implemented en passant

legal moves

.github/workflows/automatic-prerelease.yml

@@ -17,3 +17,4 @@ jobs:
           repo_token: "${{ secrets.GITHUB_TOKEN }}"
           prerelease: true
           automatic_release_tag: "latest"
+          title: "Development Build"

src/controller/controller.py

@@ -0,0 +1,63 @@
+from logic.board import Board
+from logic.move import Move
+from logic.pieces.piece import Piece
+from logic.position import Position
+from view.view import View
+
+
+class Controller:
+    def __init__(self, board: Board, view: View) -> None:
+        self._board = board
+        self._view = view
+
+        self._view.set_controller(self)
+        self._reset_selection()
+
+        self._selected_piece: Piece = None
+        self._legal_moves: list[Move] = []
+
+    def _reset_selection(self):
+        self._selected_piece = None
+        self._legal_moves = []
+        self._view.update_board(self._board, self._selected_piece, self._legal_moves)
+
+
+    def _show_legal_moves(self, pos: Position):
+        piece = self._board.piece_at(pos.x, pos.y)
+
+        if piece:
+            if piece.colour != self._board._turn:
+                return
+            self._selected_piece = piece
+            self._legal_moves = piece.legal_moves(self._board)
+            self._view.update_board(self._board, self._selected_piece, self._legal_moves)
+        else:
+            self._reset_selection()
+
+    def _make_move(self, move: Move) -> None:
+        self._board = self._board.make_move(move)
+        self._reset_selection()
+
+    def on_tile_selected(self, x: int, y: int) -> None:
+        pos = Position(x, y)
+
+        piece = self._board.piece_at(x, y)
+
+        if self._selected_piece is None \
+            or (piece is not None and piece != self._selected_piece and piece.colour == self._selected_piece.colour):
+            self._show_legal_moves(pos)
+        else:
+            legal_moves_positions = [move for move in self._legal_moves if move.pos == pos]
+            assert len(legal_moves_positions) <= 1, f"Apparently we can make multiple moves towards {pos.to_algebraic()} with {type(self._selected_piece)}, which doesn't make sense..."
+
+            if len(legal_moves_positions) == 0: # click on a square outside of the possible moves
+                self._reset_selection()
+            else:
+                move = legal_moves_positions[0]
+                self._make_move(move)
+
+        if self._board.is_checkmate_for(self._board._turn):
+            self._view.notify_checkmate(self._board._turn)
+            
+        if self._board.is_stalemate_for(self._board._turn):
+            self._view.notify_stalemate(self._board._turn)

src/logic/board.py

@@ -1,41 +1,106 @@
+from logic.move import CastleSide, Move
 from logic.pieces.bishop import Bishop
 from logic.pieces.king import King
 from logic.pieces.knight import Knight
 from logic.pieces.queen import Queen
 from logic.pieces.rook import Rook
 from logic.pieces.pawn import Pawn
-from logic.pieces.piece import Piece
+from logic.pieces.piece import Colour, Piece
 from logic.position import Position
 
+from typing import Type
+
 class Board:
     def __init__(self) -> None:
         self._white: dict[Position, Piece] = {}
         self._black: dict[Position, Piece] = {}
+        self._turn = None
+        self._white_castling_rights = set()
+        self._black_castling_rights = set()
+        self._en_passant_target = None
 
-        for x in range(8):
-            pos_w_pawn = Position(x, 1)
-            pos_b_pawn = Position(x, 6)
+    @staticmethod
+    def _piece_class_from_char(c: str) -> Type[Piece]:
+        assert len(c) == 1, f"The piece {c} isn't denoted by 1 character"
+        c = c.lower()
+        if c == "p":
+            return Pawn
+        if c == "r":
+            return Rook
+        if c == "n":
+            return Knight
+        if c == "b":
+            return Bishop
+        if c == "q":
+            return Queen
+        if c == "k":
+            return King
+        raise ValueError(f"Unknown piece '{c}'")
 
-            self._white[pos_w_pawn] = Pawn(pos_w_pawn, Piece.WHITE)
-            self._black[pos_b_pawn] = Pawn(pos_b_pawn, Piece.BLACK)
+    @staticmethod
+    def setup_FEN_position(position: str) -> "Board":
+        ret = Board()
+        index = 0
 
