autosettlers.cpp

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/*__            ___                 ***************************************
/   \          /   \          Copyright (c) 1996-2020 Freeciv21 and Freeciv
\_   \        /  __/          contributors. This file is part of Freeciv21.
 _\   \      /  /__     Freeciv21 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 3 of the  License,
       |                              or (at your option) any later version.
     _/     /\                  You should have received  a copy of the GNU
    /o)  (o/\ \_                General Public License along with Freeciv21.
    \_____/ /                     If not, see https://www.gnu.org/licenses/.
      \____/        ********************************************************/
 
// utility
#include "log.h"
#include "support.h"
#include "timing.h"
 
// common
#include "ai.h"
#include "city.h"
#include "game.h"
#include "government.h"
#include "map.h"
#include "movement.h"
#include "nation.h"
#include "packets.h"
#include "unitlist.h"
#include "workertask.h"
 
/* common/aicore */
#include "citymap.h"
#include "path_finding.h"
#include "pf_tools.h"
 
// server
#include "citytools.h"
#include "maphand.h"
#include "srv_log.h"
#include "unithand.h"
#include "unittools.h"
 
/* server/advisors */
#include "advbuilding.h"
#include "advdata.h"
#include "advgoto.h"
#include "advtools.h"
#include "infracache.h"
 
// ai
#include "handicaps.h"
 
#include "autosettlers.h"
 
/* This factor is multiplied on when calculating the want.  This is done
 * to avoid rounding errors in comparisons when looking for the best
 * possible work.  However before returning the final want we have to
 * divide by it again.  This loses accuracy but is needed since the want
 * values are used for comparison by the AI in trying to calculate the
 * goodness of building worker units. */
#define WORKER_FACTOR 1024
 
struct settlermap {
  int enroute; // unit ID of settler en route to this tile
  int eta;     // estimated number of turns until enroute arrives
};
 
action_id as_actions_transform[MAX_NUM_ACTIONS];
action_id as_actions_extra[MAX_NUM_ACTIONS];
action_id as_actions_rmextra[MAX_NUM_ACTIONS];
 
static civtimer *as_timer = nullptr;
 
void adv_settlers_free()
{
  timer_destroy(as_timer);
  as_timer = nullptr;
}
 
void auto_settlers_ruleset_init()
{
  int i;
 
  i = 0;
  action_list_add_all_by_result(as_actions_transform, &i, ACTRES_CULTIVATE);
  action_list_add_all_by_result(as_actions_transform, &i, ACTRES_PLANT);
  action_list_add_all_by_result(as_actions_transform, &i,
                                ACTRES_TRANSFORM_TERRAIN);
  action_list_end(as_actions_transform, i);
 
  i = 0;
  action_list_add_all_by_result(as_actions_extra, &i, ACTRES_IRRIGATE);
  action_list_add_all_by_result(as_actions_extra, &i, ACTRES_MINE);
  action_list_add_all_by_result(as_actions_extra, &i, ACTRES_ROAD);
  action_list_add_all_by_result(as_actions_extra, &i, ACTRES_BASE);
  action_list_end(as_actions_extra, i);
 
  i = 0;
  action_list_add_all_by_result(as_actions_rmextra, &i,
                                ACTRES_CLEAN_POLLUTION);
  action_list_add_all_by_result(as_actions_rmextra, &i,
                                ACTRES_CLEAN_FALLOUT);
  // We could have ACTRES_PILLAGE here, but currently we don't
  action_list_end(as_actions_rmextra, i);
}
 
adv_want adv_settlers_road_bonus(struct tile *ptile, struct road_type *proad)
{
#define MAX_DEP_ROADS 5
 
  int bonus = 0, i;
  bool potential_road[12], real_road[12], is_slow[12];
  int dx[12] = {-1, 0, 1, -1, 1, -1, 0, 1, 0, -2, 2, 0};
  int dy[12] = {-1, -1, -1, 0, 0, 1, 1, 1, -2, 0, 0, 2};
  int x, y;
  int rnbr;
  struct road_type *pdep_roads[MAX_DEP_ROADS];
  int dep_rnbr[MAX_DEP_ROADS];
  int dep_count = 0;
  struct extra_type *pextra;
 
  if (proad == nullptr) {
    return 0;
  }
 
  rnbr = road_number(proad);
  pextra = road_extra_get(proad);
 
  road_deps_iterate(&(pextra->reqs), pdep)
  {
    if (dep_count < MAX_DEP_ROADS) {
      pdep_roads[dep_count] = pdep;
      dep_rnbr[dep_count++] = road_number(pdep);
    }
  }
  road_deps_iterate_end;
 
  index_to_map_pos(&x, &y, tile_index(ptile));
  for (i = 0; i < 12; i++) {
    struct tile *tile1 = map_pos_to_tile(&(wld.map), x + dx[i], y + dy[i]);
 
    if (!tile1) {
      real_road[i] = false;
      potential_road[i] = false;
      is_slow[i] = false; // FIXME: should be TRUE?
    } else {
      int build_time = terrain_extra_build_time(tile_terrain(tile1),
                                                ACTIVITY_GEN_ROAD, pextra);
      int j;
 
      real_road[i] = tile_has_road(tile1, proad);
      potential_road[i] = real_road[i];
      for (j = 0; !potential_road[i] && j < dep_count; j++) {
        potential_road[i] = tile_has_road(tile1, pdep_roads[j]);
      }
 
