require 'digest/sha1'


class User < ActiveRecord::Base


  # make sure we have the required fields when saving
  validates_presence_of :user_name,
                        :password,
			:password_confirmation
  # make the name unique as it is going to be the login
  validates_uniqueness_of :user_name

  # we want password to be at least 5 characters
  validates_length_of :password,
                      :minimum => 5,
		      :message => "should be at least 5 characters long"


  # make sure that password_confirmation and password match
  attr_accessor :password_confirmation
  validates_confirmation_of :password

  #-----------------------------------------------------------------
  # lookup the user and check the password
  # set user to nil if user doesn't exist
  # or password doesn't match

  def self.login(user_name, password)

    user = User.find(:first, :conditions => ['user_name = ?', user_name])
    if user
      expected_password = encrypted_password(password, user.password_salt)
      if user.password_hash != expected_password
        user = nil
      end
    end
    user
  end

  #-----------------------------------------------------------------
  # normally for virtual attributes we
  # just need to declare:
  # attr_accessor: [fieldname]
  # to create the getter and setter
  # since password has extra logic in
  # the setter, we have to create them
  # by hand

  # password getter
  def password
    @password
  end

  #-----------------------------------------------------------------

  # password setter
  def password=(pwd)
    @password = pwd
    create_new_salt
    self.password_hash =
                User.encrypted_password(self.password, self.password_salt)
  end


  #-----------------------------------------------------------------

  def safe_delete

    transaction do
      destroy
      if User.count.zero?
        raise "Can't delete last user"
      end
    end
  end

  #-----------------------------------------------------------------

  # create the salt we will use when encrypting the password

  def create_new_salt
    self.password_salt =
    [Array.new(6){rand(256).chr}.join].pack("m").chomp
  end

  #-----------------------------------------------------------------

  # returns the hash for the password using the salt provided
  def self.encrypted_password(password, salt)
    string_to_hash = password + salt
    Digest::SHA1.hexdigest(string_to_hash)
  end

end