python-detector-worker/app.py

"""
Refactored FastAPI application using the new modular architecture.

This replaces the monolithic app.py with a clean, maintainable structure
using dependency injection and singleton managers.
"""
import logging
from contextlib import asynccontextmanager
from fastapi import FastAPI, WebSocket, HTTPException
from fastapi.responses import Response

from detector_worker.core.config import get_config_manager, validate_config
from detector_worker.core.dependency_injection import get_container
from detector_worker.core.singleton_managers import (
    ModelStateManager, StreamStateManager, SessionStateManager,
    CacheStateManager, CameraStateManager, PipelineStateManager
)
from detector_worker.communication.websocket_handler import WebSocketHandler
from detector_worker.utils.system_monitor import get_system_metrics
from detector_worker.utils.error_handler import ErrorHandler, create_logger

# Setup logging
logger = create_logger("detector_worker.main", logging.INFO)

# Global state managers (singleton instances)
model_manager = ModelStateManager()
stream_manager = StreamStateManager()
session_manager = SessionStateManager()
cache_manager = CacheStateManager()
camera_manager = CameraStateManager()
pipeline_manager = PipelineStateManager()

# Dependency injection container
container = get_container()

# Error handler
error_handler = ErrorHandler("main_app")


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Application lifespan management for startup and shutdown."""
    # Startup
    try:
        logger.info("Starting Detector Worker v2.0.0...")
        
        # Validate configuration
        config_manager = get_config_manager()
        errors = validate_config()
        
        if errors:
            logger.error(f"Configuration validation failed: {errors}")
            raise RuntimeError(f"Invalid configuration: {', '.join(errors)}")
            
        logger.info("Configuration validation passed")
        
        # Log startup information
        config = config_manager.get_all()
        logger.info(f"Max streams: {config.get('max_streams', 5)}")
        logger.info(f"Target FPS: {config.get('target_fps', 10)}")
        
        # Initialize dependency injection container
        container_stats = container.get_container().get_stats()
        logger.info(f"Dependency container initialized: {container_stats}")
        
        logger.info("Detector Worker startup complete")
        
    except Exception as e:
        logger.critical(f"Startup failed: {e}")
        raise

    # Yield control to the application
    yield

    # Shutdown
    try:
        logger.info("Shutting down Detector Worker...")
        
        # Clear all state managers
        model_manager.clear_all()
        stream_manager.clear_all()
        session_manager.clear_all()
        cache_manager.clear_all()
        camera_manager.clear_all()
        pipeline_manager.clear_all()
        
        # Clear dependency container singletons
        container.get_container().clear_singletons()
        
        logger.info("Detector Worker shutdown complete")
        
    except Exception as e:
        logger.error(f"Error during shutdown: {e}")


# Create FastAPI app with lifespan handler
app = FastAPI(
    title="Detector Worker",
    version="2.0.0",
    description="Refactored computer vision detection worker with modular architecture",
    lifespan=lifespan
)


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    """Main WebSocket endpoint for real-time communication."""
    try:
        # Create WebSocket handler using dependency injection
        ws_handler = container.resolve(WebSocketHandler)
        
        await ws_handler.handle_connection(websocket)
        
    except Exception as e:
        logger.error(f"WebSocket error: {e}")
        if not websocket.client_state.DISCONNECTED:
            await websocket.close()


@app.get("/camera/{camera_id}/image")
async def get_camera_image(camera_id: str):
    """REST endpoint to get latest frame from camera."""
    try:
        # Get latest frame from cache manager
        frame_data = cache_manager.get_latest_frame(camera_id)
        
        if frame_data is None:
            raise HTTPException(status_code=404, detail=f"No frame available for camera {camera_id}")
            
        # Return frame as image response
        return Response(
            content=frame_data,
            media_type="image/jpeg",
            headers={"Cache-Control": "no-cache, no-store, must-revalidate"}
        )
        
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error getting camera image: {e}")
        raise HTTPException(status_code=500, detail="Internal server error")


@app.get("/health")
async def health_check():
    """Health check endpoint with system metrics."""
    try:
        # Get system metrics
        system_stats = get_system_metrics()
        
        # Get state manager statistics
        stats = {
            "status": "healthy",
            "version": "2.0.0",
            "system": system_stats,
            "managers": {
                "models": model_manager.get_stats(),
                "streams": stream_manager.get_stats(),
                "sessions": session_manager.get_stats(),
                "cache": cache_manager.get_stats(),
                "cameras": camera_manager.get_stats(),
                "pipeline": pipeline_manager.get_stats()
            },
            "container": container.get_container().get_stats(),
            "errors": error_handler.get_error_stats()
        }
        
        return stats
        
    except Exception as e:
        logger.error(f"Health check failed: {e}")
        return {
            "status": "unhealthy",
            "error": str(e),
            "version": "2.0.0"
        }


@app.get("/config")
async def get_configuration():
    """Get current configuration."""
    try:
        config_manager = get_config_manager()
        return {
            "config": config_manager.get_all(),
            "validation_errors": validate_config()
        }
    except Exception as e:
        logger.error(f"Error getting configuration: {e}")
        raise HTTPException(status_code=500, detail="Internal server error")


@app.post("/config/reload")
async def reload_configuration():
    """Reload configuration from all sources."""
    try:
        config_manager = get_config_manager()
        success = config_manager.reload()
        
        if not success:
            raise HTTPException(status_code=500, detail="Failed to reload configuration")
            
        errors = validate_config()
        return {
            "success": True,
            "validation_errors": errors,
            "config": config_manager.get_all()
        }
    except Exception as e:
        logger.error(f"Error reloading configuration: {e}")
        raise HTTPException(status_code=500, detail="Internal server error")


if __name__ == "__main__":
    import uvicorn
    
    # Get configuration
    config_manager = get_config_manager()
    
    # Run the application
    uvicorn.run(
        app,
        host="0.0.0.0",
        port=8000,
        log_level="info"
    )