/***********************************************************************
Iterates through reachable cities and appraises them as a possible
base for air operations by (air)unit punit. Returns NULL if not
found. The path is stored in the path argument if not NULL.
**********************************************************************/
static struct tile *dai_find_strategic_airbase(struct ai_type *ait,
const struct unit *punit,
struct pf_path **path)
{
struct player *pplayer = unit_owner(punit);
struct pf_parameter parameter;
struct pf_map *pfm;
struct tile *best_tile = NULL;
struct city *pcity;
struct unit *pvirtual = NULL;
int best_worth = 0, target_worth;
pft_fill_unit_parameter(¶meter, punit);
pfm = pf_map_new(¶meter);
pf_map_move_costs_iterate(pfm, ptile, move_cost, FALSE) {
if (move_cost >= punit->moves_left) {
break; /* Too far! */
}
if (!is_airunit_refuel_point(ptile, pplayer,
unit_type(punit), FALSE)) {
continue; /* Cannot refuel here. */
}
if ((pcity = tile_city(ptile))
&& def_ai_city_data(pcity, ait)->grave_danger != 0) {
best_tile = ptile;
break; /* Fly there immediately!! */
}
if (!pvirtual) {
pvirtual =
unit_virtual_create(pplayer,
player_city_by_number(pplayer, punit->homecity),
unit_type(punit), punit->veteran);
}
unit_tile_set(pvirtual, ptile);
target_worth = find_something_to_bomb(ait, pvirtual, NULL, NULL);
if (target_worth > best_worth) {
/* It's either a first find or it's better than the previous. */
best_worth = target_worth;
best_tile = ptile;
/* We can still look for something better. */
}
} pf_map_move_costs_iterate_end;
if (pvirtual) {
unit_virtual_destroy(pvirtual);
}
if (path) {
/* Stores the path. */
*path = best_tile ? pf_map_path(pfm, best_tile) : NULL;
}
pf_map_destroy(pfm);
return best_tile;
}
/*****************************************************************************
Find best tile the paratrooper should jump to.
*****************************************************************************/
static struct tile *find_best_tile_to_paradrop_to(struct ai_type *ait,
struct unit *punit)
{
int best = 0;
int val;
struct tile* best_tile = NULL;
int range = unit_type(punit)->paratroopers_range;
struct city* acity;
struct player* pplayer = unit_owner(punit);
/* First, we search for undefended cities in danger */
square_iterate(unit_tile(punit), range, ptile) {
if (!map_is_known(ptile, pplayer)) {
continue;
}
acity = tile_city(ptile);
if (acity && city_owner(acity) == unit_owner(punit)
&& unit_list_size(ptile->units) == 0) {
val = city_size_get(acity) * def_ai_city_data(acity, ait)->urgency;
if (val > best) {
best = val;
best_tile = ptile;
}
}
} square_iterate_end;
if (best_tile != NULL) {
acity = tile_city(best_tile);
UNIT_LOG(LOGLEVEL_PARATROOPER, punit,
"Choose to jump in order to protect allied city %s (%d %d). "
"Benefit: %d",
city_name(acity), TILE_XY(best_tile), best);
return best_tile;
}
/* Second, we search for undefended enemy cities */
square_iterate(unit_tile(punit), range, ptile) {
acity = tile_city(ptile);
if (acity && pplayers_at_war(unit_owner(punit), city_owner(acity)) &&
(unit_list_size(ptile->units) == 0)) {
if (!map_is_known_and_seen(ptile, pplayer, V_MAIN)
&& ai_handicap(pplayer, H_FOG)) {
continue;
}
/* Prefer big cities on other continents */
val = city_size_get(acity)
+ (tile_continent(unit_tile(punit)) != tile_continent(ptile));
if (val > best) {
best = val;
best_tile = ptile;
}
}
} square_iterate_end;
/**********************************************************************
Very preliminary estimate for our intent to attack the tile (x, y).
Used by bombers only.
**********************************************************************/
static bool dai_should_we_air_attack_tile(struct ai_type *ait,
struct unit *punit, struct tile *ptile)
{
struct city *acity = tile_city(ptile);
/* For a virtual unit (punit->id == 0), all targets are good */
/* TODO: There is a danger of producing too many units that will not
* attack anything. Production should not happen if there is an idle
* unit of the same type nearby */
if (acity && punit->id != 0
&& def_ai_city_data(acity, ait)->invasion.occupy == 0
&& !unit_can_take_over(punit)) {
/* No units capable of occupying are invading */
log_debug("Don't want to attack %s, although we could",
city_name(acity));
return FALSE;
}
return TRUE;
}
