// import packages that we need

const express = require('express')

const bodyParser = require('body-parser')

const mongoose = require('mongoose')

// import our api routes

const index = require('./routes/index')

const user = require('./routes/user')

// define base uri with api version protocol defined in package.json

const env = require('./env.json')

// define app

var app = express()

// [Use native promises for backwards compatibility. Mongoose 4 returns mpromise promises by default.](http://mongoosejs.com/docs/promises.html)

mongoose.Promise = Promise

// create reusable mongo connect func

var mongoConnect = function() {

mongoose.connect(env.mongodb || 'mongodb://localhost/restapi', { server: { auto_reconnect: true } })

}

// get mongoose connection instance

var db = mongoose.connection

db.once('open', function() {

console.log('MongoDB connection opened!')

})

db.on('connected', () => {

console.info('Connected to MongoDB!')

})

db.on('reconnected', function () {

console.log('MongoDB reconnected!')

})

db.on('error', function(error) {

console.error('Error in MongoDb connection: ' + error)

mongoose.disconnect()

})

db.on('reconnected', function () {

console.log('MongoDB reconnected!')

})

db.on('disconnected', function() {

console.log('MongoDB disconnected!')

setTimeout(mongoConnect, 10000)

})

// connect to local mongodb by default if it not specified in env

mongoConnect()

// remove x-powered-by header variable

app.disable('x-powered-by')

// ? app.disable('etag');

// This function is executed every time the app receives a request and check

// mongodb readyState flag: 0 = disconnected, 1 = connected, 2 = connecting,

// 3 = disconnecting

app.use(function (req, res, next) {

if (db.readyState != 1) {

var err = new Error('Database connection problem')

err.status = 500

next(err)

}

else

next()

})

// parse application/json

app.use(bodyParser.json())

// parse application/x-www-form-urlencoded

app.use(bodyParser.urlencoded({ extended: false }))

// set 3000 port as default if it not specified in env

app.set('port', env.port || 3000)

// register api routes

app.use('/' + env.api.version, index)

app.use('/' + env.api.version + '/user', user)

// catch 404 and forward to error handler

app.use(function(req, res, next) {

var err = new Error('Not Found')

err.status = 404

next(err)

})

// error handlers

// development error handler

// will print stacktrace

if (env.environment === 'development') {

app.use(function(err, req, res, next) {

res.status(err.status || 500);

res.json({

message: err.message,

error: err

})

})

}

// production error handler

// no stacktraces leaked to user

app.use(function(err, req, res, next) {

res.status(err.status || 500);

res.json({

message: err.message,

error: {}

})

})

// start our rest api server

var server = app.listen(app.get('port'), function() {

console.log('RESTful API server listening on port ' + server.address().port)

})

// prevent too long threshold

server.timeout = 2048