#
# This module provides several helper methods for rendering the CMS contents and enabling the
# in-place editing.
#
# @api public
#
module ScrivitoHelper
  include Scrivito::RoutingHelper

  #
  # 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.
  #
  # @api public
  #
  # 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_or_widget [Scrivito::BasicObj, Scrivito::BasicWidget] A {Scrivito::BasicObj}
  #   or {Scrivito::BasicWidget} from which the +field_name+ is read.
  # @param field_name [String, Symbol] Which field of the Obj should be rendered.
  # @param html_options [Hash] HTML options to be passed to +content_tag+.
  # @param block [Proc] Optional block to render inner HTML. If none given the value of attribute
  #   will be rendered instead. +block+ is not allowed for fields of type +widget+.
  # @raise ArgumentError if the field behind +field_name+ is of type +widget+ and a +block+ is given.
  # @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+.
  #     <%= scrivito_tag :h2, @obj, :headline, class: "very_important" %>
  #
  # @example Renders an <h2> tag containing an escaped +headline+.
  #     <%= scrivito_tag :h2, @obj, :headline do %>
  #       <%= strip_tags @obj.headline %>
  #     <% end %>
  #
  # @example Render a download link for a PDF document
  #     <%= scrivito_tag :div, @obj, :pdf do %>
  #       <% if @obj.pdf %>
  #         Download: <%= link_to @obj.pdf.filename, @obj.pdf.url %>
  #       <% elsif scrivito_user %>
  #         Drop PDF here to upload
  #       <% end %>
  #     <% end %>
  def scrivito_tag(tag_name, obj_or_widget, field_name, html_options = {}, &block)
    Scrivito::CmsFieldTag.new(
      self, tag_name, obj_or_widget, field_name.to_s
    ).render(html_options, &block)
  end

  #
  # @api public
  #
  # @param tag_name [String, Symbol] Name of the html tag (e.g. +:h1+ or +:div+).
  # @param obj [Scrivito::BasicObj] A {Scrivito::BasicObj} from which field_name is read.
  # @param field_name [String, Symbol] Which field_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 [Scrivito::ChildListTag::ObjTag] list An instance, where +tag+ should be called once.
  # @yieldparam [Scrivito::BasicObj] child Each child of +toclist+
  #
  # @return [String] The rendered html tag
  #
  # @example
  #   <%= scrivito_tag_list :div, @obj, :toclist, class: "very_important" do |list, child| %>
  #     <%= list.tag :div, class: "also_important" do %>
  #       <%= link_to scrivito_path(child) do %>
  #         <%= scrivito_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 scrivito_tag_list(tag_name, obj, field_name, options = {}, &block)
    Scrivito::ChildListTag.new(tag_name, obj, field_name.to_s, self).render(options, &block)
  end

  #
  # Calculates an HTML image tag of an image stored in the CMS for inplace editing.
  #
  # @api public
  #
  # @note If you do not specify an HTML +alt+ attribute, the helper method will use
  #   +display_title+ of the target object
  #
  # @param [Obj] obj Obj with a +link_list+, +reference+, +link+ or +binary+ attribute
  # @param [String, Symbol, Hash] field_name_or_tag_options Name of +link_list+, +reference+, +link+, or +binary+
  #   attribute, which contains the image or additional HTML attributes for the tag.
  #   The +field_name+ can be omitted for binary Objs and +blob+ will be used as default.
  # @param [Hash]  tag_or_editing_options Additional HTML attributes for the tag or
  #   the editing options if no +field_name+ was given
  # @param [Hash] editing_options Additional options for inplace editing
  # @option editing_options [String] :placeholder ('/assets/scrivito/image_placeholder.png') URL
  #   or path to image to be displayed if target is missing
  #
  # @example
  #   scrivito_image_tag @obj, :my_linklist
  #   scrivito_image_tag @obj, :my_linklist, alt: 'Interesting picture', class: 'my_image'
  #   scrivito_image_tag @obj, :my_linklist, {}, placeholder: image_path('my_placeholder.png')
  #   scrivito_image_tag @obj, :my_linklist, {class: 'my_image'}, placeholder: 'http://placehold.it/350x150'
  #
  # @example Create image tag for a reference attribute.
  #   scrivito_image_tag @obj, :my_reference
  #
  # @example Create image tag for a link attribute.
  #   scrivito_image_tag @obj, :my_link
  #
  # @example Create image tag for a binary attribute
  #   scrivito_image_tag @obj, :my_binary
  #
  # @example Create image tag for a binary Obj
  #   scrivito_image_tag @image
  #
  # @return [String] HTML image tag
  #
  # @raise [ScrivitoError] if +field_name+ is not set and Obj is not binary
  #
  def scrivito_image_tag(obj, field_name_or_tag_options=nil,
                         tag_or_editing_options = {}, editing_options = {})
    field_name, tag_options, editing_options =
      if field_name_or_tag_options.is_a?(Hash)
        [nil, field_name_or_tag_options, tag_or_editing_options]
      else
        [field_name_or_tag_options, tag_or_editing_options, editing_options]
      end

    if field_name.blank?
      if obj.binary?
        field_name = :blob
      else
        raise Scrivito::ScrivitoError,
            "when omitting `field_name' you have to pass a binary obj"
      end
    end

    options = Scrivito::ImageTagHelper.new(self).options(obj, field_name,
        tag_options.with_indifferent_access, editing_options.with_indifferent_access)
    scrivito_tag('img', obj, field_name, options)
  end

