# evenwins.py 

#
# This version of evenwins.bas based on game decscription and does *not*
# follow the source. The computer chooses marbles at random.
#
# For simplicity, global variables are used to store the game state.
# A good exercise would be to replace this with a class.
#
# The code is not short, but hopefully it is easy for beginners to understand
# and modify.
#
# Infinite loops of the style "while True:" are used to simplify some of the
# code. The "continue" keyword is used in a few places to jump back to the top
# of the loop. The "return" keyword is also used to break out of functions.
# This is generally considered poor style, but in this case it simplifies the
# code and makes it easier to read (at least in my opinion). A good exercise
# would be to remove these infinite loops, and uses of continue, to follow a
# more structured style.
#

import random

# global variables
marbles_in_middle = -1
human_marbles     = -1
computer_marbles  = -1
whose_turn        = ''

# Only called during development for serious errors that are due to mistakes
# in the program. Should never be called during a regular game.
def serious_error(msg):
    print('serious_error: ' + msg)
    exit(1)

def welcome_screen():
    print('Welcome to Even Wins!')
    print('Based on evenwins.bas from Creative Computing')
    print()
    print('Even Wins is a two-person game. You start with')
    print('27 marbles in the middle of the table.')
    print()
    print('Players alternate taking marbles from the middle.')
    print('A player can take 1 to 4 marbles on their turn, and')
    print('turns cannot be skipped. The game ends when there are')
    print('no marbles left, and the winner is the one with an even')
    print('number of marbles.')
    print()

def marbles_str(n):
    if n == 1: return '1 marble'
    return f'{n} marbles'

def choose_first_player():
    global whose_turn
    while True:
        ans = input('Do you want to play first? (y/n) --> ')
        if ans == 'y': 
            whose_turn = 'human'
            return
        elif ans == 'n':
            whose_turn = 'computer'
            return
        else:
            print()
            print('Please enter "y" if you want to play first,')
            print('or "n" if you want to play second.')
            print()

def next_player():
    global whose_turn
    if whose_turn == 'human':
        whose_turn = 'computer'
    elif whose_turn == 'computer':
        whose_turn = 'human'
    else:
        serious_error(f'play_game: unknown player {whose_turn}')

# Converts a string s to an int, if possible.
def to_int(s):
    try:
        n = int(s)
        return True, n
    except:
        return False, 0

def print_board():
    global marbles_in_middle
    global human_marbles
    global computer_marbles
    print()
    print(f' marbles in the middle: {marbles_in_middle} ' + marbles_in_middle*'*')
    print(f'    # marbles you have: {human_marbles}')
    print(f'# marbles computer has: {computer_marbles}')
    print()

def human_turn():
    global marbles_in_middle
    global human_marbles

    # get number in range 1 to min(4, marbles_in_middle)
    max_choice = min(4, marbles_in_middle)
    print("It's your turn!")
    while True:
        s = input(f'Marbles to take? (1 - {max_choice}) --> ')
        ok, n = to_int(s)
        if not ok:
            print()
            print(f'  Please enter a whole number from 1 to {max_choice}')
            print()
            continue
        if n < 1:
            print()
            print('  You must take at least 1 marble!')
            print()
            continue
        if n > max_choice:
            print()
            print(f'  You can take at most {marbles_str(max_choice)}')
            print()
            continue
        print()
        print(f'Okay, taking {marbles_str(n)} ...')
        marbles_in_middle -= n
        human_marbles += n
        return

def game_over():
    global marbles_in_middle
    global human_marbles
    global computer_marbles
    print()
    print('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!')
    print('!! All the marbles are taken: Game Over!')
    print('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!')
    print()
    print_board()
    if human_marbles % 2 == 0:
        print('You are the winner! Congratulations!')
    else:
        print('The computer wins: all hail mighty silicon!')
    print('')

def computer_turn():
    global marbles_in_middle
    global computer_marbles

    print("It's the computer's turn ...")
    max_choice = min(4, marbles_in_middle)

    # choose at random
    n = random.randint(1, max_choice)
    print(f'Computer takes {marbles_str(n)} ...')
    marbles_in_middle -= n
    computer_marbles += n

def play_game():
    global marbles_in_middle
    global human_marbles
    global computer_marbles

    # initialize the game state
    marbles_in_middle = 27
    human_marbles = 0
    computer_marbles = 0
    print_board()

    while True:
        if marbles_in_middle == 0:
            game_over()
            return
        elif whose_turn == 'human':
            human_turn()
            print_board()
            next_player()
        elif whose_turn == 'computer':
            computer_turn()
            print_board()
            next_player()
        else:
            serious_error(f'play_game: unknown player {whose_turn}')

def main():
    global whose_turn

    welcome_screen()

    while True:
        choose_first_player()
        play_game()

        # ask if the user if they want to play again
        print()
        again = input('Would you like to play again? (y/n) --> ')
        if again == 'y':
            print()
            print("Ok, let's play again ...")
            print()
        else:
            print()
            print('Ok, thanks for playing ... goodbye!')
            print()
            return

if __name__ == '__main__':
    main()
