module RailsConnector

  # This module contains a helper that can be used to render attributes of the CMS models.
  # @api public
  module DisplayHelper

    # For a consistent look of your site and easy maintenance, only the display helpers
    # should be used to render an attribute <em>value</em> of a CMS model.
    #
    #   <%= display_value @obj.title %>
    # Renders the value, taking its type into account.
    # * An HtmlString will be exported by converting its links
    # * A Time will be exported in an international form: Year-Month-Day Hour:Minutes
    # * A non-HTML String will be quoted
    # * other values will be rendered unchanged
    #
    # @api public
    def display_value(value)
      case value
        when MarkdownString then markdown(convert_links(value)).html_safe
        when HtmlString then convert_links(value).html_safe
        when String then h(value)
        when Time then h(l(value))
        else value
      end
    end

    # Renders a field from the CMS, including an edit marker for the preview
    # If the option :marker is +false+, no edit marker will be rendered.
    #
    # <%= display_field @obj, :title %>
    #
    # When creating an edit marker, all options except :marker are passed to {MarkerHelper#edit_marker}.
    #
    # @api public
    def display_field(obj, attr, options = {})
      options.reverse_merge!({
        :marker => ![:id, :path, :created, :last_changed, :version].include?(attr.to_sym)
        })
      if options.delete :marker
        edit_marker(obj, attr, options) do |obj, attr|
          display_value obj[attr]
        end
      else
        display_value obj[attr]
      end
    end

    # Legacy method - deprecated
    #
    # Use display_value and display_field instead
    def display(*args)
      if args.last.kind_of? Hash
        options = args.pop
      else
        options = {}
      end
      return display_value(args.first) if args.size == 1
      display_field(args[0], args[1], options)
    end

    private

    def markdown(string)
      require 'maruku'
      Maruku.new(string).to_html
    end

    LINK_PATTERN = '<?\binternallink:(\d+)\b>?'
    LINK_EXPRESSION = %r(#{LINK_PATTERN})

    def convert_links(content_attribute)
      return content_attribute unless content_attribute =~ LINK_EXPRESSION
      link_map = content_attribute.source.text_links.each_with_object({}) do |link, map|
        map[link.id.to_s] = link
      end
      content_attribute.gsub(%r(#{LINK_PATTERN}(['"]?))) do
        link = link_map[$1.to_s]
        if link.blank?
          "#{CmsRoutingHelper::LINK_TO_UNREACHABLE}#{$2}"
        else
          uri = "#{cms_path(link)}#{$2}"
          if link.markdown?
            markdown_link(link, uri)
          else
            html_link(link, uri)
          end
        end
      end
    end

    def html_link(link, uri)
      subst = uri
      name, value =
          case link.tag_name
          when 'img', 'input'
            ['alt', link.title || ""]
          when 'a', 'link'
            ['title', begin link.title unless link.title.blank? end]
          end
      if value
        subst << %( #{name}="#{h(value)}")
      end
      subst << %( target="#{h(link.target)}") unless link.target.blank?
      subst
    end

    def markdown_link(link, uri)
      subst = "<#{uri}>"
      unless link.title.blank?
        case link.markdown_type
        when 'inline', 'reference'
          subst << %( "#{h(link.title)}")
        end
      end
      subst
    end
  end
end