1025 lines
20 KiB
Go
1025 lines
20 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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"golang.org/x/image/font"
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"golang.org/x/image/font/basicfont"
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"golang.org/x/image/math/fixed"
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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(moves string) (*Board, error) {
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board := NewBoard()
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if err := board.Parse(moves); 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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x := xi * 128
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y := yi * 128
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rect = image.Rect(x, y, x+128, y+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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img = flipImage(img)
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}
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for yi := 0; yi < 8; yi++ {
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for xi := 0; xi < 8; xi++ {
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if b.turn == Light {
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drawCoordinate(img, xi, yi, false)
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}
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if b.turn == Dark {
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drawCoordinate(img, xi, yi, true)
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}
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}
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}
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return img
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}
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func drawCoordinate(img *image.RGBA, x, y int, flipped bool) {
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if x != 7 && y != 7 {
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return
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}
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var column, row string
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if y == 7 {
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switch x {
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case 0:
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column = "a"
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case 1:
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column = "b"
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case 2:
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column = "c"
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case 3:
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column = "d"
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case 4:
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column = "e"
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case 5:
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column = "f"
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case 6:
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column = "g"
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case 7:
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column = "h"
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}
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}
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if x == 7 {
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yRow := y
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if flipped {
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yRow = 7 - y
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}
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switch yRow {
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case 0:
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row = "8"
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case 1:
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row = "7"
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case 2:
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row = "6"
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case 3:
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row = "5"
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case 4:
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row = "4"
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case 5:
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row = "3"
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case 6:
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row = "2"
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case 7:
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row = "1"
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}
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}
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drawString := func(s string, origin fixed.Point26_6) {
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color := getTileColor(x, y)
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if !flipped && color == Light {
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color = Dark
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} else if !flipped {
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color = Light
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}
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// TODO: use SN font and make it bold
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d := &font.Drawer{
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Dst: img,
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Src: image.NewUniform(color),
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Face: basicfont.Face7x13,
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Dot: origin,
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}
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d.DrawString(s)
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}
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var origin fixed.Point26_6
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if column != "" {
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origin = fixed.P(x*128+5, (y+1)*128-5)
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drawString(column, origin)
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}
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if row != "" {
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origin = fixed.P((x+1)*128-12, y*128+15)
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drawString(row, origin)
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}
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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 fmt.Sprintf("`%s`", 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(strings.Trim(pgn, " "), " ")
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err error
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)
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for _, move := range moves {
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move = strings.Trim(move, " ")
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if move == "" {
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continue
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}
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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(move string) error {
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var (
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to string
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piece string
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// if the move is ambiguous, the originating square rank must be given
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// see https://en.wikipedia.org/wiki/Algebraic_notation_(chess)#Disambiguating_moves
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fromX int
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fromY int
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collisionPiece *Piece
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err error
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)
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if piece, fromX, fromY, to, err = parseMove(move); err != nil {
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return err
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}
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// TODO: parse ambiguous captures for all pieces
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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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move_ := func() error {
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// collision detection
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if collisionPiece, err = b.getCollision(to); err != nil {
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return fmt.Errorf("invalid move %s: %v", move, err)
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} else if collisionPiece != nil {
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return fmt.Errorf("invalid move %s: position %s blocked by %s", move, to, collisionPiece)
