Rocket.Chat/app/livechat/server/hooks/sendToFacebook.js

import { callbacks } from '../../../callbacks';
import { settings } from '../../../settings';
import OmniChannel from '../lib/OmniChannel';
import { normalizeMessageAttachments } from '../../../utils/server/functions/normalizeMessageAttachments';

callbacks.add('afterSaveMessage', function(message, room) {
	// skips this callback if the message was edited
	if (message.editedAt) {
		return message;
	}

	if (!settings.get('Livechat_Facebook_Enabled') || !settings.get('Livechat_Facebook_API_Key')) {
		return message;
	}

	// only send the sms by SMS if it is a livechat room with SMS set to true
	if (!(typeof room.t !== 'undefined' && room.t === 'l' && room.facebook && room.v && room.v.token)) {
		return message;
	}

	// if the message has a token, it was sent from the visitor, so ignore it
	if (message.token) {
		return message;
	}

	// if the message has a type means it is a special message (like the closing comment), so skips
	if (message.t) {
		return message;
	}

	if (message.file) {
		message = normalizeMessageAttachments(message);
	}

	OmniChannel.reply({
		page: room.facebook.page.id,
		token: room.v.token,
		text: message.msg,
	});

	return message;
}, callbacks.priority.LOW, 'sendMessageToFacebook');