) {
      notify_player(pplayer, ptile, E_UNIT_RELOCATED, ftc_server,
                    /* TRANS: A unit is moved to resolve stack conflicts. */
                    _("Moved your %s."),
                    unit_link(punit));
    }
 
    /* TODO: Should a unit be able to bounce to a transport like is done
     * below? What if the unit can't legally enter the transport, say
     * because the transport is Unreachable and the unit doesn't have it in
     * its embarks field or because "Transport Embark" isn't enabled? Kept
     * like it was to preserve the old rules for now. -- Sveinung */
    unit_move(punit, ptile, 0, nullptr, TRUE, FALSE, FALSE, FALSE, FALSE);
    return;
  }
 
  /* Didn't find a place to bounce the unit, going to disband it.
   * Try to bounce transported units. */
  if (0 < get_transporter_occupancy(punit)) {
    struct unit_list *pcargo_units;
 
    pcargo_units = unit_transport_cargo(punit);
    unit_list_iterate_safe(pcargo_units, pcargo) {
      bounce_unit(pcargo, verbose);
    } unit_list_iterate_safe_end;
  }
 
  if (verbose) {
    notify_player(pplayer, punit_tile, E_UNIT_LOST_MISC, ftc_server,
                  /* TRANS: A unit is disbanded to resolve stack conflicts. */
                  _("Disbanded your %s."),
                  unit_tile_link(punit));
  }
 
  wipe_unit(punit, ULR_STACK_CONFLICT, nullptr);
}
 
/**********************************************************************/
static void throw_units_from_illegal_cities(struct player *pplayer,
                                            bool verbose)
{
  struct tile *ptile;
  struct city *pcity;
  struct unit *ptrans;
  struct unit_list *pcargo_units;
 
  /* Unload undesired units from transports, if possible. */
  unit_list_iterate(pplayer->units, punit) {
    ptile = unit_tile(punit);
    pcity = tile_city(ptile);
    if (pcity != nullptr
        && !pplayers_allied(city_owner(pcity), pplayer)
        && 0 < get_transporter_occupancy(punit)) {
      pcargo_units = unit_transport_cargo(punit);
      unit_list_iterate(pcargo_units, pcargo) {
        if (!pplayers_allied(unit_owner(pcargo), pplayer)) {
          if (can_unit_exist_at_tile(&(wld.map), pcargo, ptile)) {
            unit_transport_unload_send(pcargo);
          }
        }
      } unit_list_iterate_end;
    }
  } unit_list_iterate_end;
 
  /* Bounce units except transported ones which will be bounced with their
   * transport. */
  unit_list_iterate_safe(pplayer->units, punit) {
    ptile = unit_tile(punit);
    pcity = tile_city(ptile);
    if (pcity != nullptr
        && !pplayers_allied(city_owner(pcity), pplayer)) {
      ptrans = unit_transport_get(punit);
      if (ptrans == nullptr || pplayer != unit_owner(ptrans)) {
        bounce_unit(punit, verbose);
      }
    }
  } unit_list_iterate_safe_end;
 
#ifdef FREECIV_DEBUG
  /* Sanity check. */
  unit_list_iterate(pplayer->units, punit) {
    ptile = unit_tile(punit);
    pcity = tile_city(ptile);
    fc_assert_msg(pcity == nullptr
                  || pplayers_allied(city_owner(pcity), pplayer),
                  "Failed to throw %s %d from %s %d (%d, %d)",
                  unit_rule_name(punit),
                  punit->id,
                  city_name_get(pcity),
                  pcity->id,
                  TILE_XY(ptile));
  } unit_list_iterate_end;
#endif /* FREECIV_DEBUG */
}
 
/**********************************************************************/
static void resolve_stack_conflicts(struct player *pplayer,
                                    struct player *aplayer, bool verbose)
{
  unit_list_iterate_safe(pplayer->units, punit) {
    struct tile *ptile = unit_tile(punit);
 
    /* Can pass FALSE 'everyone_non_allied' since no flagless
     * unit could be stacked there to begin with. */
    if (is_non_allied_unit_tile(ptile, pplayer, FALSE)) {
      unit_list_iterate_safe(ptile->units, aunit) {
        if (unit_owner(aunit) == pplayer
            || unit_owner(aunit) == aplayer
            || !can_unit_survive_at_tile(&(wld.map), aunit, ptile)) {
          bounce_unit(aunit, verbose);
        }
      } unit_list_iterate_safe_end;
    }
  } unit_list_iterate_safe_end;
}
 
/**********************************************************************/
void resolve_unit_stacks(struct player *pplayer, struct player *aplayer,
                         bool verbose)
{
  throw_units_from_illegal_cities(pplayer, verbose);
  throw_units_from_illegal_cities(aplayer, verbose);
 
  resolve_stack_conflicts(pplayer, aplayer, verbose);
  resolve_stack_conflicts(aplayer, pplayer, verbose);
}
 
/**********************************************************************/
struct unit_list *get_units_seen_via_ally(const struct player *pplayer,
                                          const struct player *aplayer)
{
  struct unit_list *seen_units = unit_list_new();
 
  /* Anybody's units inside ally's cities */
  city_list_iterate(aplayer->cities, pcity) {
    unit_list_iterate(city_tile(pcity)->units, punit) {
      if (can_player_see_unit(pplayer, punit)) {
        unit_list_append(seen_units, punit);
      }
    } unit_list_iterate_end;
  } city_list_iterate_end;
 
  /* Ally's own units inside transports */
  unit_list_iterate(aplayer->units, punit) {
    if (unit_transported(punit) && can_player_see_unit(pplayer, punit)) {
      unit_list_append(seen_units, punit);
    }
  } unit_list_iterate_end;
 
  /* Make sure the same unit is not added in multiple phases
   * (unit within transport in a city) */
  unit_list_unique(seen_units);
 
  return seen_units;
}
 
/**********************************************************************/
void remove_allied_visibility(struct player *pplayer, struct player *aplayer,
                              const struct unit_list *seen_units)
{
  unit_list_iterate(seen_units, punit) {
    /* We need to hide units previously seen by the client. */
    if (!can_player_see_unit(pplayer, punit)) {
      unit_goes_out_of_sight(pplayer, punit);
    }
  } unit_list_iterate_end;
 
  city_list_iterate(aplayer->cities, pcity) {
    /* The player used to know what units were in these cities.  Now that
     * they don't, they need to get a new short city packet updating the
     * occupied status. */
    if (map_is_known_and_seen(pcity->tile, pplayer, V_MAIN)) {
      send_city_info(pplayer, pcity);
    }
  } city_list_iterate_end;
}
 
/**********************************************************************/
void give_allied_visibility(struct player *pplayer,
                            struct player *aplayer)
{
  unit_list_iterate(aplayer->units, punit) {
    if (can_player_see_unit(pplayer, punit)) {
      send_unit_info(pplayer->connections, punit);
    }
  } unit_list_iterate_end;
}
 
/**********************************************************************/
static bool is_refuel_tile(const struct tile *ptile,
                           const struct player *pplayer,
                           const struct unit *punit)
{
  const struct unit_type *utype;
  const struct unit_class *pclass;
 
  if (is_allied_city_tile(ptile, pplayer)) {
    return TRUE;
  }
 
  utype = unit_type_get(punit);
  if (utype_has_flag(utype, UTYF_COAST) && is_safe_ocean(&(wld.map), ptile)) {
    return TRUE;
  }
 
  pclass = utype_class(utype);
  if (pclass->cache.refuel_extras != nullptr) {
    const struct player_tile *plrtile = map_get_player_tile(ptile, pplayer);
 
    extra_type_list_iterate(pclass->cache.refuel_extras, pextra) {
      if (BV_ISSET(plrtile->extras, extra_index(pextra))) {
        return TRUE;
      }
    } extra_type_list_iterate_end;
  }
 
  return FALSE;
}
 
/**********************************************************************/
bool is_unit_being_refueled(const struct unit *punit)
{
  return unit_transported(punit) /* Carrier */
    || is_refuel_tile(unit_tile(punit), unit_owner(punit), punit);
}
 
/**********************************************************************/
bool is_refuel_point(const struct tile *ptile,
                     const struct player *pplayer,
                     const struct unit *punit)
{
  if (is_non_allied_unit_tile(ptile, pplayer,
                              unit_has_type_flag(punit, UTYF_FLAGLESS))) {
    return FALSE;
  }
 
  return is_refuel_tile(ptile, pplayer, punit) || unit_could_load_at(punit, ptile);
}
 
/**********************************************************************/
void transform_unit(struct unit *punit, const struct unit_type *to_unit,
                    int vet_loss)
{
  struct player *pplayer = unit_owner(punit);
  const struct unit_type *old_type = punit->utype;
  int old_mr = unit_move_rate(punit);
  int old_hp = unit_type_get(punit)->hp;
  int lvls;
 
  punit->utype = to_unit;
 
  /* New type may not have the same veteran system, and we may want to
   * knock some levels off. */
  lvls = utype_veteran_system(to_unit)->levels - 1;
  punit->veteran = MIN(punit->veteran, lvls);
  /* Keeping the old behavior, so first clip top, then reduce */
  punit->veteran = MAX(punit->veteran - vet_loss, 0);
 
  /* Scale HP and MP, rounding down. Be careful with integer arithmetic,
   * and don't kill the unit. unit_move_rate() is used to take into account
   * global effects like Magellan's Expedition. */
  punit->hp = MAX(punit->hp * unit_type_get(punit)->hp / old_hp, 1);
  if (old_mr == 0) {
    punit->moves_left = unit_move_rate(punit);
  } else {
    punit->moves_left = punit->moves_left * unit_move_rate(punit) / old_mr;
  }
 
  punit->current_form_turn = game.info.turn;
 
  unit_forget_last_activity(punit);
  if (!can_unit_continue_current_activity(&(wld.map), punit)) {
    unit_activities_cancel(punit);
  }
 
  /* Update unit upkeep */
  city_units_upkeep(game_city_by_number(punit->homecity));
 
  conn_list_do_buffer(pplayer->connections);
 
  unit_refresh_vision(punit);
 
  CALL_PLR_AI_FUNC(unit_transformed, pplayer, punit, old_type);
  CALL_FUNC_EACH_AI(unit_info, punit);
 
  send_unit_info(nullptr, punit);
  conn_list_do_unbuffer(pplayer->connections);
}
 
/**********************************************************************/
struct unit *create_unit(struct player *pplayer, struct tile *ptile,
                         const struct unit_type *type, int veteran_level,
                         int homecity_id, int moves_left)
{
  return create_unit_full(pplayer, ptile, type, veteran_level, homecity_id,
                          moves_left, -1, nullptr);
}
 
/**********************************************************************/
void unit_get_goods(struct unit *punit)
{
  if (punit->homecity != 0) {
    struct city *home = game_city_by_number(punit->homecity);
 
    if (home != nullptr && game.info.goods_selection == GSM_LEAVING) {
      punit->carrying = goods_from_city_to_unit(home, punit);
    }
  }
}
 
/**********************************************************************/
struct unit *create_unit_full(struct player *pplayer, struct tile *ptile,
                              const struct unit_type *type, int veteran_level,
                              int homecity_id, int moves_left, int hp_left,
                              struct unit *ptrans)
{
  struct unit *punit
    = unit_virtual_prepare(pplayer, ptile, type, veteran_level,
                           homecity_id, moves_left, hp_left);
  struct city *pcity = (!homecity_id || utype_has_flag(type, UTYF_NOHOME))
      ? nullptr : game_city_by_number(homecity_id);
  bool could_place;
 
  fc_assert_ret_val(punit, nullptr);
  could_place = place_unit(punit, pplayer, pcity, ptrans, FALSE);
  fc_assert(could_place);
  if (!could_place) {
    unit_virtual_destroy(punit);
    punit = nullptr;
  }
 
  return punit;
}
 
/**********************************************************************/
struct unit *unit_virtual_prepare(struct player *pplayer, struct tile *ptile,
                                  const struct unit_type *type,
                                  int veteran_level, int homecity_id,
                                  int moves_left, int hp_left)
{
  struct unit *punit;
 
  fc_assert_ret_val(ptile != nullptr, nullptr);
  punit = unit_virtual_create(pplayer, nullptr, type, veteran_level);
  unit_tile_set(punit, ptile);
 
  if (utype_has_flag(type, UTYF_NOHOME)) {
    punit->homecity = 0; /* None */
  } else {
    punit->homecity = homecity_id;
  }
 
  if (hp_left >= 0) {
    /* Override default full HP */
    punit->hp = hp_left;
  }
 
  if (moves_left >= 0) {
    int mr = unit_move_rate(punit);
 
    /* Override default full MP */
    /* FIXME: there are valid situations when a unit have mp
     * over its move rate. Here, keeping the old behavior. */
    punit->moves_left = MIN(moves_left, mr);
    /* Assume that if moves_left < 0 then the unit is "fresh",
     * and not moved; else the unit has had something happen
     * to it (eg, bribed) which we treat as equivalent to moved.
     * (Otherwise could pass moved arg too...)  --dwp */
    punit->moved = TRUE;
  }
 
  return punit;
}
 
/**********************************************************************/
bool place_unit(struct unit *punit, struct player *pplayer,
                struct city *pcity, struct unit *ptrans, bool force)
{
  struct tile *ptile;
 
  fc_assert_ret_val(pplayer, FALSE);
  fc_assert_ret_val(punit, FALSE);
  ptile = punit->tile;
  fc_assert_ret_val(ptile, FALSE);
 
  /* Register unit */
  punit->id = identity_number();
  idex_register_unit(&wld, punit);
 
  if (ptrans) {
    /* Set transporter for unit. */
    unit_transport_load_tp_status(punit, ptrans, force);
  }
 
  fc_assert_ret_val(unit_transport_get(punit)
                    || can_unit_exist_at_tile(&(wld.map), punit, ptile),
                    FALSE);
 
  unit_list_prepend(pplayer->units, punit);
  unit_list_prepend(ptile->units, punit);
  unit_make_contact(punit, ptile, nullptr);
  if (pcity && !unit_has_type_flag(punit, UTYF_NOHOME)) {
    fc_assert(punit->homecity == pcity->id);
    fc_assert(city_owner(pcity) == pplayer);
    unit_list_prepend(pcity->units_supported, punit);
    /* update unit upkeep */
    city_units_upkeep(pcity);
    /* Refresh the unit's homecity. */
    city_refresh(pcity);
    send_city_info(pplayer, pcity);
  }
 
  punit->server.vision = vision_new(pplayer, ptile);
  unit_refresh_vision(punit);
 
  unit_get_goods(punit);
 
  send_unit_info(nullptr, punit);
  wakeup_neighbor_sentries(punit);
 
  /* The unit may have changed the available tiles in nearby cities. */
  city_map_update_tile_now(ptile);
  sync_cities();
 
  CALL_FUNC_EACH_AI(unit_created, punit);
  CALL_PLR_AI_FUNC(unit_got, pplayer, punit);
 
  return TRUE;
}
 
/**********************************************************************/
void unit_set_removal_callback(struct unit *punit,
                               void (*callback)(struct unit *punit))
{
  /* Tried to overwrite another call back. If this assertion is triggered
   * in a case where two call back are needed it may be time to support
   * more than one unit removal call back at a time. */
  fc_assert_ret(punit->server.removal_callback == nullptr);
 
  punit->server.removal_callback = callback;
}
 
/**********************************************************************/
void unit_unset_removal_callback(struct unit *punit)
{
  punit->server.removal_callback = nullptr;
}
 
