module Scrivito

# this class is the server-side equivalent of the JavaScript class `cms_field_element`
class CmsFieldTag < Struct.new(:view, :tag_name, :obj_or_widget, :field_name)
  FIELD_TYPES_WITH_ORIGINAL_CONTENT = %w[
    binary
    date
    enum
    html
    multienum
    reference
    referencelist
    string
    text
  ]

  include TagRenderer

  def content(&block)
    if field_type == 'widgetlist'
      raise ArgumentError, 'No block allowed for widgetlist fields' if block_given?
      modifications = modification_info || []
      rendered_widgets = default_content.each_with_index.map do |widget, index|
        WidgetTag.new(view, widget, modifications[index]).render
      end
      view.safe_join(rendered_widgets)
    else
      block_given? ? view.capture { yield } : view.scrivito_value(default_content)
    end
  end

  def options
    return {} unless authenticated_editor?

    options = {
      'private-field-workspace-id' => current_workspace_id,
      'field-name'                 => field_name,
      'field-obj-class'            => obj_or_widget.obj_class_name,
      'field-type'                 => field_type,
    }

    modification = comparison.modification_for_attribute(obj_or_widget, field_name)
    if modification == Modification::EDITED && field_type != 'widgetlist'
      options['field-modification'] = modification
    end

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

    if FIELD_TYPES_WITH_ORIGINAL_CONTENT.include?(field_type)
      original_value = view.scrivito_value(current_value)
      original_content = original_content(field_type, original_value, current_value)
      encoded_content = Base64.strict_encode64(MultiJson.encode(original_content))
      options['private-field-original-content'] = encoded_content
    end

    if field_type == 'widgetlist'
      options['private-field-widget-allowed-classes'] = build_valid_widget_classes.to_json
    end

    options
  end

  def modification_info
    calculate_content_and_modification
    @content_and_modification.second
  end

  private

  def build_valid_widget_classes
    obj_or_widget.valid_widget_class_names_for(field_name).map do |widget_class|
      {
        name: widget_class,
        description: description_for_widget_class(widget_class),
      }
    end
  end

  def field_type
    @field_type ||= obj_or_widget.type_of_attribute(field_name)
  end

  def description_for_widget_class(class_name)
    class_name.constantize.description_for_editor
  end

  def default_content
    calculate_content_and_modification
    @content_and_modification.first
  end

  def calculate_content_and_modification
    @content_and_modification ||=
      comparison.diff_for(obj_or_widget, field_name) || [current_value, nil]
  end

  def comparison
    editing_context.comparison
  end

  def current_value
    obj_or_widget[field_name]
  end

  def current_workspace_id
    Workspace.current.id
  end

  def authenticated_editor?
    editing_context.authenticated_editor?
  end

  def editing_context
    EditingContextMiddleware.from_request(view.request)
  end

  def original_content(field_type, field_value, raw_value)
    case field_type
    when 'binary'        then field_value && {}
    when 'date'          then raw_value.try(:utc).try(:iso8601)
    when 'reference'     then field_value.try(:id)
    when 'referencelist' then field_value.map(&:id)
    else field_value
    end
  end

end

end