fix(notifications): throttle and batch join notifications (#2182)

* fix(notifications): throttle and batch join notifications

Instead of directly calling to show a join notification,
go through a specific method. This method will queue
names for display while a throttled function pulls
the names and shows a notification.

* squash: remove unused translation key

* squash: use default display name

* squash: move into participant actions

lang/main.json

     "notify": {
         "disconnected": "disconnected",
         "moderator": "Moderator rights granted!",
-        "connected": "connected",
+        "connectedOneMember": "__name__ connected",
+        "connectedTwoMembers": "__first__ and __second__ connected",
+        "connectedThreePlusMembers": "__name__ and __count__ others connected",
         "somebody": "Somebody",
         "me": "Me",
         "focus": "Conference focus",

modules/UI/UI.js

 } from '../../react/features/device-selection';
 import { updateDeviceList } from '../../react/features/base/devices';
 import { JitsiTrackErrors } from '../../react/features/base/lib-jitsi-meet';
-import { getLocalParticipant } from '../../react/features/base/participants';
+import {
+    getLocalParticipant,
+    showParticipantJoinedNotification
+} from '../../react/features/base/participants';
 import { openDisplayNamePrompt } from '../../react/features/display-name';
 import {
     maybeShowNotificationWithDoNotDisplay,
     const id = user.getId();
     const displayName = user.getDisplayName();
 
-    messageHandler.participantNotification(
-        displayName, 'notify.somebody', 'connected', 'notify.connected');
+    APP.store.dispatch(showParticipantJoinedNotification(displayName));
 
     if (!config.startAudioMuted
         || config.startAudioMuted > APP.conference.membersCount) {

modules/UI/util/MessageHandler.js

         $titleString.attr('data-i18n', titleKey);
 
         return $('<div>').append($titleString)
-.html();
+            .html();
     },
 
     /**
      * @param displayName the display name of the participant that is
      * associated with the notification.
      * @param displayNameKey the key from the language file for the display
-     * name. Only used if displayName i not provided.
+     * name. Only used if displayName is not provided.
      * @param cls css class for the notification
      * @param messageKey the key from the language file for the text of the
      * message.

react/features/base/participants/actions.js

+/* global interfaceConfig */
+
+import throttle from 'lodash/throttle';
+
+import { Notification, showNotification } from '../../notifications';
+
 import {
     DOMINANT_SPEAKER_CHANGED,
     KICK_PARTICIPANT,
         }
     };
 }
+
+/**
+ * An array of names of participants that have joined the conference. The array
+ * is replaced with an empty array as notifications are displayed.
+ *
+ * @private
+ * @type {string[]}
+ */
+let joinedParticipantsNames = [];
+
+/**
+ * A throttled internal function that takes the internal list of participant
+ * names, {@code joinedParticipantsNames}, and triggers the display of a
+ * notification informing of their joining.
+ *
+ * @private
+ * @type {Function}
+ */
+const _throttledNotifyParticipantConnected = throttle(dispatch => {
+    const joinedParticipantsCount = joinedParticipantsNames.length;
+
+    let notificationProps;
+
+    if (joinedParticipantsCount >= 3) {
+        notificationProps = {
+            titleArguments: {
+                name: joinedParticipantsNames[0],
+                count: joinedParticipantsCount - 1
+            },
+            titleKey: 'notify.connectedThreePlusMembers'
+        };
+    } else if (joinedParticipantsCount === 2) {
+        notificationProps = {
+            titleArguments: {
+                first: joinedParticipantsNames[0],
+                second: joinedParticipantsNames[1]
+            },
+            titleKey: 'notify.connectedTwoMembers'
+        };
+    } else if (joinedParticipantsCount) {
+        notificationProps = {
+            titleArguments: {
+                name: joinedParticipantsNames[0]
+            },
+            titleKey: 'notify.connectedOneMember'
+        };
+    }
+
+    if (notificationProps) {
+        dispatch(
+            showNotification(
+                Notification,
+                notificationProps,
+                2500));
+    }
+
+    joinedParticipantsNames = [];
+
+}, 500, { leading: false });
+
+/**
+ * Queues the display of a notification of a participant having connected to
+ * the meeting. The notifications are batched so that quick consecutive
+ * connection events are shown in one notification.
+ *
+ * @param {string} displayName - The name of the participant that connected.
+ * @returns {Function}
+ */
+export function showParticipantJoinedNotification(displayName) {
+    joinedParticipantsNames.push(
+        displayName || interfaceConfig.DEFAULT_REMOTE_DISPLAY_NAME);
+
+    return dispatch => {
+        _throttledNotifyParticipantConnected(dispatch);
+    };
+}

react/features/notifications/components/Notification.web.js

          */
         title: PropTypes.string,
 
+        /**
+         * The translation arguments that may be necessary for the title.
+         */
+        titleArguments: PropTypes.object,
+
         /**
          * The translation key to display as the title of the notification if
          * no title is provided.
      */
     render() {
         const {
-            hideErrorSupportLink,
             appearance,
-            titleKey,
+            description,
             descriptionArguments,
             descriptionKey,
-            description,
+            hideErrorSupportLink,
             isDismissAllowed,
             onDismissed,
             t,
             title,
+            titleArguments,
+            titleKey,
             uid
         } = this.props;
 
                 id = { uid }
                 isDismissAllowed = { isDismissAllowed }
                 onDismissed = { onDismissed }
-                title = { title || t(titleKey) } />
+                title = { title || t(titleKey, titleArguments) } />
         );
     }