require 'middleman-blog/uri_templates'

module Middleman

  module Blog

    ##
    # A sitemap resource manipulator that adds a tag page to the sitemap for
    # each tag in the associated blog
    ##
    class TagPages

      include UriTemplates

      ##
      # Initialise Tag pages
      #
      # @param  app             [Object] Middleman app
      # @param  blog_controller [Object] Blog controller
      ##
      def initialize( app, blog_controller )
        @sitemap            = app.sitemap
        @blog_controller    = blog_controller
        @tag_link_template  = uri_template blog_controller.options.taglink
        @tag_template       = blog_controller.options.tag_template
        @blog_data          = blog_controller.data
        @generate_tag_pages = blog_controller.options.generate_tag_pages
      end

      ##
      # Get a path to the given tag, based on the :taglink setting.
      #
      # @param  tag [String] Tag name
      # @return     [String] Safe Tag URL
      ##
      def link( tag )
        apply_uri_template @tag_link_template, tag: safe_parameterize( tag )
      end

      ##
      # Update the main sitemap resource list
      #
      # @param  resources [Object] Tag name
      # @return           [void]
      ##
      def manipulate_resource_list( resources )

        return resources unless @generate_tag_pages

        resources + @blog_data.tags.map do | tag, articles |
          tag_page_resource( tag, articles )
        end

      end

      private

      ##
      # Create the tag page resources
      #
      # @param  tag      [String] Tag name
      # @param  articles [Object] Articles
      # @return          [Object] Sitemap
      #
      # @todo Can we inject the correct locale into the metadata here
      ##
      def tag_page_resource( tag, articles )

        Sitemap::ProxyResource.new( @sitemap, link( tag ), @tag_template ).tap do | p |

          # Detect "formatted" tag in first article - trying to guess the correct format to show
          # tagname = articles.first.tags.detect { |article_tag| safe_parameterize(article_tag) == tag }

          # Add metadata in local variables so it's accessible to later extensions
          p.add_metadata locals: {
            'page_type'       => 'tag',
            'tagname'         => tag,
            'articles'        => articles,
            'blog_controller' => @blog_controller
          }

        end

      end

    end

  end

end