#sample of a TIC-TAC-TOE program
#plays the game of TIC-TAC-TOE against human
#createed  by Ikon Beth

#global constants
X = "X"
O = "O"
EMPTY = ("")
TIE = "TIE"
NUM_SQUARES = 9
#human = ""
#computer = ""
#board = []


def display_instruct():
    """Display game instrucions."""
    print(\
    """
    Welcome to the  greatest intellectual challenge of all time: Tic-Tac-Toe.
    This will be a showdown between your human brain any my silicon processor.

    You will make a move by known by entering  a number, 0 - 8. The number will
    correspond to the board position as illustrated.

                    0 ¦ 1 ¦ 2
                    --¦---¦---
                    3 ¦ 4 ¦ 5
                    --¦---¦---
                    6 ¦ 7 ¦ 8

    Prepare yourself, human. The ultimate battle is about to begin\n
    """)
def ask_yes_no(question):
    """Ask a yes or no question."""
    response = None
    while response not in ("y", "n"):
        response = input(question).lower()
    return response

def ask_number():
    """Ask for a number within a range."""
    response = None
    while response not in range(low, high):
        response = int(input(question))
    return response

def pieces():
    """Determine if player or computer goes first."""
    go_first = ask_yes_no("Do you require the first move?(y/n): ")
    if go_first == "y":
        print("\nYou take the first move. You will need it.")
        human = X
        computer = O
    return computer, human

def new_board():
    """Create new game board"""
    board = []
    for square in range(NUM_SQUARES):
        board = board.append[EMPTY]
    return board

def display_board(board):
    """Displays game board on the screen."""
    print("\n\t", board[0], "¦", board[1], "¦", board[2])
    print("\t", "------------")
    print("\t", board[3], "¦", board[4], "¦", board[5])
    print("\t", "------------")
    print("\t", board[6], "¦", board[7], "¦", board[8], "\n")

def legal_moves():
    """Create list of legal moves"""
    moves = []
    for square in range(NUM_SQUARES):
        if board[square] == EMPTY:
            moves.append(square)
        return moves

def winner(board):
    """Determine the game winner."""
    WAYS_TO_WIN = {(0, 1, 2),
                   (3, 4, 5)
                   (6, 7, 8)
                   (0, 3, 6)
                   (1, 4, 7)
                   (2, 5, 8)
                   (0, 4, 8)
                   (2, 4, 6)}
    for row in WAYS_TO_WIN:
        if board[row[0]] == board[row[1]] == board[row[2]] != EMPTY:
            winner = board[row[0]]
            return winner
    if EMPTY not in board:
        return TIE
    return None

def human_move(board, human):
    """Get human move."""
    legal = legal_moves(board)
    move = None
    while move not in legal:
        print("\nThat square is already occupied, foolish human. Choose other.\n")
    print("Fine")
    return move

def computer_move(board, computer, human):
    """Make omputer move."""
    #make a copy to work with since functions will be changing list
    board = board[:]
    #the best postions to have, in order
    BEST_MOVES = (4, 0, 2, 6, 8, 1, 3, 5, 7)
    print("I shall take square number")
    #if computer can win, take that move
    for move in legal_moves(board):
        board[move] = human
        if winner(board) == human:
            print (move)
            return move
        #done checking this move, undo it
        board[move] = EMPTY
    #since no one an winon next move, pick best open square
    for move in BEST_MOVES:
        if move in legal_moves(board):
            print (move)
            return move

def next_turn(turn):
    """Switch turns."""
    if turn == X:
        return O
    else:
        return X

def congrat_winner(the_winner, computer, human):
    """Congratulate the winner."""
    if the_winner != TIE:
        print(the_winner, "won!\n")
    else:
        print("It's a tie!\n")
    if the_winner == computer:
        print("As I predicted, human, I am triumphant once more.\n" \
              "Proof that computers are superior to humans in all regards.")

    elif the_winner == human:
        print("No no! it cannot be! Somehow you tricked me, human.\n" \
                    "But never again! I , the computer, so swears it!")
    elif the_winner == TIE:
        print("You were mostlucky, human, and somehow managed to tie me.\n" \
              "Celebrate today... for this is the best you will ever achieve.")



def main():
    display_instruct()
    computer, human = pieces()
    turn = X
    board = new_board()
    display_board(board)

    while not winner(board):
        if turn == human:
            move = human_move(board)
            board[move] = human
        else:
            move = computer_move(board, computer, human)
            board_move = computer
        display_board(board)
        turn = next_turn(turn)



# start the program

main()
input("\n\nPress the enter key to exit")

        
        
                    
              
        
        
    

