"""
Name Server and helper functions.

Pyro - Python Remote Objects.  Copyright by Irmen de Jong (irmen@razorvine.net).
"""

import warnings
import random
import re
import logging
import socket
import sys
import time
from Pyro4.threadutil import RLock, Thread
from Pyro4.errors import NamingError, PyroError, ProtocolError
from Pyro4 import core, socketutil
import Pyro4.constants

__all__ = ["locateNS", "resolve", "type_meta", "startNS", "startNSloop", "MemoryStorage"]

if sys.version_info >= (3, 0):
    basestring = str

log = logging.getLogger("Pyro4.naming")


class MemoryStorage(dict):
    """
    Storage implementation that is just an in-memory dict.
    (because it inherits from dict it is automatically a collections.MutableMapping)
    Stopping the nameserver will make the server instantly forget about everything.
    """
    def __init__(self, **kwargs):
        super(MemoryStorage, self).__init__(**kwargs)

    def __setitem__(self, key, value):
        uri, metadata = value
        super(MemoryStorage, self).__setitem__(key, (uri, metadata or frozenset()))

    def optimized_prefix_list(self, prefix, return_metadata=False):
        return None

    def optimized_regex_list(self, regex, return_metadata=False):
        return None

    def optimized_metadata_search(self, metadata_all=None, metadata_any=None, return_metadata=False):
        return None

    def everything(self, return_metadata=False):
        if return_metadata:
            return self.copy()
        return {name: uri for name, (uri, metadata) in self.items()}

    def remove_items(self, items):
        for item in items:
            try:
                del self[item]
            except KeyError:
                pass

    def close(self):
        pass


@Pyro4.expose
class NameServer(object):
    """
    Pyro name server. Provides a simple flat name space to map logical object names to Pyro URIs.
    Default storage is done in an in-memory dictionary. You can provide custom storage types.
    """
    def __init__(self, storageProvider=None):
        self.storage = storageProvider
        if storageProvider is None:
            self.storage = MemoryStorage()
            log.debug("using volatile in-memory dict storage")
        self.lock = RLock()

    def count(self):
        return len(self.storage)

    def lookup(self, name, return_metadata=False):
        """
        Lookup the given name, returns an URI if found.
        Returns tuple (uri, metadata) if return_metadata is True.
        """
        try:
            uri, metadata = self.storage[name]
            uri = core.URI(uri)
            if return_metadata:
                metadata = list(metadata) if metadata else []
                return uri, metadata
            return uri
        except KeyError:
            raise NamingError("unknown name: " + name)

    def register(self, name, uri, safe=False, metadata=None):
        """Register a name with an URI. If safe is true, name cannot be registered twice.
        The uri can be a string or an URI object. Metadata must be None, or a collection of strings."""
        if isinstance(uri, core.URI):
            uri = uri.asString()
        elif not isinstance(uri, basestring):
            raise TypeError("only URIs or strings can be registered")
        else:
            core.URI(uri)  # check if uri is valid
        if not isinstance(name, basestring):
            raise TypeError("name must be a str")
        if isinstance(metadata, basestring):
            raise TypeError("metadata should not be a str, but another iterable (set, list, etc)")
        metadata and iter(metadata)  # validate that metadata is iterable
        with self.lock:
            if safe and name in self.storage:
                raise NamingError("name already registered: " + name)
            if metadata:
                metadata = set(metadata)
            self.storage[name] = uri, metadata

    def set_metadata(self, name, metadata):
        """update the metadata for an existing registration"""
        if not isinstance(name, basestring):
            raise TypeError("name must be a str")
        if isinstance(metadata, basestring):
            raise TypeError("metadata should not be a str, but another iterable (set, list, etc)")
        metadata and iter(metadata)  # validate that metadata is iterable
        with self.lock:
            try:
                uri, old_meta = self.storage[name]
                if metadata:
                    metadata = set(metadata)
                self.storage[name] = uri, metadata
            except KeyError:
                raise NamingError("unknown name: " + name)

    def remove(self, name=None, prefix=None, regex=None):
        """Remove a registration. returns the number of items removed."""
        if name and name in self.storage and name != Pyro4.constants.NAMESERVER_NAME:
            with self.lock:
                del self.storage[name]
            return 1
        if prefix:
            items = list(self.list(prefix=prefix).keys())
            if Pyro4.constants.NAMESERVER_NAME in items:
                items.remove(Pyro4.constants.NAMESERVER_NAME)
            self.storage.remove_items(items)
            return len(items)
        if regex:
            items = list(self.list(regex=regex).keys())
            if Pyro4.constants.NAMESERVER_NAME in items:
                items.remove(Pyro4.constants.NAMESERVER_NAME)
            self.storage.remove_items(items)
            return len(items)
        return 0

