674 lines
14 KiB
Go
674 lines
14 KiB
Go
package chess
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import (
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"fmt"
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"image"
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"image/draw"
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"image/png"
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"log"
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"os"
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"strings"
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)
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type Board struct {
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tiles [8][8]*Piece
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turn Color
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moves []string
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}
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func NewBoard() *Board {
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board := &Board{turn: Light}
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board.mustSetPiece(Rook, Light, "a1")
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board.mustSetPiece(Knight, Light, "b1")
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board.mustSetPiece(Bishop, Light, "c1")
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board.mustSetPiece(Queen, Light, "d1")
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board.mustSetPiece(King, Light, "e1")
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board.mustSetPiece(Bishop, Light, "f1")
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board.mustSetPiece(Knight, Light, "g1")
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board.mustSetPiece(Rook, Light, "h1")
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board.mustSetPiece(Pawn, Light, "a2")
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board.mustSetPiece(Pawn, Light, "b2")
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board.mustSetPiece(Pawn, Light, "c2")
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board.mustSetPiece(Pawn, Light, "d2")
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board.mustSetPiece(Pawn, Light, "e2")
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board.mustSetPiece(Pawn, Light, "f2")
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board.mustSetPiece(Pawn, Light, "g2")
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board.mustSetPiece(Pawn, Light, "h2")
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board.mustSetPiece(Rook, Dark, "a8")
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board.mustSetPiece(Knight, Dark, "b8")
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board.mustSetPiece(Bishop, Dark, "c8")
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board.mustSetPiece(Queen, Dark, "d8")
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board.mustSetPiece(King, Dark, "e8")
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board.mustSetPiece(Bishop, Dark, "f8")
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board.mustSetPiece(Knight, Dark, "g8")
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board.mustSetPiece(Rook, Dark, "h8")
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board.mustSetPiece(Pawn, Dark, "a7")
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board.mustSetPiece(Pawn, Dark, "b7")
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board.mustSetPiece(Pawn, Dark, "c7")
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board.mustSetPiece(Pawn, Dark, "d7")
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board.mustSetPiece(Pawn, Dark, "e7")
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board.mustSetPiece(Pawn, Dark, "f7")
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board.mustSetPiece(Pawn, Dark, "g7")
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board.mustSetPiece(Pawn, Dark, "h7")
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return board
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}
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func NewGame(move string) (*Board, error) {
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board := NewBoard()
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if err := board.Move(move); err != nil {
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return nil, err
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}
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return board, nil
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}
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func (b *Board) Save(filename string) error {
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var (
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file *os.File
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err error
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)
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if file, err = os.Create(filename); err != nil {
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return err
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}
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defer file.Close()
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return png.Encode(file, b.Image())
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}
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func (b *Board) Image() *image.RGBA {
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var (
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img *image.RGBA
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piece *Piece
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bg *image.Uniform
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rect image.Rectangle
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p = image.Point{0, 0}
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)
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img = image.NewRGBA(image.Rect(0, 0, 1024, 1024))
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for yi := 0; yi < 8; yi++ {
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for xi := 0; xi < 8; xi++ {
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rect = image.Rect(xi*128, yi*128, (xi*128)+128, (yi*128)+128)
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bg = image.NewUniform(getTileColor(xi, yi))
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draw.Draw(img, rect, bg, p, draw.Src)
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piece = b.tiles[xi][yi]
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if piece != nil {
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pieceImg := piece.Image
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if b.turn == Dark {
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pieceImg = flipImage(pieceImg)
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}
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draw.Draw(img, rect, pieceImg, p, draw.Over)
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}
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}
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}
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if b.turn == Dark {
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return flipImage(img)
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}
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return img
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}
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func (b *Board) SetPiece(name PieceName, color Color, position string) error {
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var (
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piece *Piece
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x int
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y int
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err error
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)
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if len(position) != 2 {
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return fmt.Errorf("invalid position: %s", position)
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}
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if piece, err = NewPiece(name, color); err != nil {
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return err
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}
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if x, y, err = getXY(position); err != nil {
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return err
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}
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b.tiles[x][y] = piece
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return nil
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}
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func (b *Board) AlgebraicNotation() string {
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var text string
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for i, m := range b.moves {
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if i%2 == 0 {
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text += fmt.Sprintf("%d. %s", i/2+1, m)
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} else {
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text += fmt.Sprintf(" %s ", m)
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}
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}
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return text
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}
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func (b *Board) Parse(pgn string) error {
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var (
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moves = strings.Split(pgn, " ")
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err error
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)
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for _, move := range moves {
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if err = b.Move(move); err != nil {
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return err
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}
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}
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return nil
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}
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func (b *Board) Move(position string) error {
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var (
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err error
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// the column from which the piece is captured.
