module ActiveRecord
  module EavHashes
    def self.included (base)
      base.extend ActiveRecord::EavHashes::ClassMethods
    end

    module ClassMethods
      def eav_hash_for (hash_name, options={})
        # Fill in default options not otherwise specified
        options[:hash_name] = hash_name
        options[:parent_class_name] = self.name.to_sym
        options = ActiveRecord::EavHashes::Util::fill_options_hash options

        # Store the options hash in a class variable to create the EavHash object
        # if and when it's actually used.
        class_variable_set "@@#{hash_name}_hash_options".to_sym, options

        # Create the association, the entry update hook, and a helper method to lazy-load the entries
        class_eval <<-END_EVAL
          has_many :#{options[:entry_assoc_name]}, class_name: "#{options[:entry_class_name]}", foreign_key: "#{options[:parent_assoc_name]}_id", dependent: :delete_all
          after_save :save_#{hash_name}
          def #{hash_name}
            @#{hash_name} ||= ActiveRecord::EavHashes::EavHash.new(self, @@#{hash_name}_hash_options)
          end

          def save_#{hash_name}
            @#{hash_name}.save_entries if @#{hash_name}
          end

          def self.find_by_#{hash_name} (key, value=nil)
            self.find (ActiveRecord::EavHashes::Util::run_find_expression(key, value, @@#{hash_name}_hash_options))
          end
        END_EVAL
      end
    end
  end
end