app.js

'use strict'

const 
	bodyParser = require('body-parser'),
	crypto = require('crypto'),
	express = require('express'),
	https = require('https'),	
	request = require('request'),
	dateFormat = require('dateformat'),
	defer = require('./defer')

var app = express()
app.set('port', process.env.PORT || 3000)
app.use(bodyParser.json())

const VALIDATION_TOKEN = process.env.MESSENGER_VALIDATION_TOKEN || ''

const PAGE_ACCESS_TOKEN = process.env.MESSENGER_PAGE_ACCESS_TOKEN || ''

const API_AI_ACCESS_TOKEN = process.env.API_AI_ACCESS_TOKEN || ''

const WEATHER_API_KEY = process.env.WEATHER_API_KEY || ''

app.get('/webhook', (req, res) => {
	if (req.query['hub.mode'] === 'subscribe' &&
		req.query['hub.verify_token'] === VALIDATION_TOKEN) {
	console.log("Validating webhook")
	res.status(200).send(req.query['hub.challenge'])
	} else {
	console.error("Failed validation. Make sure the validation tokens match.")
	res.sendStatus(403)		
	}	
})

app.post('/webhook', (req, res) => {
	var data = req.body

	// Make sure this is a page subscription
	if (data.object == 'page') {
		// Iterate over each entry
		// There may be multiple if batched
		data.entry.forEach((pageEntry) => {
			var pageID = pageEntry.id
			var timeOfEvent = pageEntry.time

			// Iterate over each messaging event
			pageEntry.messaging.forEach((messagingEvent) => {
			if (messagingEvent.message) {
				receivedMessage(messagingEvent)
			}
			else {
				console.log(`Webhook received unknown messagingEvent: ${messagingEvent}`)
			}
			})
		})
		res.sendStatus(200)
	}
})

function receivedMessage(event) {
	var senderID = event.sender.id
	var recipientID = event.recipient.id
	var timeOfMessage = event.timestamp
	var message = event.message

	console.log(`Received message for user ${senderID} and page ${recipientID} at ${timeOfMessage} with message:`)
	console.log(JSON.stringify(message))

	sendReadReceipt(senderID)
	sendTypingOn(senderID);

	((senderID) => {
		request(
		{
			url: 'https://api.api.ai/v1/query',
			headers: {
				'Authorization': `Bearer ${API_AI_ACCESS_TOKEN}`,
				'Content-Type': 'application/json charset=utf-8'
			},
			method: 'GET',
			qs: {
				v: '20150910',
				query: message.text,
				sessionId: '1234567890',
				lang: 'en'
			}
		}, (error, response, body) => {
			if (!error && response.statusCode == 200) {
				var queryParams = getQueryParams(JSON.parse(body))
				sendTextMessage(senderID, formResponseMessage(queryParams))
				if (!queryParams.fallback) {
					console.log(sendTypingOn)
					sendTypingOn(senderID)
					getForecast(queryParams).then((forecast) => {
						console.log('promise')
						sendTextMessage(senderID, forecast)
					})
				}
			}
		})
	})(senderID)
}

function getQueryParams(body) {
	console.log(body.result.metadata.intentName)
	if (body.result.metadata.intentName != 'show weather')
		return {
			fallback: true,
			text: body.result.fulfillment.speech
		}

	var city = body.result.parameters.address.city
	var state = body.result.parameters.address.state
	var date = body.result.parameters.date
	var time = body.result.parameters.time
	var hasCity = city != null && city != ""
	var hasDate = date != null && date != ""
	var hasTime = time != null && time != ""
	var hasState = state != null && state != ""
	if (!hasCity) {
		if (hasState)
			city = state
		else
			city = 'your location'
	}
	else if (hasState) {
		city += ', ' + state
	}
	if (!hasDate)
		date = dateFormat(new Date(body.timestamp), 'isoDate')
	if (!hasTime) {
		if (hasDate)
			time = '00:00:00'
		else
			time = dateFormat(new Date(body.timestamp), 'isoTime')
	}