      /* If TRUE, this value indicates that this tile does not need
       * a road connector.  This is set for terrains which cannot have
       * road or where road takes "too long" to build. */
      is_slow[i] = (build_time == 0 || build_time > 5);
 
      if (!real_road[i]) {
        unit_list_iterate(tile1->units, punit)
        {
          if (punit->activity == ACTIVITY_GEN_ROAD) {
            /* If a road, or its dependency is being built here, consider as
             * if it's already built. */
            int build_rnbr;
 
            fc_assert(punit->activity_target != nullptr);
 
            build_rnbr = road_number(extra_road_get(punit->activity_target));
 
            if (build_rnbr == rnbr) {
              real_road[i] = true;
              potential_road[i] = true;
            }
            for (j = 0; !potential_road[i] && j < dep_count; j++) {
              if (build_rnbr == dep_rnbr[j]) {
                potential_road[i] = true;
              }
            }
          }
        }
        unit_list_iterate_end;
      }
    }
  }
 
  if (current_topo_has_flag(TF_HEX)) {
    // On hex map, road is always a benefit
    bonus += 20; // Later divided by 20
 
    // Road is more valuable when even longer road around does not exist.
    for (i = 0; i < 12; i++) {
      if (!real_road[i]) {
        bonus += 3;
      }
    }
 
    // Scale down the bonus.
    bonus /= 20;
  } else {
    /*
     * Consider the following tile arrangement (numbered in hex):
     *
     *   8
     *  012
     * 93 4A
     *  567
     *   B
     *
     * these are the tiles defined by the (dx,dy) arrays above.
     *
     * Then the following algorithm is supposed to determine if it's a good
     * idea to build a road here.  Note this won't work well for hex maps
     * since the (dx,dy) arrays will not cover the same tiles.
     *
     * FIXME: if you can understand the algorithm below please rewrite this
     * explanation!
     */
    if (potential_road[0] && !real_road[1] && !real_road[3]
        && (!real_road[2] || !real_road[8])
        && (!is_slow[2] || !is_slow[4] || !is_slow[7] || !is_slow[6]
            || !is_slow[5])) {
      bonus++;
    }
    if (potential_road[2] && !real_road[1] && !real_road[4]
        && (!real_road[7] || !real_road[10])
        && (!is_slow[0] || !is_slow[3] || !is_slow[7] || !is_slow[6]
            || !is_slow[5])) {
      bonus++;
    }
    if (potential_road[5] && !real_road[6] && !real_road[3]
        && (!real_road[5] || !real_road[11])
        && (!is_slow[2] || !is_slow[4] || !is_slow[7] || !is_slow[1]
            || !is_slow[0])) {
      bonus++;
    }
    if (potential_road[7] && !real_road[6] && !real_road[4]
        && (!real_road[0] || !real_road[9])
        && (!is_slow[2] || !is_slow[3] || !is_slow[0] || !is_slow[1]
            || !is_slow[5])) {
      bonus++;
    }
 
    /*   A
     *  B*B
     *  CCC
     *
     * We are at tile *.  If tile A has a road, and neither B tile does, and
     * one C tile is a valid destination, then we might want a road here.
     *
     * Of course the same logic applies if you rotate the diagram.
     */
    if (potential_road[1] && !real_road[4] && !real_road[3]
        && (!is_slow[5] || !is_slow[6] || !is_slow[7])) {
      bonus++;
    }
    if (potential_road[3] && !real_road[1] && !real_road[6]
        && (!is_slow[2] || !is_slow[4] || !is_slow[7])) {
      bonus++;
    }
    if (potential_road[4] && !real_road[1] && !real_road[6]
        && (!is_slow[0] || !is_slow[3] || !is_slow[5])) {
      bonus++;
    }
    if (potential_road[6] && !real_road[4] && !real_road[3]
        && (!is_slow[0] || !is_slow[1] || !is_slow[2])) {
      bonus++;
    }
  }
 
  return bonus;
}
 
static void consider_settler_action(
    const struct player *pplayer, enum unit_activity act,
    struct extra_type *target, adv_want extra, int new_tile_value,
    int old_tile_value, bool in_use, int delay, adv_want *best_value,
    int *best_old_tile_value, int *best_extra, bool *improve_worked,
    int *best_delay, enum unit_activity *best_act,
    struct extra_type **best_target, struct tile **best_tile,
    struct tile *ptile)
{
  bool improves;
  int total_value = 0, base_value = 0;
  int old_improvement_value;
 
  fc_assert(act != ACTIVITY_LAST);
 
  if (extra < 0) {
    extra = 0;
  }
 
  if (new_tile_value > old_tile_value) {
    improves = true;
  } else if (new_tile_value == old_tile_value && extra > 0) {
    improves = true;
  } else {
    improves = false;
  }
 
