module RailsConnector

  # @api public
  module CmsTagHelper
    FIELD_TYPES_WITH_ORIGINAL_CONTENT = %w[
      enum
      html
      multienum
      reference
      referencelist
      string
      text
    ]

    VOID_TAGS = %w[area base br col command embed hr img input keygen
        link meta param source track wbr]

    # Returns an HTML block tag containing content from an Obj.
    # Add HTML attributes by passing an attributes hash to options.
    # The helper method is somewhat similar to (and internally uses) http://api.rubyonrails.org/classes/ActionView/Helpers/TagHelper.html#method-i-content_tag.
    #
    # This helper method also renders additional data attributes, which are needed for inplace editing.
    # These attributes are only rendered when appropriate, i.e. not for a regular visitor.
    #
    # @param tag_name [String, Symbol] Name of the html tag (e.g. +:h1+ or +:div+).
    # @param obj [Obj] A {Obj} from which attribute is read.
    # @param field_name [String, Symbol] Which field of the Obj should be rendered.
    # @param options [Hash] Additional options, which are passed to +content_tag+. Use them to add HTML attributes to the tag.
    # @param block [Proc] Optional block to render inner HTML. If none given the value of attribute will be rendered instead.
    # @return [String] The rendered html tag
    #
    # @example Renders an <h2> tag containing the text of the +headline+ attribute of +@obj+ and assigns the tag a css class called +very_important+.
    #     <%= cms_tag :h2, @obj, :headline, class: "very_important" %>
    #
    # @example Renders an <h2> tag containing an escaped +headline+.
    #     <%= cms_tag :h2, @obj, :headline do %>
    #       <%= strip_tags @obj.headline %>
    #     <% end %>
    #
    # @api public
    def cms_tag(tag_name, obj_or_widget, field_name, options = {}, &block)
      begin
        field_type = obj_or_widget.type_of_attribute(field_name.to_s)
      rescue RailsConnectorError => e
        return content_tag(tag_name, '', options)
      end

      if inplace_editing_allowed?
        options = options.merge({
          'data-ip-field-name'      => field_name,
          'data-ip-field-obj-class' => obj_or_widget.obj_class,
          'data-ip-field-type'      => field_type,
        })

        if obj_or_widget.kind_of?(BasicWidget)
          options['data-ip-private-field-id'] = obj_or_widget.obj.id
          options['data-ip-private-field-widget-id'] = obj_or_widget.id
        else
          options['data-ip-private-field-id'] = obj_or_widget.id
        end
      end

      if field_type == 'widget'
        rendered_widgets = obj_or_widget[field_name].map do |widget|
          render_widget(widget, obj_or_widget, field_name, obj_or_widget)
        end
        inner_html = safe_join(rendered_widgets)
      else
        if inplace_editing_allowed? && FIELD_TYPES_WITH_ORIGINAL_CONTENT.include?(field_type)
          original_value = display_original_value(obj_or_widget[field_name])
          original_content = cms_tag_original_content(field_type, original_value)
          options['data-ip-private-field-original-content'] = MultiJson.encode(original_content)
        end

        inner_html = block_given? ? capture { yield } : display_value(obj_or_widget[field_name])
      end

      if VOID_TAGS.include?(tag_name.to_s)
        tag(tag_name, options)
      else
        content_tag(tag_name, inner_html, options)
      end
    end

    def cms_tag_original_content(field_type, field_value)
      case field_type
      when 'reference' then field_value.try(:id)
      when 'referencelist' then field_value.map(&:id)
      else field_value
      end
    end

    class List

      attr_reader :output

      def initialize(template)
        @template = template
      end

      # @param tag_name [String, Symbol] Name of the html tag (e.g. +:div+ or +:span+).
      # @param options [Hash] Additional options, which are passed to +content_tag+. Use them to add HTML attributes to the tag.
      # @return [String] The rendered html tag
      #
      # @example Render a <div> tag containing the text "random content" and assigns the tag a css class called +very_important+.
      #   <%= list.tag :div, class: "very_important" do %>
      #     random content
      #   <% end %>
      def tag(tag_name, options = {}, &block)
        if @output.present?
          raise '"list.tag" can only be called once per iteration!'
        else
          @output = @template.content_tag(tag_name, options, &block) + "\n"

          nil
        end
      end

    end

    # @param tag_name [String, Symbol] Name of the html tag (e.g. +:h1+ or +:div+).
    # @param obj [Obj] A {Obj} from which method_name is read.
    # @param method_name [String, Symbol] Which method_name of the Obj should be rendered. Currently only +toclist+ is supported
    # @param options [Hash] Additional options, which are passed to +content_tag+. Use them to add HTML attributes to the tag.
    # @yieldparam [List] list An instance, where +tag+ should be called once.
    # @yieldparam [Obj] child Each child of +toclist+
    # @return [String] The rendered html tag
    #
    # @example
    #   <%= cms_tag_list :div, @obj, :toclist, class: "very_important" do |list, child| %>
    #     <%= list.tag :div, class: "also_important" do %>
    #       <%= link_to cms_path(child) do %>
    #         <%= cms_tag :span, child, :title %>
    #       <% end %>
    #     <% end %>
    #   <% end %>
    #
    #   # results for an obj with two children in
    #
    #   <div class="very_important">
    #     <div class="also_important"><a href="/child1"><span>Child 1</span></a></div>
    #     <div class="also_important"><a href="/child2"><span>Child 2</span></a></div>
    #   </div>
    def cms_tag_list(tag_name, obj, method_name, options = {})
      if method_name.to_s == 'toclist'
        items = obj.toclist
      else
        raise "#{method_name} is not (yet) supported. Currently only toclist is supported."
      end

      inner_html = "\n".html_safe

      items.each do |item|
        list = List.new(self)

        yield list, item

        inner_html << list.output
      end

      valid_page_classes = Obj.valid_page_classes_beneath(obj.path)

      options = options.merge({
        'data-ip-private-child-list-path' => obj.path,
        'data-ip-private-child-list-allowed-classes' => valid_page_classes.to_json,
      }) if inplace_editing_allowed?

      content_tag(tag_name, inner_html, options)
    end

    def render_widget(widget, obj, field_name, container)
      renderer = WidgetRenderer.new(request)

      options = {}

      if inplace_editing_allowed?
        options['data-ip-private-widget-id'] = widget.id
        options['data-ip-private-widget-obj-class'] = widget.obj_class
        options['data-ip-private-widget-has-edit-view'] = true if renderer.has_edit_view?(widget.obj_class)
      end

      content_tag(:div, options) do
        renderer.process(:show, widget, obj, field_name, container)
      end
    end

  end

end