	return {
		fallback: false,
		time,
		hasTime,
		date,
		hasDate,
		city,
		hasCity,
		state,
		hasState
	}
}

function formResponseMessage(params) {
	if (params.fallback)
		return params.text
	var result = `You requested a weather forecast in ${params.city} for ${params.date} ${params.time}.`
	return result
}

function getForecast(params) {
	var result = defer()

	if (!params.hasCity) {
		result.resolve(`Cannot determine weather forecast in this location. Please specify the correct city name. Also, it may be that you specified the city I just don't know.`)
		return result
	}

	request(
	{
		url: 'http://api.openweathermap.org/data/2.5/forecast',
		qs: {
			q: params.city,
			APPID: WEATHER_API_KEY,
			units: 'metric'
		}
	}, (err, response, body) => {
		var allweather = JSON.parse(body)

		if (!allweather.list) {
			console.log(allweather)
			result.resolve('Cannot determine weather forecast in this location. Please try something else.')
			return result
		}

		// Picking the closest forecast available from the list
		// The weather API gives me the forecast for 5 days maximum
		var closestForecastInd = 0
		var closestForecastDt = 1e20	
		var timeRequested = new Date(params.date + ' ' + params.time)
		for (var curForecastInd in allweather.list) {
			var curDt = Math.abs((new Date(allweather.list[curForecastInd].dt_txt)) - timeRequested)
			if (curDt < closestForecastDt) {
				closestForecastInd = curForecastInd
				closestForecastDt = curDt
			}
		}

		var weather = allweather.list[closestForecastInd]
		var weatherDate = new Date(allweather.list[closestForecastInd].dt_txt)

		var str =
`Showing closest weather available: ${dateFormat(weatherDate, 'isoDate')} ${dateFormat(weatherDate, 'isoTime')}

Weather type: ${weather.weather[0].description}
Temperature: ${weather.main.temp} °C
Humidity: ${weather.main.humidity}%
Wind speed: ${weather.wind.speed} m/s
Cloudiness: ${weather.clouds.all}%`

		result.resolve(str)
	})

	return result
}

/*
 * Send a text message using the Send API.
 *
 */
function sendTextMessage(recipientId, messageText) {
	var messageData = {
		recipient: {
			id: recipientId
		},
		message: {
			text: messageText,
			metadata: "DEVELOPER_DEFINED_METADATA"
		}
	}

	callSendAPI(messageData)
}

/*
 * Send a read receipt to indicate the message has been read
 *
 */
function sendReadReceipt(recipientId) {
	console.log("Sending a read receipt to mark message as seen")

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

	callSendAPI(messageData)
}

/*
 * Turn typing indicator on
 *
 */
function sendTypingOn(recipientId) {
	console.log("Turning typing indicator on")

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

	callSendAPI(messageData)
}

/*
 * Turn typing indicator off
 *
 */
function sendTypingOff(recipientId) {
	console.log("Turning typing indicator off")

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

	callSendAPI(messageData)
}

/*
 * Send a read receipt to indicate the message has been read
 *
 */
function sendReadReceipt(recipientId) {
	console.log("Sending a read receipt to mark message as seen")

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

	callSendAPI(messageData)
}

/*
 * 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) {
	console.log(messageData)
	request(
	{
		uri: 'https://graph.facebook.com/v2.6/me/messages',
		qs: { access_token: PAGE_ACCESS_TOKEN },
		method: 'POST',
		json: messageData
	}, (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 ${messageId} to recipient ${recipientId}`)
			} else {
				console.log(`Successfully called Send API for recipient ${recipientId}`)
			}
		} else {
			console.log(error || response.statusCode)
		}
	})
}

// Start server
app.listen(app.get('port'), () => {
	console.log(`Node app is running on port ${app.get('port')}`)
})

module.exports = app