app.js

"use strict";

const dialogflow = require('dialogflow');
const config = require('./config');
const express = require('express');
const crypto = require('crypto'); // for verifying request signature
const bodyParser = require('body-parser'); //for parsing request data
const request = require('request'); // for making requests
const app = express(); // to create an app with request, express speeds up app development
const uuid = require('uuid');


// Messenger API parameters - VERIFY THAT CONFIG VARIABLES ARE SET
if (!config.FB_PAGE_TOKEN) {
	throw new Error('missing FB_PAGE_TOKEN');
}
if (!config.VERIFY_TOKEN) {
	throw new Error('missing VERIFY_TOKEN');
}
if (!config.GOOGLE_PROJECT_ID) {
	throw new Error('missing GOOGLE_PROJECT_ID');
}
if (!config.DF_LANGUAGE_CODE) {
	throw new Error('missing DF_LANGUAGE_CODE');
}
if (!config.GOOGLE_CLIENT_EMAIL) {
	throw new Error('missing GOOGLE_CLIENT_EMAIL');
}
if (!config.GOOGLE_PRIVATE_KEY) {
	throw new Error('missing GOOGLE_PRIVATE_KEY');
}
if (!config.FB_APP_SECRET) {
	throw new Error('missing FB_APP_SECRET');
}
if (!config.SERVER_URL) { //used for ink to static files
	throw new Error('missing SERVER_URL');
}
if (!config.EMAIL_FROM) {
	throw new Error('missing EMAIL_FROM');
}
if (!config.EMAIL_TO) {
	throw new Error('missing EMAIL_TO');
}

app.set('port', (process.env.PORT || 5000));

//verify request came from facebook
app.use(bodyParser.json({
	verify: verifyRequestSignature
}));

//serve static files in the public directory, statement makes the folder visible so it is accessible via HTTP
app.use(express.static('public'));

// Process application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ //body parser module
	extended: false
}));

// Process application/json
app.use(bodyParser.json());
// set up the dialogflow client
const credentials = {
    client_email: config.GOOGLE_CLIENT_EMAIL,
    private_key: config.GOOGLE_PRIVATE_KEY,
};

const sessionClient = new dialogflow.SessionsClient(
	{
		projectId: config.GOOGLE_PROJECT_ID,
		credentials
	}
);

const sessionIds = new Map();

// Index route
app.get('/', function (req, res) {
	res.send('chat bot')
});
/** 
// for Facebook verification (Heroku and Facebook token is validated)
app.get('/webhook/', function (req, res) {
	console.log("request");
	if (req.query['hub.mode'] === 'subscribe' && req.query['hub.verify_token'] === config.VERIFY_TOKEN) {
		res.status(200).send(req.query['hub.challenge']);
	} else {
		console.error("Failed validation. Make sure the validation tokens match.");
		res.sendStatus(403);
	}
});
*/
  // Adds support for GET requests to our webhook
  app.get('/webhook', (req, res) => {

    // Your verify token. Should be a random string.
    let VERIFY_TOKEN = "my_chatbot_password";
      
    // Parse the query params
    let mode = req.query['hub.mode'];
    let token = req.query['hub.verify_token'];
    let challenge = req.query['hub.challenge'];
      
    // Checks if a token and mode is in the query string of the request
    if (mode && token) {
    
      // Checks the mode and token sent is correct
      if (mode === 'subscribe' && token === VERIFY_TOKEN) {
        
        // Responds with the challenge token from the request
        console.log('WEBHOOK_VERIFIED');
        res.status(200).send(challenge);
      
      } else {
        console.error("Failed validation. Make sure the validation tokens match.");
        // Responds with '403 Forbidden' if verify tokens do not match
        res.sendStatus(403);      
      }
    }
  });

/*
 * All callbacks for Messenger are POST-ed. They will be sent to the same
 * webhook. Be sure to subscribe your app to your page to receive callbacks
 * for your page. 
 * https://developers.facebook.com/docs/messenger-platform/product-overview/setup#subscribe_app
 *
 */
app.post('/webhook/', function (req, res) {
	var data = req.body;
	console.log(JSON.stringify(data));

