Add group chat functions, slight refactoring

src/structures/Message.js

@@ -0,0 +1,74 @@
+'use strict';
+
+const Base = require('./Base');
+
+/**
+ * Represents a Message on WhatsApp
+ * @extends {Base}
+ */
+class Message extends Base {
+    constructor(client, data) {
+        super(client);
+
+        if(data) this._patch(data);
+    }
+
+    _patch(data) {
+        this.id = data.id;
+        this.body = data.body;
+        this.type = data.type;
+        this.timestamp = data.t;
+        this.from = data.from;
+        this.to = data.to;
+        this.author = data.author;
+        this.isForwarded = data.isForwarded;
+        this.broadcast = data.broadcast;
+
+        return super._patch(data);
+    }
+
+    /**
+     * 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';
+    }
+
+    static get extraFields() {
+        return [
+            'isNewMsg'
+        ];
+    }
+}
+
+module.exports = Message;