/**********************************************************************/
static void server_remove_unit_full(struct unit *punit, bool transported,
                                    enum unit_loss_reason reason)
{
  struct packet_unit_remove packet;
  struct tile *ptile = unit_tile(punit);
  struct city *pcity = tile_city(ptile);
  struct city *phomecity = game_city_by_number(punit->homecity);
  struct unit *ptrans;
  struct player *pplayer = unit_owner(punit);
 
  /* The unit is doomed. */
  punit->server.dying = TRUE;
 
#if defined(FREECIV_DEBUG) && !defined(FREECIV_NDEBUG)
  unit_list_iterate(ptile->units, pcargo) {
    fc_assert(unit_transport_get(pcargo) != punit);
  } unit_list_iterate_end;
#endif /* FREECIV_DEBUG */
 
  CALL_PLR_AI_FUNC(unit_lost, pplayer, punit);
  CALL_FUNC_EACH_AI(unit_destroyed, punit);
 
  /* Save transporter for updating below. */
  ptrans = unit_transport_get(punit);
  /* Unload unit. */
  unit_transport_unload(punit);
 
  /* Since settlers plot in new cities in the minimap before they
     are built, so that no two settlers head towards the same city
     spot, we need to ensure this reservation is cleared should
     the settler disappear on the way. */
  adv_unit_new_task(punit, AUT_NONE, nullptr);
 
  /* Clear the vision before sending unit remove. Else, we might duplicate
   * the PACKET_UNIT_REMOVE if we lose vision of the unit tile. */
  if (punit->server.vision != nullptr) {
    vision_clear_sight(punit->server.vision);
    vision_free(punit->server.vision);
    punit->server.vision = nullptr;
  }
 
  packet.unit_id = punit->id;
  /* Send to onlookers. */
  players_iterate(aplayer) {
    if (can_player_see_unit_at(aplayer, punit, unit_tile(punit),
                               transported)) {
      lsend_packet_unit_remove(aplayer->connections, &packet);
    }
  } players_iterate_end;
  /* Send to global observers. */
  conn_list_iterate(game.est_connections, pconn) {
    if (conn_is_global_observer(pconn)) {
      send_packet_unit_remove(pconn, &packet);
    }
  } conn_list_iterate_end;
 
  if (punit->server.moving != nullptr) {
    /* Do not care of this unit for running moves. */
    punit->server.moving->punit = nullptr;
  }
 
  if (punit->server.removal_callback != nullptr) {
    /* Run the unit removal call back. */
    punit->server.removal_callback(punit);
  }
 
  /* check if this unit had UTYF_GAMELOSS flag */
  if (unit_has_type_flag(punit, UTYF_GAMELOSS) && unit_owner(punit)->is_alive
      && ULR_EDITOR != reason) {
    notify_conn(game.est_connections, ptile, E_UNIT_LOST_MISC, ftc_server,
                _("Unable to defend %s, %s has lost the game."),
                unit_link(punit),
                player_name(pplayer));
    notify_player(pplayer, ptile, E_GAME_END, ftc_server,
                  _("Losing %s meant losing the game! "
                  "Be more careful next time!"),
                  unit_link(punit));
    player_status_add(unit_owner(punit), PSTATUS_DYING);
  }
 
  script_server_signal_emit("unit_lost", punit, unit_owner(punit),
                            unit_loss_reason_name(reason));
 
  script_server_remove_exported_object(punit);
  game_remove_unit(&wld, punit);
  punit = nullptr;
 
  if (ptrans != nullptr) {
    /* Update the occupy info. */
    send_unit_info(nullptr, ptrans);
  }
 
  /* This unit may have blocked tiles of adjacent cities. Update them. */
  city_map_update_tile_now(ptile);
  sync_cities();
 
  if (phomecity) {
    city_refresh(phomecity);
    send_city_info(city_owner(phomecity), phomecity);
  }
 
  if (pcity && pcity != phomecity) {
    city_refresh(pcity);
    send_city_info(city_owner(pcity), pcity);
  }
 
  if (pcity && unit_list_size(ptile->units) == 0) {
    /* The last unit in the city was killed: update the occupied flag. */
    send_city_info(nullptr, pcity);
  }
}
 
/**********************************************************************/
static void server_remove_unit(struct unit *punit,
                               enum unit_loss_reason reason)
{
  server_remove_unit_full(punit, unit_transported(punit), reason);
}
 
/**********************************************************************/
static void unit_lost_with_transport(const struct player *pplayer,
                                     struct unit *pcargo,
                                     const struct unit_type *ptransport,
                                     struct player *killer)
{
  notify_player(pplayer, unit_tile(pcargo), E_UNIT_LOST_MISC, ftc_server,
                _("%s lost when %s was lost."),
                unit_tile_link(pcargo),
                utype_name_translation(ptransport));
  /* Unit is not transported any more at this point, but it has jumped
   * off the transport and drowns outside. So it must be removed from
   * all clients.
   * However, we don't know if given client has received ANY updates
   * about the swimming unit, and we can't remove it if it's not there
   * in the first place -> we send it once here just to be sure it's
   * there. */
  send_unit_info(nullptr, pcargo);
  wipe_unit_full(pcargo, FALSE, ULR_TRANSPORT_LOST, killer);
}
 
/**********************************************************************/
static void wipe_unit_full(struct unit *punit, bool transported,
                           enum unit_loss_reason reason,
                           struct player *killer)
{
  struct tile *ptile = unit_tile(punit);
  struct player *pplayer = unit_owner(punit);
  const struct unit_type *putype_save = unit_type_get(punit); /* for notify messages */
  struct unit_list *helpless = unit_list_new();
  struct unit_list *imperiled = unit_list_new();
  struct unit_list *unsaved = unit_list_new();
  struct unit *ptrans = unit_transport_get(punit);
  struct city *pexclcity;
  struct civ_map *nmap = &(wld.map);
 
  if (killer != nullptr
      && (game.info.gameloss_style & GAMELOSS_STYLE_LOOT)
      && unit_has_type_flag(punit, UTYF_GAMELOSS)) {
    player_loot_player(killer, pplayer);
  }
 
  /* The unit is doomed. */
  punit->server.dying = TRUE;
 
  /* If a unit is being lost due to loss of its city, ensure that we don't
   * try to teleport any of its cargo to that city (which may not yet
   * have changed hands or disappeared). (It is assumed that the unit's
   * home city is always the one that is being lost/transferred/etc.) */
  if (reason == ULR_CITY_LOST) {
    pexclcity = unit_home(punit);
  } else {
    pexclcity = nullptr;
  }
 
  /* Remove unit itself from its transport */
  if (ptrans != nullptr) {
    unit_transport_unload(punit);
    send_unit_info(nullptr, ptrans);
  }
 
  /* First pull all units off of the transporter. */
  if (get_transporter_occupancy(punit) > 0) {
    /* Use iterate_safe as unloaded units will be removed from the list
     * while iterating. */
    unit_list_iterate_safe(unit_transport_cargo(punit), pcargo) {
      bool healthy = FALSE;
 
      if (!can_unit_unload(pcargo, punit)) {
        unit_list_prepend(helpless, pcargo);
      } else {
        if (!can_unit_exist_at_tile(nmap, pcargo, ptile)) {
          unit_list_prepend(imperiled, pcargo);
        } else {
          /* These units do not need to be saved. */
          healthy = TRUE;
        }
      }
 
      /* Could use unit_transport_unload_send() here, but that would
       * call send_unit_info() for the transporter unnecessarily.
       * Note that this means that unit might to get seen briefly
       * by clients other than owner's, for example as a result of
       * update of homecity common to this cargo and some other
       * destroyed unit. */
      unit_transport_unload(pcargo);
      if (pcargo->activity == ACTIVITY_SENTRY) {
        /* Activate sentried units - like planes on a disbanded carrier.
         * Note this will activate ground units even if they just change
         * transporter. */
        set_unit_activity(pcargo, ACTIVITY_IDLE, ACTION_NONE);
      }
 
      /* Unit info for unhealthy units will be sent when they are
       * assigned new transport or removed. */
      if (healthy) {
        send_unit_info(nullptr, pcargo);
      }
    } unit_list_iterate_safe_end;
  }
 
  /* Now remove the unit. */
  server_remove_unit_full(punit, transported, reason);
 
  switch (reason) {
  case ULR_KILLED:
  case ULR_EXECUTED:
  case ULR_SDI:
  case ULR_NUKE:
  case ULR_BRIBED:
  case ULR_CAPTURED:
  case ULR_CAUGHT:
  case ULR_ELIMINATED:
  case ULR_TRANSPORT_LOST:
    if (killer != nullptr) {
      killer->score.units_killed++;
    }
    pplayer->score.units_lost++;
    break;
  case ULR_BARB_UNLEASH:
  case ULR_CITY_LOST:
  case ULR_STARVED:
  case ULR_UPKEEP:
  case ULR_NONNATIVE_TERR:
  case ULR_ARMISTICE:
  case ULR_HP_LOSS:
  case ULR_FUEL:
  case ULR_STACK_CONFLICT:
  case ULR_SOLD:
    pplayer->score.units_lost++;
    break;
  case ULR_RETIRED:
  case ULR_DISBANDED:
  case ULR_USED:
  case ULR_DETONATED:
  case ULR_MISSILE:
    pplayer->score.units_used++;
    break;
  case ULR_EDITOR:
  case ULR_PLAYER_DIED:
    break;
  }
 
  /* First, sort out helpless cargo. */
  if (unit_list_size(helpless) > 0) {
    struct unit_list *remaining = unit_list_new();
 
    /* Grant priority to gameloss units and units with the EvacuateFirst
     * unit type flag. */
    unit_list_iterate_safe(helpless, pcargo) {
      if (unit_has_type_flag(pcargo, UTYF_EVAC_FIRST)
          || unit_has_type_flag(pcargo, UTYF_GAMELOSS)) {
        if (!try_to_save_unit(pcargo, putype_save, TRUE,
                              unit_has_type_flag(pcargo,
                                                 UTYF_EVAC_FIRST),
                              pexclcity)) {
          unit_list_prepend(unsaved, pcargo);
        }
      } else {
        unit_list_prepend(remaining, pcargo);
      }
    } unit_list_iterate_safe_end;
 
    /* Handle non-priority units. */
    unit_list_iterate_safe(remaining, pcargo) {
      if (!try_to_save_unit(pcargo, putype_save, TRUE, FALSE, pexclcity)) {
        unit_list_prepend(unsaved, pcargo);
      }
    } unit_list_iterate_safe_end;
 
    unit_list_destroy(remaining);
  }
  unit_list_destroy(helpless);
 
  /* Then, save any imperiled cargo. */
  if (unit_list_size(imperiled) > 0) {
    struct unit_list *remaining = unit_list_new();
 
    /* Grant priority to gameloss units and units with the EvacuateFirst
     * unit type flag. */
    unit_list_iterate_safe(imperiled, pcargo) {
      if (unit_has_type_flag(pcargo, UTYF_EVAC_FIRST)
          || unit_has_type_flag(pcargo, UTYF_GAMELOSS)) {
        if (!try_to_save_unit(pcargo, putype_save, FALSE,
                              unit_has_type_flag(pcargo,
                                                 UTYF_EVAC_FIRST),
                              pexclcity)) {
          unit_list_prepend(unsaved, pcargo);
        }
      } else {
        unit_list_prepend(remaining, pcargo);
      }
    } unit_list_iterate_safe_end;
 
    /* Handle non-priority units. */
    unit_list_iterate_safe(remaining, pcargo) {
      if (!try_to_save_unit(pcargo, putype_save, FALSE, FALSE, pexclcity)) {
        unit_list_prepend(unsaved, pcargo);
      }
    } unit_list_iterate_safe_end;
 
    unit_list_destroy(remaining);
  }
  unit_list_destroy(imperiled);
 
  /* Finally, kill off the unsaved units. */
  if (unit_list_size(unsaved) > 0) {
    unit_list_iterate_safe(unsaved, dying_unit) {
      unit_lost_with_transport(pplayer, dying_unit, putype_save, killer);
    } unit_list_iterate_safe_end;
  }
  unit_list_destroy(unsaved);
}
 
/**********************************************************************/
void wipe_unit(struct unit *punit, enum unit_loss_reason reason,
               struct player *killer)
{
  wipe_unit_full(punit, unit_transported(punit), reason, killer);
}
 
/**********************************************************************/
static bool try_to_save_unit(struct unit *punit, const struct unit_type *pttype,
                             bool helpless, bool teleporting,
                             const struct city *pexclcity)
{
  struct tile *ptile = unit_tile(punit);
  struct player *pplayer = unit_owner(punit);
  struct unit *ptransport = transporter_for_unit(punit);
 
  /* Helpless units cannot board a transport in their current state. */
  if (!helpless
      && ptransport != nullptr) {
    unit_transport_load_tp_status(punit, ptransport, FALSE);
    send_unit_info(nullptr, punit);
    return TRUE;
  } else {
    /* Only units that cannot find transport are considered for teleport. */
    if (teleporting) {
      struct city *pcity = find_closest_city(ptile, pexclcity,
                                             unit_owner(punit),
                                             FALSE, FALSE, FALSE, TRUE, FALSE,
                                             utype_class(pttype));
      if (pcity != nullptr) {
        char tplink[MAX_LEN_LINK]; /* In case unit dies when teleported */
 
        sz_strlcpy(tplink, unit_link(punit));
 
        if (teleport_unit_to_city(punit, pcity, 0, FALSE)) {
          notify_player(pplayer, ptile, E_UNIT_RELOCATED, ftc_server,
                        _("%s escaped the destruction of %s, and fled to %s."),
                        tplink,
                        utype_name_translation(pttype),
                        city_link(pcity));
          return TRUE;
        }
      }
    }
  }
 
  /* The unit could not use transport on the tile, and could not teleport. */
  return FALSE;
}
 
/**********************************************************************/
struct unit *unit_change_owner(struct unit *punit, struct player *pplayer,
                               int homecity, enum unit_loss_reason reason)
{
  struct unit *gained_unit;
  int id = 0;
 
#ifndef FREECIV_NDEBUG
  bool placed;
#endif
 
  fc_assert(!utype_player_already_has_this_unique(pplayer,
                                                  unit_type_get(punit)));
 
  /* Convert the unit to your cause. It's supposed that the original unit
   * is on a valid tile and is not transported. */
  gained_unit = unit_virtual_prepare(pplayer, unit_tile(punit),
                                     unit_type_get(punit), punit->veteran,
                                     homecity, punit->moves_left, punit->hp);
  fc_assert_action(gained_unit, goto uco_wipe); /* Tile must be valid */
 
  /* Owner changes, nationality not. */
  gained_unit->nationality = punit->nationality;
 
  /* Copy some more unit fields */
  gained_unit->fuel = punit->fuel;
  gained_unit->paradropped = punit->paradropped;
  gained_unit->birth_turn = punit->birth_turn;
  gained_unit->current_form_turn = punit->current_form_turn;
 
  /* Fog is lifted in the placing algorithm. */
#ifndef FREECIV_NDEBUG
  placed =
#endif
    place_unit(gained_unit, pplayer,
               homecity ? game_city_by_number(homecity) : nullptr,
               nullptr, FALSE);
 
  fc_assert_action(placed, unit_virtual_destroy(gained_unit); goto uco_wipe);
 
  id = gained_unit->id;
 
  /* Update unit upkeep in the new homecity */
  if (homecity > 0) {
    city_units_upkeep(game_city_by_number(homecity));
  }
 