	// Make sure this is a page subscription, this is where we catch events that come to webhook
	if (data.object == 'page') {//make sure this is page subscription
		// Iterate over each entry
		// There may be multiple if batched
		data.entry.forEach(function (pageEntry) {
			var pageID = pageEntry.id;
			var timeOfEvent = pageEntry.time;

			// Iterate over each messaging event
			pageEntry.messaging.forEach(function (messagingEvent) {
				if (messagingEvent.optin) {
					receivedAuthentication(messagingEvent);
				} else if (messagingEvent.message) {
					receivedMessage(messagingEvent);
				} else if (messagingEvent.delivery) {
					receivedDeliveryConfirmation(messagingEvent);
				} else if (messagingEvent.postback) {
					receivedPostback(messagingEvent);//a click on the button, menu or structured message
				} else if (messagingEvent.read) {
					receivedMessageRead(messagingEvent);
				} else if (messagingEvent.account_linking) {
					receivedAccountLink(messagingEvent);
				} else {
					console.log("Webhook received unknown messagingEvent: ", messagingEvent);
				}
			});
		});

		// Assume all went well.
		// You must send back a 200, within 20 seconds
		res.sendStatus(200);
	}
});

function receivedMessage(event) {
	// extract the data from the request
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;
	var timeOfMessage = event.timestamp;
	var message = event.message;

	if (!sessionIds.has(senderID)) {
		sessionIds.set(senderID, uuid.v1());
	}
	//console.log("Received message for user %d and page %d at %d with message:", senderID, recipientID, timeOfMessage);
	//console.log(JSON.stringify(message));

	var isEcho = message.is_echo; //check if the message is the echo (message sent by its page)
	var messageId = message.mid;
	var appId = message.app_id;
	var metadata = message.metadata;

	// You may get a text or attachment but not both
	var messageText = message.text;
	var messageAttachments = message.attachments;
	var quickReply = message.quick_reply;

	if (isEcho) {
		handleEcho(messageId, appId, metadata);
		return;
	} else if (quickReply) {
		handleQuickReply(senderID, quickReply, messageId);
		return;
	}


	if (messageText) {
		//send message to api.ai
		sendToDialogFlow(senderID, messageText);
	} else if (messageAttachments) {
		handleMessageAttachments(messageAttachments, senderID);
	}
}

function handleMessageAttachments(messageAttachments, senderID){
	//for now just reply
	sendTextMessage(senderID, "Attachment received. Thank you.");	
}

function handleQuickReply(senderID, quickReply, messageId) {
	var quickReplyPayload = quickReply.payload;
	console.log("Quick reply for message %s with payload %s", messageId, quickReplyPayload);
	//send payload to api.ai
	sendToDialogFlow(senderID, quickReplyPayload);
}

//https://developers.facebook.com/docs/messenger-platform/webhook-reference/message-echo
function handleEcho(messageId, appId, metadata) {
	// Just logging message echoes to console
	console.log("Received echo for message %s and app %d with metadata %s", messageId, appId, metadata);
}

function handleDialogFlowAction(sender, action, messages, contexts, parameters) {
	switch (action) {
		default:
			//unhandled action, just send back the text
            handleMessages(messages, sender);
	}
}

function handleMessage(message, sender) {
    switch (message.message) {
        case "text": //text
            message.text.text.forEach((text) => {
                if (text !== '') {
                    sendTextMessage(sender, text);
                }
            });
            break;
        case "quickReplies": //quick replies
            let replies = [];
            message.quickReplies.quickReplies.forEach((text) => {
                let reply =
                    {
                        "content_type": "text",
                        "title": text,
                        "payload": text
                    }
                replies.push(reply);
            });
            sendQuickReply(sender, message.quickReplies.title, replies);
            break;
        case "image": //image
            sendImageMessage(sender, message.image.imageUri);
            break;
    }
}

function handleCardMessages(messages, sender) {

	let elements = [];
	for (var m = 0; m < messages.length; m++) {
		let message = messages[m];
		let buttons = [];
        for (var b = 0; b < message.card.buttons.length; b++) {
            let isLink = (message.card.buttons[b].postback.substring(0, 4) === 'http');
            let button;
            if (isLink) {
                button = {
                    "type": "web_url",
                    "title": message.card.buttons[b].text,
                    "url": message.card.buttons[b].postback
                }
            } else {
                button = {
                    "type": "postback",
                    "title": message.card.buttons[b].text,
                    "payload": message.card.buttons[b].postback
                }
            }
            buttons.push(button);
        }

