require 'digest/sha2'
class User < ActiveRecord::Base
    has_and_belongs_to_many :roles
    belongs_to :store
    validates_uniqueness_of :username
    validates_presence_of :username, :first_name, :last_name
    validates_presence_of :password, :password_confirmation, :on => :update, :if => :password_required?
    validates_length_of :password, :within => 5..20, :on => :update, :if => :password_required?
    validates_confirmation_of :password, :on => :update, :if => :password_required?
    validates_presence_of :password, :password_confirmation, :on => :create
    validates_confirmation_of :password, :on => :create

    attr_accessor :password, :password_confirmation

    def self.authenticate(username, password)
        user = User.find(:first, :conditions => ['username = ?', username])
        if user.blank? ||
            Digest::SHA256.hexdigest(password   user.password_salt) != user.password_hash
            raise "Username or password invalid"
        end
        user
    end

    def password=(pass)
        unless pass.blank?
        salt = [Array.new(6){rand(256).chr}.join].pack("m").chomp
        self.password_salt, self.password_hash =
            salt, Digest::SHA256.hexdigest(pass   salt)
        end
    end

    def name
        self.first_name   " "   self.last_name
    end

    protected
    def password_required?
        !password.blank?
    end
end