  /* Be sure to wipe the converted unit! */
  /* Old homecity upkeep is updated in process */
#ifndef FREECIV_NDEBUG
  uco_wipe:
#endif
 
  wipe_unit(punit, reason, nullptr);
 
  if (!unit_is_alive(id)) {
    /* Destroyed by a script */
    return nullptr;
  }
 
  return gained_unit;   /* Returns the replacement. */
}
 
/**********************************************************************/
void kill_unit(struct unit *pkiller, struct unit *punit, bool vet)
{
  char pkiller_link[MAX_LEN_LINK], punit_link[MAX_LEN_LINK];
  struct player *pvictim = unit_owner(punit);
  struct player *pvictor = unit_owner(pkiller);
  struct tile *deftile = unit_tile(punit);
  int unitcount = 0;
  bool escaped;
  bool flagless_killer = unit_has_type_flag(pkiller, UTYF_FLAGLESS);
  bool flagless_victim = unit_has_type_flag(punit, UTYF_FLAGLESS);
  const struct civ_map *nmap = &(wld.map);
 
  sz_strlcpy(pkiller_link, unit_link(pkiller));
  sz_strlcpy(punit_link, unit_tile_link(punit));
 
  /* The unit is doomed. */
  punit->server.dying = TRUE;
 
  unit_list_iterate(deftile->units, vunit) {
    if ((flagless_killer
         || pplayers_at_war(pvictor, unit_owner(vunit))
         || unit_has_type_flag(vunit, UTYF_FLAGLESS))
        && is_unit_reachable_at(vunit, pkiller, deftile)) {
      unitcount++;
    }
  } unit_list_iterate_end;
 
  if (!is_stack_vulnerable(deftile) || unitcount == 1) {
    if (vet) {
      notify_unit_experience(pkiller);
    }
    wipe_unit(punit, ULR_KILLED, pvictor);
  } else { /* Unitcount > 1 */
    int i;
    int slots = player_slot_count();
    int num_killed[slots];
    int num_escaped[slots];
    struct unit *other_killed[slots];
 
    fc_assert(unitcount > 1);
 
    /* Initialize */
    for (i = 0; i < slots; i++) {
      num_killed[i] = 0;
      other_killed[i] = nullptr;
      num_escaped[i] = 0;
    }
 
    /* Count killed units */
    unit_list_iterate_safe(deftile->units, vunit) {
      struct player *vplayer = unit_owner(vunit);
 
      if (pplayers_at_war(pvictor, vplayer)
          && is_unit_reachable_at(vunit, pkiller, deftile)) {
        escaped = FALSE;
 
        if (is_action_enabled_unit_on_self(nmap, ACTION_ESCAPE, vunit)
            && !unit_has_type_flag(pkiller, UTYF_CANKILLESCAPING)
            && vunit->hp > 0
            && vunit->moves_left > pkiller->moves_left
            && fc_rand(2)) {
          int curr_def_bonus;
          int def_bonus = 0;
          struct tile *dsttile = nullptr;
          int move_cost;
 
          fc_assert(vunit->hp > 0);
 
          adjc_iterate(nmap, deftile, ptile2) {
            if (can_exist_at_tile(nmap, vunit->utype, ptile2)
                && tile_city(ptile2) == nullptr) {
              move_cost = map_move_cost_unit(nmap, vunit, ptile2);
              if (pkiller->moves_left <= vunit->moves_left - move_cost
                  && (is_allied_unit_tile(ptile2, pvictim)
                      || unit_list_size(ptile2->units)) == 0) {
                curr_def_bonus = tile_extras_defense_bonus(ptile2,
                                                           vunit->utype);
                if (def_bonus <= curr_def_bonus) {
                  def_bonus = curr_def_bonus;
                  dsttile = ptile2;
                }
              }
            }
          } adjc_iterate_end;
 
          if (dsttile != nullptr) {
            escaped = (action_auto_perf_unit_do(AAPC_UNIT_STACK_DEATH,
                                                vunit, tile_owner(dsttile),
                                                nullptr, nullptr, dsttile,
                                                tile_city(dsttile),
                                                nullptr, nullptr)
                       != nullptr);
 
            if (escaped) {
              num_escaped[player_index(vplayer)]++;
              unitcount--;
            }
          }
        }
 
        if (!escaped) {
          num_killed[player_index(vplayer)]++;
 
          if (vunit != punit) {
            other_killed[player_index(vplayer)] = vunit;
            other_killed[player_index(pvictor)] = vunit;
          }
        }
      }
    } unit_list_iterate_safe_end;
 
    /* Inform the destroyer again if more than one unit was killed */
    if (unitcount > 1) {
      if (flagless_victim) {
        notify_player(pvictor, unit_tile(pkiller), E_UNIT_WIN_ATT, ftc_server,
                      /* TRANS: "... Cannon ... Destroyer ...." */
                      PL_("Your attacking %s succeeded against %s "
                          "(and %d other unit)!",
                          "Your attacking %s succeeded against %s "
                          "(and %d other units)!", unitcount - 1),
                      pkiller_link,
                      punit_link,
                      unitcount - 1);
      } else {
        notify_player(pvictor, unit_tile(pkiller), E_UNIT_WIN_ATT, ftc_server,
                      /* TRANS: "... Cannon ... the Polish Destroyer ...." */
                      PL_("Your attacking %s succeeded against the %s %s "
                          "(and %d other unit)!",
                          "Your attacking %s succeeded against the %s %s "
                          "(and %d other units)!", unitcount - 1),
                      pkiller_link,
                      nation_adjective_for_player(pvictim),
                      punit_link,
                      unitcount - 1);
      }
    }
 
    if (vet) {
      notify_unit_experience(pkiller);
    }
 
    /* Inform the owners: this only tells about owned units that were killed.
     * there may have been 20 units who died but if only 2 belonged to the
     * particular player they'll only learn about those.
     *
     * Also if a large number of units die you don't find out what type
     * they all are. */
    for (i = 0; i < slots; i++) {
      if (num_killed[i] == 1) {
        if (i == player_index(pvictim)) {
          fc_assert(other_killed[i] == nullptr);
 
          if (flagless_killer) {
            notify_player(player_by_number(i), deftile,
                          E_UNIT_LOST_DEF, ftc_server,
                          /* TRANS: "Cannon ... Destroyer." */
                          _("%s lost to an attack by %s."),
                          punit_link,
                          pkiller_link);
          } else {
            notify_player(player_by_number(i), deftile,
                          E_UNIT_LOST_DEF, ftc_server,
                          /* TRANS: "Cannon ... the Polish Destroyer." */
                          _("%s lost to an attack by the %s %s."),
                          punit_link,
                          nation_adjective_for_player(pvictor),
                          pkiller_link);
          }
        } else {
          fc_assert(other_killed[i] != punit);
 
          if (flagless_victim) {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Cannon lost when Destroyer
                             * attacked Musketeers." */
                            _("%s lost when %s attacked %s."),
                            unit_link(other_killed[i]),
                            pkiller_link,
                            punit_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Cannon lost when the Polish Destroyer
                             * attacked Musketeers." */
                            _("%s lost when the %s %s attacked %s."),
                            unit_link(other_killed[i]),
                            nation_adjective_for_player(pvictor),
                            pkiller_link,
                            punit_link);
            }
          } else {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Cannon lost when Destroyer
                             * attacked the German Musketeers." */
                            _("%s lost when %s attacked the %s %s."),
                            unit_link(other_killed[i]),
                            pkiller_link,
                            nation_adjective_for_player(pvictim),
                            punit_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Cannon lost when the Polish Destroyer
                             * attacked the German Musketeers." */
                            _("%s lost when the %s %s attacked the %s %s."),
                            unit_link(other_killed[i]),
                            nation_adjective_for_player(pvictor),
                            pkiller_link,
                            nation_adjective_for_player(pvictim),
                            punit_link);
            }
          }
        }
      } else if (num_killed[i] > 1) {
        if (i == player_index(pvictim)) {
          int others = num_killed[i] - 1;
 
          if (others == 1) {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Musketeers (and Cannon) lost to an
                             * attack from Destroyer." */
                            _("%s (and %s) lost to an attack from %s."),
                            punit_link,
                            unit_link(other_killed[i]),
                            pkiller_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Musketeers (and Cannon) lost to an
                             * attack from the Polish Destroyer." */
                            _("%s (and %s) lost to an attack from the %s %s."),
                            punit_link,
                            unit_link(other_killed[i]),
                            nation_adjective_for_player(pvictor),
                            pkiller_link);
            }
          } else {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Musketeers and 3 other units lost to
                             * an attack from Destroyer."
                             * (only happens with at least 2 other units) */
                            PL_("%s and %d other unit lost to an attack "
                                "from %s.",
                                "%s and %d other units lost to an attack "
                                "from %s.", others),
                            punit_link,
                            others,
                            pkiller_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "Musketeers and 3 other units lost to
                             * an attack from the Polish Destroyer."
                             * (only happens with at least 2 other units) */
                            PL_("%s and %d other unit lost to an attack "
                                "from the %s %s.",
                                "%s and %d other units lost to an attack "
                                "from the %s %s.", others),
                            punit_link,
                            others,
                            nation_adjective_for_player(pvictor),
                            pkiller_link);
            }
          }
        } else {
          if (flagless_victim) {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "2 units lost when Destroyer
                             * attacked Musketeers."
                             * (only happens with at least 2 other units) */
                            PL_("%d unit lost when %s attacked %s.",
                                "%d units lost when %s attacked %s.",
                                num_killed[i]),
                            num_killed[i],
                            pkiller_link,
                            punit_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "2 units lost when the Polish Destroyer
                             * attacked Musketeers."
                             * (only happens with at least 2 other units) */
                            PL_("%d unit lost when the %s %s attacked %s.",
                                "%d units lost when the %s %s attacked %s.",
                                num_killed[i]),
                            num_killed[i],
                            nation_adjective_for_player(pvictor),
                            pkiller_link,
                            punit_link);
            }
          } else {
            if (flagless_killer) {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "2 units lost when Destroyer
                             * attacked the German Musketeers."
                             * (only happens with at least 2 other units) */
                            PL_("%d unit lost when %s attacked the %s %s.",
                                "%d units lost when %s attacked the %s %s.",
                                num_killed[i]),
                            num_killed[i],
                            pkiller_link,
                            nation_adjective_for_player(pvictim),
                            punit_link);
            } else {
              notify_player(player_by_number(i), deftile,
                            E_UNIT_LOST_DEF, ftc_server,
                            /* TRANS: "2 units lost when the Polish Destroyer
                             * attacked the German Musketeers."
                             * (only happens with at least 2 other units) */
                            PL_("%d unit lost when the %s %s attacked the %s %s.",
                                "%d units lost when the %s %s attacked the %s %s.",
                                num_killed[i]),
                            num_killed[i],
                            nation_adjective_for_player(pvictor),
                            pkiller_link,
                            nation_adjective_for_player(pvictim),
                            punit_link);
            }
          }
        }
      }
    }
 
    /* Inform the owner of the units that escaped.
     * 'deftile' is the original tile they defended at, not where
     * they escaped to, as there might be multiple different tiles
     * different units escaped to. */
    for (i = 0; i < slots; i++) {
      if (0 < num_escaped[i]) {
        if (flagless_killer) {
          notify_player(player_by_number(i), deftile,
                        E_UNIT_ESCAPED, ftc_server,
                        PL_("%d unit escaped from attack by %s",
                            "%d units escaped from attack by %s",
                            num_escaped[i]),
                        num_escaped[i],
                        pkiller_link);
        } else {
          notify_player(player_by_number(i), deftile,
                        E_UNIT_ESCAPED, ftc_server,
                        PL_("%d unit escaped from attack by %s %s",
                            "%d units escaped from attack by %s %s",
                            num_escaped[i]),
                        num_escaped[i],
                        nation_adjective_for_player(pvictor),
                        pkiller_link);
        }
      }
    }
 
    /* Remove the units - note the logic of which units actually die
     * must be mimiced exactly in at least one place up above. */
    punit = nullptr; /* Wiped during following iteration so unsafe to use */
 
    unit_list_iterate_safe(deftile->units, punit2) {
      if (pplayers_at_war(pvictor, unit_owner(punit2))
          && is_unit_reachable_at(punit2, pkiller, deftile)) {
        wipe_unit(punit2, ULR_KILLED, pvictor);
      }
    } unit_list_iterate_safe_end;
  }
}
 
/**********************************************************************/
void collect_ransom(struct unit *pcollector, struct unit *punit, bool vet)
{
  struct player *pvictim = unit_owner(punit);
  struct player *pvictor = unit_owner(pcollector);
  char pcollector_link[MAX_LEN_LINK], punit_link[MAX_LEN_LINK];
  struct tile *deftile = unit_tile(punit);
  int unitcount, ransom;
 
  /* The unit is doomed. */
  punit->server.dying = TRUE;
 
  unitcount = unit_list_size(deftile->units);
  ransom = unitcount * game.server.ransom_gold;
 
  if (pvictim->economic.gold < ransom) {
    ransom = pvictim->economic.gold;
  }
 
  notify_player(pvictor, unit_tile(pcollector), E_UNIT_WIN_ATT, ftc_server,
                PL_("%d Barbarian leader captured.",
                    "%d Barbarian leaders captured.",
                    unitcount),
                unitcount);
  notify_player(pvictor, unit_tile(pcollector), E_UNIT_WIN_ATT, ftc_server,
                PL_("%d gold ransom paid.",
                    "%d gold ransom paid.",
                    ransom),
                ransom);
  pvictor->economic.gold += ransom;
  pvictim->economic.gold -= ransom;
  send_player_info_c(pvictor, nullptr);   /* Let me see my new gold :-) */
 
  if (vet) {
    notify_unit_experience(pcollector);
  }
 
  sz_strlcpy(pcollector_link, unit_link(pcollector));
  sz_strlcpy(punit_link, unit_tile_link(punit));
 
  if (!is_stack_vulnerable(deftile) || unitcount == 1) {
    wipe_unit(punit, ULR_KILLED, pvictor);
  } else {
    int i;
    int slots = player_slot_count();
    int num_collected[slots];
 
    fc_assert(unitcount > 1);
 
    /* Initialize */
    for (i = 0; i < slots; i++) {
      num_collected[i] = 0;
    }
 
    /* Count captured units */
    unit_list_iterate_safe(deftile->units, vunit) {
      struct player *vplayer = unit_owner(vunit);
 
      num_collected[player_index(vplayer)]++;
    } unit_list_iterate_safe_end;
 
    for (i = 0; i < slots; i++) {
      if (num_collected[i] == 1) {
        notify_player(player_by_number(i), deftile,
                      E_UNIT_LOST_DEF, ftc_server,
                      _("%s %s collected ransom of %s."),
                      nation_adjective_for_player(pvictor),
                      pcollector_link, punit_link);
      } else if (num_collected[i] > 1) {
        notify_player(player_by_number(i), deftile,
                      E_UNIT_LOST_DEF, ftc_server,
                      PL_("%s %s collected ransom of %s and %d other unit.",
                          "%s %s collected ransom of %s and %d other units.",
                          num_collected[i] - 1),
                      nation_adjective_for_player(pvictor),
                      pcollector_link,
                      punit_link,
                      num_collected[i] - 1);
      }
    }
 
    unit_list_iterate_safe(deftile->units, punit2) {
      wipe_unit(punit2, ULR_KILLED, pvictor);
    } unit_list_iterate_safe_end;
  }
}
 
