tictactoe.py

#!/usr/bin/env python3
#
import argparse

class Game(object):

    def __init__(self):
        self.board = [0 for _ in range(9)]
        self.value_dict = {1: "X", 2: "O"}
        self.turn_taker = 1
        self.triads = self.get_triads()
        self.num_turns = 0
        self.has_winner = False
        self.winner = None
        self.winning_triad = None


    def get_triads(self):
        triads = []
        # add row triads
        for i in range(3):
            triads.append([3*i + j for j in range(3)])
        # add column triads
        for c in range(3):
            triads.append([c + 3*j for j in range(3)])
        # add diagonal triads:
        triads.append([0, 4, 8])
        triads.append([2, 4, 6])

        return triads

    def check_slot_triad(self, slot_triad):
        if slot_triad[0] != 0:
            if slot_triad[0] == slot_triad[1] and slot_triad[1] == slot_triad[2]:
                return True

        return False

    def check_for_winner(self):
        for t in self.triads:
            slot_triad = [self.board[i] for i in t]
            if self.check_slot_triad(slot_triad):
                self.winner = self.value_dict[slot_triad[0]]
                self.winning_triad = t
                return True
        return False

    def get_slot_char(self, slot_index):
        slot_value = self.board[slot_index]
        if slot_value != 0:
            # slot value is not none, so return mapping of value to char
            return self.value_dict[slot_value]
        else:
            # return the index on the board
            return "%d" % slot_index


    def get_board(self):
        column_str = ""
        for slot in range(0, 9):
            if slot % 3 == 0:
                print("\t" + column_str)
                print("\t" + "-"*len(column_str))
                column_str = ""
            else:
                column_str += "|"
            column_str += self.get_slot_char(slot)

        column_str += "\n"
        print("\t" + column_str)

    def apply_turn(self, turn_taker, slot_char):
        if slot_char not in [str(i) for i in range(9)]:
            print("> Please enter a number corresponding to an empty slot.")
            return False
        slot = int(slot_char)
        if self.board[slot]:
            print("> Slot %d is already taken, please choose again." % slot)
            return False
        else:
            self.board[slot] = turn_taker
            return True

    def prompt_for_turn(self):
        input_prompt = "> %s's turn, please enter the number for an available slot: " % \
            self.value_dict[self.turn_taker]
        slot_index = input(input_prompt)
        return slot_index

    def play(self):
        while not (self.has_winner or self.num_turns == 9):
            self.get_board()
            slot_index = self.prompt_for_turn()
            if self.apply_turn(self.turn_taker, slot_index):
                self.turn_taker = 3 - self.turn_taker
                self.num_turns += 1
                winner = self.check_for_winner()
                self.has_winner = winner

        self.get_board()
        if self.has_winner:
            print("> %s Wins with combination %s!" % (self.winner, self.winning_triad))
        else:
            assert self.num_turns == 9
            print("> Game is a tie!")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="A simple, two player tic tac toe game.")
    args = parser.parse_args()
    new_game = Game()
    new_game.play()