Add method to watch connection state of contacts

Related to:

• briar-gtk#19 (closed)
• briar!1260 (merged)

briar_wrapper/models/contacts.py

@@ -15,6 +15,9 @@ from briar_wrapper.model import Model
 class Contacts(Model):
 
     API_ENDPOINT = "contacts/"
+    CONNECTION_EVENTS = ("ContactConnectedEvent", "ContactDisconnectedEvent")
+
+    _connections_callback = None
 
     def add_pending(self, link, alias):
         url = urljoin(BASE_HTTP_URL, self.API_ENDPOINT + "add/pending/")
@@ -32,6 +35,25 @@ class Contacts(Model):
         request = _get(url, headers=self._headers).json()
         return request['link']
 
+    def watch_connections(self, callback):
+        self._connections_callback = callback
+        signal_ids = list()
+        event_callback = self._handle_connections_callback
+        for event in self.CONNECTION_EVENTS:
+            signal_id = self._api.socket_listener.connect(event,
+                                                          event_callback)
+            signal_ids.append(signal_id)
+        return signal_ids
+
+    def _handle_connections_callback(self, message):
+        contact_id = message["data"]["contactId"]
+        if message["name"] == "ContactConnectedEvent":
+            self._connections_callback(contact_id, True)
+        elif message["name"] == "ContactDisconnectedEvent":
+            self._connections_callback(contact_id, False)
+        else:
+            raise Exception(f"Wrong event in callback: {message['name']}")
+
     def _sort_contact_list(contacts):
         contacts.sort(key=itemgetter("lastChatActivity"),
                       reverse=True)