refined

var mongoose = require("mongoose");
var bcrypt = require("bcrypt");
var Schema = mongoose.Schema;
const SALT_WORK_FACTOR = 10;

var UserSchema = new Schema({
  email: { type: String, required: true, index: { unique: true } },
  password: { type: String, required: true }
});

UserSchema.pre("save", function(next) {
  var user = this;
  // only hash the password if it has been modified (or is new)
  if (!user.isModified("password")) return next();
  // generate a salt
  bcrypt.genSalt(SALT_WORK_FACTOR, function(err, salt) {
    if (err) return next(err);

    // hash the password using our new salt
    bcrypt.hash(user.password, salt, function(err, hash) {
      if (err) return next(err);

      // override the cleartext password with the hashed one
      user.password = hash;
      next();
    });
  });
});

UserSchema.methods.comparePassword = function(candidatePassword, cb) {
    bcrypt.compare(candidatePassword, this.password, function(err, isMatch) {
        if (err) return cb(err);
        cb(null, isMatch);
    });
}

module.exports = mongoose.modle('User',UserSchema);