-            pos_w_piece = Position(x, 0)
-            pos_b_piece = Position(x, 7)
+        # -- Pieces
+        pieces = "prnbqk" # possible pieces
+        numbers = "12345678" # possible number of empty squares
 
-            piece = None
-            if x == 0 or x == 7:
-                piece = Rook
-            elif x == 1 or x == 6:
-                piece = Knight
-            elif x == 2 or x == 5:
-                piece = Bishop
-            elif x == 3:
-                piece = Queen
-            elif x == 4:
-                piece = King
-            assert piece != None, f"Didn't know which piece to assign for {x = }"
-            self._white[pos_w_piece] = piece(pos_w_piece, Piece.WHITE)
-            self._black[pos_b_piece] = piece(pos_b_piece, Piece.BLACK)
+        x = 0
+        y = 7 # FEN starts from the top left, so 8th rank
+        for c in position:
+            index += 1
+            if c == " ":
+                break
+            if c in pieces or c in pieces.upper():
+                pos = Position(x, y)
+                piece = Board._piece_class_from_char(c)
+                if c.isupper():
+                    ret._white[pos] = piece(pos, Colour.WHITE)
+                else:
+                    ret._black[pos] = piece(pos, Colour.BLACK)
+
+                x += 1
+                continue
+            if c in numbers:
+                x += int(c)
+            if c == '/':
+                x = 0
+                y -= 1
+
+
+        # -- Active colour
+        if position[index] == "w":
+            ret._turn = Colour.WHITE
+        elif position[index] == "b":
+            ret._turn = Colour.BLACK
+        else:
+            raise ValueError(f"The FEN position is malformed, the active colour should be either 'w' or 'b', but is '{position[index]}'")
+        index += 2
+
+
+        # -- Castling Rights
+        for c in position[index:]:
+            index += 1
+            if c == "-" or c == " ":
+                break
+
+            sides = "kq"
+            assert c in sides or c in sides.upper(), f"The FEN position is malformed, the castling rights should be either k or q (both either lower- or upper-case), instead is '{c}'"
+            if c == "K":
+                ret._white_castling_rights.add(CastleSide.King)
+            if c == "Q":
+                ret._white_castling_rights.add(CastleSide.Queen)
+            if c == "k":
+                ret._black_castling_rights.add(CastleSide.King)
+            if c == "q":
+                ret._black_castling_rights.add(CastleSide.Queen)
+
+        # -- En passant target
+        if position[index] != "-":
+            ret._en_passant_target = position[index:index+2]
+
+        return ret
 
     def piece_at(self, x: int, y: int) -> Piece | None:
         pos = Position(x, y)
@@ -48,5 +113,117 @@ class Board:
             return white_piece
         return black_piece
 
