user auth

var mongoose = require('mongoose');
var uniqueValidator = require('mongoose-unique-validator');
var crypto = require('crypto');
// JWT for user
var jwt = require('jsonwebtoken');
// secret to sign the JWT
var secret = require('../config').secret;

// schema representing user data
var UserSchema = new mongoose.Schema(
  {
    username: {
      type: String,
      lowercase: true,
      unique: true,
      required: [true, "can't be blank"],
      match: [/^[a-zA-Z0-9]+$/, 'is invalid'],
      index: true,
    },
    email: {
      type: String,
      lowercase: true,
      unique: true,
      required: [true, "can't be blank"],
      match: [/\S+@\S+\.\S+/, 'is invalid'],
      index: true,
    },
    bio: String,
    image: String,
    hash: String,
    salt: String,
  },
  {timestamps: true}
);

UserSchema.plugin(uniqueValidator, {message: 'is already taken.'});

// record a salt and hash for the password
UserSchema.methods.setPassword = function (password) {
  this.salt = crypto.randomBytes(16).toString('hex');
  this.hash = crypto
    .pbkdf2Sync(password, this.salt, 10000, 512, 'sha512')
    .toString('hex');
};

// hash the input password with respect to the salt and see
// if it matches the set hash
UserSchema.methods.validPassword = function (password) {
  var hash = crypto
    .pbkdf2Sync(password, this.salt, 10000, 512, 'sha512')
    .toString('hex');
  return this.hash === hash;
};

// generate a JWT
UserSchema.methods.generateJWT = function() {
  var today = new Date();
  var exp = new Date(today);
  exp.setDate(today.getDate() + 60);

  return jwt.sign({
    id: this._id,
    username: this.username,
    exp: parseInt(exp.getTime() / 1000),
  }, secret);
};

// send user object to front end
UserSchema.methods.toAuthJSON = function () {
  return {
    username: this.username,
    email: this.email,
    token: this.generateJWT(),
    bio: this.bio,
    image: this,image
  };
};

// register the schema with mongoose as 'User'
mongoose.model('User', UserSchema);