Implement en passant and much more!

chess/board.go

@@ -6,67 +6,76 @@ import (
 	"github.com/samber/lo"
 )
 
-type Board map[types.Coordinate]Piece
+type Position map[types.Coordinate]Piece
 
-func (b Board) Init() {
+type Board struct {
+	position Position
+	history  []types.Move
+}
+
+func newBoard() Board {
+	return Board{
+		position: make(Position),
+		history:  make([]types.Move, 0),
+	}
+}
+
+func (b *Board) Init() {
 	var coord types.Coordinate
 
 	for i := 1; i <= 8; i++ {
 		coord.Row = 2
 		coord.Col = i
-		b[coord] = Pawn{Color: types.White}
+		b.position[coord] = Pawn{Color: types.White}
 
 		coord.Row = 7
 		coord.Col = i
-		b[coord] = Pawn{Color: types.Black}
+		b.position[coord] = Pawn{Color: types.Black}
 	}
 
-	b[types.Coordinate{Row: 1, Col: 1}] = Rook{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 1}] = Rook{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 2}] = Knight{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 2}] = Knight{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 3}] = Bishop{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 3}] = Bishop{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 4}] = Queen{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 4}] = Queen{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 5}] = King{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 5}] = King{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 6}] = Bishop{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 6}] = Bishop{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 7}] = Knight{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 7}] = Knight{Color: types.White}
-	b[types.Coordinate{Row: 1, Col: 8}] = Rook{Color: types.White}
+	b.position[types.Coordinate{Row: 1, Col: 8}] = Rook{Color: types.White}
 
-	b[types.Coordinate{Row: 8, Col: 1}] = Rook{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 1}] = Rook{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 2}] = Knight{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 2}] = Knight{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 3}] = Bishop{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 3}] = Bishop{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 4}] = Queen{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 4}] = Queen{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 5}] = King{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 5}] = King{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 6}] = Bishop{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 6}] = Bishop{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 7}] = Knight{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 7}] = Knight{Color: types.Black}
-	b[types.Coordinate{Row: 8, Col: 8}] = Rook{Color: types.Black}
+	b.position[types.Coordinate{Row: 8, Col: 8}] = Rook{Color: types.Black}
 }
 
-func (b Board) CheckMove(move types.Move) (bool, string) {
+func (b *Board) CheckAndPlay(move types.Move) (bool, string) {
 	// We make a copy of the original board to play moves on it,
 	// We can play the move on it and then check if it is invalid
 	tempBoard := b.getCopyOfBoard()
 
 	//Check start square of move
-	pieceAtStartSquare := b.getPieceAt(move.StartSquare)
+	pieceAtStartSquare := tempBoard.getPieceAt(move.StartSquare)
 	if pieceAtStartSquare == nil {
 		return false, "no piece at start square"
 	}
-	movingColor := pieceAtStartSquare.GetColor()
+	move.ColorMoved = pieceAtStartSquare.GetColor()
+	move.PieceMoved = GetShortNameForPiece(pieceAtStartSquare)
 
 	//Check end square of move
-	pieceAtEndSquare := b.getPieceAt(move.EndSquare)
+	pieceAtEndSquare := tempBoard.getPieceAt(move.EndSquare)
 	if pieceAtEndSquare != nil {
 		if pieceAtEndSquare.GetColor() == pieceAtStartSquare.GetColor() {
 			return false, "same-coloured piece at end square"
 		}
 	}
-	var wasPromotionMove bool
-	// var piece types.PieceShortName
-	switch pieceAtStartSquare.(type) {
-	case Pawn:
-		wasPromotionMove, _ = tempBoard.handlePossiblePromotion(move, movingColor)
-	}
 
-	if !wasPromotionMove {
+	wasSpecialMove := tempBoard.handleSpecialMove(move)
+
+	if !wasSpecialMove {
 		// At the moment, we do not need to check if the correct color is moving,
 		//since we are only reading moves from the player whose turn it is.
 		allMovesExceptBlocked := pieceAtStartSquare.GetAllMovesButBlocked(tempBoard, move.StartSquare)
@@ -76,18 +85,18 @@ func (b Board) CheckMove(move types.Move) (bool, string) {
 		}
 
