autosettlers.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 <math.h>
#include <stdio.h>
#include <string.h>
 
/* utility */
#include "log.h"
#include "mem.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 "packets.h"
#include "unitlist.h"
 
/* common/aicore */
#include "citymap.h"
#include "path_finding.h"
#include "pf_tools.h"
 
/* server */
#include "citytools.h"
#include "maphand.h"
#include "plrhand.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 struct timer *as_timer = NULL;
 
/**********************************************************************/
void adv_settlers_free(void)
{
  timer_destroy(as_timer);
  as_timer = NULL;
}
 
/**********************************************************************/
void auto_settlers_ruleset_init(void)
{
  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(const struct civ_map *nmap,
                                 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 == NULL) {
    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(nmap, 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 != NULL);
 
            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,
                                    adv_want new_tile_value,
                                    adv_want old_tile_value,
                                    bool in_use, int delay,
                                    adv_want *best_value,
                                    adv_want *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;
  adv_want total_value = 0;
  adv_want 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 (ADV_WANTS_EQ(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
                       || (ADV_WANTS_EQ(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, regardless 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
        || (ADV_WANTS_EQ(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 (NULL != owner && !pplayers_allied(owner, param->owner)) {
    return TB_IGNORE;
  }
  return TB_NORMAL;
}
 
/**********************************************************************/
adv_want settler_evaluate_improvements(const struct civ_map *nmap,
                                       struct unit *punit,
                                       enum unit_activity *best_act,
                                       struct extra_type **best_target,
                                       struct tile **best_tile,
                                       struct pf_path **path,
                                       struct settlermap *state)
{
  const struct player *pplayer = unit_owner(punit);
  struct pf_parameter parameter;
  struct pf_map *pfm;
  struct pf_position pos;
  adv_want oldv;             /* Current value of consideration tile. */
  adv_want 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 = NULL;
 
  pft_fill_unit_parameter(&parameter, nmap, 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(nmap, 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(nmap, 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 = NULL;
            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(nmap, act,
                                                punit, unit_home(punit),
                                                ptile,
                                                parameter.omniscience,
                                                ptile, target))) {
              adv_want 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;
            adv_want 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(nmap, try_act,
                                                      punit,
                                                      unit_home(punit),
                                                      ptile,
                                                      parameter.omniscience,
                                                      ptile, pextra))) {
                    act = actres_get_activity(taction->result);
                    eval_act = actres_get_activity(taction->result);
                    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(nmap, try_act,
                                                      punit,
                                                      unit_home(punit),
                                                      ptile,
                                                      parameter.omniscience,
                                                      ptile, pextra))) {
                    act = actres_get_activity(taction->result);
                    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 != NULL && 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(nmap, 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(nmap, 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 checking 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);
                    adv_want 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;
 
                extra_deps_iterate(&(pextra->reqs), pdep) {
                  /* Roads handled above already */
                  if (!is_extra_caused_by(pdep, EC_ROAD)) {
                    enum unit_activity eval_dep_act = ACTIVITY_LAST;
                    action_id eval_dep_action;
 
                    as_extra_action_iterate(try_act) {
                      struct action *taction = action_by_number(try_act);
 
                      if (is_extra_caused_by_action(pdep, taction)) {
                        eval_dep_action = try_act;
                        eval_dep_act = action_id_get_activity(try_act);
                        break;
                      }
                    } as_extra_action_iterate_end;
 
                    if (eval_dep_act != ACTIVITY_LAST) {
                      if (action_prob_possible(
                            action_speculate_unit_on_tile(nmap, eval_dep_action,
                                                          punit, unit_home(punit), ptile,
                                                          parameter.omniscience,
                                                          ptile, pdep))) {
                        /* Consider building dependency extra for later upgrade to
                         * target extra. See similar road implementation above for
                         * extended commentary. */
                        int dep_turns = turns + get_turns_for_activity_at(punit,
                                                                          eval_dep_act,
                                                                          ptile,
                                                                          pdep);
                        adv_want dep_value
                          = base_value + adv_city_worker_extra_get(pcity, cindex,
                                                                   pdep);
 
                        consider_settler_action(pplayer, eval_dep_act, pdep,
                                                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);
                      }
                    }
                  }
                } extra_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 = NULL;
  }
 
  if (path) {
    *path = *best_tile ? pf_map_path(pfm, *best_tile) : NULL;
  }
 
  pf_map_destroy(pfm);
 
  return best_newv;
}
 
/**********************************************************************/
struct city *settler_evaluate_city_requests(struct unit *punit,
                                            struct worker_task **best_task,
                                            struct pf_path **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 = NULL;
  struct city *taskcity = NULL;
  int dist = FC_INFINITY;
  const struct civ_map *nmap = &(wld.map);
 
  pft_fill_unit_parameter(&parameter, nmap, 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 = NULL;
 
