Dreamworld.py

"""
Work on project. Stage 2/4: Dreamworld
Project: Loan Calculator

Dreamworld

Description If you found the previous stage too easy, let's add something interesting. The best loans are probably
those with a 0% interest.

Let's make some calculations for 0% loan repayments. The user might know the period of the loan and want to calculate
the monthly payment. Or the user might know the amount of the monthly repayments and wonder how many months it will
take to repay the loan in full.

In this stage, we need to ask the user to input the loan principal amount. Then, the user should indicate what needs
to be calculated (the monthly payment amount or the number of months) and enter the required parameter. After that,
the loan calculator should output the value that the user wants to know.

Also, let’s assume we don't care about decimal places. If you get a floating-point expression as a result of the
calculation, you’ll have to do additional actions. Take a look at Example 4 where you need to calculate the monthly
payment. You know that the loan principal is 1000 and want to pay it back in 9 months. The real value of payment can
be calculated as:

payment = \dfrac{principal}{months}=\dfrac{1000}{9} =111.11...
payment= principal/months = 1000/9 = 111.11...

Of course, you can't pay that amount of money since it's a float value. You have to round up this value and make it
112. But why do we round it up instead of rounding it down? Remember that no payment can be more than the fixed
monthly payment. If your monthly repayment amount is 111, that would make the last payment 112, which is not
acceptable. If you make a monthly payment of 112, the last payment will be 104, which is fine. You can calculate the
last payment as follows:

lastpayment =principal -(periods-1)*payment = 1000 - 8*112=104
lastpayment=principal−(periods−1)∗payment=1000−8∗112=104

In this stage, you need to count the number of months or the monthly payment. If the last payment differs from the
rest, the program should display the monthly payment and the last payment.

Objectives
The behavior of your program should look like this:

Prompt a user to enter their loan principal and choose which of the two parameters they want to calculate – the
number of monthly payments or the monthly payment amount. To perform further calculations, you'll also have to ask
for the required missing value. Finally, output the results for the user. When you output how many months it will
take to repay the loan, mind the grammar of the sentence. For example, if it will take just one month to repay it,
you should output: "It will take 1 month to repay the loan" (using the singular form of "month"). In other cases,
use the plural form of "month": "It will take 7 months to repay the loan". Examples The greater-than symbol followed
by a space (> ) represents the user input. Note that this is not part of the input.

Example 1

Enter the loan principal:
> 1000
What do you want to calculate?
type "m" - for number of monthly payments,
type "p" - for the monthly payment:
> m
Enter the monthly payment:
> 150

It will take 7 months to repay the loan
Example 2

Enter the loan principal:
> 1000
What do you want to calculate?
type "m" for number of monthly payments,
type "p" for the monthly payment:
> m
Enter the monthly payment:
> 1000

It will take 1 month to repay the loan
Example 3

Enter the loan principal:
> 1000
What do you want to calculate?
type "m" for number of monthly payments,
type "p" for the monthly payment:
> p
Enter the number of months:
> 10

Your monthly payment = 100
Example 4

Enter the loan principal:
> 1000
What do you want to calculate?
type "m" for number of monthly payments,
type "p" for the monthly payment:
> p
Enter the number of months:
> 9

Your monthly payment = 112 and the last payment = 104.

"""

principal = int(input("Enter the loan principal:"))
choice = str(input("What do you want to calculate?\ntype ""m"" - for number of monthly payments,\ntype ""p""- for the "
                   "monthly payment:"))


def m_case():
    mp = int(input("Enter the monthly payment:"))
    a = (principal / mp)
    if a == 1:
        print("It will take 1 month to repay the loan")
    elif a == int(a):
        print('It will take ' + str(a) + " months to repay the loan")
    else:
        a = int(a + 1)
        print('It will take ' + str(a) + " months to repay the loan")


def p_case():
    periods = int(input("Enter the number of months:"))
    payment = principal / periods
    if payment == int(payment):
        payment = int(payment)
        print("Your monthly payment = " + str(payment))
    else:
        payment = int(payment + 1)
        lastpayment = principal - (payment * (periods - 1))
        print("Your monthly payment = " + str(payment) + " and the last payment = " + str(lastpayment) + ".")


def run():
    if choice == "m":
        m_case()
    elif choice == "p":
        p_case()
    else:
        print("Sorry you entered other than m or p.")  # Additional


run()