pyssb/ssb/muxrpc.py

from functools import wraps

from ssb.packet_stream import PSMessageType


class MuxRPCAPIException(Exception):
    pass


class MuxRPCHandler:
    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

    def __aiter__(self):
        return self

    async def __anext__(self):
        msg = await self.ps_handler.__anext__()
        self.check_message(msg)

        return msg


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)