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// for example, this would be 'e' for exd4 and 'e' for Nexd4.
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captureFrom string
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)
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if strings.Contains(position, "x") {
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// capture move
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parts := strings.Split(position, "x")
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if len(parts) != 2 {
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return fmt.Errorf("invalid move: %s", position)
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}
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if len(parts[0]) == 2 {
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// example: Nexd4
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captureFrom = parts[0][1:]
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} else if len(parts[0]) == 1 {
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if strings.ToLower(parts[0]) == parts[0] {
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// example: exd4
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captureFrom = parts[0]
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} else {
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// example: Nxd4
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captureFrom = ""
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}
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} else {
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return fmt.Errorf("invalid move: %s", position)
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}
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position = strings.Replace(position, captureFrom+"x", "", 1)
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}
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// TODO: parse captures e.g. exd5 or Nxd5
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// TODO: parse promotions
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// TODO: parse checks e.g. e5+
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// TODO: parse checkmates e.g. e5#
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// TODO: parse O-O as kingside castle and O-O-O as queenside castle
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// TODO: make sure pinned pieces cannot move
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// TODO: make sure king is not in check after move
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// ( this avoids moving into check and moving a piece that exposes the king to check e.g. pinned pieces )
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if len(position) == 2 {
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err = b.movePawn(position, captureFrom)
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} else if len(position) == 3 {
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switch strings.ToLower(position[0:1]) {
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case "r":
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err = b.moveRook(position[1:3], false)
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case "b":
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err = b.moveBishop(position[1:3], false)
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case "n":
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err = b.moveKnight(position[1:3])
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case "q":
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err = b.moveQueen(position[1:3])
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case "k":
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err = b.moveKing(position[1:3])
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default:
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err = fmt.Errorf("invalid move: %s", position)
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}
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} else {
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return fmt.Errorf("invalid move: %s", position)
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}
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if err != nil {
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return err
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}
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if b.turn == Light {
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b.turn = Dark
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} else {
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b.turn = Light
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}
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b.moves = append(b.moves, position)
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return nil
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}
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func (b *Board) movePawn(position string, captureFrom string) error {
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var (
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x int
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y int
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cX int
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cY int
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yPrev int
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piece *Piece
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err error
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)
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if x, y, err = getXY(position); err != nil {
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return err
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}
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if captureFrom != "" {
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if cX, cY, err = getXY(captureFrom + position[0:1]); err != nil {
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return err
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}
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if b.turn == Light {
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cY = y + 1
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} else {
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cY = y - 1
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}
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piece = b.getPiece(cX, cY)
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if piece == nil || piece.Name != Pawn || piece.Color != b.turn {
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// not your pawn
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return fmt.Errorf("invalid capture move for pawn: %s", position)
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}
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if cX != x-1 && cX != x+1 || (b.turn == Light && cY != y+1) || (b.turn == Dark && cY != y-1) {
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// invalid capture move
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return fmt.Errorf("invalid capture move for pawn: %s", position)
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}
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b.tiles[cX][cY] = nil
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b.tiles[x][y] = piece
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return nil
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}
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// TODO: assert move is valid:
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// * 2 moves from start position
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// * 1 move otherwise
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// * diagonal if attacking
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// * no collision with other pieces
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if b.turn == Light {
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yPrev = y + 1
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} else {
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yPrev = y - 1
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}
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piece = b.tiles[x][yPrev]
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if piece != nil && piece.Name == Pawn && piece.Color == b.turn {
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b.tiles[x][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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if b.turn == Light {
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yPrev = y + 2
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} else {
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yPrev = y - 2
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}
