from collections import defaultdict
from copy import deepcopy

E = "_"  # no pawn
O = "O"  # pawn
_ = " "  # empty space
COLS = "ABCDEFG"
ROWS = "1234567"

STARTING_BOARD = [
    [_, _, O, O, O, _, _],
    [_, _, O, O, O, _, _],
    [O, O, O, O, O, O, O],
    [O, O, O, E, O, O, O],
    [O, O, O, O, O, O, O],
    [_, _, O, O, O, _, _],
    [_, _, O, O, O, _, _],
]


def translate_rc_pos(r, c):
    return COLS[c] + ROWS[r]


def translate_pos_rc(pos):
    return ROWS.find(pos[1]), COLS.find(pos[0])


def gen_around(r, c, board):
    moves = []
    pawn = board[r][c]
    if pawn in [_, E]:
        return []
    # pawn exists
    cur_pawn = translate_rc_pos(r, c)

    # bottom pawn
    if c + 2 < len(board[r]):
        r_pawn = board[r][c + 1]
        rr_pawn = board[r][c + 2]
        if r_pawn == O and rr_pawn == E:
            next_pawn = translate_rc_pos(r, c + 2)
            moves.append(cur_pawn + next_pawn)

    # top pawn
    if c - 2 >= 0:
        r_pawn = board[r][c - 1]
        rr_pawn = board[r][c - 2]
        if r_pawn == O and rr_pawn == E:
            next_pawn = translate_rc_pos(r, c - 2)
            moves.append(cur_pawn + next_pawn)

    # right pawn
    if r + 2 < len(board):
        r_pawn = board[r + 1][c]
        rr_pawn = board[r + 2][c]
        if r_pawn == O and rr_pawn == E:
            next_pawn = translate_rc_pos(r + 2, c)
            moves.append(cur_pawn + next_pawn)

    # left pawn
    if r - 2 >= 0:
        r_pawn = board[r - 1][c]
        rr_pawn = board[r - 2][c]
        if r_pawn == O and rr_pawn == E:
            next_pawn = translate_rc_pos(r - 2, c)
            moves.append(cur_pawn + next_pawn)

    return moves


def gen_moves(board):
    moves = []
    for r, row in enumerate(board):
        for c, pawn in enumerate(row):
            if pawn == O:
                pos_moves = gen_around(r, c, board)
                moves += pos_moves

    return moves


def play_move(move, board):
    move = move.upper()
    start_pos, end_pos = move[0:2], move[2:4]
    # start row, start column; end row, end column
    sr, sc = translate_pos_rc(start_pos)
    er, ec = translate_pos_rc(end_pos)
    assert board[sr][sc] == O, "starting position is not pawn"
    assert board[er][ec] == E, "ending position is not empty"

    if ec == sc:
        if er - sr == 2:
            assert board[er - 1][ec] == O, "No pawn in between (ec==sc, er-sr)"
            board[er - 1][ec] = E
        elif sr - er == 2:
            assert board[er + 1][ec] == O, "No pawn in between (ec==sc, sr-er)"
            board[er + 1][ec] = E
        else:
            raise Exception("There must be a pawn in between.")
    elif er == sr:
        if ec - sc == 2:
            assert board[er][ec - 1] == O, "No pawn in between (er==sr, ec-sc)"
            board[er][ec - 1] = E
        elif sc - ec == 2:
            assert board[er][ec + 1] == O, "No pawn in between (er==sr, sc-ec)"
            board[er][ec + 1] = E
        else:
            raise Exception("There must be a pawn in between.")
    else:
        raise Exception("You can only jump 1.")

    board[sr][sc] = E
    board[er][ec] = O
    return board


def undo_move(move, board):
    move = move.upper()
    start_pos, end_pos = move[2:4], move[0:2]
    sr, sc = translate_pos_rc(start_pos)
    er, ec = translate_pos_rc(end_pos)
    assert board[sr][sc] == O, "starting position is not pawn"
    assert board[er][ec] == E, "ending position is not empty"

    if ec == sc:
        if er - sr == 2:
            assert board[er - 1][ec] == E, "pawn in between (ec==sc, er-sr)"
            board[er - 1][ec] = O
        elif sr - er == 2:
            assert board[er + 1][ec] == E, "pawn in between (ec==sc, sr-er)"
            board[er + 1][ec] = O
        else:
            raise Exception("There must NOT be a pawn in between.")
    elif er == sr:
        if ec - sc == 2:
            assert board[er][ec - 1] == E, "pawn in between (er==sr, ec-sc)"
            board[er][ec - 1] = O
        elif sc - ec == 2:
            assert board[er][ec + 1] == E, "pawn in between (er==sr, sc-ec)"
            board[er][ec + 1] = O
        else:
            raise Exception("There must NOT be a pawn in between.")
    else:
        raise Exception("You can only jump 1.")

