From 27743734dea2dc6fd933d55fb939efd8602208eb Mon Sep 17 00:00:00 2001
From: Ihnatus <ignatus31oct@mail.ru>
Date: Thu, 20 Oct 2022 22:23:49 +0300
Subject: [PATCH] Add "Tile" range to "Building" reqs

Is true iff there is a city on the context tile and it has the building.

See OSDN#45885

Signed-off-by: Ihnatus <ignatus31oct@mail.ru>
---
 common/metaknowledge.c | 44 ++++++++++++++++++++++++++++++++++++++++++
 common/reqtext.c       | 13 +++++++++++++
 common/requirements.c  | 15 ++++++++++++--
 doc/README.effects     |  3 ++-
 4 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/common/metaknowledge.c b/common/metaknowledge.c
index a5225027c2..687cf0a041 100644
--- a/common/metaknowledge.c
+++ b/common/metaknowledge.c
@@ -470,6 +470,50 @@ static bool is_req_knowable(const struct player *pov_player,
       /* No way to know if a city has an improvement */
       return FALSE;
     case REQ_RANGE_TILE:
+      if (context->tile == NULL) {
+        /* RPT_CERTAIN: Can't be. No tile to contain it.
+         * RPT_POSSIBLE: A tile city like that may exist but not be passed. */
+        return prob_type == RPT_CERTAIN;
+      }
+
+      {
+        const struct city *tcity = tile_city(context->tile);
+
+        if (!tcity) {
+          /* No building can be in no city if it's known
+           * there is no city */
+          if (is_great_wonder(req->source.value.building)) {
+            const struct city *wcity
+              = city_from_great_wonder(req->source.value.building);
+
+            if (!wcity
+                || player_can_see_city_externals(pov_player, wcity)) {
+              /* Player can be sure the wonder is not here */
+              return TRUE;
+              /* FIXME: deducing from known borders aside, the player
+               * may have seen wcity before and cities don't move */
+            }
+          }
+
+          return tile_is_seen(context->tile, pov_player);
+        }
+
+        if (can_player_see_city_internals(pov_player, tcity)) {
+          /* Anyone that can see city internals (like the owner) known all
+           * its improvements. */
+          return TRUE;
+        }
+
+        if (is_improvement_visible(req->source.value.building)
+            && player_can_see_city_externals(pov_player, tcity)) {
+          /* Can see visible improvements when the outside of the city is
+           * seen. */
+          return TRUE;
+        }
+      }
+
+      /* No way to know if a city has an improvement */
+      return FALSE;
     case REQ_RANGE_CADJACENT:
     case REQ_RANGE_ADJACENT:
     case REQ_RANGE_COUNT:
diff --git a/common/reqtext.c b/common/reqtext.c
index e6139b1a95..8e81381183 100644
--- a/common/reqtext.c
+++ b/common/reqtext.c
@@ -782,6 +782,19 @@ bool req_text_insert(char *buf, size_t bufsz, struct player *pplayer,
       }
       return TRUE;
     case REQ_RANGE_TILE:
+      fc_strlcat(buf, prefix, bufsz);
+      if (preq->present) {
+        cat_snprintf(buf, bufsz,
+                     _("Requires \"%s\" building in a city on the tile."),
+                     improvement_name_translation
+                     (preq->source.value.building));
+      } else {
+        cat_snprintf(buf, bufsz,
+                     _("Prevented by \"%s\" building in a city on the tile."),
+                     improvement_name_translation
+                     (preq->source.value.building));
+      }
+      return TRUE;
     case REQ_RANGE_CADJACENT:
     case REQ_RANGE_ADJACENT:
     case REQ_RANGE_COUNT:
diff --git a/common/requirements.c b/common/requirements.c
index b546af9334..e55039613a 100644
--- a/common/requirements.c
+++ b/common/requirements.c
@@ -1635,6 +1635,7 @@ static enum fc_tristate
 is_building_in_range(const struct player *target_player,
                      const struct city *target_city,
                      const struct impr_type *target_building,
+                     const struct tile *target_tile,
                      enum req_range range,
                      bool survives,
                      const struct impr_type *source)
@@ -1749,9 +1750,19 @@ is_building_in_range(const struct player *target_player,
         return TRI_MAYBE;
       }
     case REQ_RANGE_TILE:
+      if (target_tile) {
+        const struct city *pcity = tile_city(target_tile);
+
+        if (pcity) {
+          return BOOL_TO_TRISTATE(num_city_buildings(pcity, source) > 0);
+        } else {
+          return TRI_NO;
+        }
+      } else {
+        return TRI_MAYBE;
+      }
     case REQ_RANGE_CADJACENT:
     case REQ_RANGE_ADJACENT:
-      return TRI_NO;
     case REQ_RANGE_COUNT:
       break;
     }
@@ -3552,7 +3563,7 @@ bool is_req_active(const struct req_context *context,
     break;
   case VUT_IMPROVEMENT:
     eval = is_building_in_range(context->player, context->city,
-                                context->building,
+                                context->building, context->tile,
                                 req->range, req->survives,
                                 req->source.value.building);
     break;
diff --git a/doc/README.effects b/doc/README.effects
index c89698387a..836f46cbf0 100644
--- a/doc/README.effects
+++ b/doc/README.effects
@@ -56,7 +56,8 @@ MinTechs:        World, Player
 Achievement:     World, Alliance, Team, Player
 Counter:         City
 Gov:             Player
-Building:        World, Alliance, Team, Player, Continent, Traderoute, City, Local
+Building:        World, Alliance, Team, Player, Continent, Traderoute, City,
+                 Tile, Local
 BuildingGenus:   Local
 Extra:           Local, Tile, Adjacent, CAdjacent, Traderoute, City
 RoadFlag:        Local, Tile, Adjacent, CAdjacent, Traderoute, City
-- 
2.34.1