The Blockchain Service handles interactions with the Polygon blockchain for the VoxPop platform. It provides functionality for submitting perspective hashes, proposing insights, and voting on insights.

Features

Connect to Polygon PoS network (Amoy testnet)
Submit perspective hashes to the blockchain
Propose new insights
Vote on existing insights
Transaction retry mechanism with gas estimation
Mock contract interactions for development

Environment Variables

The service requires the following environment variables:

POLYGON_RPC: The RPC URL for the Polygon network (e.g., "https://rpc-amoy.polygon.technology")
PRIVATE_KEY: The private key for signing transactions (without "0x" prefix)
CONTRACT_ADDRESS: The address of the deployed VoxPop smart contract
CHAIN_ID: (Optional) The chain ID of the network (defaults to 80002 for Amoy testnet)

API Endpoints

Submit Hash

POST /blockchain/submit-hash
Content-Type: application/json

{
    "hash": "0x1234..."
}

Propose Insight

POST /blockchain/propose-insight
Content-Type: application/json

{
    "insight": "This is a new insight"
}

Vote on Insight

POST /blockchain/vote
Content-Type: application/json

{
    "insightId": "0x1234...",
    "vote": true
}

Implementation Details

Transaction Handling

Transactions are signed using the provided private key
Gas is estimated before sending transactions
Failed transactions are retried up to 3 times with a 2-second delay between attempts
Gas price is automatically suggested by the network

Contract Integration

Currently using mock contract interactions
Contract bindings will be generated from the Solidity ABI
Supports both read and write operations

Error Handling

Validates input parameters
Handles network connection issues
Provides detailed error messages
Implements graceful degradation

Development

Prerequisites

Go 1.20 or later
Access to Polygon network (Amoy testnet recommended for development)
Private key with sufficient funds for gas fees

Running Tests

go test -v ./...

Adding New Features

Add new methods to the BlockchainService struct
Implement the corresponding HTTP handlers
Add test cases in service_test.go
Update the README with new endpoint documentation

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

Future Improvements

Implement actual contract bindings
Add transaction receipt monitoring
Implement event subscription
Add support for batch transactions
Implement gas price optimization
Add support for EIP-1559 transactions
Implement transaction queue management