the FEN notation can be read to create a position

selected piece

.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/logic/board.py

@@ -7,35 +7,100 @@ from logic.pieces.pawn import Pawn
 from logic.pieces.piece import Piece
 from logic.position import Position
 
+from typing import Type
+
 class Board:
+    KING_SIDE_CASTLE = "king side castle"
+    QUEEN_SIDE_CASTLE = "queen side castle"
     def __init__(self) -> None:
         self._white: dict[Position, Piece] = {}
         self._black: dict[Position, Piece] = {}
+        self._turn = None
+        self._white_castling_write = set()
+        self._black_castling_write = 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()
 
-            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:
+            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, Piece.WHITE)
+                else:
+                    ret._black[pos] = piece(pos, Piece.BLACK)
+
+                x += 1
+                continue
+            if c in numbers:
+                x += int(c)
+            if c == '/':
+                x = 0
+                y -= 1
+
+
+        # -- Active colour
+        index = position.find(" ") # find the first space
+        index += 1
+        if position[index] == "w":
+            ret._turn = Piece.WHITE
+        elif position[index] == "b":
+            ret._turn = Piece.BLACK
+        else:
+            raise ValueError(f"The FEN position is malformed, the active colour should be either 'w' or 'b', but is '{position[index]}'")
+
+
+        # -- Castling Rights
+        for c in position:
+            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_write.add(Board.KING_SIDE_CASTLE)
+            if c == "Q":
+                ret._white_castling_write.add(Board.QUEEN_SIDE_CASTLE)
+            if c == "k":
+                ret._black_castling_write.add(Board.KING_SIDE_CASTLE)
+            if c == "q":
+                ret._black_castling_write.add(Board.QUEEN_SIDE_CASTLE)
+
+        # -- En passant target
+        index = position.find(" ", index + 1)
+        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)
@@ -47,6 +112,3 @@ class Board:
         if white_piece != None:
             return white_piece
         return black_piece
-
-def create_board():
-    return Board()

src/logic/pieces/piece.py

@@ -2,8 +2,8 @@ from logic.position import Position
 
 
 class Piece:
-    WHITE = 0
-    BLACK = 1
+    WHITE = "white"
+    BLACK = "black"
 
     def __init__(self, pos, colour) -> None:
         self.pos = pos

src/main.py

@@ -1,9 +1,11 @@
-from logic.board import create_board
+from logic.board import Board, create_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"
+    board = Board.setup_FEN_position(initial_board_position)
 
-    view = TUI(board)
+    view = GUI(board)
 
     view.show()

src/view/gui.py

@@ -0,0 +1,94 @@
+import tkinter as tk
+
+from logic.board import Board
+from logic.pieces.piece import Piece
+from logic.position import Position
+from view.view import View
+
+class GUI(View):
+    def __init__(self, board: Board) -> None:
+        super().__init__(board)
+
+        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.state = {"selected_piece": None, "legal_moves": []}
+
+        self.canvas.bind("<Button-1>", self._on_canvas_click)
+        self._draw_chess_board()
+
+
+    def _draw_chess_board(self):
+        colours = ["#F0D9B5", "#B58863"]  # Light and dark squares
+
+        for y in range(8):
+            for x in range(8):
+                colour = colours[(x + y) % 2]
+                if self.state["selected_piece"] and Position(x, 7-y) in self.state["legal_moves"]:
+                    colour = "#ADD8E6"  # Highlight legal moves
+
+                self.canvas.create_rectangle(
+                    x * self.tile_size, 
+                    y * self.tile_size, 
+                    (x + 1) * self.tile_size, 
+                    (y + 1) * self.tile_size, 
+                    fill=colour
+                )
+
+                piece = self.board.piece_at(x, 7-y)
+
+                if piece:
+                    text_colour = "white" if piece.colour == Piece.WHITE else "black"
+                    self.canvas.create_text(
+                        (x + 0.5) * self.tile_size, 
+                        (y + 0.5) * self.tile_size, 
+                        text=piece.__class__.__name__[0], 
+                        fill=text_colour, 
+                        font=("Arial", 32, "bold")
+                    )
+
+                # 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 + 0.15) * self.tile_size, 
+                        (y + 0.15) * self.tile_size, 
+                        text=8-y, 
+                        fill=text_colour, 
+                        font=("Arial", 10, "bold")
+                    )
+                if y == 7: # numbers in the top left of the first column
+                    self.canvas.create_text(
+                        (x + 0.85) * self.tile_size, 
+                        (y + 0.85) * self.tile_size, 
+                        text="abcdefgh"[x], 
+                        fill=text_colour, 
+                        font=("Arial", 10, "bold")
+                    )
+                    
+
+    def _on_canvas_click(self, event):
+        x, y = event.x // self.tile_size, event.y // self.tile_size
+        y = 7 - y
+        piece = self.board.piece_at(x, y)
+        print(f"Clicked on {x, y}, {piece = }")
+
+        if piece:
+            self.state["selected_piece"] = piece
+            self.state["legal_moves"] = piece.legal_moves(self.board)
+        else:
+            self.state["selected_piece"] = None
+            self.state["legal_moves"] = []
+
+        self.canvas.delete("all")
+        self._draw_chess_board()
+
+    def show(self) -> None:
+        self.root.mainloop()