Project Overview

Building a backend system for a decentralized voting application. It will interact with the Stacks blockchain through a Clarity smart contract for voting, while the backend, built with Node.js, will handle authentication and API requests.

Setup

Prerequisites

• Node.js (v14 or higher)
• Clarinet
• Stacks CLI

Installation

1. Clone the repository:

   git clone <repository-url>
   cd <repository-directory>

2. Install backend dependencies:

   npm install

3. Set up environment variables:
   • Create a .env file in the root directory and add required variables (e.g., PRIVATE_KEY, CONTRACT_ADDRESS).

Running the Application

1. Start the backend server:

   npm start

2. Access the frontend at http://localhost:3000.

Usage

• Submit a vote via the frontend or by making a POST request to /voting/vote.
• Fetch voting results by making a GET request to /voting/results.

API Documentation

• POST /voting/vote: Submit a vote.
• GET /voting/results: Fetch current voting results.

Smart Contract

• The smart contract is defined in contracts/voting.clar.

Contributing

See CONTRIBUTING.md for guidelines.

Project Structure

Backend (Node.js) Directory Structure:

/voting-app-backend
│
├── /src
│   ├── /controllers
│   │   ├── auth.js           # Authentication-related logic
│   │   ├── vote.js           # Handles vote submission and results retrieval
│   │
│   ├── /services
│   │   ├── clarityService.js  # Interactions with the Clarity contract via stacks.js
│   │
│   ├── /routes
│   │   ├── authRoutes.js      # Routes for authentication
│   │   ├── voteRoutes.js      # Routes for vote submission and results
│   │
│   ├── app.js                # Main Express app setup
│   ├── server.js             # Entry point to start the server
│
├── /tests
│   ├── vote.test.js          # Unit and integration tests for vote functionality
│   ├── auth.test.js          # Tests for authentication logic
│
├── package.json              # Project dependencies and scripts
├── .env                      # Environment variables (API keys, Stacks network details)
├── README.md                 # Documentation
└── Dockerfile                # Optional: Docker setup for containerizing the app

Clarity Smart Contract Directory Structure:

/voting-app-contract
│
├── contracts
│   ├── voting.clar           # Clarity smart contract for vote submission and tallying
│
├── tests
│   ├── voting_test.ts        # Tests for the Clarity contract logic
│
├── README.md                 # Documentation for deploying and interacting with the smart contract

---

Feature Branches

I'll create the following branches to develop each feature independently before merging into the main branch:

1. auth-integration: Stacks Wallet OAuth2 authentication.
2. clarity-contract: Clarity smart contract for vote submission and tallying.
3. vote-submission: Backend logic for submitting votes to the blockchain.
4. vote-results: Backend logic for fetching and computing results from the blockchain.
5. documentation: Add comprehensive documentation for the project.

---

Step-by-Step Implementation

1. Setup Node.js Backend

1. Initialize the project:

   mkdir voting-app-backend
   cd voting-app-backend
   npm init -y

2. Install necessary dependencies:

   npm install express dotenv stacks network stacks transactions
   npm install --save-dev jest supertest

3. Create essential files:

   • server.js: Entry point for the application.
   • app.js: Express configuration and middleware setup.
   • Routes, controllers, and services as per the structure outlined.

4. Setup .env file for environment variables:

   • Stacks API URL: Points to the Stacks Testnet or Mainnet.
   • MongoDB connection string (optional).
   • PORT: The port for running the Node.js server.

5. Add Stacks Wallet OAuth2 authentication (auth.js):

   • Implement the logic to authenticate users through the Stacks Wallet.
   • Store the user's wallet address to ensure voting uniqueness.

2. Build the Clarity Smart Contract

1. Create the contract (voting.clar):

   • Define the following functions:
     • Submit vote: Allows each authenticated user to cast a vote.
     • Tally results: Aggregates votes after the voting period ends.

2. Deploy the contract to the Stacks Testnet:

   • Use the Stacks CLI to deploy the contract:

     clarinet deploy contracts/voting.clar

3. Test the contract using Clarinet:

   • Write unit tests for the contract logic.
   • Test the contract's behavior when multiple votes are cast and ensure the one-vote-per-user restriction is enforced.

3. Connect Backend to Clarity Smart Contract

1. Set up interactions with the contract in the clarityService.js:

   • Use stacks.js to send transactions and interact with the deployed contract.
   • Implement functions for submitting votes and retrieving results.

2. Handle vote submission (vote.js):

   • Implement the POST /vote endpoint to submit a vote to the blockchain via the Clarity smart contract.
   • Ensure each authenticated user can only vote once.

3. Retrieve results (results.js):

   • Implement the GET /results endpoint to fetch and return the voting results from the blockchain.

4. Add Testing and Continuous Integration

1. Set up unit tests for the backend:

   • Test the API endpoints using Jest and Supertest.

2. Write integration tests for the Clarity contract:

   • Ensure all edge cases are covered, such as multiple votes and invalid submissions.

Documentation for Setup

Backend Setup:

1. Clone the repository:

   git clone https://github.com/your-username/voting-app-backend.git
   cd voting-app-backend

2. Install dependencies:

   npm install

3. Create .env file with environment variables:

   PORT=3000
   STACKS_API_URL=https://stacks-node-api.testnet.stacks.co

4. Run the server:

   npm start

Clarity Smart Contract Setup:

1. Clone the repository:

   git clone https://github.com/your-username/voting-app-contract.git
   cd voting-app-contract

2. Deploy the contract:

   clarinet deploy contracts/voting.clar

3. Run the tests:

   clarinet test