def __init__(self, message):

        self.message = message

        super(JSONRPCError, self).__init__()

    def __str__(self):

        return safe_str(self.message)

class JSONRPCErrorResponse(Response, HTTPException):

    """

    Generate a Response object with a JSON-RPC error body

    """

    def __init__(self, message=None, retid=None, code=None):

        HTTPException.__init__(self, message, self)

        Response.__init__(self,

                          json_body=dict(id=retid, result=None, error=message),

                          status=code,

                          content_type='application/json')

class JSONRPCController(TGController):

    """

     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_ip_addr(self, environ):

        return _get_ip(environ)

    def _get_method_args(self):

        """

        Return `self._rpc_args` to dispatched controller method

        chosen by __call__

        """

        return self._rpc_args

    def _dispatch(self, state, remainder=None):

        """

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

        controller and if it exists, dispatch to it.

        """

        # Since we are here we should respond as JSON

        response.content_type = 'application/json'

        environ = state.request.environ

        start = time.time()

        ip_addr = self._get_ip_addr(environ)

        self._req_id = None

        if 'CONTENT_LENGTH' not in environ:

            log.debug("No Content-Length")

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       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:

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       message="Content-Length is 0")

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

        try:

            json_body = json.loads(raw_body)

        except ValueError as e:

            # catch JSON errors Here

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       message="JSON parse error ERR:%s RAW:%r"

                                                % (e, raw_body))

        # check AUTH based on API key

        try:

            self._req_api_key = json_body['api_key']

            self._req_id = json_body['id']

            self._req_method = json_body['method']

            self._request_params = json_body['args']

            if not isinstance(self._request_params, dict):

                self._request_params = {}

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

                      self._req_method, self._request_params)

        except KeyError as e:

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       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)

            auth_user = AuthUser.make(dbuser=u, ip_addr=ip_addr)

            if auth_user is None:

                raise JSONRPCErrorResponse(retid=self._req_id,

                                           message='Invalid API key')

        except Exception as e:

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       message='Invalid API key')

        request.authuser = auth_user

        request.ip_addr = ip_addr

        self._error = None

        try:

            self._func = self._find_method()

        except AttributeError as e:

            raise JSONRPCErrorResponse(retid=self._req_id,

                                       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 = [type(arg) for arg in argspec[3] or []]

        default_empty = type(NotImplemented)

        # kw arguments required by this method

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

                                                  fillvalue=default_empty))

        # 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'

        # get our arglist and check if we provided them as args

        for arg, default in func_kwargs.iteritems():

            if arg == USER_SESSION_ATTR:

                # USER_SESSION_ATTR is something translated from API key and

                # this is checked before so we don't need validate it

                continue

            # skip the required param check if it's default value is

            # NotImplementedType (default_empty)

            if default == default_empty and arg not in self._request_params:

                raise JSONRPCErrorResponse(

                    retid=self._req_id,

                    message='Missing non optional `%s` arg in JSON DATA' % arg,

                )

        extra = set(self._request_params).difference(func_kwargs)

        if extra:

            raise JSONRPCErrorResponse(

                retid=self._req_id,

                message='Unknown %s arg in JSON DATA' %

                        ', '.join('`%s`' % arg for arg in extra),

            )

        self._rpc_args = {}

        self._rpc_args.update(self._request_params)

        self._rpc_args['action'] = self._req_method

        self._rpc_args['environ'] = environ

        log.info('IP: %s Request to %s time: %.3fs' % (

            self._get_ip_addr(environ),

            get_path_info(environ), time.time() - start)

        )

        state.set_action(self._rpc_call, [])

        state.set_params(self._rpc_args)

        return state

    def _rpc_call(self, action, environ, **rpc_args):

        """