 		//We play the move on the temporary board
-		delete(tempBoard, move.StartSquare)
+		delete(tempBoard.position, move.StartSquare)
-		tempBoard[move.EndSquare] = pieceAtStartSquare
+		tempBoard.position[move.EndSquare] = pieceAtStartSquare
 	}
 
 	//Check if king of moving color is in check -> move not allowed
 	//Do that by checking if the king is in a square attacked by the other color.
-	ownKingCoordinate := tempBoard.getSquareOfPiece(King{Color: movingColor})
+	ownKingCoordinate := tempBoard.getSquareOfPiece(King{Color: move.ColorMoved})
 	if ownKingCoordinate == nil {
-		return false, string(movingColor) + " king not found"
+		return false, string(move.ColorMoved) + " king not found"
 	}
 
-	kingIsAttacked := tempBoard.isSquareAttacked(*ownKingCoordinate, movingColor.Opposite())
+	kingIsAttacked := tempBoard.isSquareAttacked(*ownKingCoordinate, move.ColorMoved.Opposite())
 	if kingIsAttacked {
 		return false, "king is attacked after move"
 	}
@@ -106,13 +115,15 @@ func (b Board) CheckMove(move types.Move) (bool, string) {
 	// If a piece can be moved into the path, it is no checkmate
 
 	//We play the move on the real board
-	b = tempBoard
+	b.position = tempBoard.position
+	b.history = tempBoard.history
+	b.appendMoveToHistory(move)
 
 	return true, ""
 }
 
 func (b Board) getSquareOfPiece(piece Piece) *types.Coordinate {
-	for k, v := range b {
+	for k, v := range b.position {
 		if v == piece {
 			return &k
 		}
@@ -123,7 +134,7 @@ func (b Board) getSquareOfPiece(piece Piece) *types.Coordinate {
 func (b Board) isSquareAttacked(square types.Coordinate, byColor types.ChessColor) bool {
 	var attackedSquares []types.Coordinate
 
-	for square, piece := range b {
+	for square, piece := range b.position {
 		attackedSquares = append(attackedSquares, piece.GetAllMovesButBlocked(b, square)...)
 	}
 
@@ -131,7 +142,7 @@ func (b Board) isSquareAttacked(square types.Coordinate, byColor types.ChessColo
 }
 
 func (b Board) getPieceAt(coord types.Coordinate) Piece {
-	piece, found := b[coord]
+	piece, found := b.position[coord]
 	if !found {
 		return nil
 	}
@@ -139,17 +150,59 @@ func (b Board) getPieceAt(coord types.Coordinate) Piece {
 	return piece
 }
 
-func (b Board) handlePossiblePromotion(move types.Move, color types.ChessColor) (bool, types.PieceShortName) {
+func (b *Board) appendMoveToHistory(move types.Move) {
+	b.history = append(b.history, move)
+}
+
+func (b Board) getLastMove() types.Move {
+	if len(b.history) < 1 {
+		return types.Move{}
+	}
+	return b.history[len(b.history)-1]
+}
+
+func (b Board) getCopyOfBoard() Board {
+	return Board{
+		position: b.position.getCopyOfPosition(),
+		history:  b.history,
+	}
+}
+
+func (p Position) getCopyOfPosition() Position {
+	position := make(Position)
+
+	for coord, piece := range p {
+		position[coord] = piece
+	}
+	return position
+}
+
+func (b *Board) handleSpecialMove(move types.Move) bool {
+	var was bool
+	var pieceAtStartSquare = b.getPieceAt(move.StartSquare)
+
+	switch pieceAtStartSquare.(type) {
+	case Pawn:
+		was = b.handlePossiblePromotion(move)
+		if !was {
+			was = b.handleEnPassant(move, b.getLastMove())
+		}
+	}
+	return was
+}
+
+func (b *Board) handlePossiblePromotion(move types.Move) bool {
 	var isPromotionMove bool
 	var promotionToPiece types.PieceShortName
 
