require 'yaml'

module CanTango
  class PermissionEngine < Engine
    class YamlStore < Store
      attr_reader :path, :last_load_time

      # for a YamlStore, the name is the name of the yml file
      # options: extension, path

      def initialize name, options = {}
        super
      end

      def load!
        loader.load!
        @last_load_time = Time.now
      end

      def load_from_hash hash
        loader.load_from_hash hash
      end

      # return cached permissions if file has not changed since last load
      # otherwise load permissions again to reflect changes!
      def permissions
        return @permissions if changed?
        @permissions = loader.permissions
      end

      def changed?
        return true if !last_load_time
        last_modify_time <= last_load_time
      end

      def last_modify_time
        File.mtime(file_path)
      end

      CanTango.config.permission_engine.types.each do |type|
        define_method(:"#{type}_permissions") do
          loader.send(:"#{type}_permissions") || {}
        end

        define_method(:"#{type}_permissions_rules") do
          send(:"#{type}_permissions").inject({}) do |result,(pk,pv)| 
            result.merge(pv.to_hash)
          end
        end

        define_method(:"#{type}_permissions_to_hash") do
          { type.to_s => send(:"#{type}_permissions_rules") }
        end

        define_method(:"#{type}_compiled_permissions") do
          loader.send(:"#{type}_compiled_permissions")
        end

        # @stanislaw: this needs revision!

        alias_method :"#{type}_rules", :"#{type}_compiled_permissions"
      end

      def save! perms = nil
        save_permissions(perms) if perms

        File.open(file_path, 'w') do |f|
          f.write to_yaml
        end
      end

      def save_permissions perms
        load_from_hash perms
      end

      protected

      def permission_types
        CanTango.config.engine(:permission).types
      end

      def to_yaml
        permission_types.inject({}) do |collection, type|
          collection.merge(send(:"#{type}_permissions_to_hash"))
        end.to_yaml.gsub(/"(@\w+)"/,'\1') # hash.to_yaml leaves quotes on strings prefixed with @
      end

      def loader
        @loader ||= CanTango::PermissionEngine::Loader::Permissions.new file_path
      end

      def file_path
        File.join(path, file_name)
      end

      private

      def file_name
        [name, extension].join('.')
      end

      def extension
        @extension || default_ext
      end

      def default_ext
        'yml'
      end

    end
  end
end