    # noinspection PyNoneFunctionAssignment
    def list(self, prefix=None, regex=None, metadata_all=None, metadata_any=None, return_metadata=False):
        """Retrieve the registered items as a dictionary name-to-URI. The URIs
        in the resulting dict are strings, not URI objects.
        You can filter by prefix or by regex or by metadata subset (separately)"""
        def fix_set(result):
            # for python 2 compatibility we cannot send sets to the default (serpent) serializer.
            # that's why we will convert them to lists here.
            if return_metadata:
                fixed = {}
                for name, data in result.items():
                    fixed[name] = (data[0], list(data[1]))
                return fixed
            return result

        if sum(1 for x in [prefix, regex, metadata_all, metadata_any] if x is not None) > 1:
            raise ValueError("you can only filter on one thing at a time")
        with self.lock:
            if prefix:
                result = self.storage.optimized_prefix_list(prefix, return_metadata)
                if result is not None:
                    return fix_set(result)
                result = {}
                for name in self.storage:
                    if name.startswith(prefix):
                        result[name] = self.storage[name] if return_metadata else self.storage[name][0]
                return fix_set(result)
            elif regex:
                result = self.storage.optimized_regex_list(regex, return_metadata)
                if result is not None:
                    return fix_set(result)
                result = {}
                try:
                    regex = re.compile(regex)
                except re.error:
                    x = sys.exc_info()[1]
                    raise NamingError("invalid regex: " + str(x))
                else:
                    for name in self.storage:
                        if regex.match(name):
                            result[name] = self.storage[name] if return_metadata else self.storage[name][0]
                    return fix_set(result)
            elif metadata_all:
                # return the entries which have all of the given metadata as (a subset of) their metadata
                if isinstance(metadata_all, basestring):
                    raise TypeError("metadata_all should not be a str, but another iterable (set, list, etc)")
                metadata_all and iter(metadata_all)   # validate that metadata is iterable
                result = self.storage.optimized_metadata_search(metadata_all=metadata_all, return_metadata=return_metadata)
                if result is not None:
                    return fix_set(result)
                metadata_all = frozenset(metadata_all)
                result = {}
                for name, (uri, meta) in self.storage.everything(return_metadata=True).items():
                    if metadata_all.issubset(meta):
                        result[name] = (uri, meta) if return_metadata else uri
                return fix_set(result)
            elif metadata_any:
                # return the entries which have any of the given metadata as part of their metadata
                if isinstance(metadata_any, basestring):
                    raise TypeError("metadata_any should not be a str, but another iterable (set, list, etc)")
                metadata_any and iter(metadata_any)   # validate that metadata is iterable
                result = self.storage.optimized_metadata_search(metadata_any=metadata_any, return_metadata=return_metadata)
                if result is not None:
                    return fix_set(result)
                metadata_any = frozenset(metadata_any)
                result = {}
                for name, (uri, meta) in self.storage.everything(return_metadata=True).items():
                    if metadata_any & meta:
                        result[name] = (uri, meta) if return_metadata else uri
                return fix_set(result)
            else:
                # just return (a copy of) everything
                return fix_set(self.storage.everything(return_metadata))

    def ping(self):
        """A simple test method to check if the name server is running correctly."""
        pass


class NameServerDaemon(core.Daemon):
    """Daemon that contains the Name Server."""

