# -*- coding: utf-8 -*-
# zmq.py
# Copyright (C) 2015, 2016 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
The server for the events mechanism.
"""
import os
import logging
import txzmq
import re
import time


from abc import ABCMeta

# XXX some distros don't package libsodium, so we have to be prepared for
#     absence of zmq.auth
try:
    import zmq.auth
    from zmq.auth.thread import ThreadAuthenticator
except ImportError:
    pass

from txzmq.connection import ZmqEndpoint, ZmqEndpointType

from leap.common.config import flags, get_path_prefix
from leap.common.zmq_utils import zmq_has_curve

from leap.common.zmq_utils import maybe_create_and_get_certificates
from leap.common.zmq_utils import PUBLIC_KEYS_PREFIX


logger = logging.getLogger(__name__)


ADDRESS_RE = re.compile("^([a-z]+)://([^:]+):?(\d+)?$")


class TxZmqComponent(object):
    """
    A twisted-powered zmq events component.
    """
    _factory = txzmq.ZmqFactory()
    _factory.registerForShutdown()

    __metaclass__ = ABCMeta

    _component_type = None

    def __init__(self, path_prefix=None, enable_curve=True):
        """
        Initialize the txzmq component.
        """
        if path_prefix is None:
            path_prefix = get_path_prefix(flags.STANDALONE)
        self._config_prefix = os.path.join(path_prefix, "leap", "events")
        self._connections = []
        if enable_curve:
            self.use_curve = zmq_has_curve()
        else:
            self.use_curve = False

    @property
    def component_type(self):
        if not self._component_type:
            raise Exception(
                "Make sure implementations of TxZmqComponent"
                "define a self._component_type!")
        return self._component_type

    def _zmq_connect(self, connClass, address):
        """
        Connect to an address.

        :param connClass: The connection class to be used.
        :type connClass: txzmq.ZmqConnection
        :param address: The address to connect to.
        :type address: str

        :return: The binded connection.
        :rtype: txzmq.ZmqConnection
        """
        endpoint = ZmqEndpoint(ZmqEndpointType.connect, address)
        connection = connClass(self._factory)

        if self.use_curve:
            socket = connection.socket
            public, secret = maybe_create_and_get_certificates(
                self._config_prefix, self.component_type)
            server_public_file = os.path.join(
                self._config_prefix, PUBLIC_KEYS_PREFIX, "server.key")

            server_public, _ = zmq.auth.load_certificate(server_public_file)
            socket.curve_publickey = public
            socket.curve_secretkey = secret
            socket.curve_serverkey = server_public

        connection.addEndpoints([endpoint])
        return connection

    def _zmq_bind(self, connClass, address):
        """
        Bind to an address.

        :param connClass: The connection class to be used.
        :type connClass: txzmq.ZmqConnection
        :param address: The address to bind to.
        :type address: str

        :return: The binded connection and port.
        :rtype: (txzmq.ZmqConnection, int)
        """
        proto, addr, port = ADDRESS_RE.search(address).groups()

        endpoint = ZmqEndpoint(ZmqEndpointType.bind, address)
        connection = connClass(self._factory)

        if self.use_curve:
            socket = connection.socket

            public, secret = maybe_create_and_get_certificates(
                self._config_prefix, self.component_type)
            socket.curve_publickey = public
            socket.curve_secretkey = secret
            self._start_thread_auth(connection.socket)

        connection.addEndpoints([endpoint])
        return connection, port

    def _start_thread_auth(self, socket):
        """
        Start the zmq curve thread authenticator.

        :param socket: The socket in which to configure the authenticator.
        :type socket: zmq.Socket
        """
        # TODO re-implement without threads.
        logger.debug("Starting thread authenticator...")
        authenticator = ThreadAuthenticator(self._factory.context)

        # Temporary fix until we understand what the problem is
        # See https://leap.se/code/issues/7536
        time.sleep(0.5)

        authenticator.start()
        # XXX do not hardcode this here.
        authenticator.allow('127.0.0.1')
        # tell authenticator to use the certificate in a directory
        public_keys_dir = os.path.join(self._config_prefix, PUBLIC_KEYS_PREFIX)
        authenticator.configure_curve(domain="*", location=public_keys_dir)
        socket.curve_server = True  # must come before bind


class TxZmqServerComponent(TxZmqComponent):
    """
    A txZMQ server component.
    """

    _component_type = "server"


class TxZmqClientComponent(TxZmqComponent):
    """
    A txZMQ client component.
    """

    _component_type = "client"