board.shl

use "constants.shl"

structure Board
    has dummy = 0
    has squares = []
    has turn = WHITE
    has castling = { "WK": yes, "WQ": yes, "BK": yes, "BQ": yes }
    has ep_square = 0 - 1
    has halfmove = 0
    has fullmove = 1
    has history = []

    to get_king_square color
        for i in range 0 64
            p = squares[i]
            if p != EMPTY and get_piece_type(p) == KING and get_piece_color(p) == color
                give i
        give 0 - 1

    to reset
        squares = []
        repeat 64 times
            add EMPTY to squares



        squares[0] = ROOK + BLACK
        squares[1] = KNIGHT + BLACK
        squares[2] = BISHOP + BLACK
        squares[3] = QUEEN + BLACK
        squares[4] = KING + BLACK
        squares[5] = BISHOP + BLACK
        squares[6] = KNIGHT + BLACK
        squares[7] = ROOK + BLACK
        for i in range 8 16
            squares[i] = PAWN + BLACK


        for i in range 48 56
            squares[i] = PAWN + WHITE
        squares[56] = ROOK + WHITE
        squares[57] = KNIGHT + WHITE
        squares[58] = BISHOP + WHITE
        squares[59] = QUEEN + WHITE
        squares[60] = KING + WHITE
        squares[61] = BISHOP + WHITE
        squares[62] = KNIGHT + WHITE
        squares[63] = ROOK + WHITE

        turn = WHITE
        ep_square = 0 - 1
        halfmove = 0
        fullmove = 1
        history = []

    to set_fen fen_str
        squares = []
        repeat 64 times
            add EMPTY to squares

        history = []


        parts = split(fen_str)
        if empty(parts)
            give no

        placement = parts[0]
        row = 0
        col = 0
        n = len(placement)
        for i in range 0 n
            char_val = placement[i]
            if char_val == "/"
                row = row + 1
                col = 0
            elif char_val == "1" or char_val == "2" or char_val == "3" or char_val == "4" or char_val == "5" or char_val == "6" or char_val == "7" or char_val == "8"
                col = col + int(char_val)
            else
                piece = EMPTY
                if char_val == "p"
                    piece = PAWN + BLACK
                elif char_val == "n"
                    piece = KNIGHT + BLACK
                elif char_val == "b"
                    piece = BISHOP + BLACK
                elif char_val == "r"
                    piece = ROOK + BLACK
                elif char_val == "q"
                    piece = QUEEN + BLACK
                elif char_val == "k"
                    piece = KING + BLACK
                elif char_val == "P"
                    piece = PAWN + WHITE
                elif char_val == "N"
                    piece = KNIGHT + WHITE
                elif char_val == "B"
                    piece = BISHOP + WHITE
                elif char_val == "R"
                    piece = ROOK + WHITE
                elif char_val == "Q"
                    piece = QUEEN + WHITE
                elif char_val == "K"
                    piece = KING + WHITE

                squares[row * 8 + col] = piece
                col = col + 1

        turn = WHITE
        if len(parts) > 1
            if parts[1] == "b"
                turn = BLACK

        castling = { "WK": no, "WQ": no, "BK": no, "BQ": no }
        if len(parts) > 2
            c_rights = parts[2]
            n_c = len(c_rights)
            for i in range 0 n_c
                c_char = c_rights[i]
                if c_char == "K"
                    castling["WK"] = yes
                elif c_char == "Q"
                    castling["WQ"] = yes
                elif c_char == "k"
                    castling["BK"] = yes
                elif c_char == "q"
                    castling["BQ"] = yes

        ep_square = 0 - 1
        if len(parts) > 3
            ep_str = parts[3]
            if ep_str != "-" and len(ep_str) == 2
                f_idx = ord(ep_str[0]) - ord("a")
                r_idx = 8 - int(ep_str[1])
                ep_square = r_idx * 8 + f_idx