+	//TODO(m): What if message does not contain a promotion, but should be because a pawn is moved to the end square
 	messageContainsPromotion := move.IsPromotionMove()
 
 	if messageContainsPromotion {
 		promotionToPiece = *move.PromotionToPiece
 	}
 
-	switch color {
+	switch move.ColorMoved {
 	case types.White:
 		if move.StartSquare.Row == types.RangeLastValid-1 &&
 			move.EndSquare.Row == types.RangeLastValid {
@@ -164,19 +217,63 @@ func (b Board) handlePossiblePromotion(move types.Move, color types.ChessColor)
 	}
 
 	if isPromotionMove {
-		delete(b, move.StartSquare)
+		delete(b.position, move.StartSquare)
-		b[move.EndSquare] = GetPieceForShortName(promotionToPiece)
+		b.position[move.EndSquare] = GetPieceForShortName(promotionToPiece, move.ColorMoved)
 	}
 
-	return isPromotionMove, promotionToPiece
+	return isPromotionMove
 }
 
-func (b Board) getCopyOfBoard() Board {
+func (b *Board) handleEnPassant(move, lastMove types.Move) bool {
-	board := make(map[types.Coordinate]Piece)
+	var wasEnPassant bool
 
-	for coord, piece := range b {
+	if lastMove.PieceMoved != types.PawnShortName {
-		board[coord] = piece
+		return false
 	}
 
-	return board
+	switch move.ColorMoved {
+	case types.White:
+		if lastMove.StartSquare.Row != 7 || lastMove.EndSquare.Row != 5 {
+			wasEnPassant = false
+		}
+		if move.StartSquare.Row != 5 {
+			wasEnPassant = false
+		}
+		if move.EndSquare.Row != 6 {
+			wasEnPassant = false
+		}
+		if move.StartSquare.Col == lastMove.EndSquare.Col+1 &&
+			move.EndSquare.Col == lastMove.EndSquare.Col {
+			wasEnPassant = true
+		}
+		if move.StartSquare.Col == lastMove.EndSquare.Col-1 &&
+			move.EndSquare.Col == lastMove.EndSquare.Col {
+			wasEnPassant = true
+		}
+	case types.Black:
+		if lastMove.StartSquare.Row != 2 || lastMove.EndSquare.Row != 4 {
+			wasEnPassant = false
+		}
+		if move.StartSquare.Row != 4 {
+			wasEnPassant = false
+		}
+		if move.EndSquare.Row != 3 {
+			wasEnPassant = false
+		}
+		if move.StartSquare.Col == lastMove.EndSquare.Col+1 &&
+			move.EndSquare.Col == lastMove.EndSquare.Col {
+			wasEnPassant = true
+		}
+		if move.StartSquare.Col == lastMove.EndSquare.Col-1 &&
+			move.EndSquare.Col == lastMove.EndSquare.Col {
+			wasEnPassant = true
+		}
+	}
+
+	if wasEnPassant { //play the move
+		delete(b.position, lastMove.EndSquare)
+		b.position[move.EndSquare] = GetPieceForShortName(move.PieceMoved, move.ColorMoved)
+	}
+
+	return wasEnPassant
 }

chess/board_test.go

@@ -8,64 +8,191 @@ import (
 )
 
 func Test_CheckMove_validPawnMove(t *testing.T) {
-	var board = make(Board)
+	var board = newBoard()
 
-	board[types.Coordinate{Col: 1, Row: 1}] = Pawn{Color: types.White}
+	board.position[types.Coordinate{Col: 1, Row: 2}] = Pawn{Color: types.White}
-	board[types.Coordinate{Col: 1, Row: 5}] = King{Color: types.White}
+	board.position[types.Coordinate{Col: 2, Row: 4}] = Pawn{Color: types.Black}
-	board[types.Coordinate{Col: 8, Row: 5}] = King{Color: types.Black}
+	board.position[types.Coordinate{Col: 5, Row: 1}] = King{Color: types.White}
+	board.position[types.Coordinate{Col: 5, Row: 8}] = King{Color: types.Black}
 
 	move := types.Move{
-		StartSquare: types.Coordinate{Col: 1, Row: 1},
+		StartSquare: types.Coordinate{Col: 1, Row: 2},
-		EndSquare:   types.Coordinate{Col: 1, Row: 2},
+		EndSquare:   types.Coordinate{Col: 1, Row: 3},
 	}
 
