pyssb/ssb/muxrpc.py

from functools import wraps

from async_generator import async_generator, yield_

from ssb.packet_stream import PSMessageType


class MuxRPCAPIException(Exception):
    pass


class MuxRPCHandler(object):
    def check_message(self, msg):
        body = msg.body
        if isinstance(body, dict) and 'name' in body and body['name'] == 'Error':
            raise MuxRPCAPIException(body['message'])


class MuxRPCRequestHandler(MuxRPCHandler):
    def __init__(self, ps_handler):
        self.ps_handler = ps_handler

    def __await__(self):
        msg = (yield from self.ps_handler.__await__())
        self.check_message(msg)
        return msg


class MuxRPCSourceHandler(MuxRPCHandler):
    def __init__(self, ps_handler):
        self.ps_handler = ps_handler

    @async_generator
    async def __aiter__(self):
        async for msg in self.ps_handler:
            try:
                self.check_message(msg)
                await yield_(msg)
            except MuxRPCAPIException:
                raise


class MuxRPCSinkHandlerMixin(object):

    def send(self, msg, msg_type=PSMessageType.JSON, end=False):
        self.connection.send(msg, stream=True, msg_type=msg_type, req=self.req, end_err=end)


class MuxRPCDuplexHandler(MuxRPCSinkHandlerMixin, MuxRPCSourceHandler):
    def __init__(self, ps_handler, connection, req):
        super(MuxRPCDuplexHandler, self).__init__(ps_handler)
        self.connection = connection
        self.req = req


class MuxRPCSinkHandler(MuxRPCHandler, MuxRPCSinkHandlerMixin):
    def __init__(self, connection, req):
        self.connection = connection
        self.req = req


def _get_appropriate_api_handler(type_, connection, ps_handler, req):
    if type_ in {'sync', 'async'}:
        return MuxRPCRequestHandler(ps_handler)
    elif type_ == 'source':
        return MuxRPCSourceHandler(ps_handler)
    elif type_ == 'sink':
        return MuxRPCSinkHandler(connection, req)
    elif type_ == 'duplex':
        return MuxRPCDuplexHandler(ps_handler, connection, req)


class MuxRPCRequest(object):
    @classmethod
    def from_message(cls, message):
        body = message.body
        return cls('.'.join(body['name']), body['args'])

    def __init__(self, name, args):
        self.name = name
        self.args = args

    def __repr__(self):
        return '<MuxRPCRequest {0.name} {0.args}>'.format(self)


class MuxRPCMessage(object):
    @classmethod
    def from_message(cls, message):
        return cls(message.body)

    def __init__(self, body):
        self.body = body

    def __repr__(self):
        return '<MuxRPCMessage {0.body}}>'.format(self)


class MuxRPCAPI(object):
    def __init__(self):
        self.handlers = {}
        self.connection = None

    async def __await__(self):
        async for req_message in self.connection:
            body = req_message.body
            if req_message is None:
                return
            if isinstance(body, dict) and body.get('name'):
                self.process(self.connection, MuxRPCRequest.from_message(req_message))

    def add_connection(self, connection):
        self.connection = connection

    def define(self, name):
        def _handle(f):
            self.handlers[name] = f

            @wraps(f)
            def _f(*args, **kwargs):
                return f(*args, **kwargs)
            return f
        return _handle

    def process(self, connection, request):
        handler = self.handlers.get(request.name)
        if not handler:
            raise MuxRPCAPIException('Method {} not found!'.format(request.name))
        handler(connection, request)

    def call(self, name, args, type_='sync'):
        if not self.connection.is_connected:
            raise Exception('not connected')
        old_counter = self.connection.req_counter
        ps_handler = self.connection.send({
            'name': name.split('.'),
            'args': args,
            'type': type_
        }, stream=type_ in {'sink', 'source', 'duplex'})
        return _get_appropriate_api_handler(type_, self.connection, ps_handler, old_counter)