-def create_board():
-    return Board()
+    def is_check_for(self, colour: Colour) -> bool:
+        """ Is it check for the defending colour passed as parameter """
+        defending_pieces, attacking_pieces = (self._white, self._black) if colour == Colour.WHITE else (self._black, self._white)
+
+        kings = [piece for piece in defending_pieces.values() if type(piece) == King]
+        assert len(kings) == 1, f"We have more than one king for {colour}, that is no buono..."
+        king = kings[0]
+
+        for piece in attacking_pieces.values():
+            possible_pos = []
+            if type(piece) == King: 
+                # special case for the king, because it creates infinite recursion (since he looks if he's walking into a check)
+                for dx in [-1, 0, 1]:
+                    for dy in [-1, 0, 1]:
+                        x, y = piece.pos.x + dx, piece.pos.y + dy
+                        if Position.is_within_bounds(x, y):
+                            possible_pos.append(Position(x, y))
+            else:
+                possible_pos += [move.pos for move in piece.legal_moves(self, looking_for_check=True)]
+            if king.pos in possible_pos:
+                return True
+        return False
+
+    def is_checkmate_for(self, colour: Colour) -> bool:
+        """ Is it checkmate for the defending colour passed as parameter """
+        return self.is_check_for(colour) and self._no_legal_moves_for(colour)
+
+    def is_stalemate_for(self, colour: Colour) -> bool:
+        """ Is it stalemate for the defending colour passed as parameter """
+        return not self.is_check_for(colour) and self._no_legal_moves_for(colour)
+
+    def _no_legal_moves_for(self, colour: Colour) -> bool:
+        """ Return true if there are indeed no legal moves for the given colour (for checkmate or stalemate)"""
+        pieces = self._white if colour == Colour.WHITE else self._black
+        for piece in pieces.values():
+            if len(piece.legal_moves(self)) > 0:
+                return False
+        return True
+
+    def castling_rights_for(self, colour: Colour) -> set[CastleSide]:
+        return self._white_castling_rights if colour == Colour.WHITE else self._black_castling_rights
+
+    def make_move(self, move: Move) -> "Board":
+        dest_piece = self.piece_at(move.pos.x, move.pos.y) 
+
+        if dest_piece:
+            assert dest_piece.colour != move.piece.colour, "A piece cannot cannot eat another piece of the same colour"
+
+        # -- Copy current state
+        ret = Board()
+        ret._white = self._white.copy()
+        ret._black = self._black.copy()
+        ret._turn = Colour.WHITE if self._turn == Colour.BLACK else Colour.BLACK
+        ret._white_castling_rights = self._white_castling_rights.copy()
+        ret._black_castling_rights = self._black_castling_rights.copy()
+
+
+        piece = move.piece
+
+        # -- Actually make the move
+        pieces_moving, other_pieces = (ret._white, ret._black) if piece.colour == Colour.WHITE else (ret._black, ret._white)
+
+        del pieces_moving[piece.pos]
+        pieces_moving[move.pos] = piece.move_to(move.pos)
+        if move.pos in other_pieces:
+            del other_pieces[move.pos]
+
+        if move.en_passant:
+            pos_to_remove = Position(move.pos.x, move.pos.y + (1 if self._turn == Colour.BLACK else -1))
+            del other_pieces[pos_to_remove]
+
+        # -- Set en passant target if needed
+        if move.becomes_en_passant_target:
+            ret._en_passant_target = pieces_moving[move.pos]
+        else:
+            ret._en_passant_target = None
+
+        # -- Handle castling (just move the rook over)
+        if move.castle_side == CastleSide.King:
+            rook_pos = Position(7, piece.pos.y)
+            assert rook_pos in pieces_moving and type(pieces_moving[rook_pos]) == Rook, "Either rook is absent from the king side or you are trying to castle with something else than a rook..."
+            del pieces_moving[rook_pos]
+            new_rook_pos = Position(5, piece.pos.y)
+            pieces_moving[new_rook_pos] = Rook(new_rook_pos, piece.colour)
+
+        elif move.castle_side == CastleSide.Queen:
+            rook_pos = Position(0, piece.pos.y)
+            assert rook_pos in pieces_moving and type(pieces_moving[rook_pos]) == Rook, "Either rook is absent from the queen side or you are trying to castle with something else than a rook..."
+            del pieces_moving[rook_pos]
+            new_rook_pos = Position(3, piece.pos.y)
+            pieces_moving[new_rook_pos] = Rook(new_rook_pos, piece.colour)
+
+        # -- Check for castling rights
+        if piece.colour == Colour.WHITE:
+            if type(piece) == King:
+                ret._white_castling_rights = set()
+
+            if type(piece) == Rook:
+                if piece.pos.x == 0 and CastleSide.Queen in ret._white_castling_rights:
+                    ret._white_castling_rights.remove(CastleSide.Queen)
+                elif piece.pos.x == 7 and CastleSide.King in ret._white_castling_rights:
+                    ret._white_castling_rights.remove(CastleSide.King)
+        else:
+            if type(piece) == King:
+                ret._black_castling_rights = set()
+
+            if type(piece) == Rook:
+                if piece.pos.x == 0 and CastleSide.Queen in ret._black_castling_rights:
+                    ret._black_castling_rights.remove(CastleSide.Queen)
+                elif piece.pos.x == 7 and CastleSide.King in ret._black_castling_rights:
+                    ret._black_castling_rights.remove(CastleSide.King)
+
+
+        return ret

