class FSEvent

def options_string
  @options.join(' ')
end

def parse_options(options={})
  opts = []
  opts.concat(['--since-when', options[:since_when]]) if options[:since_when]
  opts.concat(['--latency', options[:latency]]) if options[:latency]
  opts.push('--no-defer') if options[:no_defer]
  opts.push('--watch-root') if options[:watch_root]
  # ruby 1.9's IO.popen(array-of-stuff) syntax requires all items to be strings
  opts.map {|opt| "#{opt}"}
end

def pipe
  @pipe ||= IO.popen("#{self.class.watcher_path} #{options_string} #{shellescaped_paths}")
end

def pipe
  @pipe ||= IO.popen([self.class.watcher_path] + @options + @paths)
end

def run
  @running = true
  # please note the use of IO::select() here, as it is used specifically to
  # preserve correct signal handling behavior in ruby 1.8.
  while @running && IO::select([pipe], nil, nil, nil)
    if line = pipe.readline
      modified_dir_paths = line.split(":").select { |dir| dir != "\n" }
      callback.call(modified_dir_paths)
    end
  end
rescue Interrupt, IOError
ensure
  stop
end

def shellescape(str)
  # An empty argument will be skipped, so return empty quotes.
  return "''" if str.empty?
  str = str.dup
  # Process as a single byte sequence because not all shell
  # implementations are multibyte aware.
  str.gsub!(/([^A-Za-z0-9_\-.,:\/@\n])/n, "\\\\\\1")
  # A LF cannot be escaped with a backslash because a backslash + LF
  # combo is regarded as line continuation and simply ignored.
  str.gsub!(/\n/, "'\n'")
  return str
end

def shellescaped_paths
  @paths.map {|path| shellescape(path)}.join(' ')
end

def stop
  if pipe
    Process.kill("KILL", pipe.pid)
    pipe.close
  end
rescue IOError
ensure
  @pipe = @running = nil
end

def watch(watch_paths, options=nil, &block)
  @paths      = watch_paths.kind_of?(Array) ? watch_paths : [watch_paths]
  @callback   = block
  if options.kind_of?(Hash)
    @options  = parse_options(options)
  elsif options.kind_of?(Array)
    @options  = options
  else
    @options  = []
  end
end