# Functions go here

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

    while True:
        response = input(question).strip()

        if response != "":
            return response

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


def phone_number_check(question):
    """Checks users enter an integer that is at least 7 digits long"""

    error = "Please enter a phone number at least 7 digits long (no spaces, decimals, letters, or symbols)."

    while True:
        response = input(question).strip()

        # Checks if the input is at least 7 digits long
        if response.isdigit() and len(response) >= 7:
            return response
        else:
            print(error)


def string_check(question, valid_answers=('yes', 'no'), num_letters=1):
    """Checks that users enter the full word or the 'n' letter/s of a word from a list 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 first letter
            elif response == item[:num_letters]:
                return item

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


# Loop for testing purposes
while True:
    print()
    # Ask user for their name (and check it's not blank)
    name = not_blank("Enter your name: ")

    # Ask user for pickup or delivery
    order_method = string_check("Pickup or delivery? (Note: Delivery is $11.99 extra) ", ['pickup', 'delivery'])

    # If delivery is chosen ask for phone number and address
    if order_method == "delivery":
        phone_number = phone_number_check("Phone number: ")
        address = not_blank("Delivery address: ")
    else:
        phone_number = None
        address = None