    # Copyright (c) 2007, 2008, 2009, 2010 Christian Neukirchen <purl.org/net/chneukirchen>
    #
    # Permission is hereby granted, free of charge, to any person obtaining a copy
    # of this software and associated documentation files (the "Software"), to
    # deal in the Software without restriction, including without limitation the
    # rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
    # sell copies of the Software, and to permit persons to whom the Software is
    # furnished to do so, subject to the following conditions:
    #
    # The above copyright notice and this permission notice shall be included in
    # all copies or substantial portions of the Software.
    #
    # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
    # THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    # IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    require 'time'
    require 'rack/utils'
    require 'rack/mime'

    module Rack
      # Rack::Directory serves entries below the +root+ given, according to the
      # path info of the Rack request. If a directory is found, the file's contents
      # will be presented in an html based index. If a file is found, the env will
      # be passed to the specified +app+.
      #
      # If +app+ is not specified, a Rack::File of the same +root+ will be used.

      class Directory
        DIR_FILE = "<tr><td class='name'><a href='%s'>%s</a></td><td class='size'>%s</td><td class='type'>%s</td><td class='mtime'>%s</td></tr>"
        DIR_PAGE = <<-PAGE
    <html><head>
      <title>%s</title>
      <meta http-equiv="content-type" content="text/html; charset=utf-8" />
      <style type='text/css'>
    table { width:100%%; }
    .name { text-align:left; }
    .size, .mtime { text-align:right; }
    .type { width:11em; }
    .mtime { width:15em; }
      </style>
    </head><body>
    <h1>%s</h1>
    <hr />
    <table>
      <tr>
        <th class='name'>Name</th>
        <th class='size'>Size</th>
        <th class='type'>Type</th>
        <th class='mtime'>Last Modified</th>
      </tr>
    %s
    </table>
    <hr />
    </body></html>
        PAGE

        attr_reader :files
        attr_accessor :root, :path

        def initialize(root, app=nil)
          @root = F.expand_path(root)
          @app = app || Rack::File.new(@root)
        end

        def call(env)
          dup._call(env)
        end

        F = ::File

        def _call(env)
          @env = env
          @script_name = env['SCRIPT_NAME']
          @path_info = Utils.unescape(env['PATH_INFO'])

          if forbidden = check_forbidden
            forbidden
          else
            @path = F.join(@root, @path_info)
            list_path
          end
        end

        def check_forbidden
          return unless @path_info.include? ".."

          body = "Forbidden\n"
          size = Rack::Utils.bytesize(body)
          return [403, {"Content-Type" => "text/plain",
            "Content-Length" => size.to_s,
            "X-Cascade" => "pass"}, [body]]
        end

        def list_directory
          @files = [['../','Parent Directory','','','']]
          glob = F.join(@path, '*')

          url_head = ([@script_name] + @path_info.split('/')).map do |part|
            Rack::Utils.escape part
          end

          Dir[glob].sort.each do |node|
            stat = stat(node)
            next  unless stat
            basename = F.basename(node)
            ext = F.extname(node)

            url = F.join(*url_head + [Rack::Utils.escape(basename)])
            size = stat.size
            type = stat.directory? ? 'directory' : Mime.mime_type(ext)
            size = stat.directory? ? '-' : filesize_format(size)
            mtime = stat.mtime.httpdate
            url << '/'  if stat.directory?
            basename << '/'  if stat.directory?

            @files << [ url, basename, size, type, mtime ]
          end

          return [ 200, {'Content-Type'=>'text/html; charset=utf-8'}, self ]
        end

        def stat(node, max = 10)
          F.stat(node)
        rescue Errno::ENOENT, Errno::ELOOP
          return nil
        end

        # TODO: add correct response if not readable, not sure if 404 is the best
        #       option
        def list_path
          @stat = F.stat(@path)

          if @stat.readable?
            return @app.call(@env) if @stat.file?
            return list_directory if @stat.directory?
          else
            raise Errno::ENOENT, 'No such file or directory'
          end

        rescue Errno::ENOENT, Errno::ELOOP
          return entity_not_found
        end

        def entity_not_found
          body = "Entity not found: #{@path_info}\n"
          size = Rack::Utils.bytesize(body)
          return [404, {"Content-Type" => "text/plain",
            "Content-Length" => size.to_s,
            "X-Cascade" => "pass"}, [body]]
        end

        def each
          show_path = @path.sub(/^#{@root}/,'')
          files = @files.map{|f| DIR_FILE % f }*"\n"
          page  = DIR_PAGE % [ show_path, show_path , files ]
          page.each_line{|l| yield l }
        end

        # Stolen from Ramaze

        FILESIZE_FORMAT = [
          ['%.1fT', 1 << 40],
          ['%.1fG', 1 << 30],
          ['%.1fM', 1 << 20],
          ['%.1fK', 1 << 10],
        ]

        def filesize_format(int)
          FILESIZE_FORMAT.each do |format, size|
            return format % (int.to_f / size) if int >= size
          end

          int.to_s + 'B'
        end
      end
    end