Feat: Scheduler implemented, WIP

backend/services/device_status_monitor.py

@@ -0,0 +1,184 @@
+"""
+Device Status Monitor
+
+Background task that monitors device reachability via SLMM polling status
+and triggers alerts when devices go offline or come back online.
+
+This service bridges SLMM's device polling with Terra-View's alert system.
+"""
+
+import asyncio
+import logging
+from datetime import datetime
+from typing import Optional, Dict
+
+from backend.database import SessionLocal
+from backend.services.slmm_client import get_slmm_client, SLMMClientError
+from backend.services.alert_service import get_alert_service
+
+logger = logging.getLogger(__name__)
+
+
+class DeviceStatusMonitor:
+    """
+    Monitors device reachability via SLMM's polling status endpoint.
+
+    Detects state transitions (online→offline, offline→online) and
+    triggers AlertService to create/resolve alerts.
+
+    Usage:
+        monitor = DeviceStatusMonitor()
+        await monitor.start()  # Start background monitoring
+        monitor.stop()  # Stop monitoring
+    """
+
+    def __init__(self, check_interval: int = 60):
+        """
+        Initialize the monitor.
+
+        Args:
+            check_interval: Seconds between status checks (default: 60)
+        """
+        self.check_interval = check_interval
+        self.running = False
+        self.task: Optional[asyncio.Task] = None
+        self.slmm_client = get_slmm_client()
+
+        # Track previous device states to detect transitions
+        self._device_states: Dict[str, bool] = {}
+
+    async def start(self):
+        """Start the monitoring background task."""
+        if self.running:
+            logger.warning("DeviceStatusMonitor is already running")
+            return
+
+        self.running = True
+        self.task = asyncio.create_task(self._monitor_loop())
+        logger.info(f"DeviceStatusMonitor started (checking every {self.check_interval}s)")
+
+    def stop(self):
+        """Stop the monitoring background task."""
+        self.running = False
+        if self.task:
+            self.task.cancel()
+        logger.info("DeviceStatusMonitor stopped")
+
+    async def _monitor_loop(self):
+        """Main monitoring loop."""
+        while self.running:
+            try:
+                await self._check_all_devices()
+            except Exception as e:
+                logger.error(f"Error in device status monitor: {e}", exc_info=True)
+
+            # Sleep in small intervals for graceful shutdown
+            for _ in range(self.check_interval):
+                if not self.running:
+                    break
+                await asyncio.sleep(1)
+
+        logger.info("DeviceStatusMonitor loop exited")
+
+    async def _check_all_devices(self):
+        """
+        Fetch polling status from SLMM and detect state transitions.
+
+        Uses GET /api/slmm/_polling/status (proxied to SLMM)
+        """
+        try:
+            # Get status from SLMM
+            status_response = await self.slmm_client.get_polling_status()
+            devices = status_response.get("devices", [])
+
+            if not devices:
+                logger.debug("No devices in polling status response")
+                return
+
+            db = SessionLocal()
+            try:
+                alert_service = get_alert_service(db)
+
+                for device in devices:
+                    unit_id = device.get("unit_id")
+                    if not unit_id:
+                        continue
+
+                    is_reachable = device.get("is_reachable", True)
+                    previous_reachable = self._device_states.get(unit_id)
+
+                    # Skip if this is the first check (no previous state)
+                    if previous_reachable is None:
+                        self._device_states[unit_id] = is_reachable
+                        logger.debug(f"Initial state for {unit_id}: reachable={is_reachable}")
+                        continue
+
+                    # Detect offline transition (was online, now offline)
+                    if previous_reachable and not is_reachable:
+                        logger.warning(f"Device {unit_id} went OFFLINE")
+                        alert_service.create_device_offline_alert(
+                            unit_id=unit_id,
+                            consecutive_failures=device.get("consecutive_failures", 0),
+                            last_error=device.get("last_error"),
+                        )
+
+                    # Detect online transition (was offline, now online)
+                    elif not previous_reachable and is_reachable:
+                        logger.info(f"Device {unit_id} came back ONLINE")
+                        alert_service.resolve_device_offline_alert(unit_id)
+
+                    # Update tracked state
+                    self._device_states[unit_id] = is_reachable
+
+                # Cleanup expired alerts while we're here
+                alert_service.cleanup_expired_alerts()
+
+            finally:
+                db.close()
+
+        except SLMMClientError as e:
+            logger.warning(f"Could not reach SLMM for status check: {e}")
+        except Exception as e:
+            logger.error(f"Error checking device status: {e}", exc_info=True)
+
+    def get_tracked_devices(self) -> Dict[str, bool]:
+        """
+        Get the current tracked device states.
+
+        Returns:
+            Dict mapping unit_id to is_reachable status
+        """
+        return dict(self._device_states)
+
+    def clear_tracked_devices(self):
+        """Clear all tracked device states (useful for testing)."""
+        self._device_states.clear()
+
+
+# Singleton instance
+_monitor_instance: Optional[DeviceStatusMonitor] = None
+
+
+def get_device_status_monitor() -> DeviceStatusMonitor:
+    """
+    Get the device status monitor singleton instance.
+
+    Returns:
+        DeviceStatusMonitor instance
+    """
+    global _monitor_instance
+    if _monitor_instance is None:
+        _monitor_instance = DeviceStatusMonitor()
+    return _monitor_instance
+
+
+async def start_device_status_monitor():
+    """Start the global device status monitor."""
+    monitor = get_device_status_monitor()
+    await monitor.start()
+
+
+def stop_device_status_monitor():
+    """Stop the global device status monitor."""
+    monitor = get_device_status_monitor()
+    monitor.stop()