mumuki/mumuki-html-runner

class HtmlPrecompileHook < Mumukit::Templates::MultiFilePrecompileHook
  VALID_EXTENSIONS = ['.html', '.js', '.css']

  def main_file
    'index.html'
  end

  def consolidate(main_content, files)
    files_by_extension = files.group_by { |file_name, _| file_name.get_extension }
    files_by_extension.each { |extension, values| files_by_extension[extension] = values.to_h }

    document = Nokogiri::HTML(main_content)
    merge_script_tags! document, files_by_extension
    merge_style_tags! document, files_by_extension

    document.to_html
      .gsub(/<!DOCTYPE[^>]+>/, '')
      .gsub(/<meta[^>]+>/, '')
  end

  def files_of(request)
    super(request).select { |file_name, _| valid_extension? file_name }
  end

  private

  def valid_extension?(file_name)
    VALID_EXTENSIONS.any? { |extension| file_name.end_with? extension }
  end

  def merge_script_tags!(document, files_by_extension)
    document.xpath("//script").each { |tag| replace_script_tag! tag, files_by_extension }
  end

  def replace_script_tag!(tag, files_by_extension)
    src = tag.get_attribute 'src'
    file = files_by_extension.dig('js', src)
    tag.replace("<script>#{file}</script>") if file.present?
  end

  def merge_style_tags!(document, files_by_extension)
    document.xpath("//link").each { |tag| replace_style_tag! tag, files_by_extension }
  end

  def replace_style_tag!(tag, files_by_extension)
    rel = tag.get_attribute 'rel'
    return if rel != 'stylesheet'

    href = tag.get_attribute 'href'
    file = files_by_extension.dig('css', href)
    tag.replace("<style>#{file}</style>") if file.present?
  end
end