Support replying directly to messages

example.js

@@ -19,7 +19,12 @@ client.on('ready', () => {
 client.on('message', (msg) => {
     console.log('MESSAGE RECEIVED', msg);
 
-    if (msg.body == 'ping') {
+    if (msg.body == 'ping reply') {
+        // Send a new message as a reply to the current one
+        msg.reply('pong');
+
+    } else if (msg.body == 'ping') {
+        // Send a new message to the same chat
         client.sendMessage(msg.from, 'pong');
     }
 })

src/models/Message.js

@@ -25,10 +25,39 @@ class Message extends Base {
         this.broadcast = data.broadcast;
     }
 
+    /**
+     * Returns the Chat this message was sent in
+     */
     getChat() {
         return this.client.getChatById(this.from);
     }
 
+    /**
+     * Sends a message as a reply. If chatId is specified, it will be sent 
+     * through the specified Chat. If not, it will send the message 
+     * in the same Chat as the original message was sent.
+     * @param {string} message 
+     * @param {?string} chatId 
+     */
+    async reply(message, chatId) {
+        if (!chatId) {
+            chatId = this.from;
+        }
+        
+        return await this.client.pupPage.evaluate((chatId, quotedMessageId, message) => {
+            let quotedMessage = Store.Msg.get(quotedMessageId);
+            if(quotedMessage.canReply()) {
+                const chat = Store.Chat.get(chatId);
+                chat.composeQuotedMsg = quotedMessage;
+                chat.sendMessage(message, {quotedMsg: quotedMessage});
+                chat.composeQuotedMsg = null;
+            } else {
+                throw new Error('This message cannot be replied to.');
+            }
+            
+        }, chatId, this.id._serialized, message);
+    }
+
     static get WAppModel() {
         return 'Msg';
     }