    def __init__(self, host=None, port=None, unixsocket=None, nathost=None, natport=None, storage=None):
        if host is None:
            host = Pyro4.config.HOST
        if port is None:
            port = Pyro4.config.NS_PORT
        if nathost is None:
            nathost = Pyro4.config.NATHOST
        if natport is None:
            natport = Pyro4.config.NATPORT or None
        storage = storage or "memory"
        if storage == "memory":
            log.debug("using volatile in-memory dict storage")
            self.nameserver = NameServer(MemoryStorage())
        elif storage.startswith("dbm:") and len(storage) > 4:
            dbmfile = storage[4:]
            log.debug("using persistent dbm storage in file %s", dbmfile)
            from Pyro4.naming_storage import DbmStorage
            self.nameserver = NameServer(DbmStorage(dbmfile))
            warning = "Warning: the DbmStorage doesn't support metadata."
            log.warning(warning)
            print(warning)
        elif storage.startswith("sql:") and len(storage) > 4:
            sqlfile = storage[4:]
            log.debug("using persistent sql storage in file %s", sqlfile)
            from Pyro4.naming_storage import SqlStorage
            self.nameserver = NameServer(SqlStorage(sqlfile))
        else:
            raise ValueError("invalid storage type '%s'" % storage)
        existing_count = self.nameserver.count()
        if existing_count > 0:
            log.debug("number of existing entries in storage: %d", existing_count)
        super(NameServerDaemon, self).__init__(host, port, unixsocket, nathost=nathost, natport=natport)
        self.register(self.nameserver, Pyro4.constants.NAMESERVER_NAME)
        metadata = {"class:Pyro4.naming.NameServer"}
        self.nameserver.register(Pyro4.constants.NAMESERVER_NAME, self.uriFor(self.nameserver), metadata=metadata)
        if Pyro4.config.NS_AUTOCLEAN > 0:
            if not AutoCleaner.override_autoclean_min and Pyro4.config.NS_AUTOCLEAN < AutoCleaner.min_autoclean_value:
                raise ValueError("NS_AUTOCLEAN cannot be smaller than " + str(AutoCleaner.min_autoclean_value))
            log.debug("autoclean enabled")
            self.cleaner_thread = AutoCleaner(self.nameserver)
            self.cleaner_thread.start()
        else:
            log.debug("autoclean not enabled")
            self.cleaner_thread = None
        log.info("nameserver daemon created")

    def close(self):
        super(NameServerDaemon, self).close()
        if self.nameserver is not None:
            self.nameserver.storage.close()
            self.nameserver = None
        if self.cleaner_thread:
            self.cleaner_thread.stop = True
            self.cleaner_thread.join()
            self.cleaner_thread = None

    def __enter__(self):
        if not self.nameserver:
            raise PyroError("cannot reuse this object")
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if self.nameserver is not None:
            self.nameserver.storage.close()
        self.nameserver = None
        if self.cleaner_thread:
            self.cleaner_thread.stop = True
            self.cleaner_thread.join()
            self.cleaner_thread = None
        return super(NameServerDaemon, self).__exit__(exc_type, exc_value, traceback)

    def handleRequest(self, conn):
        try:
            return super(NameServerDaemon, self).handleRequest(conn)
        except ProtocolError as x:
            # Notify the user that a protocol error occurred.
            # This is useful for instance when a wrong serializer is used, it helps
            # a lot to immediately see what is going wrong.
            warnings.warn("Pyro protocol error occurred: " + str(x))
            raise


class AutoCleaner(Thread):
    """
    Takes care of checking every registration in the name server.
    If it cannot be contacted anymore, it will be removed after ~20 seconds.
    """
    min_autoclean_value = 3
    max_unreachable_time = 20.0
    loop_delay = 2.0
    override_autoclean_min = False   # only for unit test purposes

    def __init__(self, nameserver):
        assert Pyro4.config.NS_AUTOCLEAN > 0
        if not self.override_autoclean_min and Pyro4.config.NS_AUTOCLEAN < self.min_autoclean_value:
            raise ValueError("NS_AUTOCLEAN cannot be smaller than "+str(self.min_autoclean_value))
        super(AutoCleaner, self).__init__()
        self.nameserver = nameserver
        self.stop = False
        self.daemon = True
        self.last_cleaned = time.time()
        self.unreachable = {}   # name->since when

    def run(self):
        while not self.stop:
            time.sleep(self.loop_delay)
            time_since_last_autoclean = time.time() - self.last_cleaned
            if time_since_last_autoclean < Pyro4.config.NS_AUTOCLEAN:
                continue
            for name, uri in self.nameserver.list().items():
                if name in (Pyro4.constants.DAEMON_NAME, Pyro4.constants.NAMESERVER_NAME):
                    continue
                try:
                    uri_obj = Pyro4.URI(uri)
                    timeout = Pyro4.config.COMMTIMEOUT or 5
                    sock = socketutil.createSocket(connect=(uri_obj.host, uri_obj.port), timeout=timeout)
                    sock.close()
                    # if we get here, the listed server is still answering on its port
                    if name in self.unreachable:
                        del self.unreachable[name]
                except socket.error:
                    if name not in self.unreachable:
                        self.unreachable[name] = time.time()
                    if time.time() - self.unreachable[name] >= self.max_unreachable_time:
                        log.info("autoclean: unregistering %s; cannot connect uri %s for %d sec", name, uri, self.max_unreachable_time)
                        self.nameserver.remove(name)
                        del self.unreachable[name]
                        continue
            self.last_cleaned = time.time()
            if self.unreachable:
                log.debug("autoclean: %d/%d names currently unreachable", len(self.unreachable), self.nameserver.count())