-	good, _ := board.CheckMove(move)
+	good, _ := board.CheckAndPlay(move)
+	assert.True(t, good)
+
+	//we take the pawn
+	secondMove := types.Move{
+		StartSquare: types.Coordinate{Col: 2, Row: 4},
+		EndSquare:   types.Coordinate{Col: 1, Row: 3},
+	}
+	good, _ = board.CheckAndPlay(secondMove)
 	assert.True(t, good)
 }
 
-func Test_CheckMove_invalidPawnMoves(t *testing.T) {
+func Test_CheckMove_enPassant(t *testing.T) {
-	var board = make(Board)
+	var board = newBoard()
 
-	board[types.Coordinate{Col: 2, Row: 5}] = Pawn{Color: types.White}
+	board.position[types.Coordinate{Col: 6, Row: 4}] = Pawn{Color: types.Black}
-	board[types.Coordinate{Col: 1, Row: 5}] = King{Color: types.White}
+	board.position[types.Coordinate{Col: 5, Row: 2}] = Pawn{Color: types.White}
-	board[types.Coordinate{Col: 7, Row: 5}] = Queen{Color: types.Black}
+	board.position[types.Coordinate{Col: 5, Row: 1}] = King{Color: types.White}
-	board[types.Coordinate{Col: 8, Row: 5}] = King{Color: types.Black}
+	board.position[types.Coordinate{Col: 5, Row: 8}] = King{Color: types.Black}
 
 	move := types.Move{
-		StartSquare: types.Coordinate{Col: 2, Row: 5},
+		StartSquare: types.Coordinate{Col: 5, Row: 2},
-		EndSquare:   types.Coordinate{Col: 2, Row: 6},
+		EndSquare:   types.Coordinate{Col: 5, Row: 4},
 	}
 
+	good, reason := board.CheckAndPlay(move)
+	assert.True(t, good)
+	assert.Empty(t, reason)
+	assert.Equal(t, Pawn{Color: types.White}, board.position[types.Coordinate{Col: 5, Row: 4}])
+
+	newMove := types.Move{
+		StartSquare: types.Coordinate{Col: 6, Row: 4},
+		EndSquare:   types.Coordinate{Col: 5, Row: 3},
+	}
+	good, reason = board.CheckAndPlay(newMove)
+	assert.True(t, good)
+	assert.Empty(t, reason)
+	// the black pawn is on its correct square
+	assert.Equal(t, Pawn{Color: types.Black}, board.position[types.Coordinate{Col: 5, Row: 3}])
+	//the white pawn is gone
+	assert.Nil(t, board.position[types.Coordinate{Col: 5, Row: 4}])
+}
+
+func Test_CheckMove_invalidPawnMoves(t *testing.T) {
 	t.Run("pawn is blocked", func(t *testing.T) {
-		testBoard := board.getCopyOfBoard()
+		var board = newBoard()
-		testBoard[types.Coordinate{Col: 2, Row: 6}] = Pawn{Color: types.Black}
+
-		legalMove, _ := testBoard.CheckMove(move)
+		board.position[types.Coordinate{Col: 2, Row: 5}] = Pawn{Color: types.White}
+		board.position[types.Coordinate{Col: 1, Row: 5}] = King{Color: types.White}
+		board.position[types.Coordinate{Col: 7, Row: 5}] = Queen{Color: types.Black}
+		board.position[types.Coordinate{Col: 8, Row: 5}] = King{Color: types.Black}
+		board.position[types.Coordinate{Col: 2, Row: 6}] = Pawn{Color: types.Black}
+
+		move := types.Move{
+			StartSquare: types.Coordinate{Col: 2, Row: 5},
+			EndSquare:   types.Coordinate{Col: 2, Row: 6},
+		}
+		legalMove, _ := board.CheckAndPlay(move)
 		assert.False(t, legalMove)
 	})
 