  #
  # Renders an attribute <em>value</em> of a CMS model.
  #
  #   <%= scrivito_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
  #
  # @note Content rendered using this method
  #   will not be editable in the Scrivito UI.
  #   If you want In-Place-Editing, use {ScrivitoHelper#scrivito_tag} instead.
  #
  # @api public
  #
  def scrivito_value(value)
    case value
      when Scrivito::HtmlString
        Scrivito::CmsRouting.new(request, main_app).convert_links(value).html_safe
      when String then h(value)
      when Time then h(l(value))
      when Scrivito::BasicWidget
        render(template: value.to_show_view_path, locals: {widget: value})
      else value
    end
  end

  #
  # Renders a field from the CMS.
  #
  # @api public
  #
  # @note Content rendered using this method will not be editable in the Scrivito UI.
  #   If you want in-place editing, then please use {ScrivitoHelper#scrivito_tag} instead.
  #
  # @param obj [Scrivito::BasicObj] an +Obj+, whose field should be rendered.
  # @param field_name [String, Symbol] the field of +obj+ to be rendered.
  #
  # @example
  #   <%= scrivito_field @obj, :title %>
  #   <%= scrivito_field @obj, 'headline' %>
  #
  def scrivito_field(obj, field_name)
    scrivito_value(obj[field_name])
  end

  #
  # Thumbnail helper generates HTML for the page class selection dialog and the widget class selection dialog.
  # The generated HTML has appropriate DOM structure and CSS classes, which are compatible with the CSS of the SDK.
  # By using this helper you ensure, that the look of your thumbnails fits into the SDK's design.
  #
  # @api public
  #
  # @param title [String] title of the thumbnail, e.g. "Content Page" or "Image Widget".
  # @param icon [Symbol, String] icon of the thumbnail.
  #   You can use one of the built-in icons or specify your own HTML.
  #   There are following built-in icons: +:content+, +:headline+, +:image+, +:scrivito+ and +:text+.
  #   If the name of the specyfied icon is unknown, then the default icon (+:scrivito+) will be displayed.
  #   If you are speifying your own HTML string, then make sure it is HTML safe.
  # @param block [Proc] the description of the thumbnail.
  #
  # @example A simple thumbnail
  #   <%= scrivito_thumbnail 'Content Page' do %>
  #     A content page.
  #   <% end %>
  #
  # @example A thumbnail with a built-in icon
  #   <%= scrivito_thumbnail 'Image Widget', :image do %>
  #     An image widget.
  #   <% end %>
  #
  # @example A thumbnail with custom icon HTML
  #   <%= scrivito_thumbnail 'Blog', content_tag(:i, '', class: 'thumbnail-blog') do %>
  #     A blog post.
  #   <% end %>
  #
  def scrivito_thumbnail(title, icon = :scrivito, &block)
    if icon.is_a?(Symbol)
      icon_code = {
        content:  '&#xf122;',
        headline: '&#xf102;',
        image:    '&#xf101;',
        scrivito: '&#xf000;',
        text:     '&#xf100;',
      }.fetch(icon, '&#xf000;')
      icon = content_tag(:i, icon_code.html_safe, class: 'scrivito_icon')
    end

    content_tag(:div, class: 'scrivito_editing_widget_preview') do
      capture do
        concat content_tag(:div, icon, class: 'scrivito_editing_widget_visualization')
        concat content_tag(:div, title, class: 'scrivito_editing_widget_title')
        concat content_tag(:div, class: 'scrivito_editing_widget_description', &block)
      end
    end
  end

  #
  # Renders all tags needed in the HTML head.
  # @api public
  #
  def scrivito_head_tags
    layout_tags = Scrivito::LayoutTags.new(self)
    capture do
      concat layout_tags.editing_auth_warning
      concat layout_tags.generator_meta_tag
    end
  end

  #
  # Renders all tags needed in the HTML body.
  # @api public
  #
  def scrivito_body_tags
    Scrivito::LayoutTags.new(self).client_config(@obj, @scrivito_resource)
  end

  {
    'cms_image_tag'               => 'scrivito_image_tag',
    'cms_path'                    => 'scrivito_path',
    'cms_tag'                     => 'scrivito_tag',
    'cms_tag_list'                => 'scrivito_tag_list',
    'cms_url'                     => 'scrivito_url',
    'display_field'               => 'scrivito_field',
    'display_value'               => 'scrivito_value',
    'render_widget'               => 'scrivito_value',
    'scrivito_after_content_tags' => 'scrivito_body_tags',
    'scrivito_header_tags'        => 'scrivito_head_tags',
  }.each_pair do |old_method_name, new_method_name|
    define_method(old_method_name) do |*args|
      raise %{
        The helper method `#{old_method_name}' has been removed.
        Please use `#{new_method_name}' instead.
      }
    end
  end

  #
  # Returns the current user.
  #
  # @api public
  # @return [Scrivito::User] if the {Scrivito::Configuration.editing_auth} callback returns an
  #   instance of {Scrivito::User}.
  # @return +nil+ otherwise.
  #
  def scrivito_user
    Scrivito::EditingContextHelper.new(request).scrivito_user
  end

  def inplace_editing_allowed?
    raise %{
      The helper method `inplace_editing_allowed?' has been removed.
      Please use helper method `scrivito_user` instead.
    }
  end

  #
  # Returns whether the GUI is in the +editable+ view.
  #
  # @api public
  # @return +true+ if the current visitor is an authenticated editor, the selected workspace is
  #   editable and the display mode is +editing+.
  # @return +false+ otherwise.
  #
  def scrivito_in_editable_view?
    Scrivito::EditingContextHelper.new(request).in_editable_view?
  end
end