def main():
    print('Welcome to the self checkout system of Wake-Mart')
    scanPrices()
    scanCoupons(total)
    clubMember()
    makePayment(balance)
    payCash()
    payDebit()

    # math section/logic
    x = scanPrices()
    y = scanCoupons()
    total = 0
    if clubMember:
        total = (x - y) - ((x - y) * 0.05)
        balance = total
        print('New subtotal after membership discount: ', balance)
    if not clubMember:
        total = x - y
        subtotal = total




def scanPrices():
    total = 0
    price = float(input('Enter price of first item [or -1 to stop]: '))
    total += price
    while price != -1:
        price = float(input('Enter price of next item[or -1 to stop]: '))
        total += price
        if price == -1:
            total += 1
            print('Subtotal: $',total)
    return total


def scanCoupons(total):
    coupontotal = 0
    coupon = float(input('Enter value of first coupon[or -1 to stop]:'))
    coupontotal += coupon
    while coupon != -1:
        coupon = float(input('Enter price of next coupon[or -1 to stop]:'))
        coupontotal += coupon
        if coupon == -1:
            coupontotal += 1
            subtotal = total - coupontotal
            print('New subtotal: $', subtotal)
    return coupontotal


def clubMember():
    member = input('Are you a member of the Wake-Mart Club?[y/n]: ')
    while member != 'y' or member != 'n':
        member = input('Invalid input. Press y for yes, n for no: ')
    if member == "y":
        return True
    elif member == "n":
        return False


def makePayment(balance):
    print('Payment Options:')
    choice = float(input('Enter 1 for cash, 2 for debit: '))
    return choice


def payCash(balance):
        print('This machine only accepts $10, $5 and $1 bills.')
        print('Balance: ', balance)
        while balance > 0:
            cash = float(input('Please enter 10, 5 or 1: '))
            balance -= cash
            if cash == 10:
                print('$10 inserted.')
                print('Balance: ', balance)
            if cash == 5:
                print('$5 inserted.')
                print('Balance: ', balance)
            if cash == 1:
                print('$1 inserted.')
                print('Balance: ', balance)
        if balance < 0:
            change = -1 * balance
            print('Change: ', change)


def payDebit(balance):
        card = float(input('Please enter 16-digit card number: '))
        pin = float(input('Please enter 4-digit pin: '))
        payment = float(input('Please enter payment amount: '))
        if payment < balance:
            payment = float(input('Payment not high enough. Please enter payment amount: '))
        if payment > balance:
            cashback = payment - balance
            print('Cash back: $', cashback)
main()