Added Scanner identification and MQTT handling

booker/scanner_announce_consumer.py

@@ -0,0 +1,77 @@
+import datetime
+import logging
+import re
+import json
+from channels.generic.websocket import AsyncWebsocketConsumer
+from booker.models import Scanner
+from asgiref.sync import sync_to_async
+from channels.db import database_sync_to_async
+from django.contrib.auth import get_user_model
+from homelog.system_user import get_system_user
+from homelog import settings
+from django.core.exceptions import ObjectDoesNotExist
+
+LOGGER = logging.getLogger(__name__)
+
+
+class ScannerAnnounceConsumer(AsyncWebsocketConsumer):
+
+    async def connect(self):
+        self.group_name = 'scanner-announce'
+        # join to group
+        await self.channel_layer.group_add(self.group_name, self.channel_name)
+        LOGGER.debug(f"send mqtt_subscribe to channel layer {settings.MQTT_CHANNEL_NAME} to answer on channel {self.group_name} (my channel is {self.channel_name})")
+        await self.channel_layer.send(settings.MQTT_CHANNEL_NAME, {
+            "type": "mqtt.subscribe",
+            "topic": "barcodescanner/+/status",
+            "group": self.group_name
+        })
+        LOGGER.debug("ScannerAnnounceConsumer initialized")
+        await self.accept()
+
+    async def receive(self, mqtt_message):
+        pass
+
+    async def disconnect(self, code):
+        await self.channel_layer.send(settings.MQTT_CHANNEL_NAME, {
+            "type": "mqtt.unsubscribe",
+            "topic": "barcodescanner/#/status",
+            "group": self.group_name
+        })
+        LOGGER.debug(f"Disconnect from scanner-announce, unsubscribing topic; code={code}")
+        await self.channel_layer.group_discard(self.group_name, self.channel_name)
+
+    async def distribute(self, event):
+        valother = event['text']
+        await self.send(text_data=valother)
+
+    @database_sync_to_async
+    def get_or_create_scanner(self, named_id, topic):
+        scanner, created = Scanner.objects.get_or_create(named_id=named_id, defaults={
+            'lwt_topic': topic,
+            'last_online_ts': datetime.datetime.now(),
+            'created_by': get_system_user(),
+            'changed_by': get_system_user()
+        })
+        if created:
+            LOGGER.debug(f"Created new scanner entry for {named_id}")
+        else:
+            LOGGER.debug(f"Updated scanner entry for {named_id}")
+        return scanner
+
+    async def mqtt_message(self, event):
+        message = event['message']
+        topic = message['topic']
+        qos = message['qos']
+        payload = message['payload']
+        print('Received a message at topic: ', topic)
+        print('with payload ', payload)
+        print('and QOS ', qos)
+        named_id = 'invalid'
+        m = re.match(r'barcodescanner\/(barcodescan-[0-9,a-f]{6})\/status', topic)
+        if m:
+            named_id = m[1]
+        await self.send(text_data=json.dumps({'message': payload, 'scanner': named_id, 'topic': topic}))
+        LOGGER.debug(f"Got MQTT message from {topic} with payload {payload}")
+        if payload == 'Online' or payload == 'online':
+            scanner = await self.get_or_create_scanner(named_id=named_id, topic=topic)