introduced internal chess engine, fixed bugs

app/chess_sim/game_board.py

@@ -153,12 +153,17 @@ class ChessBoard:
         return len(self.move_history) >= 75
     
     def is_fivefold_repetition(self) -> bool:
+        
         return self.highest_repetiton_amount() >= 5
 
     def outcome(self) -> Outcome:
         if self.is_checkmate():
             return Outcome.from_color(self.turn)
-        if self.is_stalemate() or self.is_seventyfive_moves or self.is_fivefold_repetition:
+        if self.is_stalemate():
+            return Outcome.DRAW
+        if self.is_seventyfive_moves():
+            return Outcome.DRAW
+        if self.is_fivefold_repetition():
             return Outcome.DRAW
         return Outcome.NOT_FINISHED
 
@@ -204,7 +209,7 @@ class ChessBoard:
     def init_default(cls) -> "ChessBoard":
         empty_board = [[BoardField() for _ in range(8)] for _ in range(8)]
         brd = cls(
-            empty_board, 0, [], empty_board
+            empty_board, 0, [], copy.deepcopy(empty_board)
         )
 
         # place pawns
@@ -232,8 +237,8 @@ class ChessBoard:
         for col, piece_type in enumerate(back_rank):
             brd.place(7, col, piece_type, Color.WHITE)
 
-        #set the inital board for later ref
+        # set the initial board for later ref (must be a copy, not a reference)
-        brd.initial_board = brd.fields
+        brd.initial_board = copy.deepcopy(brd.fields)
 
         return brd
     
@@ -427,10 +432,15 @@ class ChessBoard:
                     else:
                         # occupied
                         if target_field.piece.color == piece.color:
+                            if non_sliding:
+                                continue
+                            # for sliding pieces a blocker stops further squares
                             break
                         else:
-                            # opponent piece
+                            # opponent piece: capture is allowed
                             moves.append(BoardMove(pos, BoardPos((tr, tc))))
+                            if non_sliding:
+                                continue
                             break
         
         
@@ -739,3 +749,39 @@ class ChessBoard:
         bm = BoardMove(src, dst, move_type, promotion_piece=promo_piece)
         return self.make_move(bm, color)
 
+    def print_legal_moves(self, color: Color) -> None:
+        moves = self.generate_moves(color)
+        
+        if not moves:
+            print(f"{color.name}: no legal moves")
+            return
+        
+        move_strings = []
+        for move in moves:
+            from_sq = self.pos_to_algebraic(move.m_from)
+            to_sq = self.pos_to_algebraic(move.m_to)
+            move_str = f"{from_sq}-{to_sq}"
+            
+            # Add move type notation
+            if move.move_type.name == "CASTLING_KINGSIDE":
+                move_str += " (O-O)"
+            elif move.move_type.name == "CASTLING_QUEENSIDE":
+                move_str += " (O-O-O)"
+            elif move.move_type.name == "EN_PASSANT":
+                move_str += " (e.p.)"
+            elif move.promotion_piece:
+                move_str += f" (={move.promotion_piece.name[0]})"
+            
+            move_strings.append(move_str)
+        
+        print(f"\n{color.name} Legal Moves ({len(moves)} total):")
+        print("-" * 50)
+        
+        # Print in columns (6 moves per row)
+        moves_per_row = 6
+        for i in range(0, len(move_strings), moves_per_row):
+            row = move_strings[i:i + moves_per_row]
+            print("  " + "  |  ".join(f"{m:12}" for m in row))
+        print("-" * 50 + "\n")
+
+

app/sockets/socket.py

@@ -6,7 +6,13 @@ from datetime import datetime
 from threading import Lock
 from typing import Optional
 
-from chess_sim.game_board import ChessBoard, Outcome, Color
+from app.chess_sim.game_board import (
+    ChessBoard,
+    Outcome,
+    Color,
+    BoardMove,
+    PieceType,
+)
 from flask_login import current_user
 from flask import request
 from flask_socketio import emit, join_room, leave_room
@@ -27,7 +33,7 @@ class GameRoom:
     p2_user_id: Optional[int] = None
     p2_name: Optional[str] = None
     ready: dict[str, bool] = field(default_factory=dict)
-    board: ChessBoard = ChessBoard.init_default()
+    board: ChessBoard = field(default_factory=ChessBoard.init_default)
     color_by_sid: dict[str, str] = field(default_factory=dict)
     initial_ms: int = 600000
     increment_ms: int = 0
@@ -160,15 +166,18 @@ def _emit_game_over(room: GameRoom, reason: str) -> None:
     p1_result = "draw"
     p2_result = "draw"
 
+    if outcome == Outcome.WHITE_WIN:
+        winner_color = "w" 
+    else:
+        winner_color = "b"
+    if room.color_by_sid.get(room.p1_sid) == winner_color:
+        p1_result = "win"
+        p2_result = "loss"
+    else:
+        p1_result = "loss"
+        p2_result = "win"
+
 
