# Writer Service

## Overview
The Writer Service is the third and final component in the Redis pub/sub processing chain for bank-related email automation. It subscribes to messages with stage="parsed" from the Parser Service, writes the processed data to the database, and publishes a completion status with stage="written".

## Features

### Redis Integration
- Subscribes to the "parser" Redis channel for messages with stage="parsed"
- Processes parsed data and writes it to the database
- Publishes completion status to the "writer" channel with stage="written"
- Maintains message metadata and adds processing timestamps

### Database Integration
- Writes parsed transaction data to AccountRecords database
- Links transactions to build information via IBAN
- Handles duplicate detection to prevent redundant entries
- Adds date components for easier querying (year, month, day, weekday)

### Error Handling
- Robust error management for database operations
- Detailed logging of processing steps and errors
- Graceful handling of malformed messages

## Configuration

### Environment Variables
The service uses the same Redis configuration as the other services:
```
REDIS_HOST=10.10.2.15
REDIS_PORT=6379
REDIS_PASSWORD=your_strong_password_here
```

## Deployment

### Docker
The service is containerized using Docker and can be deployed using the provided Dockerfile and docker-compose configuration.

```bash
# Build and start the service
docker compose -f bank-services-docker-compose.yml up -d --build

# View logs
docker compose -f bank-services-docker-compose.yml logs -f writer_service

# Stop the service
docker compose -f bank-services-docker-compose.yml down
```

### Service Management
The `check_bank_services.sh` script provides a simple way to restart the service:

```bash
./check_bank_services.sh
```

## Architecture

### Redis Pub/Sub Chain
This service is the third and final component in a multi-stage processing chain:
1. **Email Service**: Reads emails, extracts attachments, publishes to "reader" channel with stage="red"
2. **Parser Service**: Subscribes to "reader" channel, parses Excel data, publishes to "parser" channel with stage="parsed"
3. **Writer Service** (this service): Subscribes to "parser" channel, writes data to database, publishes to "writer" channel with stage="written"

## Development

### Dependencies
- Python 3.12
- SQLAlchemy and PostgreSQL for database operations
- Redis for pub/sub messaging
- Arrow for date handling
- FastAPI for potential API endpoints