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# frozen_string_literal: true
module Banzai
module Filter
# Looks for attributes that are specified for an element. Follows the basic syntax laid out
# in https://github.com/jgm/commonmark-hs/blob/master/commonmark-extensions/test/attributes.md
# For example,
# {width=50%}
#
# However we currently have the following limitations:
# - only support images
# - only support the `width` and `height` attributes
# - attributes can not span multiple lines
# - unsupported attributes are thrown away
class AttributesFilter < HTML::Pipeline::Filter
prepend Concerns::PipelineTimingCheck
CSS = 'img'
XPATH = Gitlab::Utils::Nokogiri.css_to_xpath(CSS).freeze
ATTRIBUTES_PATTERN = %r{\A(?<matched>\{(?<attributes>.{1,100})\})}
WIDTH_HEIGHT_REGEX = %r{\A(?<name>height|width)="?(?<size>[\w%]{1,10})"?\z}
VALID_SIZE_REGEX = %r{\A\d{1,4}(%|px)?\z}
def call
doc.xpath(XPATH).each do |img|
sibling = img.next
next unless sibling && sibling.text? && sibling.content.first == '{'
match = sibling.content.match(ATTRIBUTES_PATTERN)
next unless match && match[:attributes]
match[:attributes].split(' ').each do |attribute|
next unless attribute.match?(WIDTH_HEIGHT_REGEX)
attribute_match = attribute.match(WIDTH_HEIGHT_REGEX)
img[attribute_match[:name].to_sym] = attribute_match[:size] if valid_size?(attribute_match[:size])
end
sibling.content = sibling.content.sub(match[:matched], '')
end
doc
end
private
def valid_size?(size)
size.match?(VALID_SIZE_REGEX)
end
end
end
end
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