pawns have their legal move list

src/logic/board.py

@@ -16,8 +16,8 @@ class Board:
             pos_w_pawn = Position(x, 1)
             pos_b_pawn = Position(x, 6)
 
-            self._white[pos_w_pawn] = Pawn(pos_w_pawn)
-            self._black[pos_b_pawn] = Pawn(pos_b_pawn)
+            self._white[pos_w_pawn] = Pawn(pos_w_pawn, Piece.WHITE)
+            self._black[pos_b_pawn] = Pawn(pos_b_pawn, Piece.BLACK)
 
             pos_w_piece = Position(x, 0)
             pos_b_piece = Position(x, 7)
@@ -34,9 +34,19 @@ class Board:
             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)
-            self._black[pos_b_piece] = piece(pos_b_piece)
+            self._white[pos_w_piece] = piece(pos_w_piece, Piece.WHITE)
+            self._black[pos_b_piece] = piece(pos_b_piece, Piece.BLACK)
 
+    def piece_at(self, x: int, y: int) -> Piece | None:
+        pos = Position(x, y)
+        white_piece = self._white.get(pos, None)
+        black_piece = self._black.get(pos, None)
+
+        assert white_piece == None or black_piece == None, f"There are two pieces at the same position {pos}, this shouldn't happen!"
+
+        if white_piece != None:
+            return white_piece
+        return black_piece
 
 def create_board():
     return Board()

src/logic/pieces/pawn.py

@@ -1,7 +1,31 @@
-from .piece import Piece
+from logic.position import Position
+from logic.pieces.piece import Piece
 
 class Pawn(Piece):
-    def __init__(self, pos) -> None:
-        super().__init__(pos)
-        self.already_moved = False
+    def legal_moves(self, board) -> list[Position]:
+        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)))
+            or
+            (self.colour == self.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)
+
+        # 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)))
+            or
+            (self.colour == self.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)
+
+        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))
+
+        return ret

src/logic/pieces/piece.py

@@ -2,8 +2,13 @@ from logic.position import Position
 
 
 class Piece:
-    def __init__(self, pos) -> None:
+    WHITE = 0
+    BLACK = 1
+
+    def __init__(self, pos, 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"
+        self.colour = colour
 
     def position(self) -> Position:
         return self.pos