require 'nokogiri'

module GalleryItems
  # Uploaded batches share one source document, but each photo is a gallery item.
  # Keeping this at render time also fixes batches that have already been published.
  def gallery_items(content)
    fragment = Nokogiri::HTML::DocumentFragment.parse(content)
    images = fragment.css('img')
    return [content] unless images.length > 1 && images.all? { |image|
      image['src'].to_s.start_with?('/img/arts/uploads/') && image.parent.name == 'p'
    }

    captions = fragment.css('.image-details').map(&:to_html).join
    images.each { |image| image.parent.remove }
    fragment.css('.image-details').each(&:remove)
    # Preserve the batch's existing anchor exactly once, before the first photo.
    prefix = fragment.to_html
    images.each_with_index.map do |image, index|
      "#{index.zero? ? prefix : ''}<p>#{image.to_html}</p>#{captions}"
    end
  end
end

Liquid::Template.register_filter(GalleryItems)