import struct
import binascii
import logging
import zipfile
from time import time
from collections import defaultdict

try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO

import gevent
from gevent import event, queue
from random import shuffle

from steam.steamid import SteamID
from steam.enums import EResult, EUniverse
from steam.enums.emsg import EMsg
from steam.core import crypto
from steam.core.connection import TCPConnection
from steam.core.msg import Msg, MsgProto
from eventemitter import EventEmitter
from steam.util import ip_from_int, is_proto, clear_proto_bit


logger = logging.getLogger("CMClient")


class CMClient(EventEmitter):
    TCP = 0
    UDP = 1
    verbose_debug = False

    def __init__(self, protocol=0):
        self._init_attributes()

        self.servers = CMServerList()

        if protocol == CMClient.TCP:
            self.connection = TCPConnection()
        else:
            raise ValueError("Only TCP is supported")

        self.connection.event_connected.rawlink(self._handle_disconnect)

        self.on(EMsg.ChannelEncryptRequest, self._handle_encrypt_request),
        self.on(EMsg.Multi, self._handle_multi),
        self.on(EMsg.ClientLogOnResponse, self._handle_logon),
        self.on(EMsg.ClientCMList, self._handle_cm_list),

    def emit(self, event, *args):
        if event is not None:
            logger.debug("Emit event: %s" % repr(event))
        super(CMClient, self).emit(event, *args)

    def connect(self):
        logger.debug("Connect initiated.")

        for server_addr in self.servers:
            if self.connection.connect(server_addr):
                break

            logger.debug("Failed to connect. Retrying...")

        self.current_server_addr = server_addr
        self.connected = True
        self.emit("connected")
        self._recv_loop = gevent.spawn(self._recv_messages)

    def _handle_disconnect(self, event):
        if not event.is_set():
            gevent.spawn(self.disconnect)

    def disconnect(self, reconnect=False):
        if not self.connected:
            return
        self.connected = False

        self.connection.disconnect()

        if self._heartbeat_loop:
            self._heartbeat_loop.kill()
        self._recv_loop.kill()

        self._init_attributes()

        if reconnect:
            self.emit('reconnect')
            gevent.spawn(self.connect)
        else:
            self.emit('disconnected')

    def _init_attributes(self):
        self.current_server_addr = None
        self.connected = False
        self.channel_secured = False

        self.key = None
        self.hmac_secret = None

        self.steam_id = SteamID()
        self.session_id = None

        self._recv_loop = None
        self._heartbeat_loop = None

    def send_message(self, message):
        if not isinstance(message, (Msg, MsgProto)):
            raise ValueError("Expected Msg or MsgProto, got %s" % message)

        if self.steam_id:
            message.steamID = self.steam_id
        if self.session_id:
            message.sessionID = self.session_id

        if self.verbose_debug:
            logger.debug("Outgoing: %s\n%s" % (repr(message), str(message)))
        else:
            logger.debug("Outgoing: %s", repr(message))

        data = message.serialize()

        if self.key:
            if self.hmac_secret:
                data = crypto.symmetric_encrypt_HMAC(data, self.key, self.hmac_secret)
            else:
                data = crypto.symmetric_encrypt(data, self.key)

        self.connection.put_message(data)

    def _recv_messages(self):
        for message in self.connection:
            if not self.connected:
                break

            if self.key:
                if self.hmac_secret:
                    try:
                        message = crypto.symmetric_decrypt_HMAC(message, self.key, self.hmac_secret)
                    except RuntimeError as e:
                        logger.exception(e)
                        gevent.spawn(self.disconnect)
                        return
                else:
                    message = crypto.symmetric_decrypt(message, self.key)

            gevent.spawn(self._parse_message, message)
            gevent.idle()

    def _parse_message(self, message):
        emsg_id, = struct.unpack_from("<I", message)
        emsg = EMsg(clear_proto_bit(emsg_id))

        if not self.connected and emsg != EMsg.ClientLogOnResponse:
            return

        if emsg in (EMsg.ChannelEncryptRequest,
                    EMsg.ChannelEncryptResponse,
                    EMsg.ChannelEncryptResult,
                    ):