class BroadcastServer(object):
    REQUEST_NSURI = b"GET_NSURI"

    class TransportServerAdapter(object):
        # this adapter is used to be able to pass the BroadcastServer to Daemon.combine() to integrate the event loops.
        def __init__(self, bcserver):
            self.sockets = [bcserver]

        def events(self, eventobjects):
            for bc in eventobjects:
                bc.processRequest()

    def __init__(self, nsUri, bchost=None, bcport=None):
        self.transportServer = self.TransportServerAdapter(self)
        self.nsUri = nsUri
        if bcport is None:
            bcport = Pyro4.config.NS_BCPORT
        if bchost is None:
            bchost = Pyro4.config.NS_BCHOST
        if ":" in nsUri.host:  # ipv6
            bchost = bchost or "::"
            self.sock = Pyro4.socketutil.createBroadcastSocket((bchost, bcport, 0, 0), reuseaddr=Pyro4.config.SOCK_REUSE, timeout=2.0)
        else:
            self.sock = Pyro4.socketutil.createBroadcastSocket((bchost, bcport), reuseaddr=Pyro4.config.SOCK_REUSE, timeout=2.0)
        self._sockaddr = self.sock.getsockname()
        bchost = bchost or self._sockaddr[0]
        bcport = bcport or self._sockaddr[1]
        if ":" in bchost:  # ipv6
            self.locationStr = "[%s]:%d" % (bchost, bcport)
        else:
            self.locationStr = "%s:%d" % (bchost, bcport)
        log.info("ns broadcast server created on %s", self.locationStr)
        self.running = True

    def close(self):
        log.debug("ns broadcast server closing")
        self.running = False
        try:
            self.sock.shutdown(socket.SHUT_RDWR)
        except (OSError, socket.error):
            pass
        self.sock.close()

    def getPort(self):
        return self.sock.getsockname()[1]

    def fileno(self):
        return self.sock.fileno()

    def runInThread(self):
        """Run the broadcast server loop in its own thread."""
        thread = Thread(target=self.__requestLoop)
        thread.setDaemon(True)
        thread.start()
        log.debug("broadcast server loop running in own thread")
        return thread

    def __requestLoop(self):
        while self.running:
            self.processRequest()
        log.debug("broadcast server loop terminating")

    def processRequest(self):
        try:
            data, addr = self.sock.recvfrom(100)
            if data == self.REQUEST_NSURI:
                responsedata = core.URI(self.nsUri)
                if responsedata.host == "0.0.0.0":
                    # replace INADDR_ANY address by the interface IP address that connects to the requesting client
                    try:
                        interface_ip = socketutil.getInterfaceAddress(addr[0])
                        responsedata.host = interface_ip
                    except socket.error:
                        pass
                log.debug("responding to broadcast request from %s: interface %s", addr[0], responsedata.host)
                responsedata = str(responsedata).encode("iso-8859-1")
                self.sock.sendto(responsedata, 0, addr)
        except socket.error:
            pass
        except SystemError:
            if sys.platform == "cli" and not self.running:
                # ironpython throws these systemerrors when shutting down... we can ignore them.
                pass
            else:
                raise

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        self.close()


def startNSloop(host=None, port=None, enableBroadcast=True, bchost=None, bcport=None, unixsocket=None, nathost=None, natport=None, storage=None, hmac=None):
    """utility function that starts a new Name server and enters its requestloop."""
    daemon = NameServerDaemon(host, port, unixsocket, nathost=nathost, natport=natport, storage=storage)
    daemon._pyroHmacKey = hmac
    nsUri = daemon.uriFor(daemon.nameserver)
    internalUri = daemon.uriFor(daemon.nameserver, nat=False)
    bcserver = None
    if unixsocket:
        hostip = "Unix domain socket"
    else:
        hostip = daemon.sock.getsockname()[0]
        if hostip.startswith("127."):
            print("Not starting broadcast server for localhost.")
            log.info("Not starting NS broadcast server because NS is bound to localhost")
            enableBroadcast = False
        if enableBroadcast:
            # Make sure to pass the internal uri to the broadcast responder.
            # It is almost always useless to let it return the external uri,
            # because external systems won't be able to talk to this thing anyway.
            bcserver = BroadcastServer(internalUri, bchost, bcport)
            print("Broadcast server running on %s" % bcserver.locationStr)
            bcserver.runInThread()
    existing = daemon.nameserver.count()
    if existing > 1:   # don't count our own nameserver registration
        print("Persistent store contains %d existing registrations." % existing)
    print("NS running on %s (%s)" % (daemon.locationStr, hostip))
    if not hmac:
        print("Warning: HMAC key not set. Anyone can connect to this server!")
    if daemon.natLocationStr:
        print("internal URI = %s" % internalUri)
        print("external URI = %s" % nsUri)
    else:
        print("URI = %s" % nsUri)
    try:
        daemon.requestLoop()
    finally:
        daemon.close()
        if bcserver is not None:
            bcserver.close()
    print("NS shut down.")