-    if outcome and outcome.winner is not None:
-        winner_color = "w" if outcome.winner == chess.WHITE else "b"
-        if room.color_by_sid.get(room.p1_sid) == winner_color:
-            p1_result = "win"
-            p2_result = "loss"
-        else:
-            p1_result = "loss"
-            p2_result = "win"
 
     emit("game_over", {"result": p1_result, "reason": reason}, to=room.p1_sid)
     if room.p2_sid:
@@ -296,8 +305,7 @@ def on_disconnect():
         room.p2_name = None
         room.ready.pop(sid, None)
         room.color_by_sid.pop(sid, None)
-        # initialize a new chessboard???
+        room.board = ChessBoard.init_default()
-        room.board = chess.Board()
         room.ready[room.p1_sid] = False
         room.game_active = False
         room.completed = False
@@ -307,6 +315,18 @@ def on_disconnect():
         emit("p2_connected", {"p2_name": None, "ready": False}, to=other_sid)
 
 
+def _make_room(sid: str, play_as: str, time_mode: str) -> GameRoom:
+    return GameRoom(
+        code="",  # caller will fill in the actual code
+        p1_sid=sid,
+        p1_user_id=current_user.id,
+        p1_name=current_user.username,
+        p1_pref=play_as,
+        time_mode=time_mode,
+        ready={sid: False},
+    )
+
+
 @sIO.on("create_code_game")
 def on_create_code_game(payload):
     ok, err = validate_client_event("create_code_game", payload)
@@ -324,14 +344,9 @@ def on_create_code_game(payload):
             _cleanup_room(existing.code)
 
         code = _new_code()
-        room = GameRoom(
+        room = _make_room(sid, payload["play_as"], payload["time_mode"])
-            code=code,
+        room.code = code  # assign after generation so constructor stays pure
-            p1_sid=sid,
+
-            p1_name=current_user.username,
-            p1_pref=payload["play_as"],
-            time_mode=payload["time_mode"],
-            ready={sid: False},
-        )
         games_by_code[code] = room
         code_by_sid[sid] = code
 
@@ -410,6 +425,31 @@ def on_user_ready(payload):
         _start_game_if_ready(room)
 
 
+# helpers for converting client payloads to engine moves and back
+
+def _payload_to_move(payload: dict) -> BoardMove:
+    from_sq = ChessBoard.algebraic_to_pos(payload["from_square"])
+    to_sq = ChessBoard.algebraic_to_pos(payload["to_square"])
+    promotion = payload.get("promotion")
+    prom_piece: Optional[PieceType] = None
+    if promotion:
+        mapping = {
+            "q": PieceType.QUEEN,
+            "r": PieceType.ROOK,
+            "b": PieceType.BISHOP,
+            "n": PieceType.KNIGHT,
+        }
+        prom_piece = mapping.get(promotion.lower())
+        if prom_piece is None:
+            raise ValueError("invalid promotion piece")
+    return BoardMove(from_sq, to_sq, promotion_piece=prom_piece)
+
+
+def _move_to_san(move: BoardMove) -> str:
+    # todo can be improved, very simple
+    return f"{ChessBoard.pos_to_algebraic(move.m_from)}{ChessBoard.pos_to_algebraic(move.m_to)}"
+
+
 @sIO.on("move_request")
 def on_move_request(payload):
     ok, err = validate_client_event("move_request", payload)
@@ -440,24 +480,28 @@ def on_move_request(payload):
             emit("move_reject", {"reason": "not your turn"})
             return
 
-        uci = (
-            f"{payload['from_square'].lower()}{payload['to_square'].lower()}"
-            f"{payload.get('promotion', '')}"
-        )
-
         try:
-            move = chess.Move.from_uci(uci)
+            move = _payload_to_move(payload)
         except ValueError:
+            print("rejecting move due to invalid move format")
             emit("move_reject", {"reason": "invalid move format"}, to=sid)
             return
 
-        if move not in room.board.legal_moves:
+        current_color = room.board.turn
+        legal = room.board.generate_moves(current_color)
+        if move not in legal:
+            print(f"current_color: {current_color}")
+            print("rejecting move due to illegal move")
+            print(f"move: {move}")
+            room.board.print_legal_moves(current_color)
             emit("move_reject", {"reason": "illegal move"}, to=sid)
             return
 
         mover_color = room.color_by_sid.get(sid)
-        san = room.board.san(move)
+        san = _move_to_san(move)
-        room.board.push(move)
+        # perform the move on our own engine
+        room.board.make_move(move, current_color)
+        room.move_history.append(san)
 
         if mover_color == "w":
             room.white_ms += room.increment_ms
@@ -472,7 +516,7 @@ def on_move_request(payload):
             "promotion": payload.get("promotion"),
             "san": san,
             "time_left_ms": room.white_ms if mover_color == "w" else room.black_ms,
-            "fen": room.board.fen(),
+            "fen": room.board.to_fen(),
             **_clock_payload(room),
         }
 
@@ -481,7 +525,9 @@ def on_move_request(payload):
         if other_sid:
             emit("user_move", move_payload, to=other_sid)
 
-        if room.board.is_game_over(claim_draw=True):
+        
+        if room.board.outcome() != Outcome.NOT_FINISHED:
+            print(f"ending a game due to outcome: { room.board.outcome()}")
             _emit_game_over(room, _game_over_reason(room.board))