require 'open3'
require 'stringio'
 
class YUI
  include Open3 
  JAR_PATH = File.join(File.dirname(__FILE__),'yuicompressor-2.4.2.jar')
 
  class << self
    # @param io [String|File]
    # @param options [Hash] - See YUI.cli
    # @returns String
    #
    def compress(io, options = {})
      options[:type]    ||= :js
      options[:charset] ||= "utf-8"
 
      stdin, stdout, stderr = Open3.popen3( YUI.cli(options) )
      stdin.puts streamify(io).read
      stdin.close
 
      my_stderr = stderr.read
      my_stdout = stdout.read
 
      # if compression failed, just output original IO
      if my_stderr.empty?
        return my_stdout
      else
        raise Exception, my_stderr
      end
    end
 
    # If any exceptions are raised, the original string will be
    #   returned incase you are compressing stuff during a deploy
    #   and _just_dont_care_
    def compress_safe(io, options={})
      YUI.compress(io, options)
    rescue Exception => ex
      puts ex.message
      return streamify(io).read      
    end
 
    # Sets up the command line options
    # @param options [Hash]
    #   :jar_path         - [String] Path to the jar file, default "./yuicompress-2.4.2.jar"
    #   :charset          - [String] default 'utf-8'
    #   :type             - [Symbol] Options: js/css, default :js
    #   :line_break       - [Fixnum] Column to add line break at
    #   
    #   if the type of compression is JS, then additional options:
    #     :nomunge        - [Boolean] do not obfuscate
    #     :preserve_semi  - [Boolean] preserve all semicolons
    #     :disable_opt    - [Boolean] Disable all micro optimizations
    # 
    # @returns String
    #
    def cli(options)
      _cmd = ["java -jar #{options[:jar_path] || JAR_PATH}"]
      _cmd << "--type #{options[:type]}"
      _cmd << "--charset #{options[:charset]}" if options[:charset]
      _cmd << "--charset #{options[:line_break]}" if options[:line_break]
 
      if options[:type] == :js  
        _cmd << "--nomunge" if options[:nomunge]
        _cmd << "--preserve-semi" if options[:preserve_semi]
        _cmd << "--disable-optimizations" if options[:disable_opt]
      end
 
      _cmd.join(' ') 
    end
 
    # If a file or a string, treat it like its a stream
    #
    # @param string_or_stream [File|String]
    # @return StringIO
    #
    def streamify(string_or_stream)
      if string_or_stream.respond_to?(:read)
        string_or_stream.rewind if string_or_stream.eof?
        string_or_stream
      else
        StringIO.new(string_or_stream)
      end
    end
 
  end #end class << self
 
end

YUI.compress("function weebleep(){var cool_variable= 3; return cool_variable;}") #=> "function weebleep(){var a=3;return a};"
YUI.compress(File.open( "public/javascripts/application.js")) #=> A bunch of compressed javascript
YUI.compress(File.open( "public/stylesheets/application.css"), {:type => :css}) #=> Compressed stylesheet