Send messages with correct delivery medium

Read the default delivery medium from conversations and use it when
sending messages. This allows sending messages correctly to
conversations using alternate delivery mediums, such as Google Voice.

Fixes #53.

docs/proto.rst

@@ -360,11 +360,12 @@ Field                         Number Type             Label    Description
 DeliveryMedium
 --------------
 
-=================== ====== ===================== ======== ===========
-Field               Number Type                  Label    Description
-=================== ====== ===================== ======== ===========
-:code:`medium_type` 1      `DeliveryMediumType`_ optional            
-=================== ====== ===================== ======== ===========
+=================== ====== ===================== ======== ======================================================
+Field               Number Type                  Label    Description                                           
+=================== ====== ===================== ======== ======================================================
+:code:`medium_type` 1      `DeliveryMediumType`_ optional                                                       
+:code:`phone`       2      `Phone`_              optional Phone number to use for sending Google Voice messages.
+=================== ====== ===================== ======== ======================================================
 
 DeliveryMediumOption
 --------------------

hangups/client.py

@@ -479,7 +479,8 @@ def syncallnewevents(self, timestamp):
     @asyncio.coroutine
     def sendchatmessage(
             self, conversation_id, segments, image_id=None,
-            otr_status=hangouts_pb2.OFF_THE_RECORD_STATUS_ON_THE_RECORD):
+            otr_status=hangouts_pb2.OFF_THE_RECORD_STATUS_ON_THE_RECORD,
+            delivery_medium=None):
         """Send a chat message to a conversation.
 
         conversation_id must be a valid conversation ID. segments must be a
@@ -501,6 +502,10 @@ def sendchatmessage(
             segment_pb = hangouts_pb2.Segment()
             pblite.decode(segment_pb, segment_pblite)
             segments_pb.append(segment_pb)
+        if delivery_medium is None:
+            delivery_medium = hangouts_pb2.DeliveryMedium(
+                medium_type=hangouts_pb2.DELIVERY_MEDIUM_BABEL,
+            )
 
         request = hangouts_pb2.SendChatMessageRequest(
             request_header=self._get_request_header_pb(),
@@ -513,9 +518,7 @@ def sendchatmessage(
                 ),
                 client_generated_id=self.get_client_generated_id(),
                 expected_otr=otr_status,
-                delivery_medium=hangouts_pb2.DeliveryMedium(
-                    medium_type=hangouts_pb2.DELIVERY_MEDIUM_BABEL,
-                ),
+                delivery_medium=delivery_medium,
                 event_type=hangouts_pb2.EVENT_TYPE_REGULAR_CHAT_MESSAGE,
             ),
         )

hangups/conversation.py

@@ -53,9 +53,20 @@ def _on_watermark_notification(self, notif):
 
     def update_conversation(self, conversation):
         """Update the internal Conversation."""
-        # When latest_read_timestamp is 0, this seems to indicate no change
-        # from the previous value. Word around this by saving and restoring the
-        # previous value.
+        # StateUpdate.conversation is actually a delta; fields that aren't
+        # specified are assumed to be unchanged. Until this class is
+        # refactored, hide this by saving and restoring previous values where
+        # necessary.
+
+        # delivery_medium_option
+        new_state = conversation.self_conversation_state
+        if len(new_state.delivery_medium_option) == 0:
+            old_state = self._conversation.self_conversation_state
+            new_state.delivery_medium_option.extend(
+                old_state.delivery_medium_option
+            )
+
+        # latest_read_timestamp
         old_timestamp = self.latest_read_timestamp
         self._conversation = conversation
         if parsers.to_timestamp(self.latest_read_timestamp) == 0:
@@ -98,6 +109,27 @@ def get_user(self, user_id):
         """Return the User instance with the given UserID."""
         return self._user_list.get_user(user_id)
 
+    def _get_default_delivery_medium(self):
+        """Return default DeliveryMedium to use for sending messages.
+
+        Use the first option, or an option that's marked as the current
+        default.
+        """
+        medium_options = (
+            self._conversation.self_conversation_state.delivery_medium_option
+        )
+        try:
+            default_medium = medium_options[0].delivery_medium
+        except IndexError:
+            logger.warning('Conversation %r has no delivery medium')
+            default_medium = hangouts_pb2.DeliveryMedium(
+                medium_type=hangouts_pb2.DELIVERY_MEDIUM_BABEL
+            )
+        for medium_option in medium_options:
+            if medium_option.current_default:
+                default_medium = medium_option.delivery_medium
+        return default_medium
+
     @asyncio.coroutine
     def send_message(self, segments, image_file=None, image_id=None):
         """Send a message to this conversation.
@@ -131,7 +163,8 @@ def send_message(self, segments, image_file=None, image_id=None):
             try:
                 yield from self._client.sendchatmessage(
                     self.id_, [seg.serialize() for seg in segments],
-                    image_id=image_id, otr_status=otr_status
+                    image_id=image_id, otr_status=otr_status,
+                    delivery_medium=self._get_default_delivery_medium()
                 )
             except exceptions.NetworkError as e:
                 logger.warning('Failed to send message: {}'.format(e))

hangups/hangouts.proto

@@ -428,9 +428,8 @@ enum DeliveryMediumType {
 
 message DeliveryMedium {
   optional DeliveryMediumType medium_type = 1;
-
-  // TODO: add this for sending google voice messages?
-  //optional Phone phone = 2;
+  // Phone number to use for sending Google Voice messages.
+  optional Phone phone = 2;
 }
 
 message DeliveryMediumOption {