Use a tree‐based approach for adv. text formatting
Sanitizing HTML/Markdown means parsing the content into an HTML tree under‐the‐hood anyway, and it is more accurate to do mention/hashtag replacement on the text nodes in that tree than it is to try to hack it in with regexes et cetera. This undoes the overrides of `#entities` and `#rewrite` on `AdvancedTextFormatter` but also stops using them, instead keeping track of the parsed Nokogiri tree itself and using that in the `#to_s` method. Internally, this tree uses `<mastodon-entity>` nodes to keep track of hashtags, links, and mentions. Sanitization is moved to the beginning, so it should be known that these do not appear in the input.
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kibigo!
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@ -33,67 +33,89 @@ class AdvancedTextFormatter < TextFormatter
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@text = format_markdown(text) if content_type == 'text/markdown'
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end
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# Differs from TextFormatter by not messing with newline after parsing
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# Differs from TextFormatter by operating on the parsed HTML tree ;)
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#
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# See +#tree+
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def to_s
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return ''.html_safe if text.blank?
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html = rewrite do |entity|
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if entity[:url]
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link_to_url(entity)
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elsif entity[:hashtag]
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link_to_hashtag(entity)
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elsif entity[:screen_name]
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link_to_mention(entity)
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result = tree.dup
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result.css('mastodon-entity').each do |entity|
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case entity['kind']
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when 'hashtag'
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entity.replace(link_to_hashtag({ hashtag: entity['value'] }))
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when 'link'
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entity.replace(link_to_url({ url: entity['value'] }))
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when 'mention'
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entity.replace(link_to_mention({ screen_name: entity['value'] }))
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end
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end
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html.html_safe # rubocop:disable Rails/OutputSafety
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result.to_html
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end
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# Differs from `TextFormatter` by skipping HTML tags and entities
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def entities
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@entities ||= begin
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gaps = []
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total_offset = 0
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##
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# Process the status into a Nokogiri document fragment, with entities
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# replaced with +<mastodon-entity>+s.
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#
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# Since +<mastodon-entity>+ is not allowed by the sanitizer, any such
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# elements in the output *must* have been produced by this algorithm.
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#
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# These elements will need to be replaced prior to serialization (see
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# +#to_s+).
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def tree
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if @tree.nil?
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src = text.gsub(Sanitize::REGEX_UNSUITABLE_CHARS, '')
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@tree = Nokogiri::HTML5.fragment(src)
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Sanitize.node!(@tree, Sanitize::Config::MASTODON_OUTGOING)
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document = @tree.document
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escaped = text.gsub(/<[^>]*>|&#[0-9]+;/) do |match|
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total_offset += match.length - 1
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end_offset = Regexp.last_match.end(0)
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gaps << [end_offset - total_offset, total_offset]
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' '
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end
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Extractor.extract_entities_with_indices(escaped, extract_url_without_protocol: false).map do |entity|
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start_pos, end_pos = entity[:indices]
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offset_idx = gaps.rindex { |gap| gap.first <= start_pos }
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offset = offset_idx.nil? ? 0 : gaps[offset_idx].last
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entity.merge(indices: [start_pos + offset, end_pos + offset])
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@tree.xpath('.//text()[not(ancestor::a)]').each do |text_node|
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# Iterate over text elements and build up their replacements.
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content = text_node.content
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replacement = Nokogiri::XML::NodeSet.new(document)
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processed_index = 0
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Extractor.extract_entities_with_indices(
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content,
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extract_url_without_protocol: false
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) do |entity|
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# Iterate over entities in this text node.
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advance = entity[:indices].first - processed_index
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if advance.positive?
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# Text node for content which precedes entity.
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replacement << Nokogiri::XML::Text.new(
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content[processed_index, advance],
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@tree.document
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)
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end
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elt = Nokogiri::XML::Element.new('mastodon-entity', document)
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if entity[:url]
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elt['kind'] = 'link'
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elt['value'] = entity[:url]
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elsif entity[:hashtag]
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elt['kind'] = 'hashtag'
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elt['value'] = entity[:hashtag]
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elsif entity[:screen_name]
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elt['kind'] = 'mention'
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elt['value'] = entity[:screen_name]
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end
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replacement << elt
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processed_index = entity[:indices].last
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end
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if processed_index < content.size
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# Text node for remaining content.
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replacement << Nokogiri::XML::Text.new(
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content[processed_index, content.size - processed_index],
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document
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)
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end
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text_node.replace(replacement)
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end
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end
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@tree
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end
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private
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# Differs from `TextFormatter` in that it keeps HTML; but it sanitizes at the end to remain safe
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def rewrite
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entities.sort_by! do |entity|
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entity[:indices].first
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end
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result = ''.dup
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last_index = entities.reduce(0) do |index, entity|
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indices = entity[:indices]
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result << text[index...indices.first]
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result << yield(entity)
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indices.last
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end
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result << text[last_index..-1]
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Sanitize.fragment(result, Sanitize::Config::MASTODON_OUTGOING)
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end
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def format_markdown(html)
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html = markdown_formatter.render(html)
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html.delete("\r").delete("\n")
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