src/logic/move.py

@@ -0,0 +1,40 @@
+# from logic.pieces.piece import Piece
+from logic.position import Position
+from enum import Enum
+
+class CastleSide(Enum):
+    Neither = ""
+    King = "O-O"
+    Queen = "O-O-O"
+
+class Move:
+    def __init__(self, piece: "Piece", pos: Position,/, is_capturing: bool = False, castle_side: CastleSide = CastleSide.Neither, en_passant: bool = False, becomes_en_passant_target: bool = False) -> None:
+        self.piece = piece
+        self.pos = pos
+        self.is_capturing = is_capturing
+        self.castle_side = castle_side
+        self.becomes_en_passant_target = becomes_en_passant_target
+        self.en_passant = en_passant
+
+    def to_algebraic(self) -> str:
+        raise NotImplementedError("The move can't be translated to algbraic notation, as it was not implemented")
+
+    @staticmethod
+    def from_algebraic(move: str) -> "Move":
+        raise NotImplementedError("The move can't be translated from algbraic notation, as it was not implemented")
+
+    def __str__(self) -> str:
+        if self.castle_side == CastleSide.King:
+            return "O-O"
+        if self.castle_side == CastleSide.Queen:
+            return "O-O-O"
+
+        ret = ""
+        if type(self.piece).__name__ != "Pawn":
+            ret += self.piece.letter().upper()
+
+        ret += str(self.pos)
+        return ret
+    
+    def __repr__(self) -> str:
+        return str(self)

src/logic/pieces/bishop.py

@@ -1,4 +1,24 @@
+from logic.move import Move
 from .piece import Piece
 
 class Bishop(Piece):
-    pass
+    def legal_moves(self, board: "Board", / , looking_for_check = False) -> list[Move]:
+        ret = []
+
+        # looking north east
+        ret.extend(self._look_direction(board, 1, 1))
+
+        # looking south east
+        ret.extend(self._look_direction(board, 1, -1))
+
+        # looking south west
+        ret.extend(self._look_direction(board, -1, -1))
+
+        # looking north west
+        ret.extend(self._look_direction(board, -1, 1))
+
+        if not looking_for_check and board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
+
+        return ret
+

src/logic/pieces/king.py

@@ -1,5 +1,69 @@
+from logic.move import CastleSide, Move
+from logic.position import Position
 from .piece import Piece
 
 class King(Piece):
-    pass
+    def legal_moves(self, board: "Board") -> list[Move]:
+        ret = []
+
+        # -- Regular moves
+        for dx in [-1, 0, 1]:
+            for dy in [-1, 0, 1]:
+                if dx == 0 and dy == 0: # skip current position
+                    continue
+                x = self.pos.x + dx
+                y = self.pos.y + dy
+                move = self._move_for_position(board, x, y)
+                if move:
+                    board_after_move = board.make_move(move)
+                    if not board_after_move.is_check_for(self.colour):
+                        ret.append(move)
+
+        if board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
+
+        # -- Castles
+        castling_rights = board.castling_rights_for(self.colour)
+        if len(castling_rights) == 0:
+            return ret
+
+        if CastleSide.King in castling_rights:
+            clear = True
+            for dx in range(1, 3):
+                x = self.pos.x + dx
+                y = self.pos.y
+                if board.piece_at(x, y) is not None:
+                    clear = False
+                    break
+
+                move = self._move_for_position(board, x, y)
+                board_after_move = board.make_move(move)
+                if board_after_move.is_check_for(self.colour):
+                    clear = False
+                    break
+
+            if clear:
+                ret.append(Move(self, Position(6, self.pos.y), castle_side=CastleSide.King))
+
+        if CastleSide.Queen in castling_rights:
+            clear = True
+            for dx in range(1, 3):
+                x = self.pos.x - dx
+                y = self.pos.y
+
+                if board.piece_at(x, y) is not None:
+                    clear = False
+                    break
+
+                move = self._move_for_position(board, x, y)
+                board_after_move = board.make_move(move)
+                if board_after_move.is_check_for(self.colour):
+                    clear = False
+                    break
+
+            if clear:
+                ret.append(Move(self, Position(2, self.pos.y), castle_side=CastleSide.Queen))
+
+        return ret
+
 

