# Transaction Validation Service

The Transaction Validation Service automatically validates unvalidated transactions against blockchain data every 5 seconds.

## Overview

The service runs as a background process that:
1. Fetches all transactions with `validated_at = NULL` from the database
2. Retrieves transaction data from the Solana blockchain using the explorer utility
3. Compares database transaction data with blockchain data
4. Updates validated transactions with `validated_at = NOW()`

## Features

- **Automatic Validation**: Runs every 5 seconds without manual intervention
- **Blockchain Verification**: Compares transaction details with actual blockchain data
- **Data Integrity**: Ensures sender, receiver, amount, and token mint addresses match
- **Rate Limiting**: Includes delays between API calls to respect blockchain API limits
- **Graceful Shutdown**: Properly stops validation when the server shuts down
- **Monitoring**: Provides status endpoints to monitor validation progress

## API Endpoints

### Get Validation Status
```
GET /validation/status
```

Returns:
```json
{
  "success": true,
  "validationService": {
    "isRunning": true,
    "hasInterval": true
  },
  "statistics": {
    "unvalidated": 5,
    "validated": 25,
    "total": 30
  }
}
```

### Start Validation Service
```
POST /validation/start
```

### Stop Validation Service
```
POST /validation/stop
```

## Validation Logic

A transaction is considered valid if:

1. **Sender Address**: Database `sender_address` matches blockchain `sender`
2. **Receiver Address**: Database `target_address` matches blockchain `receiver`
3. **Amount**: Database `amount` matches blockchain `amount`
4. **Token Mint**: Database `token_mint` matches blockchain `mint`

## Database Schema

The `transactions` table must include:
- `validated_at` field (TIMESTAMP, can be NULL)
- `created_at` field (TIMESTAMP)
- `updated_at` field (TIMESTAMP)

## Configuration

The service automatically starts when the server starts and stops when the server shuts down. It can also be manually controlled via the API endpoints.

## Error Handling

- Failed validations are logged but don't stop the service
- Blockchain API errors are handled gracefully
- Database connection issues are logged
- The service continues running even if individual validations fail

## Performance Considerations

- Processes transactions sequentially to avoid overwhelming the blockchain API
- Includes 100ms delays between individual transaction validations
- Runs every 5 seconds to balance responsiveness with API usage
- Logs validation progress for monitoring and debugging

## Testing

Run the test script to verify the service works correctly:

```bash
npx ts-node src/test-validation.ts
```

## Monitoring

Monitor the service through:
- Application logs (look for validation-related log entries)
- `/validation/status` endpoint for real-time status
- Database queries on the `validated_at` field
- Transaction counts (validated vs unvalidated)

## Troubleshooting

Common issues and solutions:

1. **Service not starting**: Check database connection and permissions
2. **No validations occurring**: Verify transactions exist with `validated_at = NULL`
3. **Validation failures**: Check blockchain API connectivity and transaction data integrity
4. **High API usage**: Consider increasing the validation interval or reducing batch sizes