#!/usr/bin/env python
"""
Author: Matt Murch
Last Modified: 01/22/2017
Description: Two Player, Terminal Tic Tac Toe
"""
import random
from sys import exit

playerOne = "X"
playerTwo = "O"
board = [' ',' ',' ',' ',' ',' ',' ',' ',' ']
winningCombinations = [(0,1,2),(3,4,5),(6,7,8),(0,3,6),(1,4,7),(2,5,8),(0,4,8),(2,4,6)]

#Prints the current 3x3 board
def printBoard():
	print board[0], "|", board[1], "|", board [2], "\n", board[3], "|", board[4], "|", board[5], "\n", board[6], "|", board[7], "|", board[8]

#Resets board to be filled with ' '
def clearBoard():
	for a in range(0, len(board)):
		board[a] = ' '

#Checks if any of the winning combinations equivalent and not blank. If so, it prints that that occupant is the winner and returns true.
#If not, it checks if all 9 spaces on the board are occupied by either "X" or "O". If so, it prints a tie game and returns true. Otherwise, it returns false
def checkGameEnd():
	for a in winningCombinations:
		if board[a[0]] == board[a[1]] == board[a[2]] != ' ':
			print "\n", board[a[0]], "is the winner!"
			printBoard()
			return True
	if 9 == sum((pos == 'X' or pos == 'O') for pos in board):
		print "\nTie Game!"
		printBoard()
		return True
	else:
		return False

#Requests an input. If the input is an empty spot on the board, it returns the value. Otherwise, it prints to try again. It will loop until a valid input is given.
def getValidChoice():
	while True:
		try:
			a = input()
			if board[a] == ' ' and a >= 0:
				return a
			else:
				print "Invalid move. Try again"
		except:
			print "Invalid move. Try again"

#Prints the current board, the current player's turn, and the 'key' board. Then sets the returned value from validChoice to the current player's letter in the board.
#Then checks if the game is over. If so, returns to menu. Otherwise, recalls itself with the other player as the argument.
def playerTurn(player):
	print "______________________________________________________________"
	print "______________________________________________________________"
	printBoard()
	print "\nIt is", player, "'s turn. Enter the position you would like to mark."
	print "0 | 1 | 2\n3 | 4 | 5\n6 | 7 | 8"
	board[getValidChoice()] = player
	if checkGameEnd():
		mainMenu()
	elif player == playerOne:
		playerTurn(playerTwo)
	else:
		playerTurn(playerOne)

#Sets variable to random integer 0 or 1. If 0, calls playerOne's turn. Otherwise, calls playerTwo's turn.
def newGame():
	x = random.randint(0, 1)
	if x == 0:
		playerTurn(playerOne)
	else:
		playerTurn(playerTwo)

#Prints two options. If option 1 is input, calls a newGame. If option 2 is input, exits the program. Loops until valid input is given.
def mainMenu():
	print "TIC TAC TOE\nEnter 1: Start a New Game\nEnter 2: Quit"
	while True:
		inputValue = raw_input()
		if inputValue == "1":
			clearBoard()
			newGame()
		elif inputValue == "2":
			exit()
		else:
			print "Sorry, that is not a valid input. Try again."

if __name__ == "__main__":
	mainMenu()