  // find the present value of the future benefit of this action
  if (improves || extra > 0) {
    if (!(*improve_worked) && !in_use) {
      /* Going to improve tile that is not yet in use.
       * Getting the best possible total for next citizen to work on is more
       * important than amount tile gets improved. */
      if (improves
          && (new_tile_value > *best_value
              || (new_tile_value == *best_value
                  && old_tile_value < *best_old_tile_value))) {
        *best_value = new_tile_value;
        *best_old_tile_value = old_tile_value;
        *best_extra = extra;
        *best_act = act;
        *best_target = target;
        *best_tile = ptile;
        *best_delay = delay;
      }
 
      return;
    }
 
    /* At least one of the previous best or current tile is in use
     * Prefer the tile that gets improved more, regarless of the resulting
     * total */
 
    base_value = new_tile_value - old_tile_value;
    total_value = base_value * WORKER_FACTOR;
    if (!in_use) {
      total_value /= 2;
    }
    total_value += extra * WORKER_FACTOR;
 
    // use factor to prevent rounding errors
    total_value = amortize(total_value, delay);
 
    if (*improve_worked) {
      old_improvement_value = *best_value;
    } else {
      /* Convert old best_value to improvement value compatible with in_use
       * tile value */
      old_improvement_value =
          amortize((*best_value - *best_old_tile_value) * WORKER_FACTOR / 2,
                   *best_delay);
    }
 
    if (total_value > old_improvement_value
        || (total_value == old_improvement_value
            && old_tile_value > *best_old_tile_value)) {
      if (in_use) {
        *best_value = total_value;
        *improve_worked = true;
      } else {
        *best_value = new_tile_value;
        *improve_worked = false;
      }
      *best_old_tile_value = old_tile_value;
      *best_extra = extra;
      *best_act = act;
      *best_target = target;
      *best_tile = ptile;
      *best_delay = delay;
    }
  }
}
 
static enum tile_behavior
autosettler_tile_behavior(const struct tile *ptile, enum known_type known,
                          const struct pf_parameter *param)
{
  const struct player *owner = tile_owner(ptile);
 
  if (nullptr != owner && !pplayers_allied(owner, param->owner)) {
    return TB_IGNORE;
  }
  return TB_NORMAL;
}
 
adv_want settler_evaluate_improvements(struct unit *punit,
                                       enum unit_activity *best_act,
                                       struct extra_type **best_target,
                                       struct tile **best_tile, PFPath *path,
                                       struct settlermap *state)
{
  const struct player *pplayer = unit_owner(punit);
  struct pf_parameter parameter;
  struct pf_map *pfm;
  struct pf_position pos;
  int oldv;             // Current value of consideration tile.
  int best_oldv = 9999; /* oldv of best target so far; compared if
                         * newv == best_newv; not initialized to zero,
                         * so that newv = 0 activities are not chosen. */
  adv_want best_newv = 0;
  bool improve_worked = false;
  int best_extra = 0;
  int best_delay = 0;
 
  // closest worker, if any, headed towards target tile
  struct unit *enroute = nullptr;
 
  pft_fill_unit_parameter(&parameter, punit);
  parameter.omniscience = !has_handicap(pplayer, H_MAP);
  parameter.get_TB = autosettler_tile_behavior;
  pfm = pf_map_new(&parameter);
 
  city_list_iterate(pplayer->cities, pcity)
  {
    struct tile *pcenter = city_tile(pcity);
 
    // try to work near the city
    city_tile_iterate_index(city_map_radius_sq_get(pcity), pcenter, ptile,
                            cindex)
    {
      bool consider = true;
      bool in_use = (tile_worked(ptile) == pcity);
 
      if (!in_use && !city_can_work_tile(pcity, ptile)) {
        // Don't risk bothering with this tile.
        continue;
      }
 
      if (!adv_settler_safe_tile(pplayer, punit, ptile)) {
        // Too dangerous place
        continue;
      }
 
      // Do not go to tiles that already have workers there.
      unit_list_iterate(ptile->units, aunit)
      {
        if (unit_owner(aunit) == pplayer && aunit->id != punit->id
            && unit_has_type_flag(aunit, UTYF_SETTLERS)) {
          consider = false;
        }
      }
      unit_list_iterate_end;
 
      if (!consider) {
        continue;
      }
 
      if (state) {
        enroute =
            player_unit_by_number(pplayer, state[tile_index(ptile)].enroute);
      }
 
      if (pf_map_position(pfm, ptile, &pos)) {
        int eta = FC_INFINITY, inbound_distance = FC_INFINITY, turns;
 
        if (enroute) {
          eta = state[tile_index(ptile)].eta;
          inbound_distance = real_map_distance(ptile, unit_tile(enroute));
        }
 
        /* Only consider this tile if we are closer in time and space to
         * it than our other worker (if any) travelling to the site. */
        if ((enroute && enroute->id == punit->id) || pos.turn < eta
            || (pos.turn == eta
                && (real_map_distance(ptile, unit_tile(punit))
                    < inbound_distance))) {
          if (enroute) {
            UNIT_LOG(LOG_DEBUG, punit,
                     "Considering (%d, %d) because we're closer "
                     "(%d, %d) than %d (%d, %d)",
                     TILE_XY(ptile), pos.turn,
                     real_map_distance(ptile, unit_tile(punit)), enroute->id,
                     eta, inbound_distance);
          }
 
          oldv = city_tile_value(pcity, ptile, 0, 0);
 
