python-detector-worker/app.py

"""
Detector Worker - Main FastAPI Application
Refactored modular architecture for computer vision pipeline processing.
"""
import json
import logging
import multiprocessing as mp
import os
import time
from contextlib import asynccontextmanager
from fastapi import FastAPI, WebSocket, HTTPException, Request
from fastapi.responses import Response

# Set multiprocessing start method to 'spawn' for uvicorn compatibility
if __name__ != "__main__":  # When imported by uvicorn
    try:
        mp.set_start_method('spawn', force=True)
    except RuntimeError:
        pass  # Already set

# Import new modular communication system
from core.communication.websocket import websocket_endpoint
from core.communication.state import worker_state

# Import and setup main process logging
from core.logging.session_logger import setup_main_process_logging

# Configure main process logging
setup_main_process_logging("logs")

logger = logging.getLogger("detector_worker")
logger.setLevel(logging.DEBUG)

# Store cached frames for REST API access (temporary storage)
latest_frames = {}

# Lifespan event handler (modern FastAPI approach)
@asynccontextmanager
async def lifespan(app: FastAPI):
    """Application lifespan management."""
    # Startup
    logger.info("Detector Worker started successfully")
    logger.info("WebSocket endpoint available at: ws://0.0.0.0:8001/")
    logger.info("HTTP camera endpoint available at: http://0.0.0.0:8001/camera/{camera_id}/image")
    logger.info("Health check available at: http://0.0.0.0:8001/health")
    logger.info("Ready and waiting for backend WebSocket connections")

    yield

    # Shutdown
    logger.info("Detector Worker shutting down...")
    # Clear all state
    worker_state.set_subscriptions([])
    worker_state.session_ids.clear()
    worker_state.progression_stages.clear()
    latest_frames.clear()
    logger.info("Detector Worker shutdown complete")

# Create FastAPI application with detailed WebSocket logging
app = FastAPI(title="Detector Worker", version="2.0.0", lifespan=lifespan)

# Add middleware to log all requests
@app.middleware("http")
async def log_requests(request, call_next):
    start_time = time.time()
    response = await call_next(request)
    process_time = time.time() - start_time
    logger.debug(f"HTTP {request.method} {request.url} - {response.status_code} ({process_time:.3f}s)")
    return response

# Load configuration
config_path = "config.json"
if os.path.exists(config_path):
    with open(config_path, "r") as f:
        config = json.load(f)
    logger.info(f"Loaded configuration from {config_path}")
else:
    # Default configuration
    config = {
        "poll_interval_ms": 100,
        "reconnect_interval_sec": 5,
        "target_fps": 10,
        "max_streams": 20,
        "max_retries": 3
    }
    logger.warning(f"Configuration file {config_path} not found, using defaults")

# Ensure models directory exists
os.makedirs("models", exist_ok=True)
logger.info("Ensured models directory exists")

# Stream manager is already initialized with multiprocessing in manager.py
# (shared_stream_manager is created with max_streams=20 from config)
logger.info(f"Using pre-configured stream manager with max_streams={config.get('max_streams', 20)}")

# Store cached frames for REST API access (temporary storage)
latest_frames = {}

logger.info("Starting detector worker application (refactored)")
logger.info(f"Configuration: Target FPS: {config.get('target_fps', 10)}, "
           f"Max streams: {config.get('max_streams', 5)}, "
           f"Max retries: {config.get('max_retries', 3)}")


@app.websocket("/")
async def websocket_handler(websocket: WebSocket):
    """
    Main WebSocket endpoint for backend communication.
    Handles all protocol messages according to worker.md specification.
    """
    client_info = f"{websocket.client.host}:{websocket.client.port}" if websocket.client else "unknown"
    logger.info(f"[RX ← Backend] New WebSocket connection request from {client_info}")

    try:
        await websocket_endpoint(websocket)
    except Exception as e:
        logger.error(f"WebSocket handler error for {client_info}: {e}", exc_info=True)


@app.get("/camera/{camera_id}/image")
async def get_camera_image(camera_id: str):
    """
    HTTP endpoint to retrieve the latest frame from a camera as JPEG image.

    This endpoint is preserved for backward compatibility with existing systems.

    Args:
        camera_id: The subscription identifier (e.g., "display-001;cam-001")

    Returns:
        JPEG image as binary response

    Raises:
        HTTPException: 404 if camera not found or no frame available
        HTTPException: 500 if encoding fails
    """
    try:
        from urllib.parse import unquote

        # URL decode the camera_id to handle encoded characters
        original_camera_id = camera_id
        camera_id = unquote(camera_id)
        logger.debug(f"REST API request: original='{original_camera_id}', decoded='{camera_id}'")

        # Check if camera is in active subscriptions
        subscription = worker_state.get_subscription(camera_id)
        if not subscription:
            logger.warning(f"Camera ID '{camera_id}' not found in active subscriptions")
            available_cameras = list(worker_state.subscriptions.keys())
            logger.debug(f"Available cameras: {available_cameras}")
            raise HTTPException(
                status_code=404,
                detail=f"Camera {camera_id} not found or not active"
            )

        # Check if we have a cached frame for this camera
        if camera_id not in latest_frames:
            logger.warning(f"No cached frame available for camera '{camera_id}'")
            raise HTTPException(
                status_code=404,
                detail=f"No frame available for camera {camera_id}"
            )

        frame = latest_frames[camera_id]
        logger.debug(f"Retrieved cached frame for camera '{camera_id}', shape: {frame.shape}")

        # TODO: This import will be replaced in Phase 3 (Streaming System)
        # For now, we need to handle the case where OpenCV is not available
        try:
            import cv2
            # Encode frame as JPEG
            success, buffer_img = cv2.imencode('.jpg', frame, [cv2.IMWRITE_JPEG_QUALITY, 85])
            if not success:
                raise HTTPException(status_code=500, detail="Failed to encode image as JPEG")

            # Return image as binary response
            return Response(content=buffer_img.tobytes(), media_type="image/jpeg")
        except ImportError:
            logger.error("OpenCV not available for image encoding")
            raise HTTPException(status_code=500, detail="Image processing not available")

    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error retrieving image for camera {camera_id}: {str(e)}", exc_info=True)
        raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")


@app.get("/health")
async def health_check():
    """Health check endpoint for monitoring."""
    return {
        "status": "healthy",
        "version": "2.0.0",
        "active_subscriptions": len(worker_state.subscriptions),
        "active_sessions": len(worker_state.session_ids)
    }




if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=8001)