		let element = {
            "title": message.card.title,
            "image_url":message.card.imageUri,
            "subtitle": message.card.subtitle,
			"buttons": buttons
		};
		elements.push(element);
	}
	sendGenericMessage(sender, elements);
}

function handleMessages(messages, sender) {
    let timeoutInterval = 1100;
    let previousType ;
    let cardTypes = [];
    let timeout = 0;
    for (var i = 0; i < messages.length; i++) {

        if ( previousType == "card" && (messages[i].message != "card" || i == messages.length - 1)) {
            timeout = (i - 1) * timeoutInterval;
            setTimeout(handleCardMessages.bind(null, cardTypes, sender), timeout);
            cardTypes = [];
            timeout = i * timeoutInterval;
            setTimeout(handleMessage.bind(null, messages[i], sender), timeout);
        } else if ( messages[i].message == "card" && i == messages.length - 1) {
            cardTypes.push(messages[i]);
            timeout = (i - 1) * timeoutInterval;
            setTimeout(handleCardMessages.bind(null, cardTypes, sender), timeout);
            cardTypes = [];
        } else if ( messages[i].message == "card") {
            cardTypes.push(messages[i]);
        } else  {

            timeout = i * timeoutInterval;
            setTimeout(handleMessage.bind(null, messages[i], sender), timeout);
        }

        previousType = messages[i].message;

    }
}

function handleDialogFlowResponse(sender, response) {
    let responseText = response.fulfillmentMessages.fulfillmentText;

    let messages = response.fulfillmentMessages;
    let action = response.action;
    let contexts = response.outputContexts;
    let parameters = response.parameters;

	sendTypingOff(sender);

    if (isDefined(action)) {
        handleDialogFlowAction(sender, action, messages, contexts, parameters);
    } else if (isDefined(messages)) {
        handleMessages(messages, sender);
	} else if (responseText == '' && !isDefined(action)) {
		//dialogflow could not evaluate input.
		sendTextMessage(sender, "I'm not sure what you want. Can you be more specific?");
	} else if (isDefined(responseText)) {
		sendTextMessage(sender, responseText);
	}
}

async function sendToDialogFlow(sender, textString, params) {

    sendTypingOn(sender);

    try {
        const sessionPath = sessionClient.sessionPath(
            config.GOOGLE_PROJECT_ID,
            sessionIds.get(sender)
        );

        const request = {
            session: sessionPath,
            queryInput: {
                text: {
                    text: textString,
                    languageCode: config.DF_LANGUAGE_CODE,
                }
            },
            queryParams: {
                payload: {
                    data: params
                }
            }
        };
        const responses = await sessionClient.detectIntent(request);

        const result = responses[0].queryResult;
        handleDialogFlowResponse(sender, result);
    } catch (e) {
        console.log('error');
        console.log(e);
    }

}

function sendTextMessage(recipientId, text) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			text: text
		}
	};
	callSendAPI(messageData);
}

/*
 * Send an image using the Send API.
 *
 */
function sendImageMessage(recipientId, imageUrl) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "image",
				payload: {
					url: imageUrl
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a Gif using the Send API.
 *
 */
function sendGifMessage(recipientId) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "image",
				payload: {
					url: config.SERVER_URL + "/assets/instagram_logo.gif"
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send audio using the Send API.
 *
 */
function sendAudioMessage(recipientId) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "audio",
				payload: {
					url: config.SERVER_URL + "/assets/sample.mp3"
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a video using the Send API.
 * example videoName: "/assets/allofus480.mov"
 */
function sendVideoMessage(recipientId, videoName) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "video",
				payload: {
					url: config.SERVER_URL + videoName
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a video using the Send API.
 * example fileName: fileName"/assets/test.txt"
 */
function sendFileMessage(recipientId, fileName) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "file",
				payload: {
					url: config.SERVER_URL + fileName
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a button message using the Send API.
 *
 */
function sendButtonMessage(recipientId, text, buttons) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "template",
				payload: {
					template_type: "button",
					text: text,
					buttons: buttons
				}
			}
		}
	};

	callSendAPI(messageData);
}

function sendGenericMessage(recipientId, elements) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "template",
				payload: {
					template_type: "generic",
					elements: elements
				}
			}
		}
	};

	callSendAPI(messageData);
}

function sendReceiptMessage(recipientId, recipient_name, currency, payment_method,
							timestamp, elements, address, summary, adjustments) {
	// Generate a random receipt ID as the API requires a unique ID
	var receiptId = "order" + Math.floor(Math.random() * 1000);