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piece = b.tiles[x][yPrev]
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if piece != nil && piece.Name == Pawn && piece.Color == b.turn {
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b.tiles[x][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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return fmt.Errorf("no pawn found that can move to %s", position)
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}
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func (b *Board) moveRook(position string, queen bool) error {
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var (
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x int
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y int
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xPrev int
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yPrev int
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piece *Piece
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err error
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)
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if x, y, err = getXY(position); err != nil {
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return err
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev++
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Rook) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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// direction blocked by other piece
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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yPrev--
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Rook) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev--
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Rook) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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yPrev++
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Rook) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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return fmt.Errorf("no rook found that can move to %s", position)
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}
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func (b *Board) moveBishop(position string, queen bool) error {
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var (
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x int
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y int
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xPrev int
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yPrev int
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piece *Piece
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err error
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)
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if x, y, err = getXY(position); err != nil {
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return err
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev++
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yPrev--
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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// direction blocked by other piece
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev++
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yPrev++
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev--
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yPrev++
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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xPrev = x
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yPrev = y
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for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
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xPrev--
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yPrev--
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil {
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if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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} else {
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break
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}
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}
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}
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return fmt.Errorf("no bishop found that can move to %s", position)
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}
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func (b *Board) moveKnight(position string) error {
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var (
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x int
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y int
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xPrev int
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yPrev int
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piece *Piece
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err error
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)
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if x, y, err = getXY(position); err != nil {
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return err
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}
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xPrev = x + 1
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yPrev = y - 2
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x + 2
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yPrev = y - 1
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x + 2
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yPrev = y + 1
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x + 1
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yPrev = y + 2
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x - 1
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yPrev = y + 2
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x - 2
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yPrev = y + 1
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
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b.tiles[x][y] = piece
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return nil
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}
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xPrev = x - 2
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yPrev = y - 1
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piece = b.getPiece(xPrev, yPrev)
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if piece != nil && piece.Name == Knight && piece.Color == b.turn {
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b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x - 1
|
|
yPrev = y - 2
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == Knight && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
return fmt.Errorf("no knight found that can move to %s", position)
|
|
}
|
|
|
|
func (b *Board) moveQueen(position string) error {
|
|
var (
|
|
err error
|
|
)
|
|
|
|
if err = b.moveBishop(position, true); err == nil {
|
|
return nil
|
|
}
|
|
|
|
if err = b.moveRook(position, true); err == nil {
|
|
return nil
|
|
}
|
|
|
|
return fmt.Errorf("no queen found that can move to %s", position)
|
|
}
|
|
|
|
func (b *Board) moveKing(position string) error {
|
|
// TODO: implement king moves
|
|
return nil
|
|
}
|
|
|
|
func (b *Board) mustSetPiece(name PieceName, color Color, position string) {
|
|
if err := b.SetPiece(name, color, position); err != nil {
|
|
log.Fatalf("cannot set piece %s: %v", name, err)
|
|
}
|
|
}
|
|
|
|
func (b *Board) At(position string) *Piece {
|
|
var (
|
|
x int
|
|
y int
|
|
err error
|
|
)
|
|
if x, y, err = getXY(position); err != nil {
|
|
return nil
|
|
}
|
|
return b.tiles[x][y]
|
|
}
|
|
|
|
func getXY(position string) (int, int, error) {
|
|
var (
|
|
posX rune
|
|
posY rune
|
|
x int
|
|
y int
|
|
)
|
|
runes := []rune(position)
|
|
posX = runes[0]
|
|
posY = runes[1]
|
|
|
|
if posX < 'a' && posX > 'h' {
|
|
return -1, -1, fmt.Errorf("invalid posX: %s", position)
|
|
}
|
|
|
|
if posY < '1' && posY > '8' {
|
|
return -1, -1, fmt.Errorf("invalid posY: %s", position)
|
|
}
|
|
|
|
// image origin (0,0) is at top-left corner (a8)
|
|
x = int(posX - 'a')
|
|
y = int('8' - posY)
|
|
|
|
return x, y, nil
|
|
}
|
|
|
|
func (b *Board) getPiece(x int, y int) *Piece {
|
|
if x < 0 || x >= 8 || y < 0 || y >= 8 {
|
|
return nil
|
|
}
|
|
return b.tiles[x][y]
|
|
}
|
|
|
|
func getTileColor(x, y int) Color {
|
|
if x%2 == y%2 {
|
|
return Light
|
|
} else {
|
|
return Dark
|
|
}
|
|
}
|
|
|
|
func flipImage(img image.Image) *image.RGBA {
|
|
bounds := img.Bounds()
|
|
flipped := image.NewRGBA(bounds)
|
|
|
|
// Flip the image vertically by reversing the Y coordinate
|
|
for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
|
|
for x := bounds.Min.X; x < bounds.Max.X; x++ {
|
|
flipped.Set(x, bounds.Max.Y-y-1, img.At(x, y))
|
|
}
|
|
}
|
|
|
|
return flipped
|
|
}
|