src/logic/pieces/knight.py

@@ -1,5 +1,23 @@
 from .piece import Piece
 
 class Knight(Piece):
-    pass
+    def letter(self):
+        return "n"
+
+    def legal_moves(self, board: "Board", / , looking_for_check = False) -> list["Move"]:
+        ret = []
+        for dx, dy in [
+            (+2, +1), (+1, +2), # north east
+            (+2, -1), (+1, -2), # south east
+            (-2, -1), (-1, -2), # south west
+            (-2, +1), (-1, +2), # north west
+        ]:
+            move = self._move_for_position(board, self.pos.x + dx, self.pos.y + dy)
+            if move is not None:
+                ret.append(move)
+
+        if not looking_for_check and board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
+
+        return ret
 

src/logic/pieces/pawn.py

@@ -1,31 +1,55 @@
+from logic.move import Move
+from logic.pieces.piece import Colour, Piece
 from logic.position import Position
-from logic.pieces.piece import Piece
 
 class Pawn(Piece):
-    def legal_moves(self, board) -> list[Position]:
+    def legal_moves(self, board, / , looking_for_check = False) -> list[Move]:
         ret = []
 
         # can we capture to the left?
         if self.pos.x > 0 and (
-            (self.colour == self.WHITE and (capturable_piece := board.piece_at(self.pos.x - 1, self.pos.y + 1)))
+            (self.colour == Colour.WHITE and (capturable_piece := board.piece_at(self.pos.x - 1, self.pos.y + 1)))
             or
-            (self.colour == self.BLACK and (capturable_piece := board.piece_at(self.pos.x - 1, self.pos.y - 1)))
+            (self.colour == Colour.BLACK and (capturable_piece := board.piece_at(self.pos.x - 1, self.pos.y - 1)))
         ):
             if capturable_piece.colour != self.colour:
-                ret.append(capturable_piece.pos)
+                ret.append(Move(self, capturable_piece.pos, is_capturing = True))
 
         # can we capture to the right?
         if self.pos.x < 7 and (
-            (self.colour == self.WHITE and (capturable_piece := board.piece_at(self.pos.x + 1, self.pos.y + 1)))
+            (self.colour == Colour.WHITE and (capturable_piece := board.piece_at(self.pos.x + 1, self.pos.y + 1)))
             or
-            (self.colour == self.BLACK and (capturable_piece := board.piece_at(self.pos.x + 1, self.pos.y - 1)))
+            (self.colour == Colour.BLACK and (capturable_piece := board.piece_at(self.pos.x + 1, self.pos.y - 1)))
         ):
             if capturable_piece.colour != self.colour:
-                ret.append(capturable_piece.pos)
+                ret.append(Move(self, capturable_piece.pos, is_capturing = True))
 
+        # -- Can we capture en passant?
+        if board._en_passant_target is not None and \
+            board._en_passant_target.pos.y == self.pos.y and (
+                board._en_passant_target.pos.x == self.pos.x - 1
+                or board._en_passant_target.pos.x == self.pos.x + 1
+        ):
+            if board._en_passant_target.colour != self.colour:
+                old_pos = board._en_passant_target.pos
+                new_pos = Position(old_pos.x, old_pos.y + (1 if self.colour == Colour.WHITE else -1))
+                ret.append(Move(self, new_pos, is_capturing = True, en_passant = True))
+
+        # -- Normal moves
+        if self.colour == Colour.WHITE:
             for dy in range(1, 3 if self.pos.y == 1 else 2):
                 if self.pos.y + dy > 7 or board.piece_at(self.pos.x, self.pos.y + dy):
                     break
-            ret.append(Position(self.pos.x, self.pos.y + dy))
+                pos = Position(self.pos.x, self.pos.y + dy)
+                ret.append(Move(self, pos, becomes_en_passant_target=dy==2))
+        else:
+            for dy in range(1, 3 if self.pos.y == 6 else 2):
+                if self.pos.y - dy < 0 or board.piece_at(self.pos.x, self.pos.y - dy):
+                    break
+                pos = Position(self.pos.x, self.pos.y - dy)
+                ret.append(Move(self, pos, becomes_en_passant_target=dy==2))
+
+        if not looking_for_check and board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
 
         return ret

src/logic/pieces/piece.py

@@ -1,17 +1,65 @@
+from logic.move import Move
 from logic.position import Position
+from enum import Enum
 