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}
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switch strings.ToLower(piece) {
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case "p":
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return b.movePawn(to, fromX, fromY)
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case "r":
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return b.moveRook(to, false, fromX, fromY)
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case "b":
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return b.moveBishop(to, false)
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case "n":
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return b.moveKnight(to, fromX, fromY)
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case "q":
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return b.moveQueen(to)
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case "k":
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return b.moveKing(to)
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default:
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return fmt.Errorf("invalid move %s: %v", move, err)
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}
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}
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if err = move_(); 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, move)
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return nil
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}
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func parseMove(move string) (string, int, int, string, error) {
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var (
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piece string
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fromX = -1
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fromY = -1
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to string
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from string
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)
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if strings.Contains(move, "x") {
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return parseCaptureMove(move)
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}
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if len(move) < 2 {
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return piece, fromX, fromY, to, fmt.Errorf("invalid move: %s", move)
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}
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if len(move) == 2 {
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// pawn move
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piece = "p"
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to = move
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return piece, fromX, fromY, to, nil
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}
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if len(move) == 3 {
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// unambiguous piece move
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piece = move[0:1]
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to = move[1:]
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return piece, fromX, fromY, to, nil
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}
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// last two characters are the target position
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to = move[len(move)-2:]
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// everything before is about origin
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from = move[:len(move)-2]
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// piece is first character
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piece = from[0:1]
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// we can ignore piece from here on
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from = from[1:]
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if len(from) == 1 {
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// rank or file given
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if from[0] >= 'a' && from[0] <= 'h' {
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// file given
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return piece, toFile(rune(from[0])), -1, to, nil
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}
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if from[0] >= '1' && from[0] <= '8' {
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// rank given
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return piece, -1, toRank(rune(from[0])), to, nil
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}
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return "", -1, -1, "", fmt.Errorf("invalid move: %s", move)
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}
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if len(from) == 2 {
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// file and rank given
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return piece, toFile(rune(from[0])), toRank(rune(from[1])), to, nil
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}
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return "", -1, -1, "", fmt.Errorf("invalid move: %s", move)
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}
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func parseCaptureMove(move string) (string, int, int, string, error) {
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var (
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parts = strings.Split(move, "x")
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piece string
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fromX = -1
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fromY = -1
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from = parts[0]
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to = parts[1]
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)
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if len(from) == 1 {
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// pawn move with rank given (exd4) or piece move (Nxe5)
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if strings.ToLower(from) == from {
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piece = "p"
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fromX = toFile(rune(from[0]))
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return piece, fromX, fromY, to, nil
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}
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piece = from
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return piece, fromX, fromY, to, nil
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}
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// piece is always first character
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piece = from[0:1]
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if len(from) == 2 {
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// rank or file given
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fromX = toFile(rune(from[1]))
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fromY = toRank(rune(from[1]))
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if fromX == -1 && fromY == -1 {
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return "", -1, -1, "", fmt.Errorf("invalid move: %s", move)
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}
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return piece, fromX, fromY, to, nil
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}
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if len(from) == 3 {
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// both file and rank given
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fromX = toFile(rune(from[1]))
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fromY = toRank(rune(from[1]))
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if fromX == -1 || fromY == -1 {
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return "", -1, -1, "", fmt.Errorf("invalid move: %s", move)
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}
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return piece, fromX, fromY, to, nil
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}
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return "", -1, -1, "", fmt.Errorf("invalid move: %s", move)
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}
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func toFile(r rune) int {
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if r >= 'a' && r <= 'h' {
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return int(r - 'a')
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}
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return -1
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}
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func toRank(r rune) int {
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if r >= '1' && r <= '8' {
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return int('8' - r)
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}
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return -1
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}
