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# frozen_string_literal: true
module Banzai
module Filter
# Find every image that isn't already wrapped in an `a` tag, and that has
# a `src` attribute ending with an audio or video extension, add a new audio or video node and
# a "Download" link in the case the media cannot be played.
class PlayableLinkFilter < HTML::Pipeline::Filter
def call
doc.xpath('descendant-or-self::img[not(ancestor::a)]').each do |el|
el.replace(media_node(doc, el)) if has_media_extension?(el)
end
doc
end
private
def media_type
raise NotImplementedError
end
def safe_media_ext
raise NotImplementedError
end
def extra_element_attrs(element)
{}
end
def has_media_extension?(element)
src = element.attr('data-canonical-src').presence || element.attr('src')
return unless src.present?
src_ext = File.extname(src).sub('.', '').downcase
safe_media_ext.include?(src_ext)
end
def media_element(doc, element)
media_element_attrs = {
src: element['src'],
controls: true,
'data-setup': '{}',
'data-title': element['title'] || element['alt']
}.merge!(extra_element_attrs(element))
if element['data-canonical-src']
media_element_attrs['data-canonical-src'] = element['data-canonical-src']
end
doc.document.create_element(media_type, media_element_attrs)
end
def download_link(doc, element)
link_content = element['title'] || element['alt']
link_element_attrs = {
href: element['src'],
target: '_blank',
rel: 'noopener noreferrer',
title: "Download '#{link_content}'"
}
# make sure the original non-proxied src carries over
if element['data-canonical-src']
link_element_attrs['data-canonical-src'] = element['data-canonical-src']
end
doc.document.create_element('a', link_content, link_element_attrs)
end
def media_node(doc, element)
container_element_attrs = { class: "media-container #{media_type}-container" }
doc.document.create_element('span', container_element_attrs).tap do |container|
container.add_child(media_element(doc, element))
container.add_child(download_link(doc, element))
end
end
end
end
end
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