          // Now, consider various activities...
          as_transform_action_iterate(act)
          {
            struct extra_type *target = nullptr;
            enum extra_cause cause =
                activity_to_extra_cause(action_id_get_activity(act));
            enum extra_rmcause rmcause =
                activity_to_extra_rmcause(action_id_get_activity(act));
 
            if (cause != EC_NONE) {
              target = next_extra_for_tile(ptile, cause, pplayer, punit);
            } else if (rmcause != ERM_NONE) {
              target = prev_extra_in_tile(ptile, rmcause, pplayer, punit);
            }
 
            if (adv_city_worker_act_get(pcity, cindex,
                                        action_id_get_activity(act))
                    >= 0
                && action_prob_possible(action_speculate_unit_on_tile(
                    act, punit, unit_home(punit), ptile,
                    parameter.omniscience, ptile, target))) {
              int base_value = adv_city_worker_act_get(
                  pcity, cindex, action_id_get_activity(act));
 
              turns = pos.turn
                      + get_turns_for_activity_at(
                          punit, action_id_get_activity(act), ptile, target);
              if (pos.moves_left == 0) {
                // We need moves left to begin activity immediately.
                turns++;
              }
 
              consider_settler_action(
                  pplayer, action_id_get_activity(act), target, 0.0,
                  base_value, oldv, in_use, turns, &best_newv, &best_oldv,
                  &best_extra, &improve_worked, &best_delay, best_act,
                  best_target, best_tile, ptile);
            } // endif: can the worker perform this action
          }
          as_transform_action_iterate_end;
 
          extra_type_iterate(pextra)
          {
            enum unit_activity act = ACTIVITY_LAST;
            enum unit_activity eval_act = ACTIVITY_LAST;
            int base_value;
            bool removing = tile_has_extra(ptile, pextra);
 
            if (removing) {
              as_rmextra_action_iterate(try_act)
              {
                struct action *taction = action_by_number(try_act);
                if (is_extra_removed_by_action(pextra, taction)) {
                  /* We do not even evaluate actions we can't do.
                   * Removal is not considered prerequisite for anything */
                  if (action_prob_possible(action_speculate_unit_on_tile(
                          try_act, punit, unit_home(punit), ptile,
                          parameter.omniscience, ptile, pextra))) {
                    act = action_get_activity(taction);
                    eval_act = action_get_activity(taction);
                    break;
                  }
                }
              }
              as_rmextra_action_iterate_end;
            } else {
              as_extra_action_iterate(try_act)
              {
                struct action *taction = action_by_number(try_act);
                if (is_extra_caused_by_action(pextra, taction)) {
                  eval_act = action_id_get_activity(try_act);
                  if (action_prob_possible(action_speculate_unit_on_tile(
                          try_act, punit, unit_home(punit), ptile,
                          parameter.omniscience, ptile, pextra))) {
                    act = action_get_activity(taction);
                    break;
                  }
                }
              }
              as_extra_action_iterate_end;
            }
 
            if (eval_act == ACTIVITY_LAST) {
              // No activity can provide (or remove) the extra
              continue;
            }
 
            if (removing) {
              base_value =
                  adv_city_worker_rmextra_get(pcity, cindex, pextra);
            } else {
              base_value = adv_city_worker_extra_get(pcity, cindex, pextra);
            }
 
            if (base_value >= 0) {
              adv_want extra;
              struct road_type *proad;
 
              turns = pos.turn
                      + get_turns_for_activity_at(punit, eval_act, ptile,
                                                  pextra);
              if (pos.moves_left == 0) {
                // We need moves left to begin activity immediately.
                turns++;
              }
 
              proad = extra_road_get(pextra);
 
              if (proad != nullptr && road_provides_move_bonus(proad)) {
                int mc_multiplier = 1;
                int mc_divisor = 1;
                int old_move_cost =
                    tile_terrain(ptile)->movement_cost * SINGLE_MOVE;
 
                /* Here 'old' means actually 'without the evaluated': In case
                 * of removal activity it's the value after the removal. */
 
                extra_type_by_cause_iterate(EC_ROAD, pold)
                {
                  if (tile_has_extra(ptile, pold) && pold != pextra) {
                    struct road_type *po_road = extra_road_get(pold);
 
                    /* This ignores the fact that new road may be native to
                     * units that old road is not. */
                    if (po_road->move_cost < old_move_cost) {
                      old_move_cost = po_road->move_cost;
                    }
                  }
                }
                extra_type_by_cause_iterate_end;
 
                if (proad->move_cost < old_move_cost) {
                  if (proad->move_cost >= terrain_control.move_fragments) {
                    mc_divisor =
                        proad->move_cost / terrain_control.move_fragments;
                  } else {
                    if (proad->move_cost == 0) {
                      mc_multiplier = 2;
                    } else {
                      mc_multiplier = 1 - proad->move_cost;
                    }
                    mc_multiplier += old_move_cost;
                  }
                }
 
                extra = adv_settlers_road_bonus(ptile, proad) * mc_multiplier
                        / mc_divisor;
 
