// Copyright 2015-2016, Google, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// [START app]

'use strict';

var fs = require('fs');

var util = require('util');

var express = require('express');

var app = express();

app.enable('trust proxy');

app.get('/', function(req, res, next) {

var instanceId = process.env.GAE_MODULE_INSTANCE || '1';

var userIp = util.format('%s\n', req.ip);

fs.appendFile('/tmp/seen.txt', userIp, function(err) {

if (err) { return next(err); }

fs.readFile('/tmp/seen.txt', function(err, data) {

if (err) { return next(err); }

res.set('Content-Type', 'text/plain');

res.status(200).send(util.format(

'Instance: %s\n' +

'Seen: \n%s', instanceId, data));

});

});

});

var server = app.listen(process.env.PORT || '8080', '0.0.0.0', function() {

console.log('App listening at http://%s:%s', server.address().address,

server.address().port);

console.log('Press Ctrl+C to quit.');

});

// [END app]