A WSGI-speaking JSON-RPC controller class

     See the specification:

     <http://json-rpc.org/wiki/specification>`.

     Valid controller return values should be json-serializable objects.

     Sub-classes should catch their exceptions and raise JSONRPCError

     if they want to pass meaningful errors to the client.

     """

    def _get_method_args(self):

        """

        Return `self._rpc_args` to dispatched controller method

        chosen by __call__

        """

        return self._rpc_args

    def __call__(self, environ, start_response):

        """

        Parse the request body as JSON, look up the method on the

        controller and if it exists, dispatch to it.

        """

        if 'CONTENT_LENGTH' not in environ:

            log.debug("No Content-Length")

            return jsonrpc_error(message="No Content-Length in request")

        else:

            length = environ['CONTENT_LENGTH'] or 0

            length = int(environ['CONTENT_LENGTH'])

            log.debug('Content-Length: %s', length)

        if length == 0:

            log.debug("Content-Length is 0")

            return jsonrpc_error(message="Content-Length is 0")

        raw_body = environ['wsgi.input'].read(length)

        try:

            json_body = json.loads(urllib.unquote_plus(raw_body))

        except ValueError, e:

            # catch JSON errors Here

            return jsonrpc_error(message="JSON parse error ERR:%s RAW:%r" \

                                 % (e, urllib.unquote_plus(raw_body)))

        # check AUTH based on API KEY

        try:

            self._req_api_key = json_body['api_key']

            self._req_method = json_body['method']

            self._request_params = json_body['args']

            log.debug('method: %s, params: %s',

                      self._req_method,

                      self._request_params)

        except KeyError, e:

            return jsonrpc_error(message='Incorrect JSON query missing %s' % e)

        # check if we can find this session using api_key

        try:

            u = User.get_by_api_key(self._req_api_key)

            if u is None:

                return jsonrpc_error(message='Invalid API KEY')

            auth_u = AuthUser(u.user_id, self._req_api_key)

        except Exception, e:

            return jsonrpc_error(message='Invalid API KEY')

        self._error = None

        try:

            self._func = self._find_method()

        except AttributeError, e:

            return jsonrpc_error(message=str(e))

        # now that we have a method, add self._req_params to

        # self.kargs and dispatch control to WGIController

        argspec = inspect.getargspec(self._func)

        arglist = argspec[0][1:]

        defaults = map(type, argspec[3] or [])

        default_empty = types.NotImplementedType

        # kw arguments required by this method

        func_kwargs = dict(izip_longest(reversed(arglist), reversed(defaults),

                                        fillvalue=default_empty))

        # this is little trick to inject logged in user for

        # perms decorators to work they expect the controller class to have

        # rhodecode_user attribute set

        self.rhodecode_user = auth_u

        # This attribute will need to be first param of a method that uses

        # api_key, which is translated to instance of user at that name

        USER_SESSION_ATTR = 'apiuser'

        if USER_SESSION_ATTR not in arglist:

            return jsonrpc_error(message='This method [%s] does not support '

                                 'authentication (missing %s param)' %

                                 (self._func.__name__, USER_SESSION_ATTR))