        halfmove = 0
        if len(parts) > 4
            halfmove = int(parts[4])

        fullmove = 1
        if len(parts) > 5
            fullmove = int(parts[5])

    to get_piece square
        give squares[square]

    to set_piece square piece
        squares[square] = piece

    to is_empty square
        give squares[square] == EMPTY

    to get_color piece
        if piece == EMPTY
            give 0
        if piece < BLACK
            give WHITE
        else
            give BLACK

    to get_type piece
        if piece == EMPTY
            give EMPTY
        if piece < BLACK
            give piece - WHITE
        else
            give piece - BLACK

    to set_turn t
        turn = t

    to set_ep_square sq
        ep_square = sq

    to make_move move
        state = {
            "turn": turn,
            "castling": { "WK": castling["WK"], "WQ": castling["WQ"], "BK": castling["BK"], "BQ": castling["BQ"] },
            "ep_square": ep_square,
            "halfmove": halfmove,
            "move": move
        }
        add state to history

        squares[move.to_sq] = move.piece
        if get_piece_type(move.piece) == PAWN
            to_row = int(move.to_sq / 8)
            if to_row == 0
                squares[move.to_sq] = QUEEN + WHITE
            elif to_row == 7
                squares[move.to_sq] = QUEEN + BLACK
        squares[move.from_sq] = EMPTY

        if move.flags == 2
            if turn == WHITE
                squares[move.to_sq + 8] = EMPTY
            else
                squares[move.to_sq - 8] = EMPTY

        if move.flags == 4
            if move.to_sq == 62
                squares[61] = ROOK + WHITE
                squares[63] = EMPTY
            elif move.to_sq == 58
                squares[59] = ROOK + WHITE
                squares[56] = EMPTY
            elif move.to_sq == 6
                squares[5] = ROOK + BLACK
                squares[7] = EMPTY
            elif move.to_sq == 2
                squares[3] = ROOK + BLACK
                squares[0] = EMPTY
        if move.from_sq == 60
            castling["WK"] = no
            castling["WQ"] = no
        elif move.from_sq == 4
            castling["BK"] = no
            castling["BQ"] = no
        if move.from_sq == 56 or move.to_sq == 56
            castling["WQ"] = no
        if move.from_sq == 63 or move.to_sq == 63
            castling["WK"] = no
        if move.from_sq == 0 or move.to_sq == 0
            castling["BQ"] = no
        if move.from_sq == 7 or move.to_sq == 7
            castling["BK"] = no

        ep_square = 0 - 1
        if get_piece_type(move.piece) == PAWN
            if abs(move.to_sq - move.from_sq) == 16
                ep_square = int((move.from_sq + move.to_sq) / 2)

        if turn == WHITE
            turn = BLACK
        else
            turn = WHITE
            fullmove = fullmove + 1

    to undo_move
        if empty(history)
            give no

        state = history.pop()

        move = state["move"]
        squares[move.from_sq] = move.piece
        squares[move.to_sq] = move.captured

        if move.flags == 2
            squares[move.to_sq] = EMPTY
            if state["turn"] == WHITE
                squares[move.to_sq + 8] = PAWN + BLACK
            else
                squares[move.to_sq - 8] = PAWN + WHITE

        if move.flags == 4
            if move.to_sq == 62
                squares[63] = ROOK + WHITE
                squares[61] = EMPTY
            elif move.to_sq == 58
                squares[56] = ROOK + WHITE
                squares[59] = EMPTY
            elif move.to_sq == 6
                squares[7] = ROOK + BLACK
                squares[5] = EMPTY
            elif move.to_sq == 2
                squares[0] = ROOK + BLACK
                squares[3] = EMPTY

        turn = state["turn"]
        castling = state["castling"]
        ep_square = state["ep_square"]
        halfmove = state["halfmove"]

        if turn == BLACK
            fullmove = fullmove - 1

        give yes

to create_board
    b = Board(0)
    b.reset()
    give b