import weakref

import pkg_resources

__all__ = [
    'CallContext',

    'register_protocol', 'getprotocol',
]

registered_protocols = {}


class CallContext(object):
    def __init__(self, request):
        self._request = weakref.ref(request)
        self.path = None

        self.func = None
        self.funcdef = None

    @property
    def request(self):
        return self._request()


def register_protocol(protocol):
    registered_protocols[protocol.name] = protocol


def getprotocol(name, **options):
    protocol_class = registered_protocols.get(name)
    if protocol_class is None:
        for entry_point in pkg_resources.iter_entry_points(
                'wsme.protocols', name):
            if entry_point.name == name:
                protocol_class = entry_point.load()
        if protocol_class is None:
            raise ValueError("Cannot find protocol '%s'" % name)
        registered_protocols[name] = protocol_class
    return protocol_class(**options)