 
+class Colour(Enum):
+    WHITE = "white"
+    BLACK = "black"
+
+    def __str__(self) -> str:
+        return self.value
+
 class Piece:
-    WHITE = 0
-    BLACK = 1
-
-    def __init__(self, pos, colour) -> None:
+    def __init__(self, pos: Position, colour: Colour) -> None:
         self.pos = pos
-        assert colour == self.WHITE or colour == self.BLACK, "The colour of the piece must be either Piece.WHITE or Piece.BLACK"
+        assert colour == Colour.WHITE or colour == Colour.BLACK, "The colour of the piece must be either Piece.WHITE or Piece.BLACK"
         self.colour = colour
 
+    def letter(self):
+        return type(self).__name__[0].lower()
+
+    def keep_only_blocking(self, candidates: list[Move], board: "Board") -> list[Move]:
+        ret = []
+        for move in candidates:
+            board_after_move = board.make_move(move)
+            if not board_after_move.is_check_for(self.colour):
+                ret.append(move)
+        return ret
+
+    def _look_direction(self, board: "Board", mult_dx: int, mult_dy: int):
+        ret = []
+        for d in range(1, 8):
+            dx = mult_dx * d
+            dy = mult_dy * d
+
+            move = self._move_for_position(board, self.pos.x + dx, self.pos.y + dy)
+            if move is None:
+                break
+            ret.append(move)
+            if move.is_capturing:
+                break
+
+        return ret
+
+    def _move_for_position(self, board: "Board", x: int, y: int) -> Move | None:
+        if not Position.is_within_bounds(x, y):
+            return None
+        piece = board.piece_at(x, y) 
+
+        if piece is None:
+            return Move(self, Position(x, y))
+
+        if piece.colour != self.colour:
+            return Move(self, Position(x, y), is_capturing=True)
+        return None
+
     def position(self) -> Position:
         return self.pos
 
-    def legal_moves(self, board) -> list[Position]:
+    def move_to(self, pos: Position) -> "Piece":
+        ret = type(self)(pos, self.colour)
+        return ret
+
+    def legal_moves(self, board: "Board", / , looking_for_check = False) -> list["Move"]:
         raise NotImplementedError(f"Can't say what the legal moves are for {type(self).__name__}, the method hasn't been implemented yet")

src/logic/pieces/queen.py

@@ -1,5 +1,35 @@
+from logic.move import Move
 from .piece import Piece
 
 class Queen(Piece):
-    pass
+    def legal_moves(self, board: "Board", / , looking_for_check = False) -> list[Move]:
+        ret = []
 
+        # looking north east
+        ret.extend(self._look_direction(board, 1, 1))
+
+        # looking south east
+        ret.extend(self._look_direction(board, 1, -1))
+
+        # looking south west
+        ret.extend(self._look_direction(board, -1, -1))
+
+        # looking north west
+        ret.extend(self._look_direction(board, -1, 1))
+
+        # looking east
+        ret.extend(self._look_direction(board, 1, 0))
+
+        # looking south
+        ret.extend(self._look_direction(board, 0, -1))
+
+        # looking west
+        ret.extend(self._look_direction(board, -1, 0))
+
+        # looking north
+        ret.extend(self._look_direction(board, 0, 1))
+
+        if not looking_for_check and board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
+
+        return ret

src/logic/pieces/rook.py

@@ -1,5 +1,23 @@
+from logic.move import Move
 from .piece import Piece
 
 class Rook(Piece):
-    pass
+    def legal_moves(self, board: "Board", / , looking_for_check = False) -> list[Move]:
+        ret = []
 
+        # looking east
+        ret.extend(self._look_direction(board, 1, 0))
+
+        # looking south
+        ret.extend(self._look_direction(board, 0, -1))
+
+        # looking west
+        ret.extend(self._look_direction(board, -1, 0))
+
+        # looking north
+        ret.extend(self._look_direction(board, 0, 1))
+
+        if not looking_for_check and board.is_check_for(self.colour):
+            return self.keep_only_blocking(ret, board)
+
+        return ret

src/logic/position.py

@@ -1,4 +1,7 @@
 class Position:
+    _RANKS = range(1, 9)
+    _FILES = "abcdefgh"
+
     _MIN_POS = 0
     _MAX_POS = 7
 
