MOBILE-3739 chat: Implement on leave guard

scripts/langindex.json

@@ -430,6 +430,7 @@
   "addon.mod_book.toc": "book",
   "addon.mod_chat.beep": "chat",
   "addon.mod_chat.chatreport": "chat",
+  "addon.mod_chat.confirmloss": "local_moodlemobileapp",
   "addon.mod_chat.currentusers": "chat",
   "addon.mod_chat.enterchat": "chat",
   "addon.mod_chat.entermessage": "chat",

src/addons/mod/chat/chat-lazy.module.ts

@@ -22,6 +22,7 @@ import { AddonModChatSessionMessagesPage } from './pages/session-messages/sessio
 import { CoreScreen } from '@services/screen';
 import { conditionalRoutes } from '@/app/app-routing.module';
 import { AddonModChatSessionsPage } from './pages/sessions/sessions';
+import { CanLeaveGuard } from '@guards/can-leave';
 
 const commonRoutes: Routes = [
     {
@@ -31,6 +32,7 @@ const commonRoutes: Routes = [
     {
         path: ':courseId/:cmId/chat',
         component: AddonModChatChatPage,
+        canDeactivate: [CanLeaveGuard],
     },
 ];
 

src/addons/mod/chat/lang.json

@@ -1,6 +1,7 @@
 {
     "beep": "Beep",
     "chatreport": "Chat sessions",
+    "confirmloss": "Are you sure? Chat history can be lost.",
     "currentusers": "Current users",
     "enterchat": "Click here to enter the chat now",
     "entermessage": "Enter your message",
@@ -25,4 +26,4 @@
     "showincompletesessions": "Show incomplete sessions",
     "talk": "Talk",
     "viewreport": "View past chat sessions"
-}
+}

src/addons/mod/chat/pages/chat/chat.ts

@@ -15,13 +15,14 @@
 import { Component, ViewChild, OnInit, OnDestroy } from '@angular/core';
 import { CoreAnimations } from '@components/animations';
 import { CoreSendMessageFormComponent } from '@components/send-message-form/send-message-form';
+import { CanLeave } from '@guards/can-leave';
 import { IonContent } from '@ionic/angular';
 import { CoreApp } from '@services/app';
 import { CoreNavigator } from '@services/navigator';
 import { CoreSites } from '@services/sites';
 import { CoreDomUtils } from '@services/utils/dom';
 import { CoreUtils } from '@services/utils/utils';
-import { Network, NgZone } from '@singletons';
+import { Network, NgZone, Translate } from '@singletons';
 import { CoreEventObserver, CoreEvents } from '@singletons/events';
 import { Subscription } from 'rxjs';
 import { AddonModChatUsersModalComponent, AddonModChatUsersModalResult } from '../../components/users-modal/users-modal';
@@ -37,7 +38,7 @@ import { AddonModChatFormattedMessage, AddonModChatHelper } from '../../services
     animations: [CoreAnimations.SLIDE_IN_OUT],
     styleUrls: ['chat.scss', '../../../../messages/pages/discussion/discussion.scss'],
 })
-export class AddonModChatChatPage implements OnInit, OnDestroy {
+export class AddonModChatChatPage implements OnInit, OnDestroy, CanLeave {
 
     @ViewChild(IonContent) content?: IonContent;
     @ViewChild(CoreSendMessageFormComponent) sendMessageForm?: CoreSendMessageFormComponent;
@@ -381,6 +382,22 @@ export class AddonModChatChatPage implements OnInit, OnDestroy {
         // });
     }
 
+    /**
+     * Check if we can leave the page or not.
+     *
+     * @return Resolved with true if we can leave it, rejected if not.
+     */
+    async canLeave(): Promise<boolean> {
+        if (! this.messages.some((message) => !message.special)) {
+            return true;
+        }
+
+        // Modified, confirm user wants to go back.
+        await CoreDomUtils.showConfirm(Translate.instant('addon.mod_chat.confirmloss'));
+
+        return true;
+    }
+
     /**
      * @inheritdoc
      */