app.js

//var createError = require('http-errors');
var express = require('express');
var path = require('path');
//var cookieParser = require('cookie-parser');
//var logger = require('morgan');
const
    crypto = require('crypto'),
    bodyParser = require('body-parser'),
    request = require('request');
// Use dotenv to allow local running with environment variables
require('dotenv').load();

const
    VERIFY_TOKEN = process.env.VERIFY_TOKEN,
    ACCESS_TOKEN = process.env.ACCESS_TOKEN,
    APP_SECRET = process.env.APP_SECRET;

if (!(APP_SECRET && VERIFY_TOKEN && ACCESS_TOKEN)) {
    console.error('Missing environment values.');
    //process.exit(1);
}

//pg.defaults.ssl = false;

var graphapi = request.defaults({
    baseUrl: 'https://graph.facebook.com',
    json: true,
    auth: {
        'bearer': ACCESS_TOKEN
    }
});

function verifyRequestSignature(req, res, buf) {
    var signature = req.headers['x-hub-signature'];

    if (!signature) {
        // For testing, let's log an error. In production, you should throw an error.
        console.error('Couldn\'t validate the signature.');
    } else {
        var elements = signature.split('=');
        var signatureHash = elements[1];

        var expectedHash = crypto.createHmac('sha1', APP_SECRET)
            .update(buf)
            .digest('hex');

        if (signatureHash != expectedHash) {
            throw new Error('Couldn\'t validate the request signature.');
        }
    }
}

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

//app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
//app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use(bodyParser.json({ verify: verifyRequestSignature }));
app.use('/', indexRouter);
app.use('/users', usersRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
    next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
    // set locals, only providing error in development
    res.locals.message = err.message;
    res.locals.error = req.app.get('env') === 'development' ? err : {};

    // render the error page
    res.status(err.status || 500);
    res.render('error');
});

// List out all the thanks recorded in the database
app.get('/', function(request, response) {
    response.render('pages/thanks', { results: 'ok' });
});
// Handle the webhook subscription request from Facebook
app.get('/webhook', function(request, response) {
    if (request.query['hub.mode'] === 'subscribe' &&
        request.query['hub.verify_token'] === VERIFY_TOKEN) {
        console.log('Validated webhook');
        response.status(200).send(request.query['hub.challenge']);
    } else {
        console.error('Failed validation. Make sure the validation tokens match.');
        response.sendStatus(403);
    }
});

// Handle webhook payloads from Facebook
app.post('/webhook', function(request, response) {
    if (request.body && request.body.entry) {
        request.body.entry.forEach(function(entry) {
            entry.changes.forEach(function(change) {
                if (change.field === 'mention') {
                    let mention_id = (change.value.item === 'comment') ?
                        change.value.comment_id : change.value.post_id;
                    // Like the post or comment to indicate acknowledgement
                    graphapi({
                        url: '/' + mention_id + '/likes',
                        method: 'POST'
                    }, function(error, res, body) {
                        console.log('Like', mention_id);
                    });
                    let message = change.value.message,
                        message_tags = change.value.message_tags,
                        sender = change.value.from.id,
                        permalink_url = change.value.permalink_url,
                        recipients = [],
                        managers = [],
                        query_inserts = [];
                    /*
                                      message_tags.forEach(function(message_tag) {
                                          // Ignore page / group mentions
                                          if(message_tag.type !== 'user') return;
                                          // Add the recipient to a list, for later retrieving their manager
                                          recipients.push(message_tag.id);
                                      });
                                      // Get recipients' managers in bulk using the ?ids= batch fetching method
                                      graphapi({
                                          url: '/',
                                          qs: {
                                              ids: recipients.join(','),
                                              fields: 'managers'
                                          }
                                      }, function(error,res,body) {
                                          // Add a data row for the insert query
                                          recipients.forEach(function(recipient) {
                                              // Check if we found their manager
                                              let manager = '';
                                              if(body
                                                  && body[recipient]
                                                  && body[recipient].managers
                                                  && body[recipient].managers.data[0])
                                                  manager = body[recipient].managers.data[0].id;
                                              managers[recipient] = manager;
                                              query_inserts.push(`(now(),'${permalink_url}','${recipient}','${manager}','${sender}','${message}')`);
                                          });*/
                    /* var interval = '1 week';
                     let query = 'INSERT INTO thanks VALUES '
                         + query_inserts.join(',')
                         + `; SELECT * FROM thanks WHERE create_date > now() - INTERVAL '${interval}';`;
                     pg.connect(DATABASE_URL, function(err, client, done) {
                         client.query(query, function(err, result) {
                             done();
                             if (err) {
                                 console.error(err);
                             } else if (result) {
                                 var summary = 'Thanks received!\n';
                                 // iterate through result rows, count number of thanks sent
                                 var sender_thanks_sent = 0;
                                 result.rows.forEach(function(row) {
                                     if(row.sender == sender) sender_thanks_sent++;
                                 });
                                 summary += `@[${sender}] has sent ${sender_thanks_sent} thanks in the last ${interval}\n`;

                                 // Iterate through recipients, count number of thanks received
                                 recipients.forEach(function(recipient) {
                                     let recipient_thanks_received = 0;
                                     result.rows.forEach(function(row) {
                                         if(row.recipient == recipient) recipient_thanks_received++;
                                     });
                                     if(managers[recipient]) {
                                         summary += `@[${recipient}] has received ${recipient_thanks_received} thanks in the last ${interval}. Heads up to @[${managers[recipient]}].\n`;
                                     } else {
                                         summary += `@[${recipient}] has received ${recipient_thanks_received} thanks in the last ${interval}. I don't know their manager.\n`;
                                     }
                                 });*/
                    // Comment reply with thanks stat summary
                    var summary = 'Muchas Gracias por tu comentario' + message + '\n';
                    graphapi({
                        url: '/' + mention_id + '/comments',
                        method: 'POST',
                        qs: {
                            message: summary
                        }
                    }, function(error, res, body) {
                        console.log('Comment reply', mention_id);
                    });
                    //}
                    response.sendStatus(200);
                    //});
                    //});
                    //});
                }
            });
        });
    }
});
module.exports = app;