feat: listen to group events (pedroslopez#90)

This allows you to listen for user joins or leaves, description updates, subject updates, picture updates, and group settings updates.

Co-authored-by: Pedro S. Lopez <pedroslopez@me.com>

example.js

@@ -219,6 +219,23 @@ client.on('message_ack', (msg, ack) => {
     }
 });
 
+client.on('group_join', (notification) => {
+    // User has joined or been added to the group.
+    console.log('join', notification);
+    notification.reply('User joined.');
+});
+
+client.on('group_leave', (notification) => {
+    // User has left or been kicked from the group.
+    console.log('leave', notification);
+    notification.reply('User left.');
+});
+
+client.on('group_update', (notification) => {
+    // Group picture, subject or description has been updated.
+    console.log('update', notification);
+});
+
 client.on('disconnected', (reason) => {
     console.log('Client was logged out', reason);
 });

src/Client.js

@@ -10,8 +10,7 @@ const { WhatsWebURL, UserAgent, DefaultOptions, Events, WAState } = require('./u
 const { ExposeStore, LoadUtils } = require('./util/Injected');
 const ChatFactory = require('./factories/ChatFactory');
 const ContactFactory = require('./factories/ContactFactory');
-const { ClientInfo, Message, MessageMedia, Location } = require('./structures');
-
+const { ClientInfo, Message, MessageMedia, Location, GroupNotification } = require('./structures');
 /**
  * Starting point for interacting with the WhatsApp Web API
  * @extends {EventEmitter}
@@ -146,6 +145,18 @@ class Client extends EventEmitter {
         await page.exposeFunction('onAddMessageEvent', msg => {
             if (!msg.isNewMsg) return;
 
+            if (msg.type === 'gp2') {
+                const notification = new GroupNotification(this, msg);
+                if (msg.subtype === 'add' || msg.subtype === 'invite') {
+                    this.emit(Events.GROUP_JOIN, notification);
+                } else if (msg.subtype === 'remove' || msg.subtype === 'leave') {
+                    this.emit(Events.GROUP_LEAVE, notification);
+                } else {
+                    this.emit(Events.GROUP_UPDATE, notification);
+                }
+                return;
+            }
+
             const message = new Message(this, msg);
 
             /**

src/structures/GroupNotification.js

@@ -0,0 +1,104 @@
+'use strict';
+
+const Base = require('./Base');
+
+/**
+ * Represents a GroupNotification on WhatsApp
+ * @extends {Base}
+ */
+class GroupNotification extends Base {
+    constructor(client, data) {
+        super(client);
+
+        if(data) this._patch(data);
+    }
+
+    _patch(data) {
+        /**
+         * ID that represents the groupNotification
+         * @type {object}
+         */
+        this.id = data.id;
+
+        /**
+         * Extra content
+         * @type {string}
+         */
+        this.body = data.body || '';
+
+        /** 
+         * GroupNotification type
+         * @type {GroupNotificationTypes}
+         */
+        this.type = data.subtype;
+
+        /**
+         * Unix timestamp for when the groupNotification was created
+         * @type {number}
+         */
+        this.timestamp = data.t;
+
+        /**
+         * ID for the Chat that this groupNotification was sent for.
+         * 
+         * @type {string}
+         */
+        this.chatId = typeof (data.to) === 'object' ? data.to._serialized : data.to;
+
+        /**
+         * ContactId for the user that produced the GroupNotification.
+         * @type {string}
+         */
+        this.author = typeof (data.author) === 'object' ? data.author._serialized : data.author;
+
+        /**
+         * Contact IDs for the users that were affected by this GroupNotification.
+         * @type {Array<string>}
+         */
+        this.recipientIds = [];
+
+        if (data.recipients) {
+            this.recipientIds = data.recipients;
+        }
+
+        return super._patch(data);
+    }
+
+    /**
+     * Returns the Chat this groupNotification was sent in
+     * @returns {Promise<Chat>}
+     */
+    getChat() {
+        return this.client.getChatById(this.chatId);
+    }
+
+    /**
+     * Returns the Contact this GroupNotification was produced by
+     * @returns {Promise<Contact>}
+     */
+    getContact() {
+        return this.client.getContactById(this.author);
+    }
+
+    /**
+     * Returns the Contacts affected by this GroupNotification.
+     * @returns {Promise<Array<Contact>>}
+     */
+    async getRecipients() {
+        return await Promise.all(this.recipientIds.map(async m => await this.client.getContactById(m)));
+    }
+
+    /**
+     * Sends a message to the same chat this GroupNotification was produced in.
+     * 
+     * @param {string|MessageMedia|Location} content 
+     * @param {object} options
+     * @returns {Promise<Message>}
+     */
+    async reply(content, options={}) {
+        return this.client.sendMessage(this.chatId, content, options);
+    }
+
+}
+
+module.exports = GroupNotification;

src/util/Constants.js

@@ -36,6 +36,9 @@ exports.Events = {
     MESSAGE_REVOKED_EVERYONE: 'message_revoke_everyone',
     MESSAGE_REVOKED_ME: 'message_revoke_me',
     MESSAGE_ACK: 'message_ack',
+    GROUP_JOIN: 'group_join',
+    GROUP_LEAVE: 'group_leave',
+    GROUP_UPDATE: 'group_update',
     QR_RECEIVED: 'qr',
     DISCONNECTED: 'disconnected',
     STATE_CHANGED: 'change_state',
@@ -61,6 +64,23 @@ exports.MessageTypes = {
     UNKNOWN: 'unknown'
 };
 
+/**
+ * Group notification types
+ * @readonly
+ * @enum {string}
+ */
+exports.GroupNotificationTypes = {
+    ADD: 'add',
+    INVITE: 'invite',
+    REMOVE: 'remove',
+    LEAVE: 'leave',
+    SUBJECT: 'subject',
+    DESCRIPTION: 'description',
+    PICTURE: 'picture',
+    ANNOUNCE: 'announce',
+    RESTRICT: 'restrict',
+};
+
 /**
  * Chat types
  * @readonly