# Functions go here
def int_check(question):
    """Checks users enter an integer"""

    error = "Oops - please enter an integer"

    while True:

       try:
           # Return the response if it's an integer
           response = int(input(question))

           return response

       except ValueError:
           print(error)


def not_blank(question):
    """Check that a user response is not blank"""

    while True:
        response = input(question)

        if response != "":
            return response

        print("Sorry, this can't be blank. Please try again.\n")


def string_check(question, valid_answers=('yes', 'no'),
                 num_letters=1):
    """Checks that users enter the full word
    or the first letter of a word from alist of valid responses"""

    while True:

        response = input(question).lower()

        for item in valid_answers:

            # check if the response is the entire word
            if response == item:
                return item

            # check if it's the 'n' letter
            elif response == item[:num_letters]:
                return item

        print(f"Please choose an option from {valid_ans_list}")


# Main Routine goes here

# initialise variables / non-default options for string checker
payment_ans = ('cash', 'credit')

# Ticket Price List
CHILD_PRICE = 7.50
ADULT_PRICE = 10.50
SENIOR_PRICE = 6.50

# Credit card surcharge (currently 5%)
CREDIT_SURCHARGE = 0.05

# loop for testing purpose...
while True:
    print()

    # ask user for their name (and check it's not blank)
    name = not_blank("Name: ")

    # Ask for their age and check it's between 12 and 120
    age = int_check("Age: ")

    # Output error message / success message
    if age < 12:
        print(f"{name} is too young")
        continue
    elif age > 120:
        print(f"{name} is too old")
        continue
    else:
        pass

    # ask user for payment method (cash / credit / ca / cr)
    payment_method = string_check("Payment method: ", payment_ans, 2)
    print(f"{name} has bought a ticket ({payment_method})")\

    # Output error messages / success message
    if age < 12:
        print(f"{name} is too young")
        continue

# Child ticket price is $7.50
    elif 12 <= age < 16:
        ticket_price = CHILD_PRICE

# Adult ticket ($10.50)
    elif 16 <= age < 65:
        ticket_price = ADULT_PRICE

# Senior Citizen ticket ($6.50)
    elif 65 <= age <121:
        ticket_price = SENOIR_PRICE

    else:
        print(f"{name} is too old")
        continue

# ask user for payment method (cash / credit / ca / cr)
pay_method = string_check("Payment method: ", payment_ans, 2)

if pay_method == "cash":
    surcharge = 0

# if paying by credit, calculate surcharge
else:
    surcharge = ticket_price * CREDIT_SURCHARGE

# calculate total payable...
total_to_pay = ticket_price + surcharge

print(f"{name}'s ticket cost ${ticket_price:.2f}, they paid by {payment_method}"
      f"so the surcharge is ${surcharge:.2f}\n"
      f"The total payable is ${total_to_pay:.2f}\n")