fedibird-fe/app/lib/toc_generator.rb
2019-09-20 17:13:44 +02:00

69 lines
1.5 KiB
Ruby

# frozen_string_literal: true
class TOCGenerator
TARGET_ELEMENTS = %w(h1 h2 h3 h4 h5 h6).freeze
LISTED_ELEMENTS = %w(h2 h3).freeze
class Section
attr_accessor :depth, :title, :children, :anchor
def initialize(depth, title, anchor)
@depth = depth
@title = title
@children = []
@anchor = anchor
end
delegate :<<, to: :children
end
def initialize(source_html)
@source_html = source_html
@processed = false
@target_html = ''
@headers = []
@slugs = Hash.new { |h, k| h[k] = 0 }
end
def html
parse_and_transform unless @processed
@target_html
end
def toc
parse_and_transform unless @processed
@headers
end
private
def parse_and_transform
return if @source_html.blank?
parsed_html = Nokogiri::HTML.fragment(@source_html)
parsed_html.traverse do |node|
next unless TARGET_ELEMENTS.include?(node.name)
anchor = node['id'] || node.text.parameterize
@slugs[anchor] += 1
anchor = "#{anchor}-#{@slugs[anchor]}" if @slugs[anchor] > 1
node['id'] = anchor
next unless LISTED_ELEMENTS.include?(node.name)
depth = node.name[1..-1]
latest_section = @headers.last
if latest_section.nil? || latest_section.depth >= depth
@headers << Section.new(depth, node.text, anchor)
else
latest_section << Section.new(depth, node.text, anchor)
end
end
@target_html = parsed_html.to_s
@processed = true
end
end