Description

Node API to keep track of double-entry accounting ledgers for USD and DREAM tokens.

Dreamland project

Dreamland is a meta verse company and has a concept of games, where every user can play these games and win DREAM tokens multiple times a day. A user can win upto 5 DREAM tokens on a single day.

DREAM tokens are a virtual currency and have a real monetary value. At the end of every hour, the DREAM tokens won by the user are converted to USD by calling a third-party API that provides the rate (for this project, this value was hardcode to 15 cents per token).

In this project, there are double-entry accounting ledgers that keep track of a user's tokens and the current USD value.

API defined

The APIs defined in this repo addresses the following features (one point per API):

• Accepts that a user has won some amount of DREAM token at a particular time of a day (can be fractional tokens)
• Returns the history of DREAM tokens a user has won for the current day so far
• Returns the history of USD amounts a user has won till now (till the previous day)
• Returns the stats: sum of tokens won on the current day so far and the total value of USD a user has in his account.

Getting started

1. Clone the project and install dependencies

Clone this repository:

git clone [email protected]:davidpaley/dreamland.git

Install npm dependencies:

cd dreamland
npm install

2. Set the Database URL and create and seed the database

• Create .env file with

DB_URL=postgres://[postgresUser]:[postgresPassword]@[urlConnection]/[database]

Run the following command to create your database file.

npx prisma migrate dev

And, then, execute this for seeding the DB:

npx prisma db seed

When npx prisma migrate dev is executed against a newly created database, seeding is also triggered. The seed file in prisma/seed.ts will be executed and your database will be populated with the sample data.

3. Start the REST API server

npm run dev

The server is now running on http://localhost:3000.

Using the REST API

Postman Collection

You could import in postman this file dreamland.postman_collection.json and interact with the API.

Endpoints

GET

• /api/v1/user/:id/history: get the token history of today for a user.
• /api/v1/user/:id/usd: Fetch USD history for a user.
• /api/v1/user/:id/stats: Get the number of tokens a user won today and the amount of USD that he/she has in their account.

POST

• /api/v1/exchange: Execute the exchange of all the tokens that the users have by USDs.
• /api/v1/user/:id/assignation: Set an amount of tokens to a specific user.
  • Body:
    • tokenQuantity: Decimal (required): The amount of tokens

DATABASE

Design

How the Database populate itself

Find information here.

Data types for ledger amounts

Please, check data-types file.

Infrastructure

Please, review this document

Edge cases

Please, check this document

Technical Debt

• Add automated tests.
  • Ideally 80% coverage
  • The main thing to do would be to add integration tests for the exchange token and token assignation endpoints.
• Create a cron service with Node Cron to execute the USD exchange automatically every day at the end of every hour.
• Error tracking and actual logger (instead of console log). For doing this, I would use Sentry
• Use access tokens to access this API.
• Check edge cases file and how I would avoid them.