module Authlogic
  module Session
    # = Scopes
    #
    # Authentication can be scoped, but scoping authentication can get a little tricky. Checkout the section "Scoping" in the readme for more details.
    #
    # What with_scopes focuses on is scoping the query when finding the object and the name of the cookie / session. It works very similar to
    # ActiveRecord::Base#with_scopes. It accepts a hash with any of the following options:
    #
    # * <tt>find_options:</tt> any options you can pass into ActiveRecord::Base.find. This is used when trying to find the record.
    # * <tt>id:</tt> The id of the session, this gets merged with the real id. For information ids see the id method.
    #
    # Here is how you use it:
    #
    #   UserSession.with_scope(:find_options => {:conditions => "account_id = 2"}, :id => "account_2") do
    #     UserSession.find
    #   end
    #
    # Eseentially what the above does is scope the searching of the object with the sql you provided. So instead of:
    #
    #   User.find(:first, :conditions => "login = 'ben'")
    #
    # it would be:
    #
    #   User.find(:first, :conditions => "login = 'ben' and account_id = 2")
    #
    # You will also notice the :id option. This works just like the id method. It scopes your cookies. So the name of your cookie will be:
    #
    #   account_2_user_credentials
    #
    # instead of:
    #
    #   user_credentials
    #
    # What is also nifty about scoping with an :id is that it merges your id's. So if you do:
    #
    #   UserSession.with_scope(:find_options => {:conditions => "account_id = 2"}, :id => "account_2") do
    #     session = UserSession.new
    #     session.id = :secure
    #   end
    #
    # The name of your cookies will be:
    #
    #   secure_account_2_user_credentials
    module Scopes # :nodoc:
      def self.included(klass)
        klass.extend(ClassMethods)
        klass.send(:include, InstanceMethods)
        klass.class_eval do
          attr_writer :scope
          alias_method_chain :initialize, :scopes
          alias_method_chain :search_for_record, :scopes
        end
      end
      
      # = Scopes
      module ClassMethods
        # The current scope set, should be used in the block passed to with_scope.
        def scope
          scopes[Thread.current]
        end
        
        # See the documentation for this class for more information on how to use this method.
        def with_scope(options = {}, &block)
          raise ArgumentError.new("You must provide a block") unless block_given?
          self.scope = options
          result = yield
          self.scope = nil
          result
        end
        
        private
          def scope=(value)
            scopes[Thread.current] = value
          end
          
          def scopes
            @scopes ||= {}
          end
      end
      
      module InstanceMethods
        def initialize_with_scopes(*args) # :nodoc:
          self.scope = self.class.scope
          initialize_without_scopes(*args)
        end
        
        # See the documentation for this class for more information on how to use this method.
        def scope
          @scope ||= {}
        end
        
        def search_for_record_with_scopes(*args) # :nodoc:
          klass.send(:with_scope, :find => (scope[:find_options] || {})) do
            search_for_record_without_scopes(*args)
          end
        end
      end
    end
  end
end