Digital Wallet

This is a Proof of Concept for a digital wallet system. The system is built using Go and PostgreSQL. The system lets you create multiple wallets (e.g. Store Credit, Loyalty Points, Credit line Wallet, Payouts Wallet...etc.) Each user can have an account in each wallet and can perform transactions (DEBIT/CREDIT) on the account. The account holds the balance of the user in the wallet. The system also supports multiple user tiers (e.g. basic, premium, enterprise) and each tier can have different limits on the wallet balance and different exchange rates between the wallets. The system also supports automating reward programs by making event based rule based engine that can trigger transactions based on the events.

graph TD
    U[User] -->|Belongs to| TI1(Gold Tier)
    U[User] -->|Owns| A1(Account1)
    U[User] -->|Owns| A2(Account2)
    subgraph AED
        A1(Account1) -->|DEBIT| T1(Transaction1)
        A1(Account1) -->|CREDIT| T2(Transaction2)
    end
    subgraph LOYALTY
        A2(Account2) -->|DEBIT| T3(Transaction3)
        A2(Account2) -->|CREDIT| T4(Transaction4)
    end

Loading

You can see the ERD of the system in the docs/ERD.md file. and system design in the docs/system-design.md file.

Setup

Clone the repository

git clone https://github.com/abdelrahman146/digital-wallet.git

Change the directory

cd digital-wallet

Install the dependencies

go mod tidy

Create a .env by copying the .env.example file

cp .env.example .env

Make sure you have a running PostgreSQL server and update the .env file with your database credentials Run the migrations

install the migrate tool

curl -L https://github.com/golang-migrate/migrate/releases/download/$version/migrate.$os-$arch.tar.gz | tar xvz

make migrate-up

Copy the content inside docs/swagger.yaml Open postman and click on import and paste the content You can now a colleaction of all the endpoints Run the server

make dev

The server will be running on http://localhost:3401

API Documentation

The API documentation is available at http://localhost:3401/swagger/index.html

How to try the project

You can try the project by using the postman collection and the API documentation

1. You can create different users by using the POST /api/v1/backoffice/users endpoint
2. You can create user tiers such as basic, premium, and enterprise by using the POST /api/v1/backoffice/tiers endpoint
3. You can then create multiple wallets by using the POST /api/v1/backoffice/wallets endpoint
4. You can then create users accounts in each wallet by using the POST /api/v1/backoffice/accounts endpoint
5. You can then create transactions (DEBIT/CREDIT) the accounts by using the POST /api/v1/backoffice/wallet/{walletId}/transactions endpoint.
6. You can then get the balance of the account by using the GET /api/v1/backoffice/wallet/{walletId}/accounts/{account_id} endpoint

There are many other endpoints that you can try in the postman collection. You can also check the API documentation for more information. One interesting endpoint is the POST /api/v1/backoffice/wallet/{walletId}/check-integrity endpoint which checks the integrity of the wallet by calculating the sum of all the wallet accounts and the sum of the transactions and the diff should 0.

Check List

• Wallets
• Tiers
• Users & Accounts
• Transactions / Exchange / Points Expiry
• Audit and Integrity Check
• Triggers
• Programs
• User API
• Tests
• reverse a transaction by providing some metadata value to match which transaction to reverse.

To Generate Mocks

go install go.uber.org/mock/mockgen@latest

then run the following command

make gen-mocks