-	t.Run("king of moving color is in check after move", func(t *testing.T) {
+	t.Run("pawn moves to the side", func(t *testing.T) {
-		good, _ := board.CheckMove(move)
+		var board = newBoard()
-		assert.False(t, good)
+		boardBeforeMove := board
+
+		board.position[types.Coordinate{Col: 1, Row: 5}] = King{Color: types.White}
+		board.position[types.Coordinate{Col: 8, Row: 5}] = King{Color: types.Black}
+		board.position[types.Coordinate{Col: 2, Row: 5}] = Pawn{Color: types.White}
+
+		move := types.Move{
+			StartSquare: types.Coordinate{Col: 2, Row: 5},
+			EndSquare:   types.Coordinate{Col: 3, Row: 5},
+		}
+		legal, _ := board.CheckAndPlay(move)
+
+		assert.False(t, legal)
+		assert.Equal(t, boardBeforeMove, board)
+
+		move = types.Move{
+			StartSquare: types.Coordinate{Col: 2, Row: 5},
+			EndSquare:   types.Coordinate{Col: 1, Row: 5},
+		}
+		legal, _ = board.CheckAndPlay(move)
+
+		assert.False(t, legal)
+		assert.Equal(t, boardBeforeMove, board)
+
+		move = types.Move{
+			StartSquare: types.Coordinate{Col: 2, Row: 5},
+			EndSquare:   types.Coordinate{Col: 6, Row: 5},
+		}
+		legal, _ = board.CheckAndPlay(move)
+
+		assert.False(t, legal)
+		assert.Equal(t, boardBeforeMove, board)
 	})
+
+	// t.Run("king of moving color is in check after move", func(t *testing.T) {
+	// 	good, _ := board.CheckMove(move)
+	// 	assert.False(t, good)
+	// })
 }
 
 func Test_CheckMove_validPromotion(t *testing.T) {
-	var board Board = make(Board)
+	var board Board = newBoard()
 
-	board[types.Coordinate{Col: 1, Row: 7}] = Pawn{Color: types.White}
+	board.position[types.Coordinate{Col: 1, Row: 7}] = Pawn{Color: types.White}
-	board[types.Coordinate{Col: 1, Row: 1}] = King{Color: types.White}
+	board.position[types.Coordinate{Col: 1, Row: 1}] = King{Color: types.White}
 
-	board[types.Coordinate{Col: 8, Row: 7}] = King{Color: types.Black}
+	board.position[types.Coordinate{Col: 8, Row: 7}] = King{Color: types.Black}
 
-	shortName := types.Queen
+	shortName := types.QueenShortName
 	move := types.Move{
 		StartSquare:      types.Coordinate{Col: 1, Row: 7},
 		EndSquare:        types.Coordinate{Col: 1, Row: 8},
 		PromotionToPiece: &shortName,
 	}
-
+	good, reason := board.CheckAndPlay(move)
-	good, reason := board.CheckMove(move)
 
 	assert.Empty(t, reason)
 	assert.True(t, good)
+	assert.Equal(t, Queen{Color: types.White}, board.getPieceAt(types.Coordinate{Row: 8, Col: 1}))
+}
+
+func Test_CheckMove_HistoryWorks(t *testing.T) {
+	var board = newBoard()
+
+	board.position[types.Coordinate{Col: 3, Row: 7}] = Pawn{Color: types.Black}
+	board.position[types.Coordinate{Col: 1, Row: 2}] = Pawn{Color: types.White}
+	board.position[types.Coordinate{Col: 1, Row: 5}] = King{Color: types.White}
+	board.position[types.Coordinate{Col: 8, Row: 5}] = King{Color: types.Black}
+
+	firstMove := types.Move{
+		StartSquare: types.Coordinate{Col: 1, Row: 2},
+		EndSquare:   types.Coordinate{Col: 1, Row: 3},
+	}
+	secondMove := types.Move{
+		StartSquare: types.Coordinate{Col: 3, Row: 7},
+		EndSquare:   types.Coordinate{Col: 3, Row: 5},
+	}
+	thirdMove := types.Move{
+		StartSquare: types.Coordinate{Col: 1, Row: 3},
+		EndSquare:   types.Coordinate{Col: 1, Row: 4},
+	}
+
+	good, _ := board.CheckAndPlay(firstMove)
+	assert.True(t, good)
+
+	good, _ = board.CheckAndPlay(secondMove)
+	assert.True(t, good)
+
+	good, _ = board.CheckAndPlay(thirdMove)
+	assert.True(t, good)
+
+	expectedHistory := []types.Move{
+		{
+			StartSquare: types.Coordinate{Col: 1, Row: 2},
+			EndSquare:   types.Coordinate{Col: 1, Row: 3},
+			PieceMoved:  'p',
+			ColorMoved:  "white",
+		},
+		{
+			StartSquare: types.Coordinate{Col: 3, Row: 7},
+			EndSquare:   types.Coordinate{Col: 3, Row: 5},
+			PieceMoved:  'p',
+			ColorMoved:  "black",
+		},
+		{
+			StartSquare: types.Coordinate{Col: 1, Row: 3},
+			EndSquare:   types.Coordinate{Col: 1, Row: 4},
+			PieceMoved:  'p',
+			ColorMoved:  "white",
+		},
+	}
+	assert.Equal(t, expectedHistory, board.history)
 }

