Cached get_fog_fen()

client/roundCtrl.ts

@@ -944,7 +944,7 @@ export class RoundController extends GameController {
                     fen: parts[0],
                     turnColor: this.turnColor,
                     check: msg.check,
-                    lastMove: (this.fog) ? undefined : lastMove,
+                    lastMove: lastMove,
                 });
 
                 // This have to be here, because in case of takeback 

server/fairy.py

@@ -8,6 +8,7 @@
 import logging
 import re
 import random
+from functools import cache
 
 log = logging.getLogger(__name__)
 
@@ -228,31 +229,6 @@ def game_result_no_history(self):
     def piece_to_partner(self, move):
         return self.sf.piece_to_partner(self.variant, self.fen, [move], self.chess960)
 
-    def get_fog_fen(self, persp_color):
-        fen = self.fen
-        fen_color = "w" if self.color == WHITE else "b"
-        other_color = "w" if persp_color == WHITE else "b"
-
-        # set the perspective color to sf.get_fog_fen()
-        parts = self.fen.split(" ")
-        parts[1] = parts[1].replace(fen_color, other_color)
-
-        # remove castling right of the player in fog
-        if persp_color == WHITE:
-            parts[2] = "".join((letter for letter in parts[2] if letter.isupper()))
-        else:
-            parts[2] = "".join((letter for letter in parts[2] if letter.islower()))
-        fen = " ".join(parts)
-
-        fen = sf.get_fog_fen(fen, "fogofwar")
-
-        # restore original FEN color
-        parts = fen.split(" ")
-        parts[1] = parts[1].replace(other_color, fen_color)
-        fen = " ".join(parts)
-
-        return fen
-
     def print_pos(self):
         print()
         uni_pieces = {
@@ -437,6 +413,34 @@ def shuffle_start(variant):
         return fen
 
 
+@cache
+def get_fog_fen(fen, persp_color):
+    parts = fen.split(" ")
+
+    fen_color = "w" if parts[1] == "w" else "b"
+    opp_color = "w" if persp_color == WHITE else "b"
+
+    # set the perspective color to sf.get_fog_fen()
+    parts[1] = parts[1].replace(fen_color, opp_color)
+
+    # remove castling rights of the player in fog
+    # because the resulting fog FEN may have no king
+    if persp_color == WHITE:
+        parts[2] = "".join((letter for letter in parts[2] if letter.isupper()))
+    else:
+        parts[2] = "".join((letter for letter in parts[2] if letter.islower()))
+    fen = " ".join(parts)
+
+    fen = sf.get_fog_fen(fen, "fogofwar")
+
+    # restore original FEN color
+    parts = fen.split(" ")
+    parts[1] = parts[1].replace(opp_color, fen_color)
+    fen = " ".join(parts)
+
+    return fen
+
+
 def get_san_moves(variant, fen, mlist, chess960, notation):
     if variant == "alice":
         return sf_alice.get_san_moves(variant, fen, mlist, chess960, notation)

server/game.py

@@ -34,7 +34,7 @@
     TYPE_CHECKING,
 )
 from convert import grand2zero, uci2usi, mirror5, mirror9
-from fairy import get_san_moves, NOTATION_SAN, FairyBoard, BLACK, WHITE
+from fairy import get_fog_fen, get_san_moves, NOTATION_SAN, FairyBoard, BLACK, WHITE
 from glicko2.glicko2 import gl2
 from draw import reject_draw
 from settings import URI
@@ -1125,14 +1125,10 @@ def get_board(self, full=False, persp_color=None):
             crosstable = self.crosstable if self.status > STARTED else ""
 
         if self.fow and self.status <= STARTED:
-            if persp_color is not None:
-                fen = self.board.get_fog_fen(persp_color)
-            else:
-                fen = DARK_FEN
-
-            steps[-1]["fen"] = fen
-            steps[-1]["move"] = ""
-            lastmove = ""
+            steps = get_fog_steps(steps, persp_color)
+            fen = steps[-1]["fen"]
+            if (persp_color is None) or (persp_color == self.board.color):
+                lastmove = ""
 
         if self.corr:
             clock_mins = self.stopwatch.mins * 60 * 1000
@@ -1235,3 +1231,15 @@ def takeback(self):
 
     def handle_chat_message(self, chat_message):
         self.messages.append(chat_message)
+
+
+def get_fog_steps(steps, persp_color):
+    if persp_color is None:
+        return [
+            {"fen": DARK_FEN} for step in steps
+        ]
+    else:
+        return [
+            {"fen": get_fog_fen(step["fen"], persp_color), "san": "?", "turnColor": step["turnColor"]}
+            for step in steps
+        ]

server/utils.py

@@ -643,6 +643,10 @@ async def play_move(app_state: PychessGlobalAppState, user, game, move, clocks=N
             await users[opp_name].send_game_message(gameId, response)
 
     if not invalid_move:
+        # FEN sent to visitors is different in fogofwar games!
+        if game.fow:
+            board_response = game.get_board(full=game.board.ply == 1, persp_color=None)
+
         await round_broadcast(game, board_response, channels=app_state.game_channels)
 
         if game.tournamentId is not None: