module Models
  module Extensions
    module Page
      module EditableElements

        extend ActiveSupport::Concern

        included do
          embeds_many :editable_elements

          after_save :remove_disabled_editable_elements

          # editable file callbacks
          after_save :store_file_sources!
          before_save :write_file_source_identifiers
          after_destroy :remove_file_sources!

          accepts_nested_attributes_for :editable_elements
        end

        module InstanceMethods

          def disable_parent_editable_elements(block)
            self.editable_elements.each { |el| el.disabled = true if el.from_parent? && el.block == block }
          end

          def disable_all_editable_elements
            self.editable_elements.each { |el| el.disabled = true }
          end

          def editable_element_blocks
            self.editable_elements.collect(&:block)
          end

          def editable_elements_grouped_by_blocks
            all_enabled = self.editable_elements.reject { |el| el.disabled? }
            groups = all_enabled.group_by(&:block)
            groups.delete_if { |block, elements| elements.empty? }
          end

          def find_editable_element(block, slug)
            self.editable_elements.detect { |el| el.block == block && el.slug == slug }
          end

          def find_editable_files
            self.editable_elements.find_all { |el| el.respond_to?(:source) }
          end

          def add_or_update_editable_element(attributes, type)
            element = self.find_editable_element(attributes[:block], attributes[:slug])

            if element
              element.attributes = attributes
            else
              self.editable_elements.build(attributes, type)
            end
          end

          def enable_editable_elements(block)
            self.editable_elements.each { |el| el.disabled = false if el.block == block }
          end

          def merge_editable_elements_from_page(source)
            source.editable_elements.each do |el|
              next if el.disabled? or !el.assignable?

              existing_el = self.find_editable_element(el.block, el.slug)

              if existing_el.nil? # new one from parents
                new_attributes = el.attributes.merge(:from_parent => true)
                if new_attributes['default_attribute'].present?
                  new_attributes['default_content'] = self.send(new_attributes['default_attribute']) || el.content
                else
                  new_attributes['default_content'] = el.content
                end
                
                self.editable_elements.build(new_attributes, el.class)
              else
                existing_el.attributes = { :disabled => false, :default_content => el.content }
              end
            end
          end

          def remove_disabled_editable_elements
            return unless self.editable_elements.any? { |el| el.disabled? }

            # super fast way to remove useless elements all in once (TODO callbacks)
            self.collection.update(self._selector, '$pull' => { 'editable_elements' => { 'disabled' => true } })
          end

          protected

          ## callbacks for editable files

          # equivalent to "after_save :store_source!" in EditableFile
          def store_file_sources!
            self.find_editable_files.collect(&:store_source!)
          end

          # equivalent to "before_save :write_source_identifier" in EditableFile
          def write_file_source_identifiers
            self.find_editable_files.collect(&:write_source_identifier)
          end

          # equivalent to "after_destroy :remove_source!" in EditableFile
          def remove_file_sources!
            self.find_editable_files.collect(&:remove_source!)
          end

        end

      end
    end
  end
end