with_translations.rb

module WithTranslations
  extend ActiveSupport::Concern

  included do
    belongs_to  :language
    belongs_to  :original, class_name: base_class.to_s, optional: true
    has_many    :translations, class_name: base_class.to_s, foreign_key: :original_id, dependent: :nullify
  end

  def translation_for(language)
    # If current language is language, returns itself
    return self if language_id == language.id
    # Translations have the same original_id if set
    original_id.present?  ? original.translation_for(language)
                          : translations.find_by(language_id: language.id)
  end

  def original_object
    @original_object ||= (self.original || self)
  end

  def original_with_translations
    original_object.translations + [original_object]
  end

  def translate!(language)
    translation = self.dup

    # Translate parent if needed
    if respond_to?(:parent_id) && parent_id.present?
      parent_translation = parent.translation_for(language)
      parent_translation ||= parent.translate!(language)
      translation.parent_id = parent_translation&.id
    end

    # Inherits from original_id or set it to itself
    translation.assign_attributes(
      original_id: original_object.id,
      language_id: language.id
    )

    # Handle publication
    translation.published = false if respond_to?(:published)
    # Handle featured image if object has one
    translate_featured_image(translation) if respond_to?(:featured_image) && featured_image.attached?
    translation.save
    # Handle blocks if object has any
    translate_blocks!(translation) if respond_to?(:blocks)
    translate_additional_data!(translation)

    translation
  end

  protected

  def translate_featured_image(translation)
    translation.featured_image.attach(
      io: URI.open(featured_image.url),
      filename: featured_image.filename.to_s,
      content_type: featured_image.content_type
    )
  end

  def translate_blocks!(translation)
    blocks.ordered.each do |block|
      block_duplicate = block.dup
      block_duplicate.about = translation
      block_duplicate.save
    end
  end

  def translate_additional_data!(translation)
    # Overridable method to handle custom cases
  end
end