# Tom Moertel <tom@moertel.com>
# 2006-10-31
# Haskell code filter for Typo
# Based on the <typo:code> filter.

class Plugins::Textfilters::HaskellController < TextFilterPlugin::MacroPre
  plugin_display_name "Haskell"
  plugin_description "Apply syntax highlighting to a block of Haskell code"

  def self.help_text
    %{
You can use `<typo:haskell>` to include syntax-highlighted blocks of
Haskell code.  Example:

    <typo:haskell>
    let fibs = 0 : 1 : zipWith (+) fibs (tail fibs) in take 10 fibs
    </typo:haskell>

This filter uses hscolour (http://www.cs.york.ac.uk/fp/darcs/hscolour/) by 
Malcolm Wallace.  (The HsColour tool must be executable by the user running
the Typo blog.)  Options:

* **linenumber**.  Turns on line numbering.  Use `linenumber="true"` to enable.
* **title**.  Adds a title block to the top of the code block.
* **class**.  Adds a new CSS class to the wrapper around the code block.
}
  end

  def self.macrofilter(controller,content,attrib,params,text="")
    lang       = attrib['lang'] || 'haskell'
    title      = attrib['title']
    cssclass   = attrib['class']
    linenumber = attrib['linenumber']

    text = text.to_s.gsub(/\r/,'').gsub(/\A\n/,'').chomp

    IO.popen("HsColour -css", "r+") do |f|
      pid = fork { f.write text; f.close; Kernel.exit!(0) }
      f.close_write
      text = f.read
      Process.waitpid pid
    end
    
    text.gsub!(/.*<pre>/m,"<pre><code class=\"typocode_#{lang} #{cssclass}\"><notextile>")
    text.gsub!(/<\/pre>.*/m,"</notextile>\n</code></pre>")

    if(linenumber)
      lines = text.split(/\n/).size
      linenumbers = (1..lines).to_a.collect{|line| line.to_s}.join("\n")

      text = "<table class=\"typocode_linenumber\"><tr><td class=\"lineno\">\n<pre>\n#{linenumbers}\n</pre>\n</td><td width=\"100%\">#{text}</td></tr></table>"
    end

    if(title)
      titlecode="<div class=\"codetitle\">#{title}</div>"
    else
      titlecode=''
    end

    "<div class=\"typocode\">#{titlecode}#{text}</div>"
  end

end