/**********************************************************************/
void package_unit(struct unit *punit, struct packet_unit_info *packet)
{
  packet->id = punit->id;
  packet->owner = player_number(unit_owner(punit));
  packet->nationality = player_number(unit_nationality(punit));
  packet->tile = tile_index(unit_tile(punit));
  packet->facing = punit->facing;
  packet->homecity = punit->homecity;
  output_type_iterate(o) {
    packet->upkeep[o] = punit->upkeep[o];
  } output_type_iterate_end;
  packet->veteran = punit->veteran;
  packet->type = utype_number(unit_type_get(punit));
  packet->movesleft = punit->moves_left;
  packet->hp = punit->hp;
  packet->activity = punit->activity;
  packet->activity_count = punit->activity_count;
 
  if (punit->activity_target != nullptr) {
    packet->activity_tgt = extra_index(punit->activity_target);
  } else {
    packet->activity_tgt = EXTRA_NONE;
  }
 
  packet->changed_from = punit->changed_from;
  packet->changed_from_count = punit->changed_from_count;
 
  if (punit->changed_from_target != nullptr) {
    packet->changed_from_tgt = extra_index(punit->changed_from_target);
  } else {
    packet->changed_from_tgt = EXTRA_NONE;
  }
 
  packet->ssa_controller = punit->ssa_controller;
  packet->fuel = punit->fuel;
  packet->goto_tile = (punit->goto_tile != nullptr
                       ? tile_index(punit->goto_tile) : -1);
  packet->paradropped = punit->paradropped;
  packet->done_moving = punit->done_moving;
  packet->stay        = punit->stay;
  packet->birth_turn  = punit->birth_turn;
  packet->current_form_turn = punit->current_form_turn;
  if (!unit_transported(punit)) {
    packet->transported = FALSE;
    packet->transported_by = 0;
  } else {
    packet->transported = TRUE;
    packet->transported_by = unit_transport_get(punit)->id;
  }
  if (punit->carrying != nullptr) {
    packet->carrying = goods_index(punit->carrying);
  } else {
    packet->carrying = -1;
  }
  packet->occupied = (get_transporter_occupancy(punit) > 0);
  packet->battlegroup = punit->battlegroup;
  packet->has_orders = punit->has_orders;
  if (punit->has_orders) {
    packet->orders_length = punit->orders.length;
    packet->orders_index = punit->orders.index;
    packet->orders_repeat = punit->orders.repeat;
    packet->orders_vigilant = punit->orders.vigilant;
    memcpy(packet->orders, punit->orders.list,
           punit->orders.length * sizeof(struct unit_order));
  } else {
    packet->orders_length = packet->orders_index = 0;
    packet->orders_repeat = packet->orders_vigilant = FALSE;
    /* No need to initialize array. */
  }
 
  packet->action_decision_want = punit->action_decision_want;
  packet->action_decision_tile = (punit->action_decision_tile
                                  ? tile_index(punit->action_decision_tile)
                                  : IDENTITY_NUMBER_ZERO);
}
 
/**********************************************************************/
void package_short_unit(struct unit *punit,
                        struct packet_unit_short_info *packet,
                        enum unit_info_use packet_use, int info_city_id)
{
  packet->packet_use = packet_use;
  packet->info_city_id = info_city_id;
 
  packet->id = punit->id;
 
  if (unit_has_type_flag(punit, UTYF_FLAGLESS)) {
    packet->owner = OWNER_NONE;
  } else {
    packet->owner = player_number(unit_owner(punit));
  }
 
  packet->tile = tile_index(unit_tile(punit));
  packet->facing = punit->facing;
  packet->veteran = punit->veteran;
  packet->type = utype_number(unit_type_get(punit));
  packet->hp = punit->hp;
  packet->occupied = (get_transporter_occupancy(punit) > 0);
  if (punit->activity == ACTIVITY_EXPLORE
      || punit->activity == ACTIVITY_GOTO) {
    packet->activity = ACTIVITY_IDLE;
  } else {
    packet->activity = punit->activity;
  }
 
  if (punit->activity_target == nullptr) {
    packet->activity_tgt = EXTRA_NONE;
  } else {
    packet->activity_tgt = extra_index(punit->activity_target);
  }
 
  /* Transported_by information is sent to the client even for units that
   * aren't fully known. Note that for non-allied players, any transported
   * unit can't be seen at all. For allied players we have to know if
   * transporters have room in them so that we can load units properly. */
  if (!unit_transported(punit)) {
    packet->transported = FALSE;
    packet->transported_by = 0;
  } else {
    packet->transported = TRUE;
    packet->transported_by = unit_transport_get(punit)->id;
  }
}
 
/**********************************************************************/
void unit_goes_out_of_sight(struct player *pplayer, struct unit *punit)
{
  dlsend_packet_unit_remove(pplayer->connections, punit->id);
  if (punit->server.moving != nullptr) {
    /* Update status of 'pplayer' vision for 'punit'. */
    BV_CLR(punit->server.moving->can_see_unit, player_index(pplayer));
  }
}
 
/**********************************************************************/
void send_unit_info(struct conn_list *dest, struct unit *punit)
{
  const struct player *powner;
  struct packet_unit_info info;
  struct packet_unit_short_info sinfo;
  struct unit_move_data *pdata;
 
  if (dest == nullptr) {
    dest = game.est_connections;
  }
 
  CHECK_UNIT(punit);
 
  powner = unit_owner(punit);
  package_unit(punit, &info);
  package_short_unit(punit, &sinfo, UNIT_INFO_IDENTITY, 0);
  pdata = punit->server.moving;
 
  conn_list_iterate(dest, pconn) {
    struct player *pplayer = conn_get_player(pconn);
 
    /* Be careful to consider all cases where pplayer is nullptr... */
    if (pplayer == nullptr) {
      if (pconn->observer) {
        send_packet_unit_info(pconn, &info);
      }
    } else if (pplayer == powner) {
      send_packet_unit_info(pconn, &info);
      if (pdata != nullptr) {
        BV_SET(pdata->can_see_unit, player_index(pplayer));
      }
    } else if (can_player_see_unit(pplayer, punit)) {
      send_packet_unit_short_info(pconn, &sinfo, FALSE);
      if (pdata != nullptr) {
        BV_SET(pdata->can_see_unit, player_index(pplayer));
      }
    }
  } conn_list_iterate_end;
}
 
/**********************************************************************/
void send_all_known_units(struct conn_list *dest)
{
  conn_list_do_buffer(dest);
  conn_list_iterate(dest, pconn) {
    struct player *pplayer = pconn->playing;
 
    if (pplayer == nullptr && !pconn->observer) {
      continue;
    }
 
    players_iterate(unitowner) {
      unit_list_iterate(unitowner->units, punit) {
        send_unit_info(dest, punit);
      } unit_list_iterate_end;
    } players_iterate_end;
  }
  conn_list_iterate_end;
  conn_list_do_unbuffer(dest);
  flush_packets();
}
 
/**********************************************************************/
static void do_nuke_tile(struct player *pplayer, struct tile *ptile,
                         const struct action *paction)
{
  struct city *pcity = nullptr;
  int pop_loss;
 
  pcity = tile_city(ptile);
 
  unit_list_iterate_safe(ptile->units, punit) {
 
    /* unit in a city may survive */
    if (pcity && fc_rand(100) < game.info.nuke_defender_survival_chance_pct) {
      continue;
    }
    notify_player(unit_owner(punit), ptile, E_UNIT_LOST_MISC, ftc_server,
                  _("Your %s was nuked by %s."),
                  unit_tile_link(punit),
                  pplayer == unit_owner(punit)
                  ? _("yourself")
                  : nation_plural_for_player(pplayer));
    if (unit_owner(punit) != pplayer) {
      notify_player(pplayer, ptile, E_UNIT_WIN_ATT, ftc_server,
                    _("The %s %s was nuked."),
                    nation_adjective_for_player(unit_owner(punit)),
                    unit_tile_link(punit));
    }
    wipe_unit(punit, ULR_NUKE, pplayer);
  } unit_list_iterate_safe_end;
 
 
  if (pcity) {
    struct player *owner = city_owner(pcity);
    char city_name[MAX_LEN_LINK];
 
    sz_strlcpy(city_name, city_link(pcity));
 
    notify_player(owner, ptile, E_CITY_NUKED, ftc_server,
                  _("%s was nuked by %s."),
                  city_name,
                  pplayer == owner
                  ? _("yourself")
                  : nation_plural_for_player(pplayer));
 
    if (owner != pplayer) {
      notify_player(pplayer, ptile, E_CITY_NUKED, ftc_server,
                    _("You nuked %s."),
                    city_name);
    }
 
    pop_loss = round((game.info.nuke_pop_loss_pct * city_size_get(pcity)) / 100.0);
    if (city_reduce_size(pcity, pop_loss, pplayer, "nuke")) {
      /* Send city size reduction to everyone seeing it */
      send_city_info(nullptr, pcity);
    } else {
      /* City was destroyed */
      notify_player(owner, ptile, E_CITY_NUKED, ftc_server,
                    _("%s was destroyed by the nuke."),
                    city_name);
      if (owner != pplayer) {
        notify_player(pplayer, ptile, E_CITY_NUKED, ftc_server,
                      _("Your nuke destroyed %s."),
                      city_name);
      }
    }
  }
 
  if (fc_rand(2) == 1) {
    struct extra_type *pextra;
 
    pextra = rand_extra_for_tile(ptile, EC_FALLOUT, FALSE);
    if (pextra != nullptr && !tile_has_extra(ptile, pextra)) {
      tile_add_extra(ptile, pextra);
      update_tile_knowledge(ptile);
    }
  }
}
 
/**********************************************************************/
void do_nuclear_explosion(const struct action *paction,
                          const struct unit_type *act_utype,
                          struct player *pplayer, struct tile *ptile)
{
  int nuke_radius_size
      = get_target_bonus_effects(nullptr,
                                 &(const struct req_context) {
                                   .player = pplayer,
                                 /* City: Wait for users before choosing
                                  * home city or target tile city */
                                   .tile = ptile,
                                   .unittype = act_utype,
                                   .action = paction,
                                 },
                                 nullptr,
                                 EFT_NUKE_BLAST_RADIUS_1_SQ);
 
  circle_iterate(&(wld.map), ptile, nuke_radius_size, ptile1) {
    do_nuke_tile(pplayer, ptile1, paction);
  } circle_iterate_end;
 
  script_server_signal_emit("nuke_exploded", 2, API_TYPE_TILE, ptile,
                            API_TYPE_PLAYER, pplayer);
  notify_conn(nullptr, ptile, E_NUKE, ftc_server,
              _("The %s detonated a nuke!"),
              nation_plural_for_player(pplayer));
}
 
/**********************************************************************/
bool do_airline(struct unit *punit, struct city *pdest_city,
                const struct action *paction)
{
  struct city *psrc_city = tile_city(unit_tile(punit));
 
  notify_player(unit_owner(punit), city_tile(pdest_city),
                E_UNIT_RELOCATED, ftc_server,
                _("%s transported successfully."),
                unit_link(punit));
 
  unit_move(punit, pdest_city->tile, punit->moves_left,
            nullptr, BV_ISSET(paction->sub_results, ACT_SUB_RES_MAY_EMBARK),
            /* Can only airlift to allied and domestic cities */
            FALSE, FALSE,
            BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_ENTER),
            BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_FRIGHTEN));
 
  /* Update airlift fields. */
  if (!(game.info.airlifting_style & AIRLIFTING_UNLIMITED_SRC)) {
    psrc_city->airlift--;
    send_city_info(city_owner(psrc_city), psrc_city);
  }
  if (!(game.info.airlifting_style & AIRLIFTING_UNLIMITED_DEST)) {
    pdest_city->airlift--;
    send_city_info(city_owner(pdest_city), pdest_city);
  }
 
  return TRUE;
}
 
/**********************************************************************/
void do_explore(struct unit *punit)
{
  switch (manage_auto_explorer(punit)) {
   case MR_DEATH:
     /* don't use punit! */
     return;
   case MR_NOT_ALLOWED:
     /* Needed for something else */
     return;
   case MR_OK:
     /* FIXME: manage_auto_explorer() isn't supposed to change the activity,
      * but don't count on this. See PR#39792.
      */
     if (punit->activity == ACTIVITY_EXPLORE) {
       break;
     }
 
     fc__fallthrough;
   default:
     unit_activity_handling(punit, ACTIVITY_IDLE, ACTION_NONE);
 
     /* FIXME: When the manage_auto_explorer() call changes the activity from
      * EXPLORE to IDLE, in unit_activity_handling() ai.control is left
      * alone. We reset it here. See PR#12931. */
     punit->ssa_controller = SSA_NONE;
     break;
  }
 
  send_unit_info(nullptr, punit); /* Probably duplicate */
}
 
/**********************************************************************/
bool do_paradrop(struct unit *punit, struct tile *ptile,
                 const struct action *paction)
{
  struct player *pplayer = unit_owner(punit);
  struct player *tgt_player = tile_owner(ptile);
  const struct unit_type *act_utype = unit_type_get(punit);
  const struct city *pcity;
 
  /* Hard requirements */
  /* FIXME: hard requirements belong in common/actions's
   * is_action_possible() and the explanation texts belong in
   * server/unithand's action not enabled system (expl_act_not_enabl(),
   * ane_kind, explain_why_no_action_enabled(), etc)
   */
  if (!map_is_known_and_seen(ptile, pplayer, V_MAIN)) {
    /* Only take in account values from player map. */
    const struct player_tile *plrtile = map_get_player_tile(ptile, pplayer);
 
    if (plrtile->site == nullptr) {
      bv_extras fbv;
 
      dbv_to_bv(fbv.vec, &(plrtile->extras));
 
      if (!is_native_to_class(unit_class_get(punit), plrtile->terrain,
                              &fbv)) {
        notify_player(pplayer, ptile, E_BAD_COMMAND, ftc_server,
                      _("This unit cannot paradrop into %s."),
                      terrain_name_translation(plrtile->terrain));
        return FALSE;
      }
    }
 
    if (plrtile->site != nullptr
        && plrtile->owner != nullptr
        && !pplayers_allied(pplayer, plrtile->owner)
        && !action_has_result(paction, ACTRES_PARADROP_CONQUER)) {
      notify_player(pplayer, ptile, E_BAD_COMMAND, ftc_server,
                    /* TRANS: Paratroopers ... Paradrop Unit */
                    _("%s cannot conquer a city with \"%s\"."),
                    unit_name_translation(punit),
                    action_name_translation(paction));
      return FALSE;
    }
 
    if (plrtile->site != nullptr
        && plrtile->owner != nullptr
        && (pplayers_non_attack(pplayer, plrtile->owner)
            || (player_diplstate_get(pplayer, plrtile->owner)->type
                == DS_ALLIANCE)
            || (player_diplstate_get(pplayer, plrtile->owner)->type
                == DS_TEAM))
        && action_has_result(paction, ACTRES_PARADROP_CONQUER)) {
      notify_player(pplayer, ptile, E_BAD_COMMAND, ftc_server,
                    _("Cannot attack unless you declare war first."));
      return FALSE;
    }
  }
 