    board[sr][sc] = E
    board[er][ec] = O
    return board


def print_board(board):
    print("  ", end="")
    for r in COLS:
        print(" ", r, " ", end="")
    print()
    for c, row in zip(ROWS, board):
        print(c, row, end="")
        print()


def count_pawns(board):
    count = 0
    for row in board:
        for pawn in row:
            if pawn == O:
                count += 1
    return count


def play():
    moves_this_game = []
    stat = dict(
        moves=defaultdict(int),
        num_moves=0,
    )
    board = deepcopy(STARTING_BOARD)
    i = 0
    while True:
        print("MOVE: {}".format(i))
        print_board(board)
        moves = gen_moves(board)
        stat["moves"][len(moves)] += 1
        print("MOVES: {}".format(moves))
        if len(moves) == 0:
            print("No valid moves left")
            break
        # this_move = random.choice(moves)\
        # print("Chose Move: {}".format(this_move))
        this_move = input("> ")
        moves_this_game.append(this_move)
        try:
            board = play_move(this_move, board)
        except Exception as e:
            print("invalid move")
            print(e)
            continue
        i += 1
    stat["num_moves"] = i
    return board, moves_this_game, stat


def main_play():
    game_no = 1
    gauss = defaultdict(int)
    while True:
        board, moves_this_game, stat = play()
        count = count_pawns(board)
        # print("{} Left pawns: {} | {} | {}".format(game_no, count, stat["num_moves"], sorted([(a,b) for a, b in stat['moves'].items()], key=lambda x: x[1], reverse=True)))
        print("{} Left pawns: {}".format(game_no, count))
        gauss[count] += 1
        game_no += 1
        if count == 1:
            print("Moves this game: {}".format(moves_this_game))
            print("FINISHED!")
            break


HASHES = {}


def rot_board(board):
    A = deepcopy(board)
    N = len(A[0])
    for i in range(N // 2):
        for j in range(i, N - i - 1):
            temp = A[i][j]
            A[i][j] = A[N - 1 - j][i]
            A[N - 1 - j][i] = A[N - 1 - i][N - 1 - j]
            A[N - 1 - i][N - 1 - j] = A[j][N - 1 - i]
            A[j][N - 1 - i] = temp
    return A


def hash_board(board):
    the_hash, cnt = "", 0
    prev_cell = None
    for row in board:
        for cell in row:
            if cell == _:
                continue
            if prev_cell is not None and prev_cell != cell:
                the_hash += "{}{}|".format(cnt, prev_cell)
                cnt = 0
            prev_cell = cell
            cnt += 1
    if cnt != 0:
        the_hash += "{}{}".format(cnt, prev_cell)
    return the_hash


def rot_hash_board(board):
    value = len(HASHES)
    for i in range(4):
        hash0 = hash_board(board)
        HASHES[hash0] = value
        board = rot_board(board)


class Node(object):
    def __init__(self, board, move, parent_node):
        self.parent = parent_node
        self.board = board
        self.move = move

        if self.parent:
            self.moves = self.parent.moves + [move]
        else:
            if move:
                self.moves = [move]
            else:
                self.moves = []
        self.visited = False
        self.complete = False

        self.children = gen_moves(self.board)


def iterative_main():
    board = deepcopy(STARTING_BOARD)
    moves_this_game = []
    while True:
        moves = gen_moves(board)
        if len(moves) <= 0:
            print("finished")
            pawns = count_pawns(board)
            if pawns == 1:
                print(moves_this_game)
                break
            print_board(board)
            print(moves_this_game)
            rot_hash_board(board)

            this_move = moves_this_game[-1]
            board = undo_move(this_move, board)
        else:
            this_move = moves[0]
            moves_this_game.append(this_move)
            board = play_move(this_move, board)


def main():
    root = Node(board=STARTING_BOARD, move=None, parent_node=None)
    node = root
    while True:
        if len(node.moves) == 0:
            pawns_left = count_pawns(node.board)
            if pawns_left == 1:
                print("WIN")
                break
            else:
                # backtrack
                node.visited = True
                board = undo_move(node.move, node.board)
        else:
            # there is at least one move
            move = moves[0]
            new_board = play_move(move, node.board)
            node = Node(new_board, move, node)


if __name__ == "__main__":
    main()