# VoxPop Backend Services

This directory contains the backend services for the VoxPop platform.

## Services

### Identity Service

The Identity Service manages user verification and identity proofs using Privado ID's zero-knowledge proofs:
- ZKP-based citizenship verification without exposing personal data
- Self-attestation for eligibility with legal disclaimer
- Support for multiple countries through a modular provider interface
- Structured error handling for better user experience

### Perspective Service

The Perspective Service handles user perspectives and submissions:
- Submission of perspectives on policy issues
- Validation of content length and file size
- Rate limiting for unverified users
- CAPTCHA verification for unverified users
- Storage of perspectives in IPFS via Pinata
- Retrieval of perspectives from IPFS

### Feedback Service

The Feedback Service processes user feedback and stores it on the blockchain.

### Moderation Service

The Moderation Service provides content moderation capabilities:
- Content flagging by users
- AI-based content filtering
- Moderation queue management
- Economic barriers for unverified users

### Blockchain Service

The Blockchain Service handles interactions with the Polygon blockchain:
- Submit perspective hashes
- Propose insights
- Vote on insights
- Transaction retry mechanism with gas estimation
- Mock contract interactions for development

## Development Setup

### Prerequisites

- Go 1.20 or higher
- Docker and Docker Compose
- PostgreSQL (via Docker)
- Redis (via Docker)
- Access to Polygon network (Amoy testnet recommended for development)
- Private key with sufficient funds for gas fees

### Running Locally

1. Set up environment variables:
```bash
export RPC_URL=your_ethereum_rpc_url
export CONTRACT_ADDRESS=your_contract_address
export PRIVATE_KEY=your_private_key
export POLYGON_RPC=your_polygon_rpc_url
export CHAIN_ID=80002  # For Amoy testnet
```

2. Start the database and Redis with Docker Compose:
```bash
docker-compose up -d postgres redis
```

3. Run the backend:
```bash
go run main.go
```

### Docker Setup

To run the entire stack using Docker Compose:

```bash
docker-compose up -d
```

## API Endpoints

The backend exposes the following API endpoints:

### Identity

- `POST /verify` - Verify user identity using Privado ID ZKP token
- `GET /verify/disclaimer` - Get the legal disclaimer for eligibility self-attestation

### Perspective

- `POST /perspective/submit` - Submit a perspective which will be stored in IPFS
- `GET /perspective/get/:hash` - Get a perspective by its IPFS hash
- `GET /perspective/issue/:issueId` - Get all perspectives for a specific issue

### Feedback

- `POST /submit-feedback` - Submit feedback

### Moderation

- `POST /flag-content` - Flag content for moderation
- `GET /moderation-queue` - Get the moderation queue
- `POST /moderate-content` - Moderate content (approve/reject)
- `POST /submit-for-moderation` - Submit content for AI moderation

### Blockchain

- `POST /blockchain/submit-hash` - Submit a perspective hash to the blockchain
- `POST /blockchain/propose-insight` - Propose a new insight
- `POST /blockchain/vote` - Vote on an insight

## Security Considerations

- Private keys should never be committed to version control
- Use environment variables or secure secret management
- Implement rate limiting for API endpoints
- Validate all input parameters
- Use HTTPS for all API communications

## Environment Variables

The backend services require the following environment variables:

```bash
# Database configuration
DATABASE_URL=postgres://postgres:postgres@localhost:5432/voxpop?sslmode=disable

# Redis configuration
REDIS_ADDR=localhost:6379
REDIS_PASSWORD=

# Ethereum configuration
RPC_URL=https://polygon-amoy.g.alchemy.com/v2/your_api_key
CONTRACT_ADDRESS=0xYourContractAddress
PRIVATE_KEY=yourPrivateKey

# Polygon configuration for blockchain service
POLYGON_RPC=https://rpc-amoy.polygon.technology
CHAIN_ID=80002

# IPFS via Pinata configuration
PINATA_API_KEY=your_pinata_api_key
PINATA_API_SECRET=your_pinata_api_secret
PINATA_JWT=your_pinata_jwt_token
PINATA_PRODUCTION=false

# Privado ID configuration
PRIVADO_API_KEY=your_privado_api_key
PRIVADO_API_URL=https://api.privado.ai
```