              } else {
                extra = 0;
              }
 
              if (extra_has_flag(pextra, EF_GLOBAL_WARMING)) {
                extra -= pplayer->ai_common.warmth;
              }
              if (extra_has_flag(pextra, EF_NUCLEAR_WINTER)) {
                extra -= pplayer->ai_common.frost;
              }
 
              if (removing) {
                extra = -extra;
              }
 
              if (act != ACTIVITY_LAST) {
                consider_settler_action(
                    pplayer, act, pextra, extra, base_value, oldv, in_use,
                    turns, &best_newv, &best_oldv, &best_extra,
                    &improve_worked, &best_delay, best_act, best_target,
                    best_tile, ptile);
              } else {
                fc_assert(!removing);
 
                road_deps_iterate(&(pextra->reqs), pdep)
                {
                  struct extra_type *dep_tgt;
 
                  dep_tgt = road_extra_get(pdep);
 
                  if (action_prob_possible(action_speculate_unit_on_tile(
                          ACTION_ROAD, punit, unit_home(punit), ptile,
                          parameter.omniscience, ptile, dep_tgt))) {
                    /* Consider building dependency road for later upgrade to
                     * target extra. Here we set value to be sum of
                     * dependency road and target extra values, which
                     * increases want, and turns is sum of dependency and
                     * target build turns, which decreases want. This can
                     * result in either bigger or lesser want than when
                     * checkin dependency road for the sake of itself when
                     * its turn in extra_type_iterate() is. */
                    int dep_turns =
                        turns
                        + get_turns_for_activity_at(punit, ACTIVITY_GEN_ROAD,
                                                    ptile, dep_tgt);
                    int dep_value =
                        base_value
                        + adv_city_worker_extra_get(pcity, cindex, dep_tgt);
 
                    consider_settler_action(
                        pplayer, ACTIVITY_GEN_ROAD, dep_tgt, extra,
                        dep_value, oldv, in_use, dep_turns, &best_newv,
                        &best_oldv, &best_extra, &improve_worked,
                        &best_delay, best_act, best_target, best_tile,
                        ptile);
                  }
                }
                road_deps_iterate_end;
 
                base_deps_iterate(&(pextra->reqs), pdep)
                {
                  struct extra_type *dep_tgt;
 
                  dep_tgt = base_extra_get(pdep);
                  if (action_prob_possible(action_speculate_unit_on_tile(
                          ACTION_BASE, punit, unit_home(punit), ptile,
                          parameter.omniscience, ptile, dep_tgt))) {
                    /* Consider building dependency base for later upgrade to
                     * target extra. See similar road implementation above
                     * for extended commentary. */
                    int dep_turns =
                        turns
                        + get_turns_for_activity_at(punit, ACTIVITY_BASE,
                                                    ptile, dep_tgt);
                    int dep_value =
                        base_value
                        + adv_city_worker_extra_get(pcity, cindex, dep_tgt);
 
                    consider_settler_action(
                        pplayer, ACTIVITY_BASE, dep_tgt, 0.0, dep_value,
                        oldv, in_use, dep_turns, &best_newv, &best_oldv,
                        &best_extra, &improve_worked, &best_delay, best_act,
                        best_target, best_tile, ptile);
                  }
                }
                base_deps_iterate_end;
              }
            }
          }
          extra_type_iterate_end;
        } // endif: can we arrive sooner than current worker, if any?
      }   // endif: are we travelling to a legal destination?
    }
    city_tile_iterate_index_end;
  }
  city_list_iterate_end;
 
  if (!improve_worked) {
    /* best_newv contains total value of improved tile. Check amount of
     * improvement instead. */
    best_newv = amortize(
        (best_newv - best_oldv + best_extra) * WORKER_FACTOR, best_delay);
  }
  best_newv /= WORKER_FACTOR;
 
  best_newv = MAX(best_newv, 0); // sanity
 
  if (best_newv > 0) {
    log_debug("Settler %d@(%d,%d) wants to %s at (%d,%d) with "
              "desire " ADV_WANT_PRINTF,
              punit->id, TILE_XY(unit_tile(punit)),
              get_activity_text(*best_act), TILE_XY(*best_tile), best_newv);
  } else {
    /* Fill in dummy values.  The callers should check if the return value
     * is > 0 but this will avoid confusing them. */
    *best_act = ACTIVITY_IDLE;
    *best_tile = nullptr;
  }
 
  if (path) {
    *path = *best_tile ? pf_map_path(pfm, *best_tile) : PFPath();
  }
 
  pf_map_destroy(pfm);
 
  return best_newv;
}
 
struct city *settler_evaluate_city_requests(struct unit *punit,
                                            struct worker_task **best_task,
                                            PFPath *path,
                                            struct settlermap *state)
{
  const struct player *pplayer = unit_owner(punit);
  struct pf_parameter parameter;
  struct pf_map *pfm;
  struct pf_position pos;
  int best_value = -1;
  struct worker_task *best = nullptr;
  struct city *taskcity = nullptr;
  int dist = FC_INFINITY;
 
  pft_fill_unit_parameter(&parameter, punit);
  parameter.omniscience = !has_handicap(pplayer, H_MAP);
  parameter.get_TB = autosettler_tile_behavior;
  pfm = pf_map_new(&parameter);
 
  // Have nearby cities requests?
  city_list_iterate(pplayer->cities, pcity)
  {
    worker_task_list_iterate(pcity->task_reqs, ptask)
    {
      bool consider = true;
 
