func (p *Pos) Correct() error {
return game.Pos(*p).Correct()
}
//WhatMove : return a move that happened between the before state and the board after
func WhatMove(bef *game.State, aft *board.Board) (*game.Move, *game.State, error) {
//yep, it's right! all over, again!
//but now... with concurrency!
var om *game.Move
var os *game.State
var ourmove game.Move
//var whatafter game.State
appeared := make([]changefromempty, 0, 2)
disappeared := make([]changetoempty, 0, 2)
replaced := make([]changereplace, 0, 1)
for oac := range game.AMFT {
prev := bef.Board.GPos(game.Pos(oac))
next := aft.GPos(board.Pos(oac))
if prev.Empty() && next.NotEmpty {
appeared = append(appeared, changefromempty{next.Piece, board.Pos(oac)})
} else if next.Empty() && prev.NotEmpty {
disappeared = append(disappeared, changetoempty{prev.Fig, game.Pos(oac)})
} else if next.NotEmpty && prev.NotEmpty && !(next.Piece.Equal(&prev.Fig)) {
replaced = append(replaced, changereplace{prev.Fig, next.Piece, board.Pos(oac)})
} else {
//panic([2]game.Board{*bef.Board, *aft})
//panic("replacementpanic1")
}
}
if len(replaced) > 1 {
return om, os, IllegalMoveDetected{"Too many replaced pieces!", "TooManyReplaced"}
}
if len(appeared) > len(disappeared) {
return om, os, IllegalMoveDetected{"More appeared than disappeared!", "MoreAppearedThanDisappeared"}
}
if (len(appeared) == 2) && (len(disappeared) == 2) && (len(replaced) == 0) {
var aking changefromempty
var dking changetoempty
if appeared[0].what.FigType == game.King {
aking = appeared[0]
} else if appeared[1].what.FigType == game.King {
aking = appeared[1]
} else {
return om, os, IllegalMoveDetected{"It ain't no castling!", "NotACastling"}
}
if disappeared[0].what.FigType == game.King {
dking = disappeared[0]
} else if disappeared[1].what.FigType == game.King {
dking = disappeared[1]
} else {
return om, os, IllegalMoveDetected{"It ain't no castling, though there was a king!", "NotACastlingButKing"}
}
ourmove = game.Move{From: dking.where, To: game.Pos(aking.where), Before: bef}
whatafter, err := ourmove.After()
if err != nil {
return &ourmove, whatafter, err
}
if !aft.Equal(whatafter.Board) {
panic("Legal move, yet the effect is different from what we've got on input???")
}
return &ourmove, whatafter, err
}
if len(disappeared) > 2 {
return om, os, IllegalMoveDetected{"More than 2 disappeared!", "MoreThanTwoDisappeared"}
}
if len(appeared) == 1 && len(disappeared) == 2 && len(replaced) == 0 && appeared[0].what.FigType == game.Pawn {
for _, j := range disappeared {
ourmove = game.Move{From: j.where, To: game.Pos(appeared[0].where), Before: bef, PawnPromotion: appeared[0].what.FigType}
whatafter, err := ourmove.After()
if err == nil {
if !aft.Equal(whatafter.Board) {
panic("Legal move, yet the effect is different from what we've got on input???")
}
}
return &ourmove, whatafter, err
}
}
if (len(appeared) > 0 || len(disappeared) > 1) && len(replaced) > 0 {
return om, os, IllegalMoveDetected{"Both (dis)appeared and been replaced!", "BothAppearDisappearAndReplace"}
}
if len(disappeared) == 1 && len(replaced) == 0 && len(appeared) == 0 {
return om, os, IllegalMoveDetected{"One disappearance with no reason!", "NoReasonDisappear"}
}
if len(disappeared) == 1 && len(replaced) == 1 {
ourmove = game.Move{From: disappeared[0].where, To: game.Pos(replaced[0].where), Before: bef, PawnPromotion: replaced[0].after.FigType}
whatafter, err := ourmove.After()
if err == nil {
if !aft.Equal(whatafter.Board) {
panic("Legal move, yet the effect is different from what we've got on input???")
}
}
return &ourmove, whatafter, err
}
if len(disappeared) == 1 && len(appeared) == 1 {
ourmove = game.Move{From: disappeared[0].where, To: game.Pos(appeared[0].where), Before: bef, PawnPromotion: appeared[0].what.FigType}
whatafter, err := ourmove.After()
if err == nil {
if !aft.Equal(whatafter.Board) {
panic("Legal move, yet the effect is different from what we've got on input???")
}
}
return &ourmove, whatafter, err
}
if len(disappeared) == 0 && len(appeared) == 0 && len(replaced) == 0 {
return om, bef, IllegalMoveDetected{"The board remains unchanged", "Unchanged"}
}
if len(disappeared) == 0 && len(appeared) == 0 && len(replaced) == 1 {
return om, os, IllegalMoveDetected{"One replacement with no reason (Note: promotion should be done in the same move)!", "NoReasonReplace"}
}
panic("None of the cases???")
}
