import copy
import sys
from random import choice

NEXT_PLAYER = {'X':'O', 'O':'X'}

class board(list):
    WINS = ((0,1,2), (3,4,5), (6,7,8), (0, 3, 6), (1,4,7), (2,5,8), (0,4,8), (2,4,6))
    def done(self):
        for w in board.WINS:
            # print("SELF.BOARD_CHECK: ", self.board[w[0]], self.board[w[1]], self.board[w[2]])
            if self[w[0]] == self[w[1]] == self[w[2]]:
                if self[w[0]] == 'X':
                    return True, 'X'
                elif self[w[0]] == 'O':
                    return True, 'O'
        if all([x in ['O', 'X'] for x in self]) == True:
            return True, 'TIE'
        else:
            return False, 'GOING'
    def printboard(self):
        rows = self[0:3], self[3:6], self[6:]

        print("\n")
        for row  in reversed(rows):
            for cell in row:
                if isinstance(cell, int) or cell.isdigit():
                    cell = str(int(cell) + 1)
                print(cell, end=" | ")
            print("\n--------------")

    def empty_spots(self):
        return [int(i) for i in self if i.isdigit()]

class Move:
    def __init__(self, score=0, idx=0):
        self.score = score
        self.idx = idx

class Game():

    def __init__(self, player='X', difficulty=9):
        self.current_player = 'X'
        self.difficulty = difficulty
        self.board = board([str(i) for i in range(9)])
        self.AI_PLAYER = False
        # 0 1 2
        # 3 4 5
        # 6 7 8

    def change_player(self):
        self.current_player = NEXT_PLAYER[self.current_player]


    def getbestmove(self, board, player):
        done, winner = board.done()
        # print("BOARD: ", board)
        if done is True:
            if winner == self.AI_PLAYER:
                return Move(10, None)
            elif winner != 'TIE': #human
                return Move(-10, None)
            else:
                return Move(0, None)

        empty_spots = board.empty_spots()
        # print("EMPTY INDICES: ", empty_spots)
        moves = []
        for idx in empty_spots:
            newboard = copy.copy(board)
            newboard[idx] = player
            move = Move()
            move.score = self.getbestmove(newboard, NEXT_PLAYER[player]).score
            move.idx = idx
            moves.append(move)

        if player == self.AI_PLAYER:
            return max(moves, key=lambda m: m.score)
        else:
            return min(moves, key=lambda m: m.score)


    def startgame(self):
        while True:
            self.board.printboard()
            # print(self.AI_PLAYER, self.current_player)
            if self.AI_PLAYER != self.current_player:
                move = input("Enter move: ")
                self.board[int(move)-10] = self.current_player
            else:
                if self.current_player == self.AI_PLAYER:
                    if len(self.board.empty_spots()) <= self.difficulty:
                        print("AI MOVE..")
                        move = self.getbestmove(self.board, self.AI_PLAYER)
                        self.board[move.idx] = self.AI_PLAYER
                    else:
                        print("RANDOM GUESS")
                        self.board[choice(self.board.empty_spots())] = self.AI_PLAYER

            self.change_player()
            done, winner = self.board.done()

            if done is True:
                self.board.printboard()
                if winner == 'TIE':
                    print("TIE")
                else:
                    print("WINNER IS :", winner )
                break

def main():
    g = Game(player='X')
    g.AI_PLAYER = 'O'
    g.startgame()

if __name__ == '__main__':
    main()