Reward Points Exercise

Simple Flask app that accepts HTTP requests and returns responses based on conditions outlined in the section below.

Premise

• Every user has an accounts that stores points per payers.
• Payer submit transactions.
  • Each transaction should include payer, points,timestamp information.
  • Transactions are not necessarily added in the order of their transaction timestamps.
  • A transaction will be added to earnings list (or withdraws list) if positive points (or negative points).
  • Transactions are stored in memory on the back end.
  • A payer's total points can go below 0 in the middle of adding transactions, but it won't be below 0 after adding all transactions.
• The user can spend points.
  • The user's total points can't go below 0.
  • When spending points, the oldest points are spent first based on their transaction's timestamp, regardless of payer.

Usage

1. You must have python and pip installed.

2. Clone repo locally

   git clone https://github.com/xuxiaqing2011/Reward-Points
   

3. Go to the project's root directory

   cd /my/path/to/Reward-Points
   

4. Install packages

   pip install -r requirements.txt
   

5. Start the server

   python app.py
   

6. Verify the app is running by visiting http://localhost:5000/. You should see the following greeting:
   "Home Page"

Making API calls

NOTE Because this web service doesn't use any durable data store, there will be no data in the backend whenever the sever is started, which means:

• The user will initially have a balance of zero.
• accounts, earnings, withdraws will be empty.

From any curl tool such as Postman or a basic shell curl command, make requests to http://localhost:5000/ENDPOINT where ENDPOINT is one of the routes described below. For POST requests, such as adding a transaction or spending points, use JSON schema.

Routes

Currently only the following routes are implemented:

1. Show Points: /check_balance

   GET http://localhost:5000/check_balance
   

   This route gives the user accounts information, which reveals points per payer.

2. Add points: /add_transactions

   POST http://localhost:5000/add_transactions
   Example JSON: { "payer": "DANNON", "points": 1000, "timestamp": "2020-11-02T14:00:00Z" }
   

   NOTE: Transactions with positive points are added to earnings and inserted at the right place based on timestamp (later -> early). Transactions with negative points are added to withdraws, and these transactions are used to negate the positive points before spending.

3. Spend points: /spend_points

   POST http://localhost:5000/spend_points
   Example JSON: { "points": 5000 }
   

   NOTE: Spending uses positive points from the earliest transaction in earnings list. But before that, we will first check if the same payer appears in the withdraws list (meaning payer withdraws points). If they do, full/part of the positive points are used to negate the nagetive points. Any remaining positive points will be used for spending.

Running Tests

Run tests in test_app.py from the project's main directory:

pytest

Tests check that the app should:

• GET all points by payer
• POST a new transaction
• POST spend points available
• NOT POST spend a negative/unavailable amount of points