	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "template",
				payload: {
					template_type: "receipt",
					recipient_name: recipient_name,
					order_number: receiptId,
					currency: currency,
					payment_method: payment_method,
					timestamp: timestamp,
					elements: elements,
					address: address,
					summary: summary,
					adjustments: adjustments
				}
			}
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a message with Quick Reply buttons.
 *
 */
function sendQuickReply(recipientId, text, replies, metadata) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			text: text,
			metadata: isDefined(metadata)?metadata:'',
			quick_replies: replies
		}
	};

	callSendAPI(messageData);
}

/*
 * Send a read receipt to indicate the message has been read
 *
 */
function sendReadReceipt(recipientId) {

	var messageData = {
		recipient: {
			id: recipientId
		},
		sender_action: "mark_seen"
	};

	callSendAPI(messageData);
}

/*
 * Turn typing indicator on
 *
 */
function sendTypingOn(recipientId) {

	var messageData = {
		recipient: {
			id: recipientId
		},
		sender_action: "typing_on"
	};

	callSendAPI(messageData);
}

/*
 * Turn typing indicator off
 *
 */
function sendTypingOff(recipientId) {

	var messageData = {
		recipient: {
			id: recipientId
		},
		sender_action: "typing_off"
	};

	callSendAPI(messageData);
}

/*
 * Send a message with the account linking call-to-action
 *
 */
function sendAccountLinking(recipientId) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			attachment: {
				type: "template",
				payload: {
					template_type: "button",
					text: "Welcome. Link your account.",
					buttons: [{
						type: "account_link",
						url: config.SERVER_URL + "/authorize"
          }]
				}
			}
		}
	};

	callSendAPI(messageData);
}

function greetUserText(userId) {
	//first read user firstname
	request({
		uri: 'https://graph.facebook.com/v2.7/' + userId,
		qs: {
			access_token: config.FB_PAGE_TOKEN
		}

	}, function (error, response, body) {
		if (!error && response.statusCode == 200) {

			var user = JSON.parse(body);

			if (user.first_name) {
				console.log("FB user: %s %s, %s",
					user.first_name, user.last_name, user.gender);

				sendTextMessage(userId, "Welcome " + user.first_name + '!');
			} else {
				console.log("Cannot get data for fb user with id",
					userId);
			}
		} else {
			console.error(response.error);
		}

	});
}

/*
 * Call the Send API. The message data goes in the body. If successful, we'll 
 * get the message id in a response 
 *
 */
function callSendAPI(messageData) {
	request({
		uri: 'https://graph.facebook.com/v2.6/me/messages',
		qs: {
			access_token: config.FB_PAGE_TOKEN
		},
		method: 'POST',
		json: messageData

	}, function (error, response, body) {
		if (!error && response.statusCode == 200) {
			var recipientId = body.recipient_id;
			var messageId = body.message_id;

			if (messageId) {
				console.log("Successfully sent message with id %s to recipient %s",
					messageId, recipientId);
			} else {
				console.log("Successfully called Send API for recipient %s",
					recipientId);
			}
		} else {
			console.error("Failed calling Send API", response.statusCode, response.statusMessage, body.error);
		}
	});
}

/*
 * Postback Event
 *
 * This event is called when a postback is tapped on a Structured Message. 
 * https://developers.facebook.com/docs/messenger-platform/webhook-reference/postback-received
 * 
 */
function receivedPostback(event) {
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;
	var timeOfPostback = event.timestamp;

	// The 'payload' param is a developer-defined field which is set in a postback 
	// button for Structured Messages. 
	var payload = event.postback.payload;

	switch (payload) {
		default:
			//unindentified payload
			sendTextMessage(senderID, "I'm not sure what you want. Can you be more specific?");
			break;