 
  /* Kill the unit when the landing goes wrong. */
 
  /* Safe terrain, really? Not transformed since player last saw it. */
  if (!can_unit_exist_at_tile(&(wld.map), punit, ptile)
      && (!BV_ISSET(paction->sub_results, ACT_SUB_RES_MAY_EMBARK)
          || !unit_could_load_at(punit, ptile))) {
    map_show_circle(pplayer, ptile, act_utype->vision_radius_sq);
    notify_player(pplayer, ptile, E_UNIT_LOST_MISC, ftc_server,
                  _("Your %s paradropped into the %s and was lost."),
                  unit_tile_link(punit),
                  terrain_name_translation(tile_terrain(ptile)));
    pplayer->score.units_lost++;
    server_remove_unit(punit, ULR_NONNATIVE_TERR);
    return TRUE;
  }
 
  pcity = tile_city(ptile);
 
  if ((pcity != nullptr && !pplayers_allied(pplayer, city_owner(pcity))
       && !action_has_result(paction, ACTRES_PARADROP_CONQUER))
      || is_non_allied_unit_tile(ptile, pplayer,
                                 unit_has_type_flag(punit, UTYF_FLAGLESS))) {
    struct player *main_victim = nullptr;
    struct player *secondary_victim = nullptr;
    char victim_link[MAX_LEN_LINK];
 
    map_show_circle(pplayer, ptile, act_utype->vision_radius_sq);
    unit_make_contact(punit, ptile, pplayer);
    notify_player(pplayer, ptile, E_UNIT_LOST_MISC, ftc_server,
                  _("Your %s was killed by enemy units at the "
                    "paradrop destination."),
                  unit_tile_link(punit));
    /* TODO: Should defender score.units_killed get increased too?
     * What if there's units of several allied players? Should the
     * city owner or owner of the first/random unit get the kill? */
    pplayer->score.units_lost++;
 
    if (pcity != nullptr) {
      struct player *owner = city_owner(pcity);
 
      if (!pplayers_at_war(pplayer, owner)) {
        main_victim = owner;
      } else {
        secondary_victim = owner;
      }
 
      sz_strlcpy(victim_link, city_link(pcity));
    } else {
      sz_strlcpy(victim_link, tile_link(ptile));
    }
 
    if (main_victim == nullptr) {
      unit_list_iterate(ptile->units, tgt) {
        struct player *owner = unit_owner(tgt);
 
        if (!pplayers_at_war(pplayer, owner)) {
          main_victim = owner;
          break;
        } else if (secondary_victim == nullptr) {
          secondary_victim = owner;
        }
      } unit_list_iterate_end;
 
      if (main_victim == nullptr) {
        /* There's no victim with whom the attacker isn't in war,
         * fallback to one with whom there's already a war. */
        main_victim = secondary_victim;
      }
    }
 
    action_consequence_caught(paction, pplayer, act_utype,
                              main_victim, ptile,
                              victim_link);
 
    server_remove_unit(punit, ULR_KILLED);
    return TRUE;
  }
 
  /* All ok */
  punit->paradropped = TRUE;
  if (unit_move(punit, ptile,
                /* Done by Action_Success_Actor_Move_Cost */
                0,
                nullptr, BV_ISSET(paction->sub_results,
                                  ACT_SUB_RES_MAY_EMBARK),
                paction->result == ACTRES_PARADROP_CONQUER,
                paction->result == ACTRES_PARADROP_CONQUER,
                BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_ENTER),
                BV_ISSET(paction->sub_results, ACT_SUB_RES_HUT_FRIGHTEN))) {
    /* Ensure we finished on valid state. */
    fc_assert(can_unit_exist_at_tile(&(wld.map), punit, unit_tile(punit))
              || unit_transported(punit));
  }
 
  /* May cause an incident */
  action_consequence_success(paction, pplayer, act_utype, tgt_player,
                             ptile, tile_link(ptile));
 
  return TRUE;
}
 
/**********************************************************************/
static bool hut_get_limited(struct unit *punit)
{
  bool ok = TRUE;
  int hut_chance = fc_rand(12);
  struct player *pplayer = unit_owner(punit);
  const struct civ_map *nmap = &(wld.map);
 
  /* 1 in 12 to get barbarians */
  if (hut_chance != 0) {
    int cred = 25;
 
    notify_player(pplayer, unit_tile(punit), E_HUT_GOLD, ftc_server,
                  PL_("You found %d gold.",
                      "You found %d gold.", cred), cred);
    pplayer->economic.gold += cred;
  } else if (city_exists_within_max_city_map(nmap, unit_tile(punit), TRUE)
             || unit_has_type_flag(punit, UTYF_GAMELOSS)) {
    notify_player(pplayer, unit_tile(punit),
                  E_HUT_BARB_CITY_NEAR, ftc_server,
                  _("An abandoned village is here."));
  } else {
    notify_player(pplayer, unit_tile(punit), E_HUT_BARB_KILLED, ftc_server,
                  _("Your %s has been killed by barbarians!"),
                  unit_tile_link(punit));
    wipe_unit(punit, ULR_BARB_UNLEASH, nullptr);
    ok = FALSE;
  }
 
  return ok;
}
 
/**********************************************************************/
static void unit_enter_hut(struct unit *punit, bool frighten_hut)
{
  struct player *pplayer = unit_owner(punit);
  int id = punit->id;
  struct tile *ptile = unit_tile(punit);
  bool hut = FALSE;
  const struct req_context context = {
    .player = pplayer,
    .tile = ptile,
  };
 
  extra_type_by_rmcause_iterate(ERM_ENTER, pextra) {
    if (tile_has_extra(ptile, pextra)
        && are_reqs_active(&context,
                           &(const struct req_context) {
                             .player = tile_owner(ptile),
                           },
                           &pextra->rmreqs,
                           RPT_CERTAIN)
       ) {
      hut = TRUE;
      /* FIXME: are all enter-removes extras worth counting? */
      pplayer->server.huts++;
 
      destroy_extra(ptile, pextra);
      update_tile_knowledge(unit_tile(punit));
 
      /* FIXME: enable different classes
       * to behave differently with different huts */
      if (frighten_hut) {
        script_server_signal_emit("hut_frighten", punit,
                                  extra_rule_name(pextra));
      } else if (is_ai(pplayer) && has_handicap(pplayer, H_LIMITEDHUTS)) {
        /* AI with H_LIMITEDHUTS only gets 25 gold (or barbs if unlucky) */
        (void) hut_get_limited(punit);
      } else {
        script_server_signal_emit("hut_enter", punit, extra_rule_name(pextra));
      }
 
      /* We need punit for the callbacks, can't continue if the unit died */
      if (!unit_is_alive(id)) {
        break;
      }
    }
  } extra_type_by_rmcause_iterate_end;
 
  if (hut) {
    send_player_info_c(pplayer, pplayer->connections); /* eg, gold */
  }
  return;
}
 
/**********************************************************************/
void unit_transport_load_send(struct unit *punit, struct unit *ptrans)
{
  bv_player can_see_unit;
 
  fc_assert_ret(punit != nullptr);
  fc_assert_ret(ptrans != nullptr);
 
  BV_CLR_ALL(can_see_unit);
  players_iterate(pplayer) {
    if (can_player_see_unit(pplayer, punit)) {
      BV_SET(can_see_unit, player_index(pplayer));
    }
  } players_iterate_end;
 
  unit_transport_load(punit, ptrans, FALSE);
 
  players_iterate(pplayer) {
    if (BV_ISSET(can_see_unit, player_index(pplayer))
        && !can_player_see_unit(pplayer, punit)) {
      unit_goes_out_of_sight(pplayer, punit);
    }
  } players_iterate_end;
 
  send_unit_info(nullptr, punit);
  send_unit_info(nullptr, ptrans);
}
 
/**********************************************************************/
static void unit_transport_load_tp_status(struct unit *punit,
                                          struct unit *ptrans,
                                          bool force)
{
  bool had_cargo;
 
  fc_assert_ret(punit != nullptr);
  fc_assert_ret(ptrans != nullptr);
 
  had_cargo = get_transporter_occupancy(ptrans) > 0;
 
  unit_transport_load(punit, ptrans, force);
 
  if (!had_cargo) {
    /* Transport's loaded status changed */
    send_unit_info(nullptr, ptrans);
  }
}
 
/**********************************************************************/
void unit_transport_unload_send(struct unit *punit)
{
  struct unit *ptrans;
 
  fc_assert_ret(punit);
 
  ptrans = unit_transport_get(punit);
 
  fc_assert_ret(ptrans);
 
  unit_transport_unload(punit);
 
  send_unit_info(nullptr, punit);
  send_unit_info(nullptr, ptrans);
}
 
/**********************************************************************/
static void autoattack_prob_free(struct autoattack_prob *prob)
{
  free(prob);
}
 
/**********************************************************************/
static int compare_units(const struct autoattack_prob *const *p1,
                         const struct autoattack_prob *const *q1)
{
  const struct unit *p1unit = game_unit_by_number((*p1)->unit_id);
  const struct unit *q1unit = game_unit_by_number((*q1)->unit_id);
 
  /* Sort by transport depth first. This makes sure that no transport
   * attacks before its cargo does -- cargo sorts earlier in the list. */
  {
    const struct unit *p1trans = p1unit, *q1trans = q1unit;
 
    /* Walk the transport stacks in parallel, so as to bail out as soon as
     * one of them is empty (avoid walking deep stacks more often than
     * necessary). */
    while (p1trans && q1trans) {
      p1trans = unit_transport_get(p1trans);
      q1trans = unit_transport_get(q1trans);
    }
    if (!p1trans && q1trans) {
      /* q1 is at greater depth (perhaps it's p1's cargo). It should sort
       * earlier in the list (p1 > q1). */
      return 1;
    } else if (p1trans && !q1trans) {
      /* p1 is at greater depth, so should sort earlier (p1 < q1). */
      return -1;
    }
    /* else same depth, so move on to checking win chance: */
  }
 
  /* Put the units with the highest probability of success first. The up
   * side of this is that units with bonuses against the victim attacks
   * before other units. The downside is that strong units can be led
   * away by sacrificial units. */
  return (-1
          /* Assume the worst. */
          * action_prob_cmp_pessimist((*p1)->prob, (*q1)->prob));
}
 
/**********************************************************************/
static bool unit_survive_autoattack(struct unit *punit)
{
  struct autoattack_prob_list *autoattack;
  int moves = punit->moves_left;
  int sanity1 = punit->id;
  struct civ_map *nmap = &(wld.map);
 
  if (!game.server.autoattack) {
    return TRUE;
  }
 
  autoattack = autoattack_prob_list_new_full(autoattack_prob_free);
 
  /* Kludge to prevent attack power from dropping to zero during calc */
  punit->moves_left = MAX(punit->moves_left, 1);
 
  adjc_iterate(nmap, unit_tile(punit), ptile) {
    /* First add all eligible units to a autoattack list */
    unit_list_iterate(ptile->units, penemy) {
      struct autoattack_prob *probability = fc_malloc(sizeof(*probability));
      struct tile *tgt_tile = unit_tile(punit);
 
      fc_assert_action(tgt_tile, continue);
 
      probability->prob =
          action_auto_perf_unit_prob(AAPC_UNIT_MOVED_ADJ,
                                     penemy, unit_owner(punit), nullptr, nullptr,
                                     tgt_tile, tile_city(tgt_tile),
                                     punit, nullptr);
 
      if (action_prob_possible(probability->prob)) {
        probability->unit_id = penemy->id;
        autoattack_prob_list_prepend(autoattack, probability);
      } else {
        FC_FREE(probability);
      }
    } unit_list_iterate_end;
  } adjc_iterate_end;
 
  /* Sort the potential attackers from highest to lowest success
   * probability. */
  if (autoattack_prob_list_size(autoattack) >= 2) {
    autoattack_prob_list_sort(autoattack, &compare_units);
  }
 
  autoattack_prob_list_iterate_safe(autoattack, peprob, penemy) {
    int sanity2 = penemy->id;
    struct tile *ptile = unit_tile(penemy);
    struct unit *enemy_defender = get_defender(nmap, punit, ptile, nullptr);
    double punitwin, penemywin;
    double threshold = 0.25;
    struct tile *tgt_tile = unit_tile(punit);
 
    fc_assert(tgt_tile);
 
    if (tile_city(ptile) && unit_list_size(ptile->units) == 1) {
      /* Don't leave city defenseless */
      threshold = 0.90;
    }
 
    if (enemy_defender != nullptr) {
      punitwin = unit_win_chance(nmap, punit, enemy_defender, nullptr);
    } else {
      /* 'penemy' can attack 'punit' but it may be not reciproque. */
      punitwin = 1.0;
    }
 
    /* Previous attacks may have changed the odds. Recalculate. */
    peprob->prob =
        action_auto_perf_unit_prob(AAPC_UNIT_MOVED_ADJ,
                                   penemy, unit_owner(punit), nullptr, nullptr,
                                   tgt_tile, tile_city(tgt_tile),
                                   punit, nullptr);
 
    if (!action_prob_possible(peprob->prob)) {
      /* No longer legal. */
      continue;
    }
 
    /* Assume the worst. */
    penemywin = action_prob_to_0_to_1_pessimist(peprob->prob);
 
    if ((penemywin > 1.0 - punitwin
         || unit_has_type_flag(punit, UTYF_PROVOKING))
        && penemywin > threshold) {
 
#ifdef REALLY_DEBUG_THIS
      log_test("AA %s -> %s (%d,%d) %.2f > %.2f && > %.2f",
               unit_rule_name(penemy), unit_rule_name(punit),
               TILE_XY(unit_tile(punit)), penemywin,
               1.0 - punitwin, threshold);
#endif
 
      unit_activity_handling(penemy, ACTIVITY_IDLE, ACTION_NONE);
      action_auto_perf_unit_do(AAPC_UNIT_MOVED_ADJ,
                               penemy, unit_owner(punit), nullptr, nullptr,
                               tgt_tile, tile_city(tgt_tile), punit, nullptr);
    } else {
#ifdef REALLY_DEBUG_THIS
      log_test("!AA %s -> %s (%d,%d) %.2f > %.2f && > %.2f",
               unit_rule_name(penemy), unit_rule_name(punit),
               TILE_XY(unit_tile(punit)), penemywin,
               1.0 - punitwin, threshold);
#endif
      continue;
    }
 
    if (game_unit_by_number(sanity2)) {
      send_unit_info(nullptr, penemy);
    }
    if (game_unit_by_number(sanity1)) {
      send_unit_info(nullptr, punit);
    } else {
      autoattack_prob_list_destroy(autoattack);
      return FALSE; /* moving unit dead */
    }
  } autoattack_prob_list_iterate_safe_end;
 
  autoattack_prob_list_destroy(autoattack);
  if (game_unit_by_number(sanity1)) {
    /* We could have lost movement in combat */
    punit->moves_left = MIN(punit->moves_left, moves);
    send_unit_info(nullptr, punit);
    return TRUE;
  } else {
    return FALSE;
  }
}
 
/**********************************************************************/
static void cancel_orders(struct unit *punit, char *dbg_msg)
{
  free_unit_orders(punit);
  send_unit_info(nullptr, punit);
  log_debug("%s", dbg_msg);
}
 
/**********************************************************************/
static void wakeup_neighbor_sentries(struct unit *punit)
{
  bool alone_in_city;
 
  if (tile_city(unit_tile(punit)) != nullptr) {
    int count = 0;
 
    unit_list_iterate(unit_tile(punit)->units, aunit) {
      /* Consider only units not transported. */
      if (!unit_transported(aunit)) {
        count++;
      }
    } unit_list_iterate_end;
 
    alone_in_city = (1 == count);
  } else {
    alone_in_city = FALSE;
  }
 
  /* There may be sentried units with a sightrange > 3, but we don't
     wake them up if the punit is farther away than 3. */
  square_iterate(&(wld.map), unit_tile(punit), 3, ptile) {
    unit_list_iterate(ptile->units, penemy) {
      int distance_sq = sq_map_distance(unit_tile(punit), ptile);
      int radius_sq = get_unit_vision_at(penemy, unit_tile(penemy), V_MAIN);
 
      if (!pplayers_allied(unit_owner(punit), unit_owner(penemy))
          && penemy->activity == ACTIVITY_SENTRY
          && radius_sq >= distance_sq
          /* If the unit moved on a city, and the unit is alone, consider
           * it is visible. */
          && (alone_in_city
              || can_player_see_unit(unit_owner(penemy), punit))
          /* On board transport; don't awaken */
          && can_unit_exist_at_tile(&(wld.map), penemy, unit_tile(penemy))) {
        set_unit_activity(penemy, ACTIVITY_IDLE, ACTION_NONE);
        send_unit_info(nullptr, penemy);
      }
    } unit_list_iterate_end;
  } square_iterate_end;
 