      // Do not go to tiles that already have workers there.
      unit_list_iterate(ptask->ptile->units, aunit)
      {
        if (unit_owner(aunit) == pplayer && aunit->id != punit->id
            && unit_has_type_flag(aunit, UTYF_SETTLERS)) {
          consider = false;
        }
      }
      unit_list_iterate_end;
 
      if (consider
          && auto_settlers_speculate_can_act_at(punit, ptask->act,
                                                parameter.omniscience,
                                                ptask->tgt, ptask->ptile)) {
        // closest worker, if any, headed towards target tile
        struct unit *enroute = nullptr;
 
        if (state) {
          enroute = player_unit_by_number(
              pplayer, state[tile_index(ptask->ptile)].enroute);
        }
 
        if (pf_map_position(pfm, ptask->ptile, &pos)) {
          int value = (ptask->want + 1) * 10 / (pos.turn + 1);
 
          if (value > best_value) {
            int eta = FC_INFINITY, inbound_distance = FC_INFINITY;
 
            if (enroute) {
              eta = state[tile_index(ptask->ptile)].eta;
              inbound_distance =
                  real_map_distance(ptask->ptile, unit_tile(enroute));
            }
 
            /* Only consider this tile if we are closer in time and space to
             * it than our other worker (if any) travelling to the site. */
            if (pos.turn < dist
                && ((enroute && enroute->id == punit->id) || pos.turn < eta
                    || (pos.turn == eta
                        && (real_map_distance(ptask->ptile, unit_tile(punit))
                            < inbound_distance)))) {
              dist = pos.turn;
              best = ptask;
              best_value = value;
              taskcity = pcity;
            }
          }
        }
      }
    }
    worker_task_list_iterate_end;
  }
  city_list_iterate_end;
 
  *best_task = best;
 
  if (!path->empty()) {
    *path = best ? pf_map_path(pfm, best->ptile) : PFPath();
  }
 
  pf_map_destroy(pfm);
 
  return taskcity;
}
 
void auto_settler_findwork(struct player *pplayer, struct unit *punit,
                           struct settlermap *state, int recursion)
{
  struct worker_task *best_task;
  enum unit_activity best_act;
  struct tile *best_tile = nullptr;
  struct extra_type *best_target;
  PFPath path;
  struct city *taskcity;
 
  // time it will take worker to complete its given task
  int completion_time = 0;
 
  if (recursion > unit_list_size(pplayer->units)) {
    fc_assert(recursion <= unit_list_size(pplayer->units));
    adv_unit_new_task(punit, AUT_NONE, nullptr);
    set_unit_activity(punit, ACTIVITY_IDLE);
    send_unit_info(nullptr, punit);
    return; // avoid further recursion.
  }
 
  CHECK_UNIT(punit);
 
  fc_assert_ret(pplayer && punit);
  fc_assert_ret(unit_is_cityfounder(punit)
                || unit_has_type_flag(punit, UTYF_SETTLERS));
 
  // Have nearby cities requests?
 
  taskcity = settler_evaluate_city_requests(punit, &best_task, &path, state);
 
  if (taskcity != nullptr) {
    if (!path.empty()) {
      completion_time = path[-1].turn;
    }
 
    adv_unit_new_task(punit, AUT_AUTO_SETTLER, best_tile);
 
    best_target = best_task->tgt;
 
    if (auto_settler_setup_work(pplayer, punit, state, recursion, &path,
                                best_task->ptile, best_task->act,
                                &best_target, completion_time)) {
      clear_worker_task(taskcity, best_task);
    }
 
    return;
  }
 
  /*** Try find some work ***/
 
  if (unit_has_type_flag(punit, UTYF_SETTLERS)) {
    TIMING_LOG(AIT_WORKERS, TIMER_START);
    settler_evaluate_improvements(punit, &best_act, &best_target, &best_tile,
                                  &path, state);
    if (!path.empty()) {
      completion_time = path[-1].turn;
    }
    TIMING_LOG(AIT_WORKERS, TIMER_STOP);
 
    adv_unit_new_task(punit, AUT_AUTO_SETTLER, best_tile);
 
    auto_settler_setup_work(pplayer, punit, state, recursion, &path,
                            best_tile, best_act, &best_target,
                            completion_time);
  }
}
 
bool auto_settler_setup_work(struct player *pplayer, struct unit *punit,
                             struct settlermap *state, int recursion,
                             PFPath *path, struct tile *best_tile,
                             enum unit_activity best_act,
                             struct extra_type **best_target,
                             int completion_time)
{
  // Run the "autosettler" program
  if (punit->server.adv->task == AUT_AUTO_SETTLER) {
    struct pf_map *pfm = nullptr;
    struct pf_parameter parameter;
    bool working = false;
    struct unit *displaced;
 
    if (!best_tile) {
      UNIT_LOG(LOG_DEBUG, punit, "giving up trying to improve terrain");
      return false; // We cannot do anything
    }
 