def startNS(host=None, port=None, enableBroadcast=True, bchost=None, bcport=None, unixsocket=None, nathost=None, natport=None, storage=None, hmac=None):
    """utility fuction to quickly get a Name server daemon to be used in your own event loops.
    Returns (nameserverUri, nameserverDaemon, broadcastServer)."""
    daemon = NameServerDaemon(host, port, unixsocket, nathost=nathost, natport=natport, storage=storage)
    daemon._pyroHmacKey = hmac
    bcserver = None
    nsUri = daemon.uriFor(daemon.nameserver)
    if not unixsocket:
        hostip = daemon.sock.getsockname()[0]
        if hostip.startswith("127."):
            # not starting broadcast server for localhost.
            enableBroadcast = False
        if enableBroadcast:
            internalUri = daemon.uriFor(daemon.nameserver, nat=False)
            bcserver = BroadcastServer(internalUri, bchost, bcport)
    return nsUri, daemon, bcserver


def locateNS(host=None, port=None, broadcast=True, hmac_key=None):
    """Get a proxy for a name server somewhere in the network."""
    if host is None:
        # first try localhost if we have a good chance of finding it there
        if Pyro4.config.NS_HOST in ("localhost", "::1") or Pyro4.config.NS_HOST.startswith("127."):
            if ":" in Pyro4.config.NS_HOST:  # ipv6
                hosts = ["[%s]" % Pyro4.config.NS_HOST]
            else:
                # Some systems (Debian Linux) have 127.0.1.1 in the hosts file assigned to the hostname,
                # try this too for convenience sake (only if it's actually used as a valid ip address)
                try:
                    socket.gethostbyaddr("127.0.1.1")
                    hosts = [Pyro4.config.NS_HOST] if Pyro4.config.NS_HOST == "127.0.1.1" else [Pyro4.config.NS_HOST, "127.0.1.1"]
                except socket.error:
                    hosts = [Pyro4.config.NS_HOST]
            for host in hosts:
                uristring = "PYRO:%s@%s:%d" % (Pyro4.constants.NAMESERVER_NAME, host, port or Pyro4.config.NS_PORT)
                log.debug("locating the NS: %s", uristring)
                proxy = core.Proxy(uristring)
                proxy._pyroHmacKey = hmac_key
                try:
                    proxy._pyroBind()
                    log.debug("located NS")
                    return proxy
                except PyroError:
                    pass
        if broadcast:
            # broadcast lookup
            if not port:
                port = Pyro4.config.NS_BCPORT
            log.debug("broadcast locate")
            sock = Pyro4.socketutil.createBroadcastSocket(reuseaddr=Pyro4.config.SOCK_REUSE, timeout=0.7)
            for _ in range(3):
                try:
                    for bcaddr in Pyro4.config.parseAddressesString(Pyro4.config.BROADCAST_ADDRS):
                        try:
                            sock.sendto(BroadcastServer.REQUEST_NSURI, 0, (bcaddr, port))
                        except socket.error:
                            x = sys.exc_info()[1]
                            err = getattr(x, "errno", x.args[0])
                            # handle some errno's that some platforms like to throw:
                            if err not in Pyro4.socketutil.ERRNO_EADDRNOTAVAIL and err not in Pyro4.socketutil.ERRNO_EADDRINUSE:
                                raise
                    data, _ = sock.recvfrom(100)
                    sock.close()
                    if sys.version_info >= (3, 0):
                        data = data.decode("iso-8859-1")
                    log.debug("located NS: %s", data)
                    proxy = core.Proxy(data)
                    proxy._pyroHmacKey = hmac_key
                    return proxy
                except socket.timeout:
                    continue
            try:
                sock.shutdown(socket.SHUT_RDWR)
            except (OSError, socket.error):
                pass
            sock.close()
            log.debug("broadcast locate failed, try direct connection on NS_HOST")
        else:
            log.debug("skipping broadcast lookup")
        # broadcast failed or skipped, try PYRO directly on specific host
        host = Pyro4.config.NS_HOST
        port = Pyro4.config.NS_PORT
    # pyro direct lookup
    if not port:
        port = Pyro4.config.NS_PORT
    if core.URI.isUnixsockLocation(host):
        uristring = "PYRO:%s@%s" % (Pyro4.constants.NAMESERVER_NAME, host)
    else:
        # if not a unix socket, check for ipv6
        if ":" in host:
            host = "[%s]" % host
        uristring = "PYRO:%s@%s:%d" % (Pyro4.constants.NAMESERVER_NAME, host, port)
    uri = core.URI(uristring)
    log.debug("locating the NS: %s", uri)
    proxy = core.Proxy(uri)
    proxy._pyroHmacKey = hmac_key
    try:
        proxy._pyroBind()
        log.debug("located NS")
        return proxy
    except PyroError as x:
        e = NamingError("Failed to locate the nameserver")
        if sys.version_info >= (3, 0):
            e.__cause__ = x
        raise e


