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# encoding: utf-8

module Nanoc3::Filters
  class ColorizeSyntax < Nanoc3::Filter

    DEFAULT_COLORIZER = :coderay

    def run(content, params={})
      require 'nokogiri'

      # Take colorizers from parameters
      @colorizers = Hash.new(DEFAULT_COLORIZER)
      (params[:colorizers] || {}).each_pair do |language, colorizer|
        @colorizers[language] = colorizer
      end

      # Colorize
      doc = Nokogiri::HTML.fragment(content)
      doc.css('pre > code[class^="lang"]').each do |element|
        language = element['class'][/lang-([^ ]+)/].sub(/^lang-/, '')
        element.parent.replace(
          Nokogiri.make(highlight(element.inner_text, language, params))
        )
      end

      doc.to_s
    end

  private

    KNOWN_COLORIZERS = [ :coderay, :pygmentize ]

    def highlight(code, language, params={})
      colorizer = @colorizers[language]
      if KNOWN_COLORIZERS.include?(colorizer)
        send(colorizer, code, language, params[colorizer])
      else
        raise RuntimeError, "I don’t know how to highlight code using the “#{colorizer}” colorizer"
      end
    end

    def pygmentize(code, language, params={})
      IO.popen("pygmentize -l #{language} -f html", "r+") do |io|
        io.write(code)
        io.close_write
        return io.read
      end
    end
  
    def coderay(code, language, params={})
      require 'coderay'

      CodeRay.scan(code, language).div(params)
    end

  end
end