    // Mark the square as taken.
    displaced =
        player_unit_by_number(pplayer, state[tile_index(best_tile)].enroute);
 
    if (displaced) {
      fc_assert(state[tile_index(best_tile)].enroute == displaced->id);
      fc_assert(
          state[tile_index(best_tile)].eta > completion_time
          || (state[tile_index(best_tile)].eta == completion_time
              && (real_map_distance(best_tile, unit_tile(punit))
                  < real_map_distance(best_tile, unit_tile(displaced)))));
      UNIT_LOG(displaced->server.debug ? LOG_AI_TEST : LOG_DEBUG, punit,
               "%d (%d,%d) has displaced %d (%d,%d) for worksite %d,%d",
               punit->id, completion_time,
               real_map_distance(best_tile, unit_tile(punit)), displaced->id,
               state[tile_index(best_tile)].eta,
               real_map_distance(best_tile, unit_tile(displaced)),
               TILE_XY(best_tile));
    }
 
    state[tile_index(best_tile)].enroute = punit->id;
    state[tile_index(best_tile)].eta = completion_time;
 
    if (displaced) {
      struct tile *goto_tile = punit->goto_tile;
      int saved_id = punit->id;
      struct tile *old_pos = unit_tile(punit);
 
      displaced->goto_tile = nullptr;
      auto_settler_findwork(pplayer, displaced, state, recursion + 1);
      if (nullptr == player_unit_by_number(pplayer, saved_id)) {
        /* Actions of the displaced settler somehow caused this settler
         * to die. (maybe by recursively giving control back to this unit)
         */
        return false;
      }
      if (goto_tile != punit->goto_tile || old_pos != unit_tile(punit)
          || punit->activity != ACTIVITY_IDLE) {
        /* Actions of the displaced settler somehow caused this settler
         * to get a new job, or to already move toward current job.
         * (A displaced B, B displaced C, C displaced A)
         */
        UNIT_LOG(LOG_DEBUG, punit,
                 "%d itself acted due to displacement recursion. "
                 "Was going from (%d, %d) to (%d, %d). "
                 "Now heading from (%d, %d) to (%d, %d).",
                 punit->id, TILE_XY(old_pos), TILE_XY(goto_tile),
                 TILE_XY(unit_tile(punit)), TILE_XY(punit->goto_tile));
        return false;
      }
    }
 
    UNIT_LOG(LOG_DEBUG, punit, "is heading to do %s(%s) at (%d, %d)",
             unit_activity_name(best_act),
             best_target && *best_target ? extra_rule_name(*best_target)
                                         : "-",
             TILE_XY(best_tile));
 
    if (!path->empty()) {
      pft_fill_unit_parameter(&parameter, punit);
      parameter.omniscience = !has_handicap(pplayer, H_MAP);
      parameter.get_TB = autosettler_tile_behavior;
      pfm = pf_map_new(&parameter);
      *path = pf_map_path(pfm, best_tile);
    }
 
    if (!path->empty()) {
      bool alive;
 
      alive = adv_follow_path(punit, *path, best_tile);
      *path = PFPath(); // Done moving have an empty path
      if (alive && same_pos(unit_tile(punit), best_tile)
          && punit->moves_left > 0) {
        // Reached destination and can start working immediately
        if (activity_requires_target(best_act)) {
          unit_activity_handling_targeted(punit, best_act, best_target);
        } else {
          unit_activity_handling(punit, best_act);
        }
        send_unit_info(nullptr, punit); // FIXME: probably duplicate
 
        UNIT_LOG(LOG_DEBUG, punit, "reached its worksite and started work");
        working = true;
      } else if (alive) {
        UNIT_LOG(LOG_DEBUG, punit,
                 "didn't start work yet; got to (%d, %d) with "
                 "%d move frags left",
                 TILE_XY(unit_tile(punit)), punit->moves_left);
      }
    } else {
      UNIT_LOG(LOG_DEBUG, punit, "does not find path (%d, %d) -> (%d, %d)",
               TILE_XY(unit_tile(punit)), TILE_XY(best_tile));
    }
 
    if (pfm) {
      pf_map_destroy(pfm);
    }
 
    return working;
  }
 
  return false;
}
#undef LOG_SETTLER
 
bool adv_settler_safe_tile(const struct player *pplayer, struct unit *punit,
                           struct tile *ptile)
{
  unit_list_iterate(ptile->units, defender)
  {
    if (is_military_unit(defender)) {
      return true;
    }
  }
  unit_list_iterate_end;
 
  return !is_square_threatened(pplayer, ptile,
                               !has_handicap(pplayer, H_FOG));
}
 
void auto_settlers_player(struct player *pplayer)
{
  struct settlermap *state;
 
  state = new settlermap[MAP_INDEX_SIZE]();
 
  as_timer = timer_renew(as_timer, TIMER_CPU, TIMER_DEBUG);
  timer_start(as_timer);
 
  if (is_ai(pplayer)) {
    // Set up our city map.
    citymap_turn_init(pplayer);
  }
 
  whole_map_iterate(&(wld.map), ptile)
  {
    state[tile_index(ptile)].enroute = -1;
    state[tile_index(ptile)].eta = FC_INFINITY;
  }
  whole_map_iterate_end;
 
  // Initialize the infrastructure cache, which is used shortly.
  initialize_infrastructure_cache(pplayer);
 
