require 'digest/sha1'
class User < ActiveRecord::Base 
  attr_accessor :remember_me
  attr_accessor :current_password
  
  # Max & min lengths for all fields 
  SCREEN_NAME_MIN_LENGTH = 4 
  SCREEN_NAME_MAX_LENGTH = 20 
  PASSWORD_MIN_LENGTH = 4 
  PASSWORD_MAX_LENGTH = 40 
  EMAIL_MAX_LENGTH = 50 
  SCREEN_NAME_RANGE = SCREEN_NAME_MIN_LENGTH..SCREEN_NAME_MAX_LENGTH 
  PASSWORD_RANGE = PASSWORD_MIN_LENGTH..PASSWORD_MAX_LENGTH 

  # Text box sizes for display in the views 
  SCREEN_NAME_SIZE = 20 
  PASSWORD_SIZE = 10 
  EMAIL_SIZE = 30 

  validates_uniqueness_of :screen_name, :email 
  validates_confirmation_of :password
  validates_length_of :screen_name, :within => SCREEN_NAME_RANGE
  validates_length_of :password, :within => PASSWORD_RANGE 
  validates_length_of :email, :maximum => EMAIL_MAX_LENGTH 

  validates_format_of :screen_name, 
                      :with => /^[A-Z0-9_]*$/i, 
                      :message => "must contain only letters, " + 
                                  "numbers, and underscores" 
  validates_format_of :email, 
                      :with => /^[A-Z0-9._%-]+@([A-Z0-9-]+\.)+[A-Z]{2,4}$/i, 
                      :message => "must be a valid email address"

  # Log a user in.
  def login!(session)
    session[:user_id] = id
  end
  
  # Log a user out.
  def self.logout!(session, cookies)
    session[:user_id] = nil
    cookies.delete(:authorization_token)
  end
  
  # Clear the password (typically to suppress its display in a view).
  def clear_password!
    self.password = nil
    self.password_confirmation = nil
    self.current_password = nil
  end
  
  # Remember a user for future login.
  def remember!(cookies)
    cookie_expiration = 10.years.from_now
    cookies[:remember_me] = { :value   => "1",
                              :expires =>  cookie_expiration }
    self.authorization_token =  unique_identifier
    save!
    cookies[:authorization_token] = { :value   => authorization_token,
                                      :expires => cookie_expiration }
  end
  
  # Forget a user's login status.
  def forget!(cookies)
    cookies.delete(:remember_me)
    cookies.delete(:authorization_token)
  end

  # Return true if the user wants the login status remembered.
  def remember_me?
    remember_me == "1"
  end

  private
  
  # Generate a unique identifier for a user.
  def unique_identifier
    Digest::SHA1.hexdigest("#{screen_name}:#{password}")
  end
end