func doesMate(logger *logger.Logger, board *core.Board, depth int) core.Moves {
if depth < 0 {
return nil
}
logger = logger.Push()
// If every move leads to a mate, we are good. Return longest chain.
longest := make(core.Moves, 0, 10)
possible_moves := board.ListMoves()
if len(possible_moves) == 0 {
// We are either mated or in stalemate. We might have found a solution
if core.Is_in_check(board) {
logger.Log(fmt.Sprintf("We are mated\n%s", board))
return longest
} else {
return nil
}
}
for _, m := range possible_moves {
b := m.Perform_move(board)
more_moves := Find(logger, b, depth-1)
if more_moves == nil {
return nil
}
more_moves = append(more_moves, m)
if len(longest) < len(more_moves) {
longest = more_moves
}
}
logger.Log(fmt.Sprintf("all moves lead to mate, board=\n%s", board))
return longest
}
func Find(logger *logger.Logger, board *core.Board, depth int) core.Moves {
if depth < 0 {
return nil
}
logger = logger.Push()
possible_moves := board.ListMoves()
logger.Log(fmt.Sprintf("Entering Find, depth=%d, board=\n%s, possible=%d\n", depth, board, len(possible_moves)))
// the goal is to force ourselves into a mating position
if len(possible_moves) == 0 {
if core.Is_in_check(board) {
logger.Log(fmt.Sprintf("We are mated\n%s", board))
return make(core.Moves, 0, 10)
} else {
return nil
}
}
for _, m := range possible_moves {
// if all moves leads to a selfmate, we are good.
// todo: keep shortest chain
b := m.Perform_move(board)
logger.Log(fmt.Sprintf("played %s, board=\n%s\n", m, b))
more_moves := doesSelfMate(logger, b, depth-1)
if more_moves != nil {
logger.Log(fmt.Sprintf("all moves lead to selfmate, board=\n%s", board))
more_moves = append(more_moves, m)
return more_moves
}
}
return nil
}