	}

	console.log("Received postback for user %d and page %d with payload '%s' " +
		"at %d", senderID, recipientID, payload, timeOfPostback);

}

/*
 * Message Read Event
 *
 * This event is called when a previously-sent message has been read.
 * https://developers.facebook.com/docs/messenger-platform/webhook-reference/message-read
 * 
 */
function receivedMessageRead(event) {
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;

	// All messages before watermark (a timestamp) or sequence have been seen.
	var watermark = event.read.watermark;
	var sequenceNumber = event.read.seq;

	console.log("Received message read event for watermark %d and sequence " +
		"number %d", watermark, sequenceNumber);
}

/*
 * Account Link Event
 *
 * This event is called when the Link Account or UnLink Account action has been
 * tapped.
 * https://developers.facebook.com/docs/messenger-platform/webhook-reference/account-linking
 * 
 */
function receivedAccountLink(event) {
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;

	var status = event.account_linking.status;
	var authCode = event.account_linking.authorization_code;

	console.log("Received account link event with for user %d with status %s " +
		"and auth code %s ", senderID, status, authCode);
}

/*
 * Delivery Confirmation Event
 *
 * This event is sent to confirm the delivery of a message. Read more about 
 * these fields at https://developers.facebook.com/docs/messenger-platform/webhook-reference/message-delivered
 *
 */
function receivedDeliveryConfirmation(event) {
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;
	var delivery = event.delivery;
	var messageIDs = delivery.mids;
	var watermark = delivery.watermark;
	var sequenceNumber = delivery.seq;

	if (messageIDs) {
		messageIDs.forEach(function (messageID) {
			console.log("Received delivery confirmation for message ID: %s",
				messageID);
		});
	}

	console.log("All message before %d were delivered.", watermark);
}

/*
 * Authorization Event
 *
 * The value for 'optin.ref' is defined in the entry point. For the "Send to 
 * Messenger" plugin, it is the 'data-ref' field. Read more at 
 * https://developers.facebook.com/docs/messenger-platform/webhook-reference/authentication
 *
 */
function receivedAuthentication(event) {
	var senderID = event.sender.id;
	var recipientID = event.recipient.id;
	var timeOfAuth = event.timestamp;

	// The 'ref' field is set in the 'Send to Messenger' plugin, in the 'data-ref'
	// The developer can set this to an arbitrary value to associate the 
	// authentication callback with the 'Send to Messenger' click event. This is
	// a way to do account linking when the user clicks the 'Send to Messenger' 
	// plugin.
	var passThroughParam = event.optin.ref;

	console.log("Received authentication for user %d and page %d with pass " +
		"through param '%s' at %d", senderID, recipientID, passThroughParam,
		timeOfAuth);

	// When an authentication is received, we'll send a message back to the sender
	// to let them know it was successful.
	sendTextMessage(senderID, "Authentication successful");
}

/*
 * Verify that the callback came from Facebook. Using the App Secret from 
 * the App Dashboard, we can verify the signature that is sent with each 
 * callback in the x-hub-signature field, located in the header.
 *
 * https://developers.facebook.com/docs/graph-api/webhooks#setup
 *
 */
function verifyRequestSignature(req, res, buf) {
	var signature = req.headers["x-hub-signature"]; //read the signature from the requests header
	//if there is no signature and error is thrown
	if (!signature) {
		throw new Error('Couldn\'t validate the signature.');
	} else {
		var elements = signature.split('=');
		var method = elements[0];
		var signatureHash = elements[1];

		var expectedHash = crypto.createHmac('sha1', config.FB_APP_SECRET) //compare the signature hash to the config file
			.update(buf)
			.digest('hex');

		if (signatureHash != expectedHash) {
			throw new Error("Couldn't validate the request signature."); //if the signature hash doest much to config file signature => throw an error
		}
	}
}

function isDefined(obj) {
	if (typeof obj == 'undefined') {
		return false;
	}

	if (!obj) {
		return false;
	}

	return obj != null;
}

// Spin up the server
app.listen(app.get('port'), function () {
	console.log('running on port', app.get('port'));
});