@@ -9,6 +12,14 @@ class Position:
         self.x = x
         self.y = y
 
+    @staticmethod
+    def is_within_bounds(x: int, y: int) -> bool:
+        return x >= Position._MIN_POS and x <= Position._MAX_POS \
+            and y >= Position._MIN_POS and y <= Position._MAX_POS
+
+    def to_algebraic(self) -> str:
+        return f"{Position._FILES[self.x]}{Position._RANKS[self.y]}"
+
     def __eq__(self, value: object, /) -> bool:
         if type(value) != type(self):
             return False
@@ -18,8 +29,7 @@ class Position:
         return hash((self.x, self.y))
 
     def __str__(self) -> str:
-        return f"{self.x, self.y}"
+        return f"{Position._FILES[self.x]}{Position._RANKS[self.y]}"
 
     def __repr__(self) -> str:
         return str(self)
-

src/main.py

@@ -1,9 +1,14 @@
-from logic.board import create_board
+from controller.controller import Controller
+from logic.board import Board
+from view.gui import GUI
 from view.tui import TUI
 
 if __name__ == "__main__":
-    board = create_board()
+    initial_board_position = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"
+    board = Board.setup_FEN_position(initial_board_position)
 
-    view = TUI(board)
+    view = GUI()
+
+    controller = Controller(board, view)
 
     view.show()

