"""
 craps.py

 rules:
   roll two dice
     if 2, 3, 12 => lose
     if 7, 11 => win
     otherwise result is "point"
   then continue to roll
     if get point you win
     if 7 => lose
     otherwise keep rolling

 Running it looks like this:

  $ python craps.py 
  -- craps odds --
  You won  49493  games out of  100000  so your odds are winning are  0.49493

 In class coding exercise | Oct 2018 | cs.marlboro.college
"""
from random import randint

DEBUG = False

def print_debug(message):
    if DEBUG:
        print("debug: ", message)

def roll(n_dice=2, sides=6):
    """ return sum of two dice """
    total = 0
    for i in range(n_dice):
        total = total + randint(1, sides)
    return total

def win_at_craps():
    """ simulate craps; return True win """
    print_debug("-- win_at_craps() --")
    first_roll = roll()
    print_debug("Your first roll is {}".format(first_roll))
    if first_roll in (7, 11):
        print_debug("You win!")
        return True
    elif first_roll in (2, 3, 12):
        print_debug("You lose! (sucker...)")
        return False
    else:
        while True:
            next_roll = roll()
            print_debug("next roll is {}".format(next_roll))
            if next_roll == first_roll:
                print_debug("You win (finally)")
                return True
            elif next_roll == 7:
                print_debug("You lose (finally)")
                return False
            
def main():
    print("-- craps odds --")
    wins = 0
    n_games = 100000
    for i in range(n_games):
        if win_at_craps():
            wins = wins + 1
    print("You won ", wins, " games out of ", n_games, \
          " so your odds are winning are ", wins/n_games)
        
if __name__ == '__main__':
    import doctest
    doctest.testmod()
    main()