        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 != NULL) {
    *path = best ? pf_map_path(pfm, best->ptile) : NULL;
  }
 
  pf_map_destroy(pfm);
 
  return taskcity;
}
 
/**********************************************************************/
#define LOG_SETTLER LOG_DEBUG
void auto_settler_findwork(const struct civ_map *nmap,
                           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 = NULL;
  struct extra_type *best_target;
  struct pf_path *path = NULL;
  struct city *taskcity;
 
  /* Time it will take worker to complete its given task */
  int completion_time = 0;
 
  /* Terminate what might be an infinite recursion of two units
   * displacing each other, but leave enough space for
   * finite recursion. */
  if (recursion > 5
      && recursion > unit_list_size(pplayer->units) * 1.5) {
    log_warn("Workers displacing each other recursing too much.");
 
    adv_unit_new_task(punit, AUT_NONE, NULL);
    set_unit_activity(punit, ACTIVITY_IDLE);
    send_unit_info(NULL, 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 != NULL) {
    if (path != NULL) {
      completion_time = pf_path_last_position(path)->turn;
    }
 
    adv_unit_new_task(punit, AUT_AUTO_SETTLER, best_tile);
 
    best_target = best_task->tgt;
 
    if (auto_settler_setup_work(nmap, pplayer, punit, state, recursion,
                                path, best_task->ptile, best_task->act,
                                &best_target, completion_time)) {
      clear_worker_task(taskcity, best_task);
    }
 
    if (path != NULL) {
      pf_path_destroy(path);
    }
 
    return;
  }
 
  /*** Try find some work ***/
 
  if (unit_has_type_flag(punit, UTYF_SETTLERS)) {
    TIMING_LOG(AIT_WORKERS, TIMER_START);
    settler_evaluate_improvements(nmap, punit, &best_act, &best_target,
                                  &best_tile, &path, state);
    if (path) {
      completion_time = pf_path_last_position(path)->turn;
    }
    TIMING_LOG(AIT_WORKERS, TIMER_STOP);
 
    adv_unit_new_task(punit, AUT_AUTO_SETTLER, best_tile);
 
    auto_settler_setup_work(nmap, pplayer, punit, state, recursion, path,
                            best_tile, best_act, &best_target,
                            completion_time);
 
    if (NULL != path) {
      pf_path_destroy(path);
    }
  }
}
 
/**********************************************************************/
bool auto_settler_setup_work(const struct civ_map *nmap,
                             struct player *pplayer, struct unit *punit,
                             struct settlermap *state, int recursion,
                             struct pf_path *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 = NULL;
    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 = NULL;
      auto_settler_findwork(nmap, pplayer, displaced, state, recursion + 1);
      if (NULL == 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) {
      pft_fill_unit_parameter(&parameter, nmap, 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) {
      bool alive;
 
      alive = adv_follow_path(punit, path, best_tile);
 
      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(NULL, 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 civ_map *nmap,
                           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;
 
  if (is_square_threatened(nmap, pplayer, ptile,
                           !has_handicap(pplayer, H_FOG))) {
    return FALSE;
  }
 
  return TRUE;
}
 
/**********************************************************************/
void auto_settlers_player(struct player *pplayer) 
{
  struct settlermap *state;
  const struct civ_map *nmap = &(wld.map);
 
  state = fc_calloc(MAP_INDEX_SIZE, sizeof(*state));
 
  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(nmap, 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(nmap, 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(nmap, 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)) {
 
#ifdef LOG_TIMERS
    log_verbose("%s autosettlers consumed %g milliseconds.",
                nation_rule_name(nation_of_player(pplayer)),
                1000.0 * timer_read_seconds(as_timer));
#else
    log_verbose("%s autosettlers finished",
                nation_rule_name(nation_of_player(pplayer)));
#endif
 
  }
 
  FC_FREE(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)
{
  const struct civ_map *nmap = &(wld.map);
 
  action_by_activity_iterate(paction, activity) {
    if (action_get_actor_kind(paction) != AAK_UNIT) {
      /* Not relevant. */
      continue;
    }
 
    switch (action_get_target_kind(paction)) {
    case ATK_CITY:
      return action_prob_possible(action_speculate_unit_on_city(
                                    nmap, 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(
                                    nmap, paction->id,
                                    punit, unit_home(punit), ptile,
                                    omniscient_cheat,
                                    ptile));
    case ATK_TILE:
      return action_prob_possible(action_speculate_unit_on_tile(
                                    nmap, paction->id,
                                    punit, unit_home(punit), ptile,
                                    omniscient_cheat,
                                    ptile, target));
    case ATK_EXTRAS:
      return action_prob_possible(action_speculate_unit_on_extras(
                                    nmap, paction->id,
                                    punit, unit_home(punit), ptile,
                                    omniscient_cheat,
                                    ptile, target));
    case ATK_SELF:
      return action_prob_possible(action_speculate_unit_on_self(
                                    nmap, 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;
    }
  } action_by_activity_iterate_end;
 
  log_debug("No action found for activity %d", activity);
 
  return FALSE;
}