src/view/gui.py

@@ -0,0 +1,155 @@
+import tkinter as tk
+from tkinter import messagebox
+from typing import Type
+from PIL import ImageTk, Image
+import os
+
+from logic.board import Board
+from logic.move import Move
+from logic.pieces.bishop import Bishop
+from logic.pieces.king import King
+from logic.pieces.knight import Knight
+from logic.pieces.pawn import Pawn
+from logic.pieces.piece import Colour, Piece
+from logic.pieces.queen import Queen
+from logic.pieces.rook import Rook
+from logic.position import Position
+from view.view import View
+
+class GUI(View):
+    def __init__(self) -> None:
+        super().__init__()
+
+        self.root = tk.Tk()
+        self.root.title("Chess Board")
+
+        self.tile_size = 80
+        board_size = self.tile_size * 8
+
+        self.canvas = tk.Canvas(self.root, width=board_size, height=board_size)
+        self.canvas.pack()
+
+        self.canvas.bind("<Button-1>", self._on_canvas_click)
+
+        self._piece_images = self._load_piece_images("res/")
+
+    def _piece_svg(self, root: str, piece: Type[Piece], colour: Colour) -> ImageTk.PhotoImage:
+        piece_name = piece.__name__.lower()
+
+        path = os.path.join(root, f"{"white" if colour == Colour.WHITE else "black"}-{piece_name}.png")
+        img = Image.open(path)
+
+        if img.mode == "LA":
+            img = img.convert(mode="RGBA")
+            img.save(path)
+
+        return ImageTk.PhotoImage(img)
+
+    def _load_piece_images(self, root: str) -> dict[Type[Piece], dict[Colour, ImageTk.PhotoImage]]:
+        ret = {}
+        for piece in [Pawn, Rook, Knight, Bishop, Queen, King]:
+            if piece not in ret:
+                ret[piece] = {}
+            ret[piece][Colour.WHITE] = self._piece_svg(root, piece, Colour.WHITE)
+            ret[piece][Colour.BLACK] = self._piece_svg(root, piece, Colour.BLACK)
+
+        return ret
+
+    def _on_canvas_click(self, event):
+        x, y = event.x // self.tile_size, event.y // self.tile_size
+        y = 7 - y
+
+        self._controller.on_tile_selected(x, y)
+
+    def notify_checkmate(self, colour: Colour) -> None:
+        messagebox.showinfo("Checkmate",  f"{colour} is currently checkmated") 
+        
+    def notify_stalemate(self, colour: Colour) -> None:
+        messagebox.showinfo("Stalemate",  f"{colour} is currently stalemated") 
+        
+
+    def update_board(self, board: Board, selected_piece: Piece, legal_moves: list[Move]) -> None:
+        self.canvas.delete("all")
+        self._draw_chess_board(board, selected_piece, legal_moves)
+
+
+    def _draw_chess_board(self, board: Board, selected_piece = None, legal_moves = []):
+        colours = ["#EDD6B0", "#B88762"]  # Light and dark squares
+        alt_colours = ["#F6EB72", "#DCC34B"]  # Light and dark squares, when selected
+        circle_colours = ["#CCB897", "#9E7454"] # circles to show legal moves
+
+        for y in range(8):
+            for x in range(8):
+                colour = colours[(x + y) % 2]
+                pos = Position(x, 7-y)
+                if selected_piece is not None and pos == selected_piece.pos:
+                    colour = alt_colours[(x + y) % 2]
+
+                self.canvas.create_rectangle(
+                    x * self.tile_size, 
+                    y * self.tile_size, 
+                    (x + 1) * self.tile_size, 
+                    (y + 1) * self.tile_size, 
+                    fill=colour,
+                    outline=colour,
+                )
+
+                if selected_piece is not None:
+                    possible_positions = [move.pos for move in legal_moves] 
+                    if pos in possible_positions:
+                        colour = circle_colours[(x + y) % 2]
+                        move = [move for move in legal_moves if move.pos == pos][0]
+                        if move.is_capturing:
+                            radius = .40 * self.tile_size
+                            self.canvas.create_oval(
+                                (x + .5) * self.tile_size - radius,
+                                (y + .5) * self.tile_size - radius,
+                                (x + .5) * self.tile_size + radius,
+                                (y + .5) * self.tile_size + radius,
+                                fill="",
+                                outline=colour,
+                                width=.075 * self.tile_size,
+                            )
+                        else:
+                            radius = .15 * self.tile_size
+                            self.canvas.create_oval(
+                                (x + .5) * self.tile_size - radius,
+                                (y + .5) * self.tile_size - radius,
+                                (x + .5) * self.tile_size + radius,
+                                (y + .5) * self.tile_size + radius,
+                                fill=colour,
+                                outline=colour,
+                            )
+
+                piece = board.piece_at(x, 7-y)
+
+                if piece:
+                    self.canvas.create_image(
+                        (x + 0.5) * self.tile_size, 
+                        (y + 0.9) * self.tile_size, 
+                        image=self._piece_images[type(piece)][piece.colour],
+                        anchor=tk.S,
+                    )
+
+                # Cell annotations
+                text_colour = colours[(x + y + 1) % 2] # the other colour
+
+                if x == 0: # numbers in the top left of the first column
+                    self.canvas.create_text(
+                        (x + .15) * self.tile_size, 
+                        (y + .15) * self.tile_size, 
+                        text=8-y, 
+                        fill=text_colour, 
+                        font=("Arial", 12, "bold")
+                    )
+                if y == 7: # numbers in the top left of the first column
+                    self.canvas.create_text(
+                        (x + .85) * self.tile_size, 
+                        (y + .85) * self.tile_size, 
+                        text="abcdefgh"[x], 
+                        fill=text_colour, 
+                        font=("Arial", 12, "bold")
+                    )
+
+    def show(self) -> None:
+        self.root.mainloop()

src/view/view.py

@@ -1,10 +1,24 @@
 from logic.board import Board
+from logic.move import Move
+from logic.pieces.piece import Colour, Piece
 
 
 class View:
-    def __init__(self, board: Board) -> None:
-        self.board: Board = board
+    def __init__(self) -> None:
+        self._controller: "Controller" = None
 
     def show(self) -> None:
         raise NotImplementedError(f"Can't show the board, the show() method of {type(self)} is not implemented")
 
+    def update_board(self, board: Board, selected_piece: Piece, legal_moves: list[Move]) -> None:
+        raise NotImplementedError(f"Can't update the board, the update_board() method of {type(self)} is not implemented")
+
+    def notify_checkmate(self, colour: Colour) -> None:
+        raise NotImplementedError(f"Can't notify of the checkmate, the notify_checkmate() method of {type(self)} is not implemented")
+
+    def notify_stalemate(self, colour: Colour) -> None:
+        raise NotImplementedError(f"Can't notify of the stalemate, the notify_stalemate() method of {type(self)} is not implemented")
+
+    def set_controller(self, controller: "Controller") -> None:
+        self._controller = controller
+