Simple Pay-Later Service

As a pay later service we allow our users to buy goods from a merchant now, and then allow them to pay for those goods at a later date.

The service works inside the boundary of following simple constraints -

• Let's say that for every transaction paid through us, merchants offer us a discount.

  • For example, if the transaction amount is Rs.100, and merchant discount offered to us is 10%, we pay Rs. 90 back to the merchant.
  • The discount varies from merchant to merchant.
  • A merchant can decide to change the discount it offers to us, at any point in time.

• All users get onboarded with a credit limit, beyond which they can't transact.

  • If a transaction value crosses this credit limit, we reject the transaction.

Use Cases

There are various use cases our service is intended to fulfil -

• allow merchants to be onboarded with the amount of discounts they offer
• allow merchants to change the discount they offer
• allow users to be onboarded (name, email-id and credit-limit)
• allow a user to carry out a transaction of some amount with a merchant.
• allow a user to pay back their dues (full or partial)
• Reporting:
  • how much discount we received from a merchant till date
  • dues for a user so far
  • which users have reached their credit limit
  • total dues from all users together

CLI

Run application -

ruby simple_pay_later_service.rb sample_input.txt

sample_input.txt

new user user1 u1@users.com 300
new user user2 u2@users.com 400
new user user3 u3@users.com 500
new merchant m1 0.5%
new merchant m2 1.5%
new merchant m3 1.25%
new txn user2 m1 500
new txn user1 m2 300
new txn user1 m3 10
report users-at-credit-limit
new txn user3 m3 200
new txn user3 m3 300
report users-at-credit-limit
report discount m3
payback user3 400
report total-dues

Output

user1 (300)
user2 (400)
user3 (500)
"m1 (0.5%)"
"m2 (1.5%)"
"m3 (1.25%)"
rejected! (reason: credit limit)
Sucess!
rejected! (reason: credit limit)
user1
Sucess!
Sucess!
user1
user3
6.25
user3(dues 100)
300
400