typing api: Use recipients format based on server version.

Zulip server versions >= 2.0.0-rc1 require user ID arrays in the
'to' argument for the typing endpoint, whereas we currently send
email arrays. This change was made in zulip/zulip commit 2f634f8.

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 in
1.5.0-547-gd9b10727fa, in early 2017; 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, tryGetActiveAccount } 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 +26,42 @@ 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);
 
-  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, for
+  // versions before this, email arrays are used. If current server version is
+  // undetermined, user ID arrays are optimistically used.
+  // Support for user ID arrays was added in zulip/zulip commit 2f634f8.
+  let useEmailArrays: boolean;
+  const activeAccount: Account | void = tryGetActiveAccount(state);
+  if (!activeAccount || activeAccount.zulipVersion === undefined) {
+    useEmailArrays = false;
+  } else {
+    useEmailArrays = !new ZulipVersion('activeAccount.zulipVersion').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 +82,7 @@ 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 +95,5 @@ export const sendTypingStop = (narrow: Narrow) => async (
     return;
   }
 
-  const auth = getAuth(getState());
-  typing_status.update(typingWorker(auth), null);
+  typing_status.update(typingWorker(getState()), null);
 };