  /* An extra consideration for the benefit of cleaning up pollution/fallout.
   * This depends heavily on the calculations in update_environmental_upset.
   * Aside from that it's more or less a WAG that simply grows incredibly
   * large as an environmental disaster approaches. */
  pplayer->ai_common.warmth = (WARMING_FACTOR * game.info.heating
                                   / ((game.info.warminglevel + 1) / 2)
                               + game.info.globalwarming);
  pplayer->ai_common.frost = (COOLING_FACTOR * game.info.cooling
                                  / ((game.info.coolinglevel + 1) / 2)
                              + game.info.nuclearwinter);
 
  log_debug("Warmth = %d, game.globalwarming=%d", pplayer->ai_common.warmth,
            game.info.globalwarming);
  log_debug("Frost = %d, game.nuclearwinter=%d", pplayer->ai_common.frost,
            game.info.nuclearwinter);
 
  /* Auto-settle with a settler unit if it's under AI control (e.g. human
   * player auto-settler mode) or if the player is an AI.  But don't
   * auto-settle with a unit under orders even for an AI player - these come
   * from the human player and take precedence. */
  unit_list_iterate_safe(pplayer->units, punit)
  {
    if ((punit->ssa_controller == SSA_AUTOSETTLER || is_ai(pplayer))
        && (unit_type_get(punit)->adv.worker || unit_is_cityfounder(punit))
        && !unit_has_orders(punit) && punit->moves_left > 0) {
      log_debug("%s %s at (%d, %d) is controlled by server side agent %s.",
                nation_rule_name(nation_of_player(pplayer)),
                unit_rule_name(punit), TILE_XY(unit_tile(punit)),
                server_side_agent_name(SSA_AUTOSETTLER));
      if (punit->activity == ACTIVITY_SENTRY) {
        unit_activity_handling(punit, ACTIVITY_IDLE);
      }
      if (punit->activity == ACTIVITY_GOTO && punit->moves_left > 0) {
        unit_activity_handling(punit, ACTIVITY_IDLE);
      }
      if (punit->activity != ACTIVITY_IDLE) {
        if (!is_ai(pplayer)) {
          if (!adv_settler_safe_tile(pplayer, punit, unit_tile(punit))) {
            unit_activity_handling(punit, ACTIVITY_IDLE);
          }
        } else {
          CALL_PLR_AI_FUNC(settler_cont, pplayer, pplayer, punit, state);
        }
      }
      if (punit->activity == ACTIVITY_IDLE) {
        if (!is_ai(pplayer)) {
          auto_settler_findwork(pplayer, punit, state, 0);
        } else {
          CALL_PLR_AI_FUNC(settler_run, pplayer, pplayer, punit, state);
        }
      }
    }
  }
  unit_list_iterate_safe_end;
  // Reset auto settler state for the next run.
  if (is_ai(pplayer)) {
    CALL_PLR_AI_FUNC(settler_reset, pplayer, pplayer);
  }
 
  if (timer_in_use(as_timer)) {
    log_time(QStringLiteral("%1 autosettlers consumed %2 milliseconds.")
                 .arg(nation_rule_name(nation_of_player(pplayer)))
                 .arg(1000.0 * timer_read_seconds(as_timer)));
  }
 
  delete[] state;
}
 
void adv_unit_new_task(struct unit *punit, enum adv_unit_task task,
                       struct tile *ptile)
{
  if (punit->server.adv->task == task) {
    // Already that task
    return;
  }
 
  punit->server.adv->task = task;
 
  CALL_PLR_AI_FUNC(unit_task, unit_owner(punit), punit, task, ptile);
}
 
bool auto_settlers_speculate_can_act_at(const struct unit *punit,
                                        enum unit_activity activity,
                                        bool omniscient_cheat,
                                        struct extra_type *target,
                                        const struct tile *ptile)
{
  struct action *paction = nullptr;
 
  action_iterate(act_id)
  {
    paction = action_by_number(act_id);
 
    if (action_get_actor_kind(paction) != AAK_UNIT) {
      // Not relevant.
      continue;
    }
 
    if (action_get_activity(paction) == activity) {
      // Found one
      break;
    }
  }
  action_iterate_end;
 
  if (paction == nullptr) {
    // The action it self isn't there. It can't be enabled.
    return false;
  }
 
  switch (action_get_target_kind(paction)) {
  case ATK_CITY:
    return action_prob_possible(action_speculate_unit_on_city(
        paction->id, punit, unit_home(punit), ptile, omniscient_cheat,
        tile_city(ptile)));
  case ATK_UNIT:
    fc_assert_ret_val(action_get_target_kind(paction) != ATK_UNIT, false);
    break;
  case ATK_UNITS:
    return action_prob_possible(
        action_speculate_unit_on_units(paction->id, punit, unit_home(punit),
                                       ptile, omniscient_cheat, ptile));
  case ATK_TILE:
    return action_prob_possible(action_speculate_unit_on_tile(
        paction->id, punit, unit_home(punit), ptile, omniscient_cheat, ptile,
        target));
  case ATK_SELF:
    return action_prob_possible(action_speculate_unit_on_self(
        paction->id, punit, unit_home(punit), ptile, omniscient_cheat));
  case ATK_COUNT:
    fc_assert_ret_val(action_get_target_kind(paction) != ATK_COUNT, false);
    break;
  }
 
  fc_assert(false);
  return false;
}