  /* Wakeup patrolling units we bump into.
     We do not wakeup units further away than 3 squares... */
  square_iterate(&(wld.map), unit_tile(punit), 3, ptile) {
    unit_list_iterate(ptile->units, ppatrol) {
      if (punit != ppatrol
          && unit_has_orders(ppatrol)
          && ppatrol->orders.vigilant) {
        if (maybe_cancel_patrol_due_to_enemy(ppatrol)) {
          cancel_orders(ppatrol, "  stopping because of nearby enemy");
          notify_player(unit_owner(ppatrol), unit_tile(ppatrol),
                        E_UNIT_ORDERS, ftc_server,
                        _("Orders for %s aborted after enemy movement was "
                          "spotted."),
                        unit_link(ppatrol));
        }
      }
    } unit_list_iterate_end;
  } square_iterate_end;
}
 
/**********************************************************************/
static bool unit_move_consequences(struct unit *punit,
                                   struct tile *src_tile,
                                   struct tile *dst_tile,
                                   bool passenger,
                                   bool conquer_city_allowed)
{
  struct city *fromcity = tile_city(src_tile);
  struct city *tocity = tile_city(dst_tile);
  struct city *homecity_start_pos = nullptr;
  struct city *homecity_end_pos = nullptr;
  int homecity_id_start_pos = punit->homecity;
  int homecity_id_end_pos = punit->homecity;
  struct player *pplayer_start_pos = unit_owner(punit);
  struct player *pplayer_end_pos = pplayer_start_pos;
  const struct unit_type *type_start_pos = unit_type_get(punit);
  const struct unit_type *type_end_pos = type_start_pos;
  bool refresh_homecity_start_pos = FALSE;
  bool refresh_homecity_end_pos = FALSE;
  int saved_id = punit->id;
  bool alive = TRUE;
  const struct civ_map *nmap = &(wld.map);
 
  if (tocity && conquer_city_allowed) {
    if (!passenger) {
      /* The unit that does the move may conquer. */
      unit_conquer_city(punit, tocity);
    }
 
    /* Run for passengers too. A passenger may have been killed when its
     * transport conquered a city. (unit_conquer_city() can cause Lua code
     * to run) */
 
    alive = unit_is_alive(saved_id);
    if (alive) {
      /* In case script has changed something about unit */
      pplayer_end_pos = unit_owner(punit);
      type_end_pos = unit_type_get(punit);
      homecity_id_end_pos = punit->homecity;
    }
  }
 
  if (homecity_id_start_pos != 0) {
    homecity_start_pos = game_city_by_number(homecity_id_start_pos);
  }
  if (homecity_id_start_pos != homecity_id_end_pos) {
    homecity_end_pos = game_city_by_number(homecity_id_end_pos);
  } else {
    homecity_end_pos = homecity_start_pos;
  }
 
  /* We only do refreshes for non-AI players to now make sure the AI turns
     doesn't take too long. Perhaps we should make a special refresh_city
     functions that only refreshed happines. */
 
  /* might have changed owners or may be destroyed */
  tocity = tile_city(dst_tile);
 
  if (tocity) { /* entering a city */
    if (tocity->owner == pplayer_end_pos) {
      if (tocity != homecity_end_pos && is_human(pplayer_end_pos)) {
        city_refresh(tocity);
        send_city_info(pplayer_end_pos, tocity);
      }
    }
    if (homecity_start_pos) {
      refresh_homecity_start_pos = TRUE;
    }
  }
 
  if (fromcity) { /* leaving a city */
    if (homecity_start_pos) {
      refresh_homecity_start_pos = TRUE;
    }
    if (fromcity != homecity_start_pos
        && fromcity->owner == pplayer_start_pos
        && is_human(pplayer_start_pos)) {
      city_refresh(fromcity);
      send_city_info(pplayer_start_pos, fromcity);
    }
  }
 
  /* Entering/leaving a fortress or friendly territory */
  if (homecity_start_pos || homecity_end_pos) {
    bool friendly_end = FALSE;
 
    if (game.info.happyborders != HB_DISABLED && tile_owner(src_tile) != tile_owner(dst_tile)) {
      friendly_end = TRUE;
    } else {
      int max_friendliness_range = tile_has_not_aggressive_extra_for_unit(dst_tile,
                                                                          type_end_pos);
 
      if (max_friendliness_range >= 0
          && is_friendly_city_near(nmap, pplayer_end_pos, dst_tile, max_friendliness_range)) {
        friendly_end = TRUE;
      } else {
        max_friendliness_range = tile_has_not_aggressive_extra_for_unit(src_tile,
                                                                        type_start_pos);
 
        if (max_friendliness_range >= 0
            && is_friendly_city_near(nmap, pplayer_start_pos, src_tile, max_friendliness_range)) {
          friendly_end = TRUE;
        }
      }
    }
 
    if (friendly_end) {
      refresh_homecity_start_pos = TRUE;
      refresh_homecity_end_pos = TRUE;
    }
  }
 
  if (refresh_homecity_start_pos && is_human(pplayer_start_pos)) {
    city_refresh(homecity_start_pos);
    send_city_info(pplayer_start_pos, homecity_start_pos);
  }
  if (refresh_homecity_end_pos
      && (!refresh_homecity_start_pos
          || homecity_start_pos != homecity_end_pos)
      && is_human(pplayer_end_pos)) {
    city_refresh(homecity_end_pos);
    send_city_info(pplayer_end_pos, homecity_end_pos);
  }
 
  city_map_update_tile_now(dst_tile);
  sync_cities();
 
  return alive;
}
 
/**********************************************************************/
static void check_unit_activity(struct unit *punit)
{
  switch (punit->activity) {
  case ACTIVITY_IDLE:
  case ACTIVITY_SENTRY:
  case ACTIVITY_EXPLORE:
  case ACTIVITY_GOTO:
    break;
  case ACTIVITY_CLEAN:
  case ACTIVITY_MINE:
  case ACTIVITY_IRRIGATE:
  case ACTIVITY_CULTIVATE:
  case ACTIVITY_PLANT:
  case ACTIVITY_FORTIFIED:
  case ACTIVITY_PILLAGE:
  case ACTIVITY_TRANSFORM:
  case ACTIVITY_FORTIFYING:
  case ACTIVITY_BASE:
  case ACTIVITY_GEN_ROAD:
  case ACTIVITY_CONVERT:
  case ACTIVITY_LAST:
    set_unit_activity(punit, ACTIVITY_IDLE, ACTION_NONE);
    break;
  };
}
 
/**********************************************************************/
static struct unit_move_data *unit_move_data_get(struct unit *punit,
                                                 const struct tile *psrctile,
                                                 const struct tile *pdesttile)
{
  struct unit_move_data *pdata;
  struct player *powner = unit_owner(punit);
 
  if (punit->server.moving) {
    /* Recursive moving (probably due to a script). */
    pdata = punit->server.moving;
    pdata->ref_count++;
    fc_assert_msg(pdata->punit == punit,
                  "Unit number %d (%p) was going to die, but "
                  "server attempts to move it.",
                  punit->id, punit);
    fc_assert_msg(pdata->old_vision == nullptr,
                  "Unit number %d (%p) has done an incomplete move.",
                  punit->id, punit);
  } else {
    pdata = fc_malloc(sizeof(*pdata));
    pdata->ref_count = 1;
    pdata->punit = punit;
    punit->server.moving = pdata;
    BV_CLR_ALL(pdata->can_see_unit);
  }
  pdata->powner = powner;
  BV_CLR_ALL(pdata->can_see_move);
  pdata->old_vision = punit->server.vision;
 
  return pdata;
}
 
/**********************************************************************/
static void unit_move_by_data(struct unit_move_data *pdata,
                              const struct tile *psrctile,
                              struct tile *pdesttile)
{
  struct vision *new_vision;
  struct unit *punit = pdata->punit;
  int mod = unit_vision_range_modifiers(punit, pdesttile);
  const v_radius_t radius_sq
    = V_RADIUS(get_unit_vision_base(punit, V_MAIN, mod),
               get_unit_vision_base(punit, V_INVIS, mod),
               get_unit_vision_base(punit, V_SUBSURFACE, mod));
 
  /* Remove unit from the source tile. */
  fc_assert(unit_tile(punit) == psrctile);
 
#ifndef FREECIV_NDEBUG
  bool success =
#endif
    unit_list_remove(psrctile->units, punit);
  fc_assert(success);
 
  /* Set new tile. */
  unit_tile_set(punit, pdesttile);
  unit_list_prepend(pdesttile->units, punit);
 
  if (unit_transported(punit)) {
    /* Silently free orders since they won't be applicable anymore. */
    free_unit_orders(punit);
  }
 
  /* Check unit activity. */
  check_unit_activity(punit);
  unit_did_action(punit);
  unit_forget_last_activity(punit);
 
  /* We first unfog the destination, then send the move,
   * and then fog the old territory. This means that the player
   * gets a chance to see the newly explored territory while the
   * client moves the unit, and both areas are visible during the
   * move */
 
  /* Enhance vision if unit steps into a fortress */
  new_vision = vision_new(pdata->powner, pdesttile);
  punit->server.vision = new_vision;
  vision_change_sight(new_vision, radius_sq);
  ASSERT_VISION(new_vision);
}
 
/**********************************************************************/
static void unit_move_data_unref(struct unit_move_data *pdata)
{
  fc_assert_ret(pdata != nullptr);
  fc_assert_ret(pdata->ref_count > 0);
  fc_assert_msg(pdata->old_vision == nullptr,
                "Unit number %d (%p) has done an incomplete move.",
                pdata->punit != nullptr ? pdata->punit->id : -1, pdata->punit);
 
  pdata->ref_count--;
  if (pdata->ref_count == 0) {
    if (pdata->punit != nullptr) {
      fc_assert(pdata->punit->server.moving == pdata);
      pdata->punit->server.moving = nullptr;
    }
    free(pdata);
  }
}
 
/**********************************************************************/
static struct unit_move_data_list *construct_move_data_list(struct unit *punit,
                                                            const struct tile *psrctile,
                                                            struct tile *pdesttile,
                                                            bool adj)
{
  struct unit_move_data_list *plist
    = unit_move_data_list_new_full(unit_move_data_unref);
  struct unit_move_data *pdata;
 
  /* Make new data for 'punit'. */
  pdata = unit_move_data_get(punit, psrctile, pdesttile);
  unit_move_data_list_prepend(plist, pdata);
 
  /* Add all contained units. */
  unit_cargo_iterate(punit, pcargo) {
    struct unit_move_data *cargo_data;
 
    cargo_data = unit_move_data_get(pcargo, psrctile, pdesttile);
    unit_move_data_list_append(plist, cargo_data);
  } unit_cargo_iterate_end;
 
  /* Determine the players able to see the move(s), now that the player
   * vision has been increased. */
  if (adj) {
    /* Main unit for adjacent move: the move is visible for every player
     * able to see on the matching unit layer. */
    enum vision_layer vlayer = unit_type_get(punit)->vlayer;
 
    players_iterate(oplayer) {
      if (map_is_known_and_seen(psrctile, oplayer, vlayer)
          || map_is_known_and_seen(pdesttile, oplayer, vlayer)) {
        BV_SET(pdata->can_see_unit, player_index(oplayer));
        BV_SET(pdata->can_see_move, player_index(oplayer));
      }
    } players_iterate_end;
  }
 
  unit_move_data_list_iterate(plist, pmove_data) {
 
    unit_move_by_data(pmove_data, psrctile, pdesttile);
 
    if (adj && pmove_data->punit == punit) {
      /* If positions are adjacent, we have already handled 'punit'. See
       * above. */
      continue;
    }
 
    players_iterate(oplayer) {
      if ((adj
           && can_player_see_unit_at(oplayer, pmove_data->punit, psrctile,
                                     pmove_data != pdata))
          || can_player_see_unit_at(oplayer, pmove_data->punit, pdesttile,
                                    pmove_data != pdata)) {
        BV_SET(pmove_data->can_see_unit, player_index(oplayer));
        BV_SET(pmove_data->can_see_move, player_index(oplayer));
      }
      if (can_player_see_unit_at(oplayer, pmove_data->punit, psrctile,
                                 pmove_data != pdata)) {
        /* The unit was seen with its source tile even if it was
         * teleported. */
        BV_SET(pmove_data->can_see_unit, player_index(oplayer));
      }
    } players_iterate_end;
  } unit_move_data_list_iterate_end;
 
  return plist;
}
 
/**********************************************************************/
bool unit_move(struct unit *punit, struct tile *pdesttile, int move_cost,
               struct unit *embark_to, bool find_embark_target,
               bool conquer_city_allowed, bool conquer_extras_allowed,
               bool enter_hut, bool frighten_hut)
{
  struct player *pplayer;
  struct tile *psrctile;
  struct city *psrccity;
  struct city *pdestcity;
  struct unit *ptransporter;
  struct packet_unit_info src_info, dest_info;
  struct packet_unit_short_info src_sinfo, dest_sinfo;
  struct unit_move_data_list *plist;
  struct unit_move_data *pdata;
  int saved_id;
  bool unit_lives;
  bool adj;
  enum direction8 facing;
  bool flagless = unit_has_type_flag(punit, UTYF_FLAGLESS);
 
  /* Some checks. */
  fc_assert_ret_val(punit != nullptr, FALSE);
  fc_assert_ret_val(pdesttile != nullptr, FALSE);
 
  pplayer = unit_owner(punit);
  saved_id = punit->id;
  psrctile = unit_tile(punit);
  adj = base_get_direction_for_step(&(wld.map), psrctile, pdesttile, &facing);
 
  conn_list_do_buffer(game.est_connections);
 
  /* Unload the unit if on a transport. */
  ptransporter = unit_transport_get(punit);
  if (ptransporter != nullptr) {
    /* Unload unit _before_ setting the new tile! */
    unit_transport_unload(punit);
    /* Send updated information to anyone watching that transporter
     * was unloading cargo. */
    send_unit_info(nullptr, ptransporter);
  }
 
  /* Wakup units next to us before we move. */
  wakeup_neighbor_sentries(punit);
 
  /* Make info packets at 'psrctile'. */
  if (adj) {
    /* If tiles are adjacent, we will show the move to users able
     * to see it. */
    package_unit(punit, &src_info);
    package_short_unit(punit, &src_sinfo, UNIT_INFO_IDENTITY, 0);
  }
 
  /* Set unit orientation */
  if (adj) {
    /* Only change orientation when moving to adjacent tile */
    punit->facing = facing;
  }
 
  plist = construct_move_data_list(punit, psrctile, pdesttile, adj);
 
  /* Move magic. */
  punit->moved = TRUE;
  punit->moves_left = MAX(0, punit->moves_left - move_cost);
  if (punit->moves_left == 0 && !unit_has_orders(punit)) {
    /* The next order may not require any remaining move fragments. */
    punit->done_moving = TRUE;
  }
 
  /* No longer relevant. */
  punit->action_decision_tile = nullptr;
  punit->action_decision_want = ACT_DEC_NOTHING;
 
  /* Claim ownership of fortress? */
  if (conquer_extras_allowed
      && tile_has_claimable_base(pdesttile, unit_type_get(punit))) {
    /* Yes. We claim *all* bases if there's *any* claimable base(s).
     * Even if original unit cannot claim other kind of bases, the
     * first claimed base will have influence over other bases,
     * or something like that. */
    tile_claim_bases(pdesttile, pplayer);
  }
 
  pdata = unit_move_data_list_front(plist);
  fc_assert(pdata->punit == punit);
 
  /* Check timeout settings. */
  if (current_turn_timeout() != 0 && game.server.timeoutaddenemymove > 0) {
    bool new_information_for_enemy = FALSE;
 
