const
  debug = require('debug')('agm:db'),
  mongoose = require('mongoose');
// Our custom middleware
mongoose.Promise = global.Promise;  // Disable Promise depreciated warning
const opts = {
  user: 'agm', pass: 'Agm2017',
  connectTimeoutMS: 40000,
  // TCP Connection timeout setting. Best = 2-3X time of longest operation (30 minutes)
  socketTimeoutMS: 1.8e+6,
  // The number of milliseconds to wait before initiating keepAlive on the TCP socket.  
  keepAlive: true, keepAliveInitialDelay: 30000,
  // for better performace in Production invironment
  autoIndex: false,
  // Disable buffering commands to report error as soon as connections get disconnected
  bufferCommands: false,
  useNewUrlParser: true,
  useFindAndModify: false,
  useCreateIndex: true,
  useUnifiedTopology: true,
  family: 4
}
mongoose.connect('mongodb://localhost:27017/agmission?authSource=agmission', opts);
mongoose.connection.on('disconnected', () => { debug('-> MongoDB lost connection'); });
mongoose.connection.on('reconnect', () => { debug('-> MongoDB reconnected'); });
mongoose.connection.on('connected', () => { debug('-> MongoDB connected'); });
mongoose.connection.on('reconnectFailed', () => { debug('-> MongoDB gave up reconnecting'); });
mongoose.connection.on('error', console.error.bind(console, 'MongoDB connection errors:'));

function postExit() {
  if (mongoose.connection) {
    mongoose.connection.close(() => {
      debug('Mongoose default connection disconnected through app termination');
      process.exit(0);
    });
  } else {
    process.exit(0);
  }
}
// If the Node process ends, close the Mongoose connection 
process.on('SIGINT', function () {  // Windows
  postExit();
});

module.exports = mongoose.connection;