        Call the specified RPC Method

        """

        raw_response = ''

        try:

            raw_response = getattr(self, action)(**rpc_args)

            if isinstance(raw_response, HTTPError):

                self._error = str(raw_response)

        except JSONRPCError as e:

            self._error = unicode(e)

        except Exception as e:

            log.error('Encountered unhandled exception: %s',

                      traceback.format_exc(),)

            json_exc = JSONRPCError('Internal server error')

            self._error = unicode(json_exc)

        if self._error is not None:

            raw_response = None

        response = dict(id=self._req_id, result=raw_response, error=self._error)

        try:

            return json.dumps(response)

        except TypeError as e:

            return json.dumps(

                dict(

                    id=self._req_id,

                    result=None,

                    error="Error encoding response"

                )

            )

    def _find_method(self):

        """

        Return method named by `self._req_method` in controller if able

        """

        log.debug('Trying to find JSON-RPC method: %s', self._req_method)

        if self._req_method.startswith('_'):

            raise AttributeError("Method not allowed")

        try:

            func = getattr(self, self._req_method, None)

        except UnicodeEncodeError:

            raise AttributeError("Problem decoding unicode in requested "

                                 "method name.")

        if isinstance(func, types.MethodType):

            return func

        else:

            raise AttributeError("No such method: %s" % (self._req_method,))

                .order_by(Gist.created_on.desc())

        ]

    def create_gist(self, files, owner=Optional(OAttr('apiuser')),

                    gist_type=Optional(Gist.GIST_PUBLIC), lifetime=Optional(-1),

                    description=Optional('')):

        """

        Creates new Gist

        :param files: files to be added to gist

            {'filename': {'content':'...', 'lexer': null},

             'filename2': {'content':'...', 'lexer': null}}

        :type files: dict

        :param owner: gist owner, defaults to api method caller

        :type owner: Optional(str or int)

        :param gist_type: type of gist 'public' or 'private'

        :type gist_type: Optional(str)

        :param lifetime: time in minutes of gist lifetime

        :type lifetime: Optional(int)

        :param description: gist description

        :type description: Optional(str)

        OUTPUT::

          id : <id_given_in_input>

          result : {

            "msg": "created new gist",

            "gist": {}

          }

          error :  null

        ERROR OUTPUT::

          id : <id_given_in_input>

          result : null

          error :  {

            "failed to create gist"

          }

        """

        try:

            if isinstance(owner, Optional):

                owner = request.authuser.user_id

            owner = get_user_or_error(owner)

            description = Optional.extract(description)

            gist_type = Optional.extract(gist_type)

            lifetime = Optional.extract(lifetime)

            gist = GistModel().create(description=description,

                                      owner=owner,

                                      ip_addr=request.ip_addr,

                                      gist_mapping=files,

                                      gist_type=gist_type,

                                      lifetime=lifetime)

            Session().commit()

            return dict(

                msg='created new gist',

                gist=gist.get_api_data()

            )

        except Exception:

            log.error(traceback.format_exc())

            raise JSONRPCError('failed to create gist')

    # def update_gist(self, gistid, files, owner=Optional(OAttr('apiuser')),

    #                 gist_type=Optional(Gist.GIST_PUBLIC),

    #                 gist_lifetime=Optional(-1), gist_description=Optional('')):

    #     gist = get_gist_or_error(gistid)

    #     updates = {}

    # permission check inside

    def delete_gist(self, gistid):

        """

        Deletes existing gist

        :param gistid: id of gist to delete

        :type gistid: str

        OUTPUT::

          id : <id_given_in_input>

          result : {

            "deleted gist ID: <gist_id>",

            "gist": null

          }

          error :  null

        ERROR OUTPUT::

          id : <id_given_in_input>

          result : null

          error :  {

            "failed to delete gist ID:<gist_id>"

          }

        """

        gist = get_gist_or_error(gistid)

        if not HasPermissionAny('hg.admin')():

            if gist.owner_id != request.authuser.user_id:

                raise JSONRPCError('gist `%s` does not exist' % (gistid,))

        try:

            GistModel().delete(gist)

            Session().commit()

            return dict(

                msg='deleted gist ID:%s' % (gist.gist_access_id,),

                gist=None

            )

        except Exception:

            log.error(traceback.format_exc())

            raise JSONRPCError('failed to delete gist ID:%s'

                               % (gist.gist_access_id,))

