From 4902475caf8b8efa631e7cf763dc4de904325cc8 Mon Sep 17 00:00:00 2001
From: Fabio Manganiello <info@fabiomanganiello.com>
Date: Tue, 9 Mar 2021 11:50:40 +0100
Subject: [PATCH] Added active_scan mode to bluetooth.scanner backend to
 actively perform a lookup name on each device discovered at least once [see
 #174]

---
 .../backend/bluetooth/scanner/__init__.py     | 84 +++++++++++++++++--
 platypush/plugins/bluetooth/__init__.py       |  2 +-
 2 files changed, 77 insertions(+), 9 deletions(-)

diff --git a/platypush/backend/bluetooth/scanner/__init__.py b/platypush/backend/bluetooth/scanner/__init__.py
index a9eed886..60140453 100644
--- a/platypush/backend/bluetooth/scanner/__init__.py
+++ b/platypush/backend/bluetooth/scanner/__init__.py
@@ -1,6 +1,9 @@
+import time
+from threading import Thread, RLock
 from typing import Dict, Optional
 
 from platypush.backend.sensor import SensorBackend
+from platypush.context import get_plugin
 from platypush.message.event.bluetooth import BluetoothDeviceFoundEvent, BluetoothDeviceLostEvent
 
 
@@ -20,10 +23,13 @@ class BluetoothScannerBackend(SensorBackend):
 
     """
 
-    def __init__(self, device_id: Optional[int] = None, scan_duration: int = 10, **kwargs):
+    def __init__(self, device_id: Optional[int] = None, scan_duration: int = 10, active_scan: bool = False, **kwargs):
         """
         :param device_id: Bluetooth adapter ID to use (default configured on the ``bluetooth`` plugin if None).
         :param scan_duration:  How long the scan should run (default: 10 seconds).
+        :param active_scan: Set to True if you want to actively track the devices through a periodic
+            ``.lookup_name`` call. This is likely to produce a more accurate tracking, but it may negatively impact the
+            duration of devices that run on battery.
         """
         super().__init__(plugin='bluetooth', plugin_args={
             'device_id': device_id,
@@ -31,17 +37,79 @@ class BluetoothScannerBackend(SensorBackend):
         }, **kwargs)
 
         self._last_seen_devices = {}
+        self._devices_to_track = set()
+        self._tracking_thread: Optional[Thread] = None
+        self._bt_lock = RLock()
+        self.active_scan = active_scan
+        self.scan_duration = scan_duration
+
+    def _add_last_seen_device(self, dev):
+        addr = dev.pop('addr')
+        if addr not in self._last_seen_devices:
+            self.bus.post(BluetoothDeviceFoundEvent(address=addr, **dev))
+        self._last_seen_devices[addr] = {'addr': addr, **dev}
+
+        if self.active_scan and addr not in self._devices_to_track:
+            self._devices_to_track.add(addr)
+
+    def _remove_last_seen_device(self, addr: str):
+        dev = self._last_seen_devices.get(addr)
+        if not dev:
+            return
+
+        self.bus.post(BluetoothDeviceLostEvent(address=addr, **dev))
+        del self._last_seen_devices[addr]
+
+    def _addr_tracker(self, addr):
+        with self._bt_lock:
+            name = get_plugin('bluetooth').lookup_name(addr, timeout=self.scan_duration)
+
+        if name is None:
+            self._remove_last_seen_device(addr)
+        else:
+            self._add_last_seen_device({'addr': addr, 'name': name})
+
+    def _bt_tracker(self):
+        self.logger.info('Starting Bluetooth tracker')
+        while not self.should_stop():
+            trackers = []
+            for addr in self._devices_to_track:
+                tracker = Thread(target=self._addr_tracker, args=(addr,))
+                tracker.start()
+                trackers.append(tracker)
+
+            for tracker in trackers:
+                tracker.join(timeout=self.scan_duration)
+
+            time.sleep(self.scan_duration)
+
+        self.logger.info('Bluetooth tracker stopped')
+
+    def get_measurement(self):
+        with self._bt_lock:
+            return super().get_measurement()
 
     def process_data(self, data: Dict[str, dict], new_data: Dict[str, dict]):
         for addr, dev in data.items():
-            if addr not in self._last_seen_devices:
-                self.bus.post(BluetoothDeviceFoundEvent(address=dev.pop('addr'), **dev))
-            self._last_seen_devices[addr] = {'addr': addr, **dev}
+            self._add_last_seen_device(dev)
 
-        for addr, dev in self._last_seen_devices.copy().items():
-            if addr not in data:
-                self.bus.post(BluetoothDeviceLostEvent(address=dev.pop('addr'), **dev))
-                del self._last_seen_devices[addr]
+        if not self.active_scan:
+            for addr, dev in self._last_seen_devices.copy().items():
+                if addr not in data:
+                    self._remove_last_seen_device(addr)
+
+    def run(self):
+        if self.active_scan:
+            self._tracking_thread = Thread(target=self._bt_tracker)
+            self._tracking_thread.start()
+
+        super().run()
+
+    def on_stop(self):
+        super().on_stop()
+        if self._tracking_thread and self._tracking_thread.is_alive():
+            self.logger.info('Waiting for the Bluetooth tracking thread to stop')
+            self._tracking_thread.join(timeout=self.scan_duration)
 
 
 # vim:sw=4:ts=4:et:
diff --git a/platypush/plugins/bluetooth/__init__.py b/platypush/plugins/bluetooth/__init__.py
index 1d4e3ba2..0c72921e 100644
--- a/platypush/plugins/bluetooth/__init__.py
+++ b/platypush/plugins/bluetooth/__init__.py
@@ -118,7 +118,7 @@ class BluetoothPlugin(SensorPlugin):
         """
         from bluetooth import lookup_name
 
-        self.logger.info('Looking up name for device {}'.format(addr))
+        self.logger.debug('Looking up name for device {}'.format(addr))
         name = lookup_name(addr, timeout=timeout)
 
         dev = {