    /* FIXME: Seen enemy cargo in a non-enemy transport should count too,
    *         if they are ever seen. */
    phase_players_iterate(penemy) {
      /* Increase the timeout if an enemy unit moves and the
       * timeoutaddenemymove setting is in use. */
      if (penemy->is_connected
          && pplayer != penemy
          && pplayers_at_war(pplayer, penemy)
          && BV_ISSET(pdata->can_see_move, player_index(penemy))) {
        new_information_for_enemy = TRUE;
        break;
      }
    } phase_players_iterate_end;
 
    if (new_information_for_enemy) {
      increase_timeout_because_unit_moved();
    }
  }
 
  if (!adj && action_tgt_city(punit, pdesttile, FALSE)) {
    /* The unit can perform an action to the city at the destination tile.
     * A long distance move (like an airlift) doesn't ask what action to
     * perform before moving. Ask now. */
 
    punit->action_decision_want = ACT_DEC_PASSIVE;
    punit->action_decision_tile = pdesttile;
  }
 
  /* Notifications of the move to the clients. */
  if (adj) {
    /* Special case: 'punit' is moving to adjacent position. Then we show
     * 'punit' move to all users able to see 'psrctile' or 'pdesttile'. */
 
    /* Make info packets at 'pdesttile'. */
    package_unit(punit, &dest_info);
    package_short_unit(punit, &dest_sinfo, UNIT_INFO_IDENTITY, 0);
 
    conn_list_iterate(game.est_connections, pconn) {
      struct player *aplayer = conn_get_player(pconn);
 
      if (aplayer == nullptr) {
        if (pconn->observer) {
          /* Global observers see all... */
          send_packet_unit_info(pconn, &src_info);
          send_packet_unit_info(pconn, &dest_info);
        }
      } else if (BV_ISSET(pdata->can_see_move, player_index(aplayer))) {
        if (aplayer == pplayer) {
          send_packet_unit_info(pconn, &src_info);
          send_packet_unit_info(pconn, &dest_info);
        } else {
          send_packet_unit_short_info(pconn, &src_sinfo, FALSE);
          send_packet_unit_short_info(pconn, &dest_sinfo, FALSE);
        }
      }
    } conn_list_iterate_end;
  }
 
  /* Other moves. */
  unit_move_data_list_iterate(plist, pmove_data) {
    if (adj && pmove_data == pdata) {
      /* If positions are adjacent, we have already shown 'punit' move.
       * See above. */
      continue;
    }
 
    /* Make info packets at 'pdesttile'. */
    package_unit(pmove_data->punit, &dest_info);
    package_short_unit(pmove_data->punit, &dest_sinfo,
                       UNIT_INFO_IDENTITY, 0);
 
    conn_list_iterate(game.est_connections, pconn) {
      struct player *aplayer = conn_get_player(pconn);
 
      if (aplayer == nullptr) {
        if (pconn->observer) {
          /* Global observers see all... */
          send_packet_unit_info(pconn, &dest_info);
        }
      } else if (BV_ISSET(pmove_data->can_see_move, player_index(aplayer))) {
        if (aplayer == pmove_data->powner) {
          send_packet_unit_info(pconn, &dest_info);
        } else {
          send_packet_unit_short_info(pconn, &dest_sinfo, FALSE);
        }
      }
    } conn_list_iterate_end;
  } unit_move_data_list_iterate_end;
 
  /* Clear old vision. */
  unit_move_data_list_iterate(plist, pmove_data) {
    if (pmove_data->old_vision != nullptr) {
      vision_clear_sight(pmove_data->old_vision);
      vision_free(pmove_data->old_vision);
      pmove_data->old_vision = nullptr;
    }
  } unit_move_data_list_iterate_end;
 
  /* Move consequences. */
  unit_move_data_list_iterate(plist, pmove_data) {
    struct unit *aunit = pmove_data->punit;
 
    if (aunit != nullptr
        && unit_owner(aunit) == pmove_data->powner
        && unit_tile(aunit) == pdesttile) {
      (void) unit_move_consequences(aunit, psrctile, pdesttile,
                                    pdata != pmove_data,
                                    conquer_city_allowed);
    }
  } unit_move_data_list_iterate_end;
 
  unit_lives = (pdata->punit == punit);
 
  /* Wakeup units and make contact. */
  if (unit_lives) {
    wakeup_neighbor_sentries(punit);
  }
 
  /* Do not pass 'punit' to unit_make_contact(), as it
   * might refer to a dead unit.
   * Flagless units do not make contact. */
  if (!flagless) {
    unit_make_contact(nullptr, pdesttile, pplayer);
  }
 
  if (unit_lives) {
    /* Special checks for ground units in the ocean. */
    if (embark_to || !can_unit_survive_at_tile(&(wld.map), punit, pdesttile)) {
      if (embark_to != nullptr) {
        ptransporter = embark_to;
      } else if (find_embark_target) {
        /* TODO: Consider to stop supporting find_embark_target and make all
         * callers that wants auto loading set embark_to. */
        ptransporter = transporter_for_unit(punit);
      } else {
        ptransporter = nullptr;
      }
      if (ptransporter) {
        unit_transport_load_tp_status(punit, ptransporter, FALSE);
 
        /* Set activity to sentry if boarding a ship. */
        if (is_human(pplayer)
            && !unit_has_orders(punit)
            && punit->ssa_controller == SSA_NONE
            && !can_unit_exist_at_tile(&(wld.map), punit, pdesttile)) {
          set_unit_activity(punit, ACTIVITY_SENTRY, ACTION_NONE);
        }
 
        send_unit_info(nullptr, punit);
      }
    }
  }
 
  /* Remove units going out of sight. */
  unit_move_data_list_iterate_rev(plist, pmove_data) {
    struct unit *aunit = pmove_data->punit;
 
    if (aunit == nullptr) {
      continue; /* Died! */
    }
 
    players_iterate(aplayer) {
      if (BV_ISSET(pmove_data->can_see_unit, player_index(aplayer))
          && !can_player_see_unit(aplayer, aunit)) {
        unit_goes_out_of_sight(aplayer, aunit);
      }
    } players_iterate_end;
  } unit_move_data_list_iterate_rev_end;
 
  /* Inform the owner's client about actor unit arrival. Can, depending on
   * the client settings, cause the client to start the process that makes
   * the action selection dialog pop up. */
  pdestcity = tile_city(pdesttile);
  if (pdestcity != nullptr) {
    /* Arrival in a city counts. */
 
    unit_move_data_list_iterate(plist, pmove_data) {
      struct unit *ptrans;
      bool ok;
      struct unit *act_unit;
      struct player *act_player;
 
      act_unit = pmove_data->punit;
      act_player = unit_owner(act_unit);
 
      if (act_unit == nullptr
          || !unit_is_alive(act_unit->id)) {
        /* The unit died before reaching this point. */
        continue;
      }
 
      if (unit_tile(act_unit) != pdesttile) {
        /* The unit didn't arrive at the destination tile. */
        continue;
      }
 
      if (!is_human(act_player)) {
        /* Only humans need reminders. */
        continue;
      }
 
      if (!unit_transported(act_unit)) {
        /* Don't show the action selection dialog again. Non transported
         * units are handled before they move to the tile.  */
        continue;
      }
 
      /* Open action dialog only if 'act_unit' and all its transporters
       * (recursively) don't have orders. */
      if (unit_has_orders(act_unit)) {
        /* The unit it self has orders. */
        continue;
      }
 
      for (ptrans = unit_transport_get(act_unit);;
           ptrans = unit_transport_get(ptrans)) {
        if (ptrans == nullptr) {
          /* No (recursive) transport has orders. */
          ok = TRUE;
          break;
        } else if (unit_has_orders(ptrans)) {
          /* A unit transporting the unit has orders */
          ok = FALSE;
          break;
        }
      }
 
      if (!ok) {
        /* A unit transporting act_unit has orders. */
        continue;
      }
 
      if (action_tgt_city(act_unit, pdesttile, FALSE)) {
        /* There is a valid target. */
 
        act_unit->action_decision_want = ACT_DEC_PASSIVE;
        act_unit->action_decision_tile = pdesttile;
 
        /* Let the client know that this unit wants the player to decide
         * what to do. */
        send_unit_info(player_reply_dest(act_player), act_unit);
      }
    } unit_move_data_list_iterate_end;
  }
 
  unit_move_data_list_destroy(plist);
  /* Check cities at source and destination. */
  psrccity = tile_city(psrctile);
  if (psrccity != nullptr) {
    refresh_dumb_city(psrccity);
  }
  if (pdestcity != nullptr) {
    refresh_dumb_city(pdestcity);
  }
 
  if (unit_lives) {
    /* Let the scripts run ... */
    script_server_signal_emit("unit_moved", punit, psrctile, pdesttile);
    unit_lives = unit_is_alive(saved_id);
  }
 
  if (unit_lives) {
    /* Autoattack. */
    unit_lives = unit_survive_autoattack(punit);
  }
 
  if (unit_lives && (enter_hut || frighten_hut)) {
    /* Is there a hut? */
    unit_enter_hut(punit, frighten_hut);
    fc_assert(!(enter_hut && frighten_hut));
    unit_lives = unit_is_alive(saved_id);
  }
 
  conn_list_do_unbuffer(game.est_connections);
 
  if (unit_lives) {
    CALL_FUNC_EACH_AI(unit_move_seen, punit);
  }
 
  return unit_lives;
}
 
/**********************************************************************/
static bool maybe_cancel_goto_due_to_enemy(struct unit *punit,
                                           struct tile *ptile)
{
  struct player *owner = unit_owner(punit);
 
  return (is_non_allied_unit_tile(ptile, owner,
                                  unit_has_type_flag(punit, UTYF_FLAGLESS))
          || is_non_allied_city_tile(ptile, owner));
}
 
/**********************************************************************/
static bool maybe_cancel_patrol_due_to_enemy(struct unit *punit)
{
  bool cancel = FALSE;
  int radius_sq = get_unit_vision_at(punit, unit_tile(punit), V_MAIN);
  struct player *pplayer = unit_owner(punit);
 
  circle_iterate(&(wld.map), unit_tile(punit), radius_sq, ptile) {
    struct unit *penemy = tile_non_allied_unit(ptile, pplayer,
                                               unit_has_type_flag(punit, UTYF_FLAGLESS));
    struct vision_site *pdcity = map_get_player_site(ptile, pplayer);
 
    if ((penemy && can_player_see_unit(pplayer, penemy))
        || (pdcity && !pplayers_allied(pplayer, vision_site_owner(pdcity))
            && pdcity->occupied)) {
      cancel = TRUE;
      break;
    }
  } circle_iterate_end;
 
  return cancel;
}
 
/**********************************************************************/
static inline bool player_is_watching(struct unit *punit, const bool fresh)
{
  /* The player just sent the orders to the unit. The unit has moves left.
   * It is therefore safe to assume that the player already is paying
   * attention to the unit. */
  return fresh && punit->moves_left > 0;
}
 
/**********************************************************************/
bool execute_orders(struct unit *punit, const bool fresh)
{
  struct act_prob prob;
  bool performed;
  const char *name;
  bool res, last_order;
  int unitid = punit->id;
  struct player *pplayer = unit_owner(punit);
  int moves_made = 0;
  const struct civ_map *nmap = &(wld.map);
 
  fc_assert_ret_val(unit_has_orders(punit), TRUE);
 
  if (punit->activity != ACTIVITY_IDLE) {
    /* Unit's in the middle of an activity; wait for it to finish. */
    punit->done_moving = TRUE;
    return TRUE;
  }
 
  log_debug("Executing orders for %s %d", unit_rule_name(punit), punit->id);
 
  /* Any time the orders are canceled we should give the player a message. */
 
  while (TRUE) {
    struct unit_order order;
 
    struct action *oaction;
 
    struct tile *dst_tile;
    struct city *tgt_city;
    struct unit *tgt_unit;
    int tgt_id;
    int sub_tgt_id;
    struct extra_type *pextra;
 
    if (punit->done_moving) {
      log_debug("  stopping because we're done this turn");
      return TRUE;
    }
 
    if (punit->orders.vigilant && maybe_cancel_patrol_due_to_enemy(punit)) {
      /* "Patrol" orders are stopped if an enemy is near. */
      cancel_orders(punit, "  stopping because of nearby enemy");
      notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                    _("Orders for %s aborted as there are units nearby."),
                    unit_link(punit));
      return TRUE;
    }
 
    if (moves_made == punit->orders.length) {
      /* For repeating orders, don't repeat more than once per turn. */
      log_debug("  stopping because we ran a round");
      punit->done_moving = TRUE;
      send_unit_info(nullptr, punit);
      return TRUE;
    }
    moves_made++;
 
    order = punit->orders.list[punit->orders.index];
 
    /* An ORDER_PERFORM_ACTION that doesn't specify an action should not get
     * this far. */
    fc_assert_action((order.order != ORDER_PERFORM_ACTION
                      || action_id_exists(order.action)),
                     continue);
 
    switch (order.order) {
    case ORDER_MOVE:
    case ORDER_ACTION_MOVE:
    case ORDER_FULL_MP:
      if (0 == punit->moves_left) {
        log_debug("  stopping because of no more move points");
        return TRUE;
      }
      break;
    case ORDER_PERFORM_ACTION:
      if (action_mp_full_makes_legal(punit, order.action)) {
        log_debug("  stopping. Not enough move points this turn");
        return TRUE;
      }
      break;
    case ORDER_ACTIVITY:
    case ORDER_LAST:
      /* Those actions don't require moves left. */
      break;
    }
 
    last_order = (!punit->orders.repeat
                  && punit->orders.index + 1 == punit->orders.length);
 
    if (last_order) {
      /* Clear the orders before we engage in the move. That way any
       * has_orders checks will yield FALSE and this will be treated as
       * a normal move. This is important: for instance a caravan goto
       * will popup the caravan dialog on the last move only. */
      free_unit_orders(punit);
    }
 
    /* Advance the orders one step forward. This is needed because any
     * updates sent to the client as a result of the action should include
     * the new index value. Note that we have to send_unit_info() somewhere
     * after this point so that the client is properly updated. */
    punit->orders.index++;
 
    switch (order.order) {
    case ORDER_FULL_MP:
      if (punit->moves_left < unit_move_rate(punit)) {
        /* If the unit doesn't have full MP then it just waits until the
         * next turn. We assume that the next turn it will have full MP
         * (there's no check for that). */
        punit->done_moving = TRUE;
        log_debug("  waiting this turn");
        send_unit_info(nullptr, punit);
      }
      break;
    case ORDER_ACTIVITY:
      {
        enum unit_activity activity = order.activity;
 
        fc_assert(activity == ACTIVITY_SENTRY);
 
        if (can_unit_do_activity(nmap, punit, activity, order.action)) {
          punit->done_moving = TRUE;
          set_unit_activity(punit, activity, order.action);
          send_unit_info(nullptr, punit);
 
          break;
        }
      }
 
      cancel_orders(punit, "  orders canceled because of failed activity");
      notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                    _("Orders for %s aborted since they "
                      "give an invalid activity."),
                    unit_link(punit));
      return TRUE;
    case ORDER_MOVE:
    case ORDER_ACTION_MOVE:
      /* Move unit */
      if (!(dst_tile = mapstep(&(wld.map), unit_tile(punit), order.dir))) {
        cancel_orders(punit, "  move order sent us to invalid location");
        notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                      _("Orders for %s aborted since they "
                        "give an invalid location."),
                      unit_link(punit));
        return TRUE;
      }
 
      if (order.order != ORDER_ACTION_MOVE
          && maybe_cancel_goto_due_to_enemy(punit, dst_tile)) {
        /* Plain move required: no attack, trade route etc. */
        cancel_orders(punit, "  orders canceled because of enemy");
        notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                      _("Orders for %s aborted as there "
                        "are units in the way."),
                      unit_link(punit));
        return TRUE;
      }
 
      log_debug("  moving to %d,%d", TILE_XY(dst_tile));
      res = unit_move_handling(punit, dst_tile,
                               order.order != ORDER_ACTION_MOVE);
      if (!player_unit_by_number(pplayer, unitid)) {
        log_debug("  unit died while moving.");
        /* A player notification should already have been sent. */
        return FALSE;
      }
 
      if (res && !same_pos(dst_tile, unit_tile(punit))) {
        /* Movement succeeded but unit didn't move. */
        log_debug("  orders resulted in combat.");
        send_unit_info(nullptr, punit);
        return TRUE;
      }
 
      if (!res) {
        fc_assert(0 <= punit->moves_left);
 