def resolve(uri, hmac_key=None):
    """
    Resolve a 'magic' uri (PYRONAME, PYROMETA) into the direct PYRO uri.
    It finds a name server, and use that to resolve a PYRONAME uri into the direct PYRO uri pointing to the named object.
    If uri is already a PYRO uri, it is returned unmodified.
    You can consider this a shortcut function so that you don't have to locate and use a name server proxy yourself.
    Note: if you need to resolve more than a few names, consider using the name server directly instead of repeatedly
    calling this function, to avoid the name server lookup overhead from each call.
    """
    if isinstance(uri, basestring):
        uri = core.URI(uri)
    elif not isinstance(uri, core.URI):
        raise TypeError("can only resolve Pyro URIs")
    if uri.protocol == "PYRO":
        return uri
    log.debug("resolving %s", uri)
    if uri.protocol == "PYRONAME":
        with locateNS(uri.host, uri.port, hmac_key=hmac_key) as nameserver:
            return nameserver.lookup(uri.object)
    elif uri.protocol == "PYROMETA":
        with locateNS(uri.host, uri.port, hmac_key=hmac_key) as nameserver:
            candidates = nameserver.list(metadata_all=uri.object)
            if candidates:
                candidate = random.choice(list(candidates.values()))
                log.debug("resolved to candidate %s", candidate)
                return core.URI(candidate)
            raise NamingError("no registrations available with desired metadata properties %s" % uri.object)
    else:
        raise PyroError("invalid uri protocol")


def type_meta(class_or_object, prefix="class:"):
    """extracts type metadata from the given class or object, can be used as Name server metadata."""
    if hasattr(class_or_object, "__mro__"):
        return {prefix+c.__module__+"."+c.__name__ for c in class_or_object.__mro__ if c.__module__ not in ("builtins", "__builtin__")}
    if hasattr(class_or_object, "__class__"):
        return type_meta(class_or_object.__class__)
    return frozenset()


def main(args=None):
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option("-n", "--host", dest="host", help="hostname to bind server on")
    parser.add_option("-p", "--port", dest="port", type="int", help="port to bind server on (0=random)")
    parser.add_option("-u", "--unixsocket", help="Unix domain socket name to bind server on")
    parser.add_option("-s", "--storage", help="Storage system to use (memory, dbm:file, sql:file)", default="memory")
    parser.add_option("", "--bchost", dest="bchost", help="hostname to bind broadcast server on (default is \"\")")
    parser.add_option("", "--bcport", dest="bcport", type="int",
                      help="port to bind broadcast server on (0=random)")
    parser.add_option("", "--nathost", dest="nathost", help="external hostname in case of NAT")
    parser.add_option("", "--natport", dest="natport", type="int", help="external port in case of NAT")
    parser.add_option("-x", "--nobc", dest="enablebc", action="store_false", default=True,
                      help="don't start a broadcast server")
    parser.add_option("-k", "--key", help="the HMAC key to use")
    options, args = parser.parse_args(args)
    startNSloop(options.host, options.port, enableBroadcast=options.enablebc,
                bchost=options.bchost, bcport=options.bcport, unixsocket=options.unixsocket,
                nathost=options.nathost, natport=options.natport, storage=options.storage,
                hmac=options.key)


if __name__ == "__main__":
    main()
