typing api: Use recipients format based on server version.

Zulip server versions >= 2.0.0-rc1 (zulip/zulip@2f634f8c0) require
user ID arrays in the 'to' argument for the typing endpoint, whereas
we currently send email arrays.

Check the Zulip version and use the appropriate format of the
argument, i.e., for versions >= 2.0.0-rc1 or when the Zulip server
version is undetermined [1], use user ID arrays, otherwise, use
email arrays.

[1] The server started providing its version as early as
zulip/zulip@d9b10727fa (released in 1.6.0, in 2017-06). It's more
likely that we failed to parse a new, exotic version-string format
than that someone's actually trying to connect to a Zulip server
that doesn't provide one.

Fixes #3732.

Author: agrawal-d

src/users/usersActions.js

@@ -1,12 +1,13 @@
 /* @flow strict-local */
 import * as typing_status from '@zulip/shared/js/typing_status';
 
-import type { Dispatch, GetState, Narrow } from '../types';
+import type { Auth, Account, Dispatch, GetState, GlobalState, Narrow } from '../types';
 import * as api from '../api';
 import { PRESENCE_RESPONSE } from '../actionConstants';
-import { getAuth, tryGetAuth } from '../selectors';
+import { getAuth, tryGetAuth, getActiveAccount, getServerVersion } from '../selectors';
 import { isPrivateOrGroupNarrow, caseNarrowPartial } from '../utils/narrow';
-import { getAllUsersByEmail } from './userSelectors';
+import { getAllUsersByEmail, getUserForId } from './userSelectors';
+import { ZulipVersion } from '../utils/zulipVersion';
 
 export const reportPresence = (isActive: boolean = true, newUserInput: boolean = false) => async (
   dispatch: Dispatch,
@@ -25,17 +26,40 @@ export const reportPresence = (isActive: boolean = true, newUserInput: boolean =
   });
 };
 
-const typingWorker = auth => ({
-  get_current_time: () => new Date().getTime(),
+const typingWorker = (state: GlobalState) => {
+  const auth: Auth = getAuth(state);
+  const serverVersion: ZulipVersion | void = getServerVersion(state);
 
-  notify_server_start: (user_ids_array: number[]) => {
-    api.typing(auth, JSON.stringify(user_ids_array), 'start');
-  },
+  // User ID arrays are only supported in server versions >= 2.0.0-rc1
+  // (zulip/zulip@2f634f8c0). For versions before this, email arrays
+  // are used. If current server version is undetermined, user ID
+  // arrays are optimistically used.
+  let useEmailArrays: boolean;
+  if (serverVersion === undefined) {
+    useEmailArrays = false;
+  } else {
+    useEmailArrays = !serverVersion.isAtLeast(new ZulipVersion('2.0.0-rc1'));
+  }
+
+  const getRecipients = user_ids_array => {
+    if (useEmailArrays) {
+      return JSON.stringify(user_ids_array.map(userId => getUserForId(state, userId).email));
+    }
+    return JSON.stringify(user_ids_array);
+  };
+
+  return {
+    get_current_time: () => new Date().getTime(),
 
-  notify_server_stop: (user_ids_array: number[]) => {
-    api.typing(auth, JSON.stringify(user_ids_array), 'stop');
-  },
-});
+    notify_server_start: (user_ids_array: number[]) => {
+      api.typing(auth, getRecipients(user_ids_array), 'start');
+    },
+
+    notify_server_stop: (user_ids_array: number[]) => {
+      api.typing(auth, getRecipients(user_ids_array), 'stop');
+    },
+  };
+};
 
 export const sendTypingStart = (narrow: Narrow) => async (
   dispatch: Dispatch,
@@ -56,9 +80,7 @@ export const sendTypingStart = (narrow: Narrow) => async (
     }
     return user.user_id;
   });
-
-  const auth = getAuth(getState());
-  typing_status.update(typingWorker(auth), recipientIds);
+  typing_status.update(typingWorker(getState()), recipientIds);
 };
 
 // TODO call this on more than send: blur, navigate away,
@@ -71,6 +93,5 @@ export const sendTypingStop = (narrow: Narrow) => async (
     return;
   }
 
-  const auth = getAuth(getState());
-  typing_status.update(typingWorker(auth), null);
+  typing_status.update(typingWorker(getState()), null);
 };