chess/game.go

@@ -1,9 +1,9 @@
 package chess
 
 import (
+	"log"
 	"mchess_server/api"
 	"mchess_server/types"
-	"log"
 	"time"
 
 	"github.com/google/uuid"
@@ -25,7 +25,7 @@ const (
 func NewGame() *Game {
 	var game Game = Game{
 		id:    uuid.New(),
-		board: make(map[types.Coordinate]Piece),
+		board: newBoard(),
 	}
 	game.board.Init()
 
@@ -75,7 +75,7 @@ func (game *Game) Handle() {
 			gameState = CheckMove
 
 		case CheckMove:
-			valid, reason := game.board.CheckMove(receivedMove)
+			valid, reason := game.board.CheckAndPlay(receivedMove)
 
 			if valid {
 				gameState = CheckPlayerChange

chess/piece_interface.go

@@ -9,22 +9,41 @@ type Piece interface {
 	GetColor() types.ChessColor
 }
 
-func GetPieceForShortName(name types.PieceShortName) Piece {
+func GetPieceForShortName(name types.PieceShortName, color types.ChessColor) Piece {
 	var piece Piece
 
 	switch name {
 	case 'p':
-		piece = Pawn{}
+		piece = Pawn{Color: color}
 	case 'q':
-		piece = Queen{}
+		piece = Queen{Color: color}
 	case 'k':
-		piece = King{}
+		piece = King{Color: color}
 	case 'b':
-		piece = Bishop{}
+		piece = Bishop{Color: color}
 	case 'r':
-		piece = Rook{}
+		piece = Rook{Color: color}
 	case 'n':
-		piece = Knight{}
+		piece = Knight{Color: color}
 	}
 	return piece
 }
+
+func GetShortNameForPiece(piece Piece) types.PieceShortName {
+	var name types.PieceShortName
+	switch piece.(type) {
+	case Pawn:
+		name = 'p'
+	case Queen:
+		name = 'q'
+	case King:
+		name = 'k'
+	case Bishop:
+		name = 'b'
+	case Rook:
+		name = 'r'
+	case Knight:
+		name = 'n'
+	}
+	return name
+}

types/move.go

@@ -1,14 +1,13 @@
 package types
 
 type Move struct {
-	StartSquare Coordinate `json:"startSquare"`
+	StartSquare      Coordinate `json:"startSquare"`
-	EndSquare   Coordinate `json:"endSquare"`
+	EndSquare        Coordinate `json:"endSquare"`
-    PromotionToPiece *PieceShortName `json:"promotionToPiece,omitempty"` 
+	PieceMoved       PieceShortName
+	ColorMoved       ChessColor
+	PromotionToPiece *PieceShortName `json:"promotionToPiece,omitempty"`
 }
 
 func (m Move) IsPromotionMove() bool {
-    if m.PromotionToPiece != nil {
+	return m.PromotionToPiece != nil
-        return true
-    }
-    return false
 }

types/shortname.go

@@ -3,10 +3,10 @@ package types
 type PieceShortName rune
 
 const (
-	Pawn   PieceShortName = 'p'
+	PawnShortName   PieceShortName = 'p'
-	Rook   PieceShortName = 'r'
+	RookShortName   PieceShortName = 'r'
-	Knight PieceShortName = 'n'
+	KnightShortName PieceShortName = 'n'
-	Bishop PieceShortName = 'b'
+	BishopShortName PieceShortName = 'b'
-	Queen  PieceShortName = 'q'
+	QueenShortName  PieceShortName = 'q'
-	King   PieceShortName = 'k'
+	KingShortName   PieceShortName = 'k'
 )