topicActions [nfc]: Update deleteMessagesForTopic to use streamId.

This also involved changing the call to `deleteMessagesForTopic`
appropriately.
The change is done to facilitate migration to `stream_id` instead of
stream name for identifying streams.

Related: #3918

src/message/messageActionSheet.js

@@ -146,7 +146,7 @@ const muteTopic = async ({ auth, stream, topic, subscriptions }) => {
 muteTopic.title = 'Mute topic';
 muteTopic.errorMessage = 'Failed to mute topic';
 
-const deleteTopic = async ({ auth, stream, topic, dispatch, _ }) => {
+const deleteTopic = async ({ auth, stream, topic, subscriptions, dispatch, _ }) => {
   const alertTitle = _('Are you sure you want to delete the topic “{topic}”?', { topic });
   const AsyncAlert = async (): Promise<boolean> =>
     new Promise((resolve, reject) => {
@@ -173,7 +173,10 @@ const deleteTopic = async ({ auth, stream, topic, dispatch, _ }) => {
       );
     });
   if (await AsyncAlert()) {
-    await dispatch(deleteMessagesForTopic(stream, topic));
+    const sub = subscriptions.find(x => x.name === stream);
+    if (sub) {
+      await dispatch(deleteMessagesForTopic(sub.stream_id, topic));
+    }
   }
 };
 deleteTopic.title = 'Delete topic';

src/topics/topicActions.js

@@ -40,25 +40,24 @@ export const fetchTopicsForStream = (narrow: Narrow) => async (
   dispatch(fetchTopics(stream.stream_id));
 };
 
-export const deleteMessagesForTopic = (streamName: string, topic: string) => async (
+export const deleteMessagesForTopic = (streamId: number, topic: string) => async (
   dispatch: Dispatch,
   getState: GetState,
 ) => {
   const state = getState();
   const outbox = getOutbox(state);
+  const currentStream: Stream | void = getStreams(state).find(
+    (stream: Stream) => stream.stream_id === streamId,
+  );
+
   outbox.forEach((outboxMessage: Outbox) => {
     if (
       outboxMessage.type === 'stream'
-      && streamNameOfStreamMessage(outboxMessage) === streamName
+      && streamNameOfStreamMessage(outboxMessage) === currentStream?.name
       && outboxMessage.subject === topic
     ) {
       dispatch(deleteOutboxMessage(outboxMessage.id));
     }
   });
-  const currentStream: Stream | void = getStreams(state).find(
-    (stream: Stream) => stream.name === streamName,
-  );
-  if (currentStream) {
-    await api.deleteTopic(getAuth(state), currentStream.stream_id, topic);
-  }
+  await api.deleteTopic(getAuth(state), streamId, topic);
 };