feat: dashboard screenshot upload & retention (last 20 per client)

- Listener: subscribe to dashboard topic, forward screenshots to API
- API: store latest + last 20 timestamped screenshots per client, auto-delete older files
- Docs: updated README, TECH-CHANGELOG, and copilot-instructions for screenshot upload and retention policy

listener/listener.py

@@ -2,29 +2,73 @@ import os
 import json
 import logging
 import datetime
+import base64
+import requests
 import paho.mqtt.client as mqtt
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 from models.models import Client
+logging.basicConfig(level=logging.DEBUG, format='%(asctime)s [%(levelname)s] %(message)s')
 
+# Load .env in development
 if os.getenv("ENV", "development") == "development":
-    from dotenv import load_dotenv
-    load_dotenv(".env")
+    try:
+        from dotenv import load_dotenv
+        load_dotenv(".env")
+    except Exception:
+        pass
 
-# ENV-abhängige Konfiguration
+# ENV-dependent configuration
 ENV = os.getenv("ENV", "development")
 LOG_LEVEL = os.getenv("LOG_LEVEL", "INFO" if ENV == "production" else "DEBUG")
-DB_URL = os.environ.get(
-    "DB_CONN", "mysql+pymysql://user:password@db/infoscreen")
-
-# Logging
-logging.basicConfig(level=logging.DEBUG,
-                    format='%(asctime)s [%(levelname)s] %(message)s')
+DB_URL = os.environ.get("DB_CONN", "mysql+pymysql://user:password@db/infoscreen")
 
 # DB-Konfiguration
 engine = create_engine(DB_URL)
 Session = sessionmaker(bind=engine)
 
+# API configuration
+API_BASE_URL = os.getenv("API_BASE_URL", "http://server:8000")
+
+
+def handle_screenshot(uuid, payload):
+    """
+    Handle screenshot data received via MQTT and forward to API.
+    Payload can be either raw binary image data or JSON with base64-encoded image.
+    """
+    try:
+        # Try to parse as JSON first
+        try:
+            data = json.loads(payload.decode())
+            if "image" in data:
+                # Payload is JSON with base64 image
+                api_payload = {"image": data["image"]}
+                headers = {"Content-Type": "application/json"}
+                logging.debug(f"Forwarding base64 screenshot from {uuid} to API")
+            else:
+                logging.warning(f"Screenshot JSON from {uuid} missing 'image' field")
+                return
+        except (json.JSONDecodeError, UnicodeDecodeError):
+            # Payload is raw binary image data - encode to base64 for API
+            image_b64 = base64.b64encode(payload).decode('utf-8')
+            api_payload = {"image": image_b64}
+            headers = {"Content-Type": "application/json"}
+            logging.debug(f"Forwarding binary screenshot from {uuid} to API (encoded as base64)")
+
+        # Forward to API endpoint
+        api_url = f"{API_BASE_URL}/api/clients/{uuid}/screenshot"
+        response = requests.post(api_url, json=api_payload, headers=headers, timeout=10)
+
+        if response.status_code == 200:
+            logging.info(f"Screenshot von {uuid} erfolgreich an API weitergeleitet")
+        else:
+            logging.error(f"API returned status {response.status_code} for screenshot from {uuid}: {response.text}")
+
+    except requests.exceptions.RequestException as e:
+        logging.error(f"Failed to forward screenshot from {uuid} to API: {e}")
+    except Exception as e:
+        logging.error(f"Error handling screenshot from {uuid}: {e}")
+
 
 def on_connect(client, userdata, flags, reasonCode, properties):
     """Callback for when client connects or reconnects (API v2)."""
@@ -32,7 +76,9 @@ def on_connect(client, userdata, flags, reasonCode, properties):
         # Subscribe on every (re)connect so we don't miss heartbeats after broker restarts
         client.subscribe("infoscreen/discovery")
         client.subscribe("infoscreen/+/heartbeat")
-        logging.info(f"MQTT connected (reasonCode: {reasonCode}); (re)subscribed to discovery and heartbeats")
+        client.subscribe("infoscreen/+/screenshot")
+        client.subscribe("infoscreen/+/dashboard")
+        logging.info(f"MQTT connected (reasonCode: {reasonCode}); (re)subscribed to discovery, heartbeats, screenshots, and dashboards")
     except Exception as e:
         logging.error(f"Subscribe failed on connect: {e}")
 
@@ -42,6 +88,39 @@ def on_message(client, userdata, msg):
     logging.debug(f"Empfangene Nachricht auf Topic: {topic}")
 
     try:
+        # Dashboard-Handling (nested screenshot payload)
+        if topic.startswith("infoscreen/") and topic.endswith("/dashboard"):
+            uuid = topic.split("/")[1]
+            try:
+                payload_text = msg.payload.decode()
+                data = json.loads(payload_text)
+                shot = data.get("screenshot")
+                if isinstance(shot, dict):
+                    # Prefer 'data' field (base64) inside screenshot object
+                    image_b64 = shot.get("data")
+                    if image_b64:
+                        logging.debug(f"Dashboard enthält Screenshot für {uuid}; Weiterleitung an API")
+                        # Build a lightweight JSON with image field for API handler
+                        api_payload = json.dumps({"image": image_b64}).encode("utf-8")
+                        handle_screenshot(uuid, api_payload)
+                # Update last_alive if status present
+                if data.get("status") == "alive":
+                    session = Session()
+                    client_obj = session.query(Client).filter_by(uuid=uuid).first()
+                    if client_obj:
+                        client_obj.last_alive = datetime.datetime.now(datetime.UTC)
+                        session.commit()
+                    session.close()
+            except Exception as e:
+                logging.error(f"Fehler beim Verarbeiten des Dashboard-Payloads von {uuid}: {e}")
+            return
+
+        # Screenshot-Handling
+        if topic.startswith("infoscreen/") and topic.endswith("/screenshot"):
+            uuid = topic.split("/")[1]
+            handle_screenshot(uuid, msg.payload)
+            return
+
         # Heartbeat-Handling
         if topic.startswith("infoscreen/") and topic.endswith("/heartbeat"):
             uuid = topic.split("/")[1]

listener/requirements.txt

@@ -2,3 +2,4 @@ paho-mqtt>=2.0
 SQLAlchemy>=2.0
 pymysql
 python-dotenv
+requests>=2.31.0