class Rack::Directory

def call(env)
  # strip body if this is a HEAD call
  @head.call env
end

def check_bad_request(path_info)
  return if Utils.valid_path?(path_info)
  body = "Bad Request\n"
  [400, { CONTENT_TYPE => "text/plain",
    CONTENT_LENGTH => body.bytesize.to_s,
    "x-cascade" => "pass" }, [body]]
end

def check_forbidden(path_info)
  return unless path_info.include? ".."
  return if ::File.expand_path(::File.join(@root, path_info)).start_with?(@root)
  body = "Forbidden\n"
  [403, { CONTENT_TYPE => "text/plain",
    CONTENT_LENGTH => body.bytesize.to_s,
    "x-cascade" => "pass" }, [body]]
end

def entity_not_found(path_info)
  body = "Entity not found: #{path_info}\n"
  [404, { CONTENT_TYPE => "text/plain",
    CONTENT_LENGTH => body.bytesize.to_s,
    "x-cascade" => "pass" }, [body]]
end

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

def get(env)
  script_name = env[SCRIPT_NAME]
  path_info = Utils.unescape_path(env[PATH_INFO])
  if client_error_response = check_bad_request(path_info) || check_forbidden(path_info)
    client_error_response
  else
    path = ::File.join(@root, path_info)
    list_path(env, path, path_info, script_name)
  end
end

def initialize(root, app = nil)
  @root = ::File.expand_path(root)
  @app = app || Files.new(@root)
  @head = Head.new(method(:get))
end

def list_directory(path_info, path, script_name)
  url_head = (script_name.split('/') + path_info.split('/')).map do |part|
    Utils.escape_path part
  end
  # Globbing not safe as path could contain glob metacharacters
  body = DirectoryBody.new(@root, path, ->(basename) do
    stat = stat(::File.join(path, basename))
    next unless stat
    url = ::File.join(*url_head + [Utils.escape_path(basename)])
    mtime = stat.mtime.httpdate
    if stat.directory?
      type = 'directory'
      size = '-'
      url << '/'
      if basename == '..'
        basename = 'Parent Directory'
      else
        basename << '/'
      end
    else
      type = Mime.mime_type(::File.extname(basename))
      size = filesize_format(stat.size)
    end
    [ url, basename, size, type, mtime ]
  end)
  [ 200, { CONTENT_TYPE => 'text/html; charset=utf-8' }, body ]
end

def list_path(env, path, path_info, script_name)
  if (stat = stat(path)) && stat.readable?
    return @app.call(env) if stat.file?
    return list_directory(path_info, path, script_name) if stat.directory?
  end
  entity_not_found(path_info)
end

def stat(path)
  ::File.stat(path)
rescue Errno::ENOENT, Errno::ELOOP
  return nil
end