# Exchange Module Technical Documentation

## Implementation Guide

### Core Components

1. **Base Collector**
   - Inherit from `BaseDataCollector`
   - Implement required abstract methods
   - Handle connection lifecycle

2. **WebSocket Client**
   - Implement exchange-specific WebSocket handling
   - Manage subscriptions and message parsing
   - Handle reconnection logic

3. **Configuration**
   - Define exchange-specific parameters
   - Implement validation rules
   - Set up default values

### Factory Implementation

The `ExchangeFactory` uses a registry pattern for dynamic collector creation:

```python
@dataclass
class ExchangeCollectorConfig:
    """Configuration for creating an exchange collector."""
    exchange: str
    symbol: str
    data_types: List[DataType]
    auto_restart: bool = True
    health_check_interval: float = 30.0
    store_raw_data: bool = True
    custom_params: Optional[Dict[str, Any]] = None

    def __post_init__(self):
        """Validate configuration after initialization."""
        if not self.exchange:
            raise InvalidConfigurationError("Exchange name cannot be empty")
        if not self.symbol:
            raise InvalidConfigurationError("Symbol cannot be empty")
        if not self.data_types:
            raise InvalidConfigurationError("At least one data type must be specified")
```

### Registry Configuration

Exchange capabilities are defined in the registry:

```python
EXCHANGE_REGISTRY = {
    'okx': {
        'collector': 'data.exchanges.okx.collector.OKXCollector',
        'websocket': 'data.exchanges.okx.websocket.OKXWebSocketClient',
        'name': 'OKX',
        'supported_pairs': ['BTC-USDT', 'ETH-USDT', 'SOL-USDT', 'DOGE-USDT', 'TON-USDT'],
        'supported_data_types': ['trade', 'orderbook', 'ticker', 'candles']
    }
}
```

### Error Handling

Custom exceptions hierarchy for precise error handling:

```python
class ExchangeError(Exception):
    """Base exception for all exchange-related errors."""
    pass

class ExchangeNotSupportedError(ExchangeError):
    """Exchange not supported/found in registry."""
    pass

class InvalidConfigurationError(ExchangeError):
    """Invalid exchange configuration."""
    pass

# Usage example:
try:
    collector = ExchangeFactory.create_collector(config)
except ExchangeNotSupportedError as e:
    logger.error(f"Exchange not supported: {e}")
except InvalidConfigurationError as e:
    logger.error(f"Invalid configuration: {e}")
```

### Logging Integration

The module uses the project's unified logging system:

```python
from utils.logger import get_logger

logger = get_logger('exchanges')

class ExchangeFactory:
    @staticmethod
    def create_collector(config: ExchangeCollectorConfig) -> BaseDataCollector:
        logger.info(f"Creating collector for {config.exchange} {config.symbol}")
        try:
            # Implementation
            logger.debug("Collector created successfully")
        except Exception as e:
            logger.error(f"Failed to create collector: {e}")
            raise
```

## Testing Guidelines

### Unit Tests

```python
def test_exchange_factory_validation():
    """Test configuration validation."""
    config = ExchangeCollectorConfig(
        exchange="okx",
        symbol="BTC-USDT",
        data_types=[DataType.TRADE]
    )
    is_valid, errors = ExchangeFactory.validate_config(config)
    assert is_valid
    assert not errors

def test_invalid_exchange():
    """Test handling of invalid exchange."""
    with pytest.raises(ExchangeNotSupportedError):
        ExchangeFactory.create_collector(
            ExchangeCollectorConfig(
                exchange="invalid",
                symbol="BTC-USDT",
                data_types=[DataType.TRADE]
            )
        )
```

### Integration Tests

```python
async def test_collector_lifecycle():
    """Test collector startup and shutdown."""
    collector = create_okx_collector("BTC-USDT")
    
    await collector.start()
    assert collector.is_running()
    
    await asyncio.sleep(5)  # Allow time for connection
    status = collector.get_status()
    assert status['status'] == 'running'
    
    await collector.stop()
    assert not collector.is_running()
```

## Performance Considerations

1. **Memory Management**
   - Implement proper cleanup in collector shutdown
   - Monitor message queue sizes
   - Clear unused subscriptions

2. **Connection Management**
   - Implement exponential backoff for reconnections
   - Monitor connection health
   - Handle rate limits properly

3. **Data Processing**
   - Process messages asynchronously
   - Batch updates when possible
   - Use efficient data structures

## Future Improvements

1. **Rate Limiting**
   ```python
   class ExchangeRateLimit:
       def __init__(self, requests_per_second: int):
           self.rate = requests_per_second
           self.tokens = requests_per_second
           self.last_update = time.time()
   ```

2. **Automatic Retries**
   ```python
   async def with_retry(func, max_retries=3, backoff_factor=1.5):
       for attempt in range(max_retries):
           try:
               return await func()
           except ExchangeError as e:
               if attempt == max_retries - 1:
                   raise
               wait_time = backoff_factor ** attempt
               await asyncio.sleep(wait_time)
   ```

3. **Exchange-Specific Validation**
   ```python
   class ExchangeValidator:
       def __init__(self, exchange_info: dict):
           self.rules = exchange_info.get('validation_rules', {})
           
       def validate_symbol(self, symbol: str) -> bool:
           pattern = self.rules.get('symbol_pattern')
           return bool(re.match(pattern, symbol))
   ```