class Kramdown::Parser::GFM

def generate_gfm_header_id(text)
  result = text.downcase
  result.gsub!(NON_WORD_RE, '')
  result.tr!(" \t", '-')
  @id_counter[result] += 1
  result << (@id_counter[result] > 0 ? "-#{@id_counter[result]}" : '')
  @options[:auto_id_prefix] + result
end

def initialize(source, options)
  super
  @options[:auto_id_stripping] = true
  @id_counter = Hash.new(-1)
  @span_parsers.delete(:line_break) if @options[:hard_wrap]
  if @options[:gfm_quirks].include?(:paragraph_end)
    atx_header_parser = :atx_header_gfm_quirk
    @paragraph_end = self.class::PARAGRAPH_END_GFM
  else
    atx_header_parser = :atx_header_gfm
    @paragraph_end = self.class::PARAGRAPH_END
  end
  {:codeblock_fenced => :codeblock_fenced_gfm,
    :atx_header => atx_header_parser}.each do |current, replacement|
    i = @block_parsers.index(current)
    @block_parsers.delete(current)
    @block_parsers.insert(i, replacement)
  end
  i = @span_parsers.index(:escaped_chars)
  @span_parsers[i] = :escaped_chars_gfm if i
  @span_parsers << :strikethrough_gfm
end

def paragraph_end
  @paragraph_end
end

def parse
  super
  update_elements(@root)
end

def parse_atx_header_gfm_quirk
  start_line_number = @src.current_line_number
  @src.check(ATX_HEADER_MATCH)
  level, text, id = @src[1], @src[2].to_s.strip, @src[3]
  return false if text.empty?
  @src.pos += @src.matched_size
  el = new_block_el(:header, nil, nil, :level => level.length, :raw_text => text, :location => start_line_number)
  add_text(text, el)
  el.attr['id'] = id if id
  @tree.children << el
  true
end

def parse_strikethrough_gfm
  line_number = @src.current_line_number
  @src.pos += @src.matched_size
  el = Element.new(:html_element, 'del', {}, :category => :span, :line => line_number)
  @tree.children << el
  env = save_env
  reset_env(:src => Kramdown::Utils::StringScanner.new(@src.matched[2..-3], line_number),
            :text_type => :text)
  parse_spans(el)
  restore_env(env)
  el
end

def update_elements(element)
  element.children.map! do |child|
    if child.type == :text && @options[:hard_wrap] && child.value =~ /\n/
      children = []
      lines = child.value.split(/\n/, -1)
      omit_trailing_br = (Kramdown::Element.category(element) == :block && element.children[-1] == child &&
                          lines[-1].empty?)
      lines.each_with_index do |line, index|
        new_element_options = { :location => child.options[:location] + index }
        children << Element.new(:text, (index > 0 ? "\n#{line}" : line), nil, new_element_options)
        children << Element.new(:br, nil, nil, new_element_options) if index < lines.size - 2 ||
          (index == lines.size - 2 && !omit_trailing_br)
      end
      children
    elsif child.type == :html_element
      child
    elsif child.type == :header && @options[:auto_ids] && !child.attr.has_key?('id')
      child.attr['id'] = generate_gfm_header_id(child.options[:raw_text])
      child
    else
      update_elements(child)
      child
    end
  end.flatten!
end

def update_raw_text(item)
  raw_text = ''
  append_text = lambda do |child|
    if child.type == :text || child.type == :codespan || child.type ==:math
      raw_text << child.value
    elsif child.type == :entity
      raw_text << child.value.char
    elsif child.type == :smart_quote
      raw_text << ::Kramdown::Utils::Entities.entity(child.value.to_s).char
    elsif child.type == :typographic_sym
      raw_text << ::Kramdown::Utils::Entities.entity(child.value.to_s).char
    else
      child.children.each {|c| append_text.call(c)}
    end
  end
  append_text.call(item)
  item.options[:raw_text] = raw_text
end