sharing: Make the app not quit after share to zulip concludes.

Previously after content was shared to zulip the app would quit,
regardless of the fact that the content was shared successfully or
failed to share, now the behaviour is as follows:
- If user cancels sharing/sharing fails, user is returned back
  to the previous view.
- If app was started from share intent, user returns to home screen
  of zulip.
- If share is successful user is navigated to chat screen where the
  content was shared.

Author: AkashDhiman

src/nav/navActions.js

@@ -29,6 +29,9 @@ export const resetToMainTabs = (): GenericNavigationAction =>
 export const navigateToChat = (narrow: Narrow): GenericNavigationAction =>
   StackActions.push('chat', { narrow, editMessage: null });
 
+export const replaceWithChat = (narrow: Narrow): GenericNavigationAction =>
+  StackActions.replace('chat', { narrow });
+
 export const navigateToUsersScreen = (): GenericNavigationAction => StackActions.push('users');
 
 export const navigateToSearch = (): GenericNavigationAction => StackActions.push('search-messages');

src/sharing/ShareToPm.js

@@ -1,7 +1,6 @@
 /* @flow strict-local */
 import React from 'react';
-import { View, Image, ScrollView, Modal, BackHandler } from 'react-native';
-
+import { View, Image, ScrollView, Modal } from 'react-native';
 import type { RouteProp } from '../react-navigation';
 import type { SharingNavigationProp } from './SharingScreen';
 import * as NavigationService from '../nav/NavigationService';
@@ -12,9 +11,12 @@ import { connect } from '../react-redux';
 import { ZulipButton, Input, Label } from '../common';
 import UserItem from '../users/UserItem';
 import { getAuth } from '../selectors';
-import { navigateBack } from '../nav/navActions';
+import { navigateBack, replaceWithChat } from '../nav/navActions';
 import ChooseRecipientsScreen from './ChooseRecipientsScreen';
 import { handleSend } from './send';
+import { pmNarrowFromRecipients } from '../utils/narrow';
+import { pmKeyRecipientsFromIds } from '../utils/recipient';
+import { getOwnUserId } from '../users/userSelectors';
 
 const styles = createStyleSheet({
   wrapper: {
@@ -58,7 +60,7 @@ const styles = createStyleSheet({
 type Props = $ReadOnly<{|
   navigation: SharingNavigationProp<'share-to-pm'>,
   route: RouteProp<'share-to-pm', {| sharedData: SharedData |}>,
-
+  ownUserId: UserId,
   dispatch: Dispatch,
   auth: Auth,
 |}>;
@@ -105,13 +107,24 @@ class ShareToPm extends React.Component<Props, State> {
     const data = { selectedRecipients, message, sharedData, type: 'pm' };
 
     this.setSending();
-    await handleSend(data, auth, _);
-    this.finishShare();
+    try {
+      await handleSend(data, auth, _);
+      this.shareSuccess();
+    } catch (err) {
+      this.finishShare();
+    }
+  };
+
+  shareSuccess = () => {
+    const { selectedRecipients } = this.state;
+    const { ownUserId } = this.props;
+    const recipients = pmKeyRecipientsFromIds(selectedRecipients, ownUserId);
+    const narrow = pmNarrowFromRecipients(recipients);
+    NavigationService.dispatch(replaceWithChat(narrow));
   };
 
   finishShare = () => {
     NavigationService.dispatch(navigateBack());
-    BackHandler.exitApp();
   };
 
   handleMessageChange = message => {
@@ -195,4 +208,5 @@ class ShareToPm extends React.Component<Props, State> {
 
 export default connect(state => ({
   auth: getAuth(state),
+  ownUserId: getOwnUserId(state),
 }))(ShareToPm);

src/sharing/ShareToStream.js

@@ -1,7 +1,6 @@
 /* @flow strict-local */
 import React from 'react';
-import { View, Image, ScrollView, BackHandler } from 'react-native';
-
+import { View, Image, ScrollView } from 'react-native';
 import type { SharingNavigationProp } from './SharingScreen';
 import type { RouteProp } from '../react-navigation';
 import * as NavigationService from '../nav/NavigationService';
@@ -16,7 +15,7 @@ import TopicAutocomplete from '../autocomplete/TopicAutocomplete';
 import AnimatedScaleComponent from '../animation/AnimatedScaleComponent';
 import { streamNarrow } from '../utils/narrow';
 import { getAuth } from '../selectors';
-import { navigateBack } from '../nav/navActions';
+import { navigateBack, replaceWithChat } from '../nav/navActions';
 import { fetchTopicsForStream } from '../topics/topicActions';
 import { handleSend } from './send';
 
@@ -128,13 +127,22 @@ class ShareToStream extends React.Component<Props, State> {
     const data = { stream, topic, message, sharedData, type: 'stream' };
 
     this.setSending();
-    await handleSend(data, auth, _);
-    this.finishShare();
+    try {
+      await handleSend(data, auth, _);
+      this.shareSuccess();
+    } catch (err) {
+      this.finishShare();
+    }
+  };
+
+  shareSuccess = () => {
+    const { stream } = this.state;
+    const narrow = streamNarrow(stream);
+    NavigationService.dispatch(replaceWithChat(narrow));
   };
 
   finishShare = () => {
     NavigationService.dispatch(navigateBack());
-    BackHandler.exitApp();
   };
 
   isSendButtonEnabled = () => {