drafts: Save stream_id along with stream names for drafts.

This commit changes snapshot_message to store stream_id for
drafts along with stream names. The stream_id field is
undefined if draft is for empty or invalid stream name.

After this change:
  - If draft has a valid stream_id stored and it maps to
    a stream, then we display the stream name from the
    obtained stream object.

  - If draft.stream_id is undefined or doesn't map to a stream,
    then we display the name stored in draft.stream, which can
    be invalid (no stream of this name existed ever), can be
    empty and can also be name of a deactivated stream.

This change helps us to show correct stream-name for drafts
in case of renaming a stream.

Fixes #15155.

frontend_tests/node_tests/drafts.js

@@ -32,7 +32,12 @@ mock_esm("../../static/js/stream_data", {
     get_color() {
         return "#FFFFFF";
     },
+    get_sub(stream_name) {
+        assert.equal(stream_name, "stream");
+        return {stream_id: 30};
+    },
 });
+const sub_store = mock_esm("../../static/js/sub_store");
 user_settings.twenty_four_hour_time = false;
 
 const {localstorage} = zrequire("localstorage");
@@ -55,6 +60,7 @@ const compose_args_for_legacy_draft = {
 
 const draft_1 = {
     stream: "stream",
+    stream_id: 30,
     topic: "topic",
     type: "stream",
     content: "Test stream message",
@@ -214,6 +220,7 @@ test("format_drafts", ({override, mock_template}) => {
         topic: "topic",
         type: "stream",
         content: "Test stream message",
+        stream_id: 30,
         updatedAt: feb12().getTime(),
     };
     const draft_2 = {
@@ -300,6 +307,11 @@ test("format_drafts", ({override, mock_template}) => {
     const stub_render_now = timerender.render_now;
     override(timerender, "render_now", (time) => stub_render_now(time, new Date(1549958107000)));
 
+    sub_store.get = function (stream_id) {
+        assert.equal(stream_id, 30);
+        return {name: "stream"};
+    };
+
     mock_template("draft_table_body.hbs", false, (data) => {
         // Tests formatting and sorting of drafts
         assert.deepEqual(data.drafts, expected);
@@ -310,6 +322,19 @@ test("format_drafts", ({override, mock_template}) => {
     override(drafts, "set_initial_element", noop);
 
     $.create("#drafts_table .draft-row", {children: []});
+    drafts.launch();
+
+    $.clear_all_elements();
+    $.create("#drafts_table .draft-row", {children: []});
+    $("#draft_overlay").css = () => {};
+
+    sub_store.get = function (stream_id) {
+        assert.equal(stream_id, 30);
+        return {name: "stream-rename"};
+    };
+
+    expected[0].stream = "stream-rename";
+
     drafts.launch();
     timerender.__Rewire__("render_now", stub_render_now);
 });

static/js/drafts.js

@@ -20,6 +20,7 @@ import * as narrow from "./narrow";
 import * as overlays from "./overlays";
 import * as people from "./people";
 import * as stream_data from "./stream_data";
+import * as sub_store from "./sub_store";
 import * as timerender from "./timerender";
 import * as util from "./util";
 
@@ -107,6 +108,10 @@ export function snapshot_message() {
         message.private_message_recipient = recipient;
     } else {
         message.stream = compose_state.stream_name();
+        const sub = stream_data.get_sub(message.stream);
+        if (sub) {
+            message.stream_id = sub.stream_id;
+        }
         message.topic = compose_state.topic();
     }
     return message;
@@ -241,9 +246,17 @@ export function format_draft(draft) {
         // In case there is no stream for the draft, we need a
         // single space char for proper rendering of the stream label
         const space_string = new Handlebars.SafeString(" ");
-        const stream = draft.stream.length > 0 ? draft.stream : space_string;
+        let stream = draft.stream.length > 0 ? draft.stream : space_string;
+        if (draft.stream_id) {
+            const sub = sub_store.get(draft.stream_id);
+            if (sub && sub.name !== stream) {
+                stream = sub.name;
+                draft.stream = stream;
+                draft_model.editDraft(id, draft);
+            }
+        }
         let draft_topic = util.get_draft_topic(draft);
-        const draft_stream_color = stream_data.get_color(draft.stream);
+        const draft_stream_color = stream_data.get_color(stream);
 
         if (draft_topic === "") {
             draft_topic = compose.empty_topic_placeholder();