        /* Movement failed (ZOC, etc.) */
        cancel_orders(punit, "  attempt to move failed.");
 
        if (!player_is_watching(punit, fresh)
            /* The final move "failed" because the unit needs to ask the
             * player what action it should take.
             *
             * The action decision request notifies the player. Its
             * location at the unit's last order makes it clear to the
             * player who the decision is for. ("The Spy I sent to Berlin
             * has arrived.")
             *
             * A notification message is therefore redundant. */
            && !(last_order
                 && punit->action_decision_want == ACT_DEC_ACTIVE
                 && punit->action_decision_tile == dst_tile)) {
          /* The player may have missed this. No one else will announce it
           * in a satisfying manner. Inform the player. */
          notify_player(pplayer, unit_tile(punit),
                        E_UNIT_ORDERS, ftc_server,
                        _("Orders for %s aborted because of failed move."),
                        unit_link(punit));
        }
 
        return TRUE;
      }
      break;
    case ORDER_PERFORM_ACTION:
      oaction = action_by_number(order.action);
 
      /* Checked in unit_order_list_is_sane() */
      fc_assert_action(oaction != nullptr, continue);
 
      log_debug("  orders: doing action %s", action_rule_name(oaction));
 
      dst_tile = index_to_tile(&(wld.map), order.target);
 
      if (dst_tile == nullptr) {
        /* Could be at the edge of the map while trying to target a tile
         * outside of it. */
 
        cancel_orders(punit, "  target location doesn't exist");
        illegal_action_msg(unit_owner(punit), E_UNIT_ORDERS, punit,
                           order.action, dst_tile, nullptr, nullptr);
 
        return TRUE;
      }
 
      /* Get the target city from the target tile. */
      tgt_city = tile_city(dst_tile);
 
      if (tgt_city == nullptr
          && action_id_get_target_kind(order.action) == ATK_CITY) {
        /* This action targets a city but no city target was found. */
 
        cancel_orders(punit, "  perform action vs city with no city");
        illegal_action_msg(unit_owner(punit), E_UNIT_ORDERS, punit,
                           order.action, dst_tile, tgt_city, nullptr);
 
        return TRUE;
      }
 
      /* Get a target unit at the target tile. */
      tgt_unit = action_tgt_unit(punit, dst_tile, TRUE);
 
      if (tgt_unit == nullptr
          && action_id_get_target_kind(order.action) == ATK_UNIT) {
        /* This action targets a unit but no target unit was found. */
 
        cancel_orders(punit, "  perform action vs unit with no unit");
        illegal_action_msg(unit_owner(punit), E_UNIT_ORDERS, punit,
                           order.action, dst_tile, tgt_city, tgt_unit);
 
        return TRUE;
      }
 
      /* Server side sub target assignment */
      if (oaction->target_complexity == ACT_TGT_COMPL_FLEXIBLE
          && order.sub_target == NO_TARGET) {
        /* Try to find a sub target. */
        sub_tgt_id = action_sub_target_id_for_action(oaction, punit);
      } else {
        /* The client should have specified a sub target if needed */
        sub_tgt_id = order.sub_target;
      }
 
      /* Get a target extra at the target tile */
      pextra = (sub_tgt_id == NO_TARGET ?
                  nullptr :
                  extra_by_number(sub_tgt_id));
 
      if (action_get_sub_target_kind(oaction) == ASTK_EXTRA_NOT_THERE
          && pextra != nullptr
          && actres_creates_extra(oaction->result, pextra)
          && tile_has_extra(dst_tile, pextra)) {
        /* Already there. Move on to the next order. */
        break;
      }
 
      if (action_get_sub_target_kind(oaction) == ASTK_EXTRA
          && pextra != nullptr
          && actres_removes_extra(oaction->result, pextra)
          && !tile_has_extra(dst_tile, pextra)) {
        /* Already not there. Move on to the next order. */
        break;
      }
 
      /* No target selected. */
      tgt_id = -1;
 
      /* Assume impossible until told otherwise. */
      prob = ACTPROB_IMPOSSIBLE;
 
      switch (action_id_get_target_kind(order.action)) {
      case ATK_STACK:
        prob = action_prob_vs_stack(nmap, punit, order.action,
                                    dst_tile);
        tgt_id = dst_tile->index;
        break;
      case ATK_TILE:
        prob = action_prob_vs_tile(nmap, punit, order.action,
                                   dst_tile, pextra);
        tgt_id = dst_tile->index;
        break;
      case ATK_EXTRAS:
        prob = action_prob_vs_extras(nmap, punit, order.action,
                                     dst_tile, pextra);
        tgt_id = dst_tile->index;
        break;
      case ATK_CITY:
        prob = action_prob_vs_city(nmap, punit, order.action,
                                   tgt_city);
        tgt_id = tgt_city->id;
        break;
      case ATK_UNIT:
        prob = action_prob_vs_unit(nmap, punit, order.action,
                                   tgt_unit);
 
        tgt_id = tgt_unit->id;
        break;
      case ATK_SELF:
        prob = action_prob_self(nmap, punit, order.action);
 
        tgt_id = unitid;
        break;
      case ATK_COUNT:
        log_error("Invalid action target kind");
 
        /* The check below will abort and cancel the orders because prob
         * was initialized to impossible above this switch statement. */
 
        break;
      }
 
      if (!action_prob_possible(prob)) {
        /* The player has enough information to know that this action is
         * against the rules. Don't risk any punishment by trying to
         * perform it. */
 
        cancel_orders(punit, "  illegal action");
        notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                      _("%s could not do %s to %s."),
                      unit_link(punit),
                      action_id_name_translation(order.action),
                      tile_link(dst_tile));
 
        /* Try to explain what rule made it illegal. */
        illegal_action_msg(unit_owner(punit), E_BAD_COMMAND, punit,
                           order.action, dst_tile, tgt_city, tgt_unit);
 
        return TRUE;
      }
 
      if (action_id_has_result_safe(order.action, ACTRES_FOUND_CITY)) {
        /* This action needs a name. */
        name = city_name_suggestion(pplayer, unit_tile(punit));
      } else {
        /* This action doesn't need a name. */
        name = "";
      }
 
      performed = unit_perform_action(pplayer,
                                      unitid,
                                      tgt_id,
                                      sub_tgt_id,
                                      name,
                                      order.action,
                                      ACT_REQ_PLAYER);
 
      if (!player_unit_by_number(pplayer, unitid)) {
        /* The unit "died" while performing the action. */
        return FALSE;
      }
 
      if (!performed) {
        /* The action wasn't performed as ordered. */
 
        cancel_orders(punit, "  failed action");
        notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                      _("Orders for %s aborted because "
                        "doing %s to %s failed."),
                      unit_link(punit),
                      action_id_name_translation(order.action),
                      tile_link(dst_tile));
 
        return TRUE;
      }
 
      if (action_id_get_act_time(order.action, punit, dst_tile, pextra)
          != ACT_TIME_INSTANTANEOUS) {
        /* Done at turn change. */
        punit->done_moving = TRUE;
        send_unit_info(nullptr, punit);
        break;
      }
 
      break;
    case ORDER_LAST:
      /* Should be caught when loading the unit orders from the savegame or
       * when receiving the unit orders from the client. */
      fc_assert_msg(order.order != ORDER_LAST, "Invalid order: last.");
      cancel_orders(punit, "  invalid order!");
      notify_player(pplayer, unit_tile(punit), E_UNIT_ORDERS, ftc_server,
                    _("Your %s has invalid orders."),
                    unit_link(punit));
      return TRUE;
    }
 
    if (last_order) {
      fc_assert(!punit->has_orders);
      log_debug("  stopping because orders are complete");
      return TRUE;
    }
 
    if (punit->orders.index == punit->orders.length) {
      fc_assert(punit->orders.repeat);
      /* Start over. */
      log_debug("  repeating orders.");
      punit->orders.index = 0;
    }
  } /* end while */
}
 
/**********************************************************************/
static int get_unit_vision_base(const struct unit *punit,
                                enum vision_layer vlayer,
                                const int base)
{
  switch (vlayer) {
  case V_MAIN:
    return MAX(0, base);
  case V_INVIS:
  case V_SUBSURFACE:
    return CLIP(0, base, 2);
  case V_COUNT:
    break;
  }
 
  log_error("Unsupported vision layer variant: %d.", vlayer);
 
  return 0;
}
 
/**********************************************************************/
static int unit_vision_range_modifiers(const struct unit *punit,
                                       const struct tile *ptile)
{
  const struct unit_type *utype = unit_type_get(punit);
 
  return (utype->vision_radius_sq
          + get_target_bonus_effects(nullptr,
                                     &(const struct req_context) {
                                       .player = unit_owner(punit),
                                       .tile = ptile,
                                       .unittype = utype,
                                       .unit = punit,
                                     },
                                     nullptr, EFT_UNIT_VISION_RADIUS_SQ));
}
 
/**********************************************************************/
int get_unit_vision_at(const struct unit *punit, const struct tile *ptile,
                       enum vision_layer vlayer)
{
  return get_unit_vision_base(punit, vlayer,
                              unit_vision_range_modifiers(punit, ptile));
}
 
/**********************************************************************/
void unit_refresh_vision(struct unit *punit)
{
  struct vision *uvision = punit->server.vision;
  const struct tile *utile = unit_tile(punit);
  int mod = unit_vision_range_modifiers(punit, utile);
  const v_radius_t radius_sq
    = V_RADIUS(get_unit_vision_base(punit, V_MAIN, mod),
               get_unit_vision_base(punit, V_INVIS, mod),
               get_unit_vision_base(punit, V_SUBSURFACE, mod));
 
  vision_change_sight(uvision, radius_sq);
  ASSERT_VISION(uvision);
}
 
/**********************************************************************/
void unit_list_refresh_vision(struct unit_list *punitlist)
{
  unit_list_iterate(punitlist, punit) {
    unit_refresh_vision(punit);
  } unit_list_iterate_end;
}
 
/**********************************************************************/
bool unit_can_do_action_now(const struct unit *punit)
{
  time_t dt;
 
  if (!punit) {
    return FALSE;
  }
 
  if (game.server.unitwaittime <= 0) {
    return TRUE;
  }
 
  if (punit->server.action_turn != game.info.turn - 1) {
    return TRUE;
  }
 
  dt = time(nullptr) - punit->server.action_timestamp;
  if (dt < game.server.unitwaittime) {
    char buf[64];
    format_time_duration(game.server.unitwaittime - dt, buf, sizeof(buf));
    notify_player(unit_owner(punit), unit_tile(punit), E_BAD_COMMAND,
                  ftc_server, _("Your unit may not act for another %s "
                                "this turn. See /help unitwaittime."), buf);
    return FALSE;
  }
 
  return TRUE;
}
 
/**********************************************************************/
void unit_did_action(struct unit *punit)
{
  if (!punit) {
    return;
  }
 
  punit->server.action_timestamp = time(nullptr);
  punit->server.action_turn = game.info.turn;
}
 
/**********************************************************************/
bool unit_can_be_retired(struct unit *punit)
{
  /* check if there is enemy nearby */
  square_iterate(&(wld.map), unit_tile(punit), 3, ptile) {
    if (is_enemy_city_tile(ptile, unit_owner(punit))
        || is_enemy_unit_tile(ptile, unit_owner(punit))) {
      return FALSE;
    }
  }
  square_iterate_end;
 
  return TRUE;
}
 
/**********************************************************************/
void random_movements(struct player *pplayer)
{
  const struct civ_map *nmap = &(wld.map);
 
  game.server.random_move_time = pplayer;
 
  unit_list_iterate_safe(pplayer->units, punit) {
    if (unit_has_type_flag(punit, UTYF_RANDOM_MOVEMENT)) {
      bool moved = TRUE;
      struct tile *curtile = unit_tile(punit);
      int id = punit->id;
 
      while (moved && unit_is_alive(id) && punit->moves_left > 0) {
        /*
         * List of all 8 directions
         */
        enum direction8 dirs[8] = {
          DIR8_NORTHWEST, DIR8_NORTH, DIR8_NORTHEAST, DIR8_WEST, DIR8_EAST,
          DIR8_SOUTHWEST, DIR8_SOUTH, DIR8_SOUTHEAST
        };
        int n;
 
        moved = FALSE;
 
        for (n = 8; n > 0 && !moved; n--) {
          enum direction8 choice = (enum direction8) fc_rand(n);
          struct tile *dest = mapstep(&(wld.map), curtile, dirs[choice]);
 
          if (dest != nullptr) {
            if (action_prob_possible(action_prob_vs_stack(nmap, punit, ACTION_ATTACK,
                                                          dest))) {
              if (unit_perform_action(pplayer, id, tile_index(dest), NO_TARGET,
                                      "", ACTION_ATTACK, ACT_REQ_RULES)) {
                moved = TRUE;
                break;
              }
            }
 
            if (!moved) {
              if (is_action_enabled_unit_on_tile(nmap, ACTION_UNIT_MOVE, punit, dest,
                                                 nullptr)) {
                if (unit_perform_action(pplayer, id, tile_index(dest),
                                        NO_TARGET, "", ACTION_UNIT_MOVE,
                                        ACT_REQ_RULES)) {
                  moved = TRUE;
                }
              } else if (is_action_enabled_unit_on_tile(nmap, ACTION_UNIT_MOVE2,
                                                        punit, dest, nullptr)) {
                if (unit_perform_action(pplayer, id, tile_index(dest),
                                        NO_TARGET, "", ACTION_UNIT_MOVE2,
                                        ACT_REQ_RULES)) {
                  moved = TRUE;
                }
              } else if (is_action_enabled_unit_on_tile(nmap, ACTION_UNIT_MOVE3,
                                                        punit, dest, nullptr)) {
                if (unit_perform_action(pplayer, id, tile_index(dest),
                                        NO_TARGET, "", ACTION_UNIT_MOVE3,
                                        ACT_REQ_RULES)) {
                  moved = TRUE;
                }
              }
            }
          }
 
          if (!moved) {
            /* Choice was bad, so replace it with the last direction
             * in the list. On the next iteration, one fewer choice
             * will remain. */
            dirs[choice] = dirs[n - 1];
          }
        }
      }
    }
  } unit_list_iterate_safe_end;
 
  game.server.random_move_time = nullptr;
}
 
/**********************************************************************/
void unit_make_contact(const struct unit *punit,
                       struct tile *ptile, struct player *pplayer)
{
  fc_assert_ret(punit != nullptr
                || (ptile != nullptr && pplayer != nullptr));
 
  if (punit != nullptr && unit_has_type_flag(punit, UTYF_FLAGLESS)) {
    return; /* Flagless unit can't make contact */
  }
 
  maybe_make_contact(ptile != nullptr ? ptile : unit_tile(punit),
                     pplayer != nullptr ? pplayer : unit_owner(punit));
}