class Rack::Recursive

def call(env)
  @script_name = env["SCRIPT_NAME"]
  @app.call(env.merge('rack.recursive.include' => method(:include)))
rescue ForwardRequest => req
  call(env.merge(req.env))
end

def include(env, path)
  unless path.index(@script_name) == 0 && (path[@script_name.size] == ?/ ||
                                           path[@script_name.size].nil?)
    raise ArgumentError, "can only include below #{@script_name}, not #{path}"
  end
  env = env.merge("PATH_INFO" => path, "SCRIPT_NAME" => @script_name,
                  "REQUEST_METHOD" => "GET",
                  "CONTENT_LENGTH" => "0", "CONTENT_TYPE" => "",
                  "rack.input" => StringIO.new(""))
  @app.call(env)
end

def initialize(app)
  @app = app
end