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func (b *Board) validateMove(search PieceName, fromX int, fromY int) func(*Piece, int, int) bool {
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return func(p *Piece, xPrev int, yPrev int) bool {
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// does piece originate from given origin?
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from := (fromX == -1 || xPrev == fromX) && (fromY == -1 || yPrev == fromY)
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// is this the piece we're looking for?
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found := p != nil && p.Name == search && p.Color == b.turn
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return from && found
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}
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}
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func (b *Board) movePawn(position string, fromX int, fromY int) error {
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var (
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toX int
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toY 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 toX, toY, err = getXY(position); err != nil {
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return err
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}
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if fromX != -1 {
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if b.turn == Light {
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fromY = toY + 1
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} else {
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fromY = toY - 1
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}
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piece = b.getPiece(fromX, fromY)
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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 fromX != toX-1 && fromX != toX+1 || (b.turn == Light && fromY != toY+1) || (b.turn == Dark && fromY != toY-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[fromX][fromY] = nil
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b.tiles[toX][toY] = piece
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return nil
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}
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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 = toY + 1
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} else {
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yPrev = toY - 1
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}
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piece = b.tiles[toX][yPrev]
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if piece != nil && piece.Name == Pawn && piece.Color == b.turn {
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b.tiles[toX][yPrev] = nil
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b.tiles[toX][toY] = piece
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return nil
|
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}
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|
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if b.turn == Light {
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yPrev = toY + 2
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} else {
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yPrev = toY - 2
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}
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piece = b.tiles[toX][yPrev]
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if piece != nil && piece.Name == Pawn && piece.Color == b.turn {
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b.tiles[toX][yPrev] = nil
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b.tiles[toX][toY] = piece
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return nil
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}
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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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|
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func (b *Board) moveRook(position string, queen bool, fromX int, fromY int) error {
|
|
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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|
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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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|
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checkRookMove := b.validateMove(Rook, fromX, fromY)
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checkQueenMove := b.validateMove(Queen, fromX, fromY)
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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 {
|
|
if (!queen && checkRookMove(piece, xPrev, yPrev)) || (queen && checkQueenMove(piece, xPrev, yPrev)) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
// direction blocked by other piece
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
yPrev--
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if (!queen && checkRookMove(piece, xPrev, yPrev)) || (queen && checkQueenMove(piece, xPrev, yPrev)) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
xPrev--
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if (!queen && checkRookMove(piece, xPrev, yPrev)) || (queen && checkQueenMove(piece, xPrev, yPrev)) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
yPrev++
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if (!queen && checkRookMove(piece, xPrev, yPrev)) || (queen && checkQueenMove(piece, xPrev, yPrev)) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
return fmt.Errorf("no rook found that can move to %s", position)
|
|
}
|
|
|
|
func (b *Board) moveBishop(position string, queen bool) error {
|
|
var (
|
|
x int
|
|
y int
|
|
xPrev int
|
|
yPrev int
|
|
piece *Piece
|
|
err error
|
|
)
|
|
|
|
if x, y, err = getXY(position); err != nil {
|
|
return err
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
xPrev++
|
|
yPrev--
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
// direction blocked by other piece
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
xPrev++
|
|
yPrev++
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
xPrev--
|
|
yPrev++
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
xPrev = x
|
|
yPrev = y
|
|
for xPrev >= 0 && xPrev < 8 && yPrev >= 0 && yPrev < 8 {
|
|
xPrev--
|
|
yPrev--
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil {
|
|
if ((!queen && piece.Name == Bishop) || (queen && piece.Name == Queen)) && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
}
|
|
|
|
return fmt.Errorf("no bishop found that can move to %s", position)
|
|
}
|
|
|
|
func (b *Board) moveKnight(position string, fromX int, fromY int) error {
|
|
var (
|
|
x int
|
|
y int
|
|
xPrev int
|
|
yPrev int
|
|
piece *Piece
|
|
err error
|
|
)
|
|
|
|
if x, y, err = getXY(position); err != nil {
|
|
return err
|
|
}
|
|
|
|
checkMove := b.validateMove(Knight, fromX, fromY)
|
|
|
|
xPrev = x + 1
|
|
yPrev = y - 2
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x + 2
|
|
yPrev = y - 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x + 2
|
|
yPrev = y + 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x + 1
|
|
yPrev = y + 2
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x - 1
|
|
yPrev = y + 2
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x - 2
|
|
yPrev = y + 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x - 2
|
|
yPrev = y - 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
xPrev = x - 1
|
|
yPrev = y - 2
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if checkMove(piece, xPrev, yPrev) {
|
|
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, -1, -1); err == nil {
|
|
return nil
|
|
}
|
|
|
|
return fmt.Errorf("no queen found that can move to %s", position)
|
|
}
|
|
|
|
func (b *Board) moveKing(position string) error {
|
|
var (
|
|
x int
|
|
y int
|
|
xPrev int
|
|
yPrev int
|
|
piece *Piece
|
|
err error
|
|
)
|
|
|
|
if x, y, err = getXY(position); err != nil {
|
|
return err
|
|
}
|
|
|
|
// ^
|
|
xPrev = x + 0
|
|
yPrev = y - 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// ^>
|
|
xPrev = x + 1
|
|
yPrev = y - 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// >
|
|
xPrev = x + 1
|
|
yPrev = y + 0
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// v>
|
|
xPrev = x + 1
|
|
yPrev = y + 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// v
|
|
xPrev = x + 0
|
|
yPrev = y + 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// <v
|
|
xPrev = x - 1
|
|
yPrev = y + 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// <
|
|
xPrev = x - 1
|
|
yPrev = y + 0
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
// <^
|
|
xPrev = x - 1
|
|
yPrev = y - 1
|
|
piece = b.getPiece(xPrev, yPrev)
|
|
if piece != nil && piece.Name == King && piece.Color == b.turn {
|
|
b.tiles[xPrev][yPrev] = nil
|
|
b.tiles[x][y] = piece
|
|
return nil
|
|
}
|
|
|
|
return fmt.Errorf("no king found that can move to %s", position)
|
|
}
|
|
|
|
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 move: %s", position)
|
|
}
|
|
|
|
if posY < '1' || posY > '8' {
|
|
return -1, -1, fmt.Errorf("invalid move: %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 (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
|
|
} 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
|
|
}
|