    # permission check inside

    def get_changesets(self, repoid, start=None, end=None, start_date=None,

                       end_date=None, branch_name=None, reverse=False, with_file_list=False, max_revisions=None):

        repo = get_repo_or_error(repoid)

        if not HasRepoPermissionLevel('read')(repo.repo_name):

            raise JSONRPCError('Access denied to repo %s' % repo.repo_name)

        format = "%Y-%m-%dT%H:%M:%S"

        try:

            return [e.__json__(with_file_list) for e in

                repo.scm_instance.get_changesets(start,

                                                 end,

                                                 datetime.strptime(start_date, format) if start_date else None,

                                                 datetime.strptime(end_date, format) if end_date else None,

                                                 branch_name,

                                                 reverse, max_revisions)]

        except EmptyRepositoryError as e:

            raise JSONRPCError(e.message)

    # permission check inside

    def get_changeset(self, repoid, raw_id, with_reviews=Optional(False)):

        repo = get_repo_or_error(repoid)

        if not HasRepoPermissionLevel('read')(repo.repo_name):

            raise JSONRPCError('Access denied to repo %s' % repo.repo_name)

        changeset = repo.get_changeset(raw_id)

        if isinstance(changeset, EmptyChangeset):

            raise JSONRPCError('Changeset %s does not exist' % raw_id)

        info = dict(changeset.as_dict())

        with_reviews = Optional.extract(with_reviews)

        if with_reviews:

            reviews = ChangesetStatusModel().get_statuses(

                                repo.repo_name, raw_id)

            info["reviews"] = reviews

        return info

    # permission check inside

    def get_pullrequest(self, pullrequest_id):

        """

        Get given pull request by id

        """

        pull_request = PullRequest.get(pullrequest_id)

        if pull_request is None:

            raise JSONRPCError('pull request `%s` does not exist' % (pullrequest_id,))

        if not HasRepoPermissionLevel('read')(pull_request.org_repo.repo_name):

            raise JSONRPCError('not allowed')

        return pull_request.get_api_data()

    # permission check inside

    def comment_pullrequest(self, pull_request_id, comment_msg=u'', status=None, close_pr=False):

        """

        Add comment, close and change status of pull request.

        """

        apiuser = get_user_or_error(request.authuser.user_id)

        pull_request = PullRequest.get(pull_request_id)

        if pull_request is None:

            raise JSONRPCError('pull request `%s` does not exist' % (pull_request_id,))

        if (not HasRepoPermissionLevel('read')(pull_request.org_repo.repo_name)):

            raise JSONRPCError('No permission to add comment. User needs at least reading permissions'

                               ' to the source repository.')

        owner = apiuser.user_id == pull_request.owner_id

        reviewer = apiuser.user_id in [reviewer.user_id for reviewer in pull_request.reviewers]

        if close_pr and not (apiuser.admin or owner):

            raise JSONRPCError('No permission to close pull request. User needs to be admin or owner.')

        if status and not (apiuser.admin or owner or reviewer):

            raise JSONRPCError('No permission to change pull request status. User needs to be admin, owner or reviewer.')

        if pull_request.is_closed():

            raise JSONRPCError('pull request is already closed')

        comment = ChangesetCommentsModel().create(

            text=comment_msg,

            repo=pull_request.org_repo.repo_id,

            author=apiuser.user_id,

            pull_request=pull_request.pull_request_id,

            f_path=None,

            line_no=None,

            closing_pr=close_pr

        )

        action_logger(apiuser,

                      'user_commented_pull_request:%s' % pull_request_id,

                      pull_request.org_repo, request.ip_addr)

        if status:

            ChangesetStatusModel().set_status(

                pull_request.org_repo_id,

                status,

                apiuser.user_id,

                comment,

                pull_request=pull_request_id

            )

        if close_pr:

            PullRequestModel().close_pull_request(pull_request_id)

            action_logger(apiuser,

                          'user_closed_pull_request:%s' % pull_request_id,

                          pull_request.org_repo, request.ip_addr)

        Session().commit()

        return True