add REST API endpoint for image retrieval; implement error handling and response formatting

app.py

@@ -14,8 +14,9 @@ import asyncio
 import psutil
 import zipfile
 from urllib.parse import urlparse
-from fastapi import FastAPI, WebSocket
+from fastapi import FastAPI, WebSocket, HTTPException
 from fastapi.websockets import WebSocketDisconnect
+from fastapi.responses import Response
 from websockets.exceptions import ConnectionClosedError
 from ultralytics import YOLO
 
@@ -121,6 +122,45 @@ def fetch_snapshot(url: str):
         logger.error(f"Exception fetching snapshot from {url}: {str(e)}")
         return None
 
+####################################################
+# REST API endpoint for image retrieval
+####################################################
+@app.get("/camera/{camera_id}/image")
+async def get_camera_image(camera_id: str):
+    """
+    Get the current frame from a camera as JPEG image
+    """
+    try:
+        with streams_lock:
+            if camera_id not in streams:
+                raise HTTPException(status_code=404, detail=f"Camera {camera_id} not found or not active")
+            
+            stream = streams[camera_id]
+            buffer = stream["buffer"]
+            
+            if buffer.empty():
+                raise HTTPException(status_code=404, detail=f"No frame available for camera {camera_id}")
+            
+            # Get the latest frame (non-blocking)
+            try:
+                frame = buffer.queue[-1]  # Get the most recent frame without removing it
+            except IndexError:
+                raise HTTPException(status_code=404, detail=f"No frame available for camera {camera_id}")
+        
+        # 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 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)}")
+
 ####################################################
 # Detection and frame processing functions
 ####################################################