From d3966685dbebebfa31dec28e0cfced46f683bbda Mon Sep 17 00:00:00 2001 From: ekzyis Date: Thu, 26 Sep 2024 00:13:21 +0200 Subject: [PATCH] Check for collisions with own pieces on target --- chess/board.go | 78 +++++++++++++++++++++++++++++++++------------ chess/board_test.go | 20 ++++++++++++ chess/piece.go | 28 ++++++++++++++++ 3 files changed, 106 insertions(+), 20 deletions(-) diff --git a/chess/board.go b/chess/board.go index 03927e1..78e95e1 100644 --- a/chess/board.go +++ b/chess/board.go @@ -269,19 +269,22 @@ func (b *Board) Parse(pgn string) error { return nil } -func (b *Board) Move(position string) error { +func (b *Board) Move(move string) error { var ( - err error + piece string + targetPosition string // the column from which the piece is captured. // for example, this would be 'e' for exd4 and 'e' for Nexd4. - captureFrom string + captureFrom string + collisionPiece *Piece + err error ) - if strings.Contains(position, "x") { + if strings.Contains(move, "x") { // capture move - parts := strings.Split(position, "x") + parts := strings.Split(move, "x") if len(parts) != 2 { - return fmt.Errorf("invalid move: %s", position) + return fmt.Errorf("invalid move: %s", move) } if len(parts[0]) == 2 { // example: Nexd4 @@ -295,10 +298,10 @@ func (b *Board) Move(position string) error { captureFrom = "" } } else { - return fmt.Errorf("invalid move: %s", position) + return fmt.Errorf("invalid move: %s", move) } - position = strings.Replace(position, captureFrom+"x", "", 1) + move = strings.Replace(move, captureFrom+"x", "", 1) } // TODO: parse captures e.g. exd5 or Nxd5 @@ -310,25 +313,36 @@ func (b *Board) Move(position string) error { // TODO: make sure king is not in check after move // ( this avoids moving into check and moving a piece that exposes the king to check e.g. pinned pieces ) - if len(position) == 2 { - err = b.movePawn(position, captureFrom) - } else if len(position) == 3 { - switch strings.ToLower(position[0:1]) { + if len(move) == 2 { + err = b.movePawn(move, captureFrom) + } else if len(move) == 3 { + + piece = move[0:1] + targetPosition = move[1:3] + + // collision detection + if collisionPiece, err = b.getCollision(targetPosition); err != nil { + return fmt.Errorf("invalid move %s: %v", move, err) + } else if collisionPiece != nil { + return fmt.Errorf("invalid move %s: position %s blocked by %s", move, targetPosition, collisionPiece) + } + + switch strings.ToLower(piece) { case "r": - err = b.moveRook(position[1:3], false) + err = b.moveRook(targetPosition, false) case "b": - err = b.moveBishop(position[1:3], false) + err = b.moveBishop(targetPosition, false) case "n": - err = b.moveKnight(position[1:3]) + err = b.moveKnight(targetPosition) case "q": - err = b.moveQueen(position[1:3]) + err = b.moveQueen(targetPosition) case "k": - err = b.moveKing(position[1:3]) + err = b.moveKing(targetPosition) default: - err = fmt.Errorf("invalid move: %s", position) + err = fmt.Errorf("invalid move %s: %v", move, err) } } else { - return fmt.Errorf("invalid move: %s", position) + return fmt.Errorf("invalid move %s: %v", move, err) } if err != nil { @@ -341,7 +355,7 @@ func (b *Board) Move(position string) error { b.turn = Light } - b.moves = append(b.moves, position) + b.moves = append(b.moves, move) return nil } @@ -752,6 +766,30 @@ func (b *Board) getPiece(x int, y int) *Piece { return b.tiles[x][y] } +func (b *Board) getCollision(position string) (*Piece, error) { + var ( + x, y int + p *Piece + collision bool + err error + ) + if x, y, err = getXY(position); err != nil { + return nil, err + } + + p = b.getPiece(x, y) + + // check if position is occupied by own piece + collision = p != nil && p.Color == b.turn + if collision { + return p, nil + } + + // TODO: check if path is blocked by some piece + + return nil, nil +} + func getTileColor(x, y int) Color { if x%2 == y%2 { return Light diff --git a/chess/board_test.go b/chess/board_test.go index 0858521..aff03d2 100644 --- a/chess/board_test.go +++ b/chess/board_test.go @@ -120,6 +120,26 @@ func TestBoardMoveKnight(t *testing.T) { assertNoPiece(t, b, "g8") } +func TestBoardMoveKnightInvalid(t *testing.T) { + b := chess.NewBoard() + + // out of reach + assertMoveError(t, b, "Ng3", "no knight found that can move to g3") + assertMoveError(t, b, "Nb3", "no knight found that can move to b3") + + // blocked by own piece + assertMoveError(t, b, "Nd2", "d2 blocked by white pawn") + assertMoveError(t, b, "Ne2", "e2 blocked by white pawn") + + b.Move("Nf3") + + assertMoveError(t, b, "Ng6", "no knight found that can move to g6") + assertMoveError(t, b, "Nb6", "no knight found that can move to b6") + + assertMoveError(t, b, "Ne7", "e7 blocked by black pawn") + assertMoveError(t, b, "Nd7", "d7 blocked by black pawn") +} + func TestBoardMoveBishop(t *testing.T) { b := chess.NewBoard() diff --git a/chess/piece.go b/chess/piece.go index d3ce93b..f932a44 100644 --- a/chess/piece.go +++ b/chess/piece.go @@ -16,6 +16,34 @@ type Piece struct { Image image.Image } +func (p *Piece) String() string { + n := "" + switch p.Name { + case Pawn: + n = "pawn" + case Knight: + n = "knight" + case Bishop: + n = "bishop" + case Rook: + n = "rook" + case Queen: + n = "queen" + case King: + n = "king" + } + + c := "" + switch p.Color { + case Light: + c = "white" + case Dark: + c = "black" + } + + return fmt.Sprintf("%s %s", c, n) +} + type PieceName string const (