class User < ActiveRecord::Base

  attr_accessor :password
  attr_accessible(:name, :email, :password, :password_confirmation)

  has_many :microposts, :dependent => :destroy

  email_regex = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i

  validates :name,  :presence   => true,
                    :length     => { :maximum => 50 }
  validates :email, :presence   => true,
                    :format     => { :with => email_regex},
                    :uniqueness => { :case_sensitive => false }

  #Automatically create the virtual attribure 'password_confirmation'.
  validates :password, :presence      => true,
                       :confirmation  => true,
                       :length        => { :within => 6..20 }

  before_save :encrypt_password

  #return true if the user's password matches the submitted password.

  def has_password?(submitted_password)
    encrypted_password == encrypt(submitted_password)
  end

  def self.authenticate(email, submitted_password)
    user = find_by_email(email)
    return nil   if user.nil?
    return user  if user.has_password?(submitted_password)
  end

  def self.authenticate_with_salt(id, cookie_salt)
    user = find_by_id(id)
    (user && user.salt == cookie_salt) ? user : nil
  end

  def feed
    # This is a preliminary - filled out in chapter 12.
    Micropost.where("user_id = ?", id)
  end


  private

    def encrypt_password
      self.salt = make_salt if new_record?
      self.encrypted_password = encrypt(password)
    end

    def encrypt(string)
      secure_hash("#{salt}--#{string}")
    end

    def make_salt
      secure_hash("#{Time.now.utc}--#{password}")
    end

    def secure_hash(string)
      Digest::SHA2.hexdigest(string)
    end


end