            msg = Msg(emsg, message)
        else:
            try:
                if is_proto(emsg_id):
                    msg = MsgProto(emsg, message)
                else:
                    msg = Msg(emsg, message, extended=True)
            except Exception as e:
                logger.fatal("Failed to deserialize message: %s (is_proto: %s)",
                             str(emsg),
                             is_proto(emsg_id)
                             )
                logger.exception(e)

        if self.verbose_debug:
            logger.debug("Incoming: %s\n%s" % (repr(msg), str(msg)))
        else:
            logger.debug("Incoming: %s", repr(msg))

        self.emit(emsg, msg)

    def _handle_encrypt_request(self, msg):
        logger.debug("Securing channel")

        try:
            if msg.body.protocolVersion != 1:
                raise RuntimeError("Unsupported protocol version")
            if msg.body.universe != EUniverse.Public:
                raise RuntimeError("Unsupported universe")
        except RuntimeError as e:
            logger.exception(e)
            gevent.spawn(self.disconnect)
            return

        resp = Msg(EMsg.ChannelEncryptResponse)

        challenge = msg.body.challenge
        key, resp.body.key = crypto.generate_session_key(challenge)
        resp.body.crc = binascii.crc32(resp.body.key) & 0xffffffff

        self.send_message(resp)

        msg, = self.wait_event(EMsg.ChannelEncryptResult, timeout=5)
        if msg is None:
            gevent.spawn(self.disconnect, True)
            return

        if msg.body.eresult != EResult.OK:
            logger.debug("Failed to secure channel: %s" % msg.body.eresult)
            gevent.spawn(self.disconnect)
            return


        self.key = key
        if challenge:
            logger.debug("Channel secured")
            self.hmac_secret = key[:16]
        else:
            logger.debug("Channel secured (legacy mode)")

        self.channel_secured = True
        self.emit('channel_secured')

    def _handle_multi(self, msg):
        logger.debug("Unpacking CMsgMulti")

        if msg.body.size_unzipped:
            logger.debug("Unzipping body")

            data = zipfile.ZipFile(StringIO(msg.body.message_body)).read('z')

            if len(data) != msg.body.size_unzipped:
                logger.fatal("Unzipped size mismatch")
                gevent.spawn(self.disconnect)
                return
        else:
            data = msg.body.message_body

        while len(data) > 0:
            size, = struct.unpack_from("<I", data)
            self._parse_message(data[4:4+size])
            data = data[4+size:]

    def _heartbeat(self, interval):
        message = MsgProto(EMsg.ClientHeartBeat)

        while True:
            gevent.sleep(interval)
            self.send_message(message)

    def _handle_logon(self, msg):
        result = msg.body.eresult

        if result in (EResult.TryAnotherCM,
                      EResult.ServiceUnavailable
                      ):
            self.servers.mark_bad(self.current_server_addr)
            self.disconnect(True)
            return

        elif result == EResult.OK:
            logger.debug("Logon completed")

            self.steam_id = SteamID(msg.header.steamid)
            self.session_id = msg.header.client_sessionid

            if self._heartbeat_loop:
                self._heartbeat_loop.kill()

            logger.debug("Heartbeat started.")

            interval = msg.body.out_of_game_heartbeat_seconds
            self._heartbeat_loop = gevent.spawn(self._heartbeat, interval)

    def _handle_cm_list(self, msg):
        logger.debug("Updating CM list")

        new_servers = zip(map(ip_from_int, msg.body.cm_addresses), msg.body.cm_ports)
        self.servers.merge_list(new_servers)


class CMServerList(object):
    Good = 1
    Bad = 2

    def __init__(self, bad_timespan=300):
        self._log = logging.getLogger("CMServerList")

        self.bad_timespan = bad_timespan
        self.list = defaultdict(dict)

        # build-in list
        self.merge_list([("208.64.200.201", 27017), ("208.64.200.201", 27018),
                         ("208.64.200.201", 27019), ("208.64.200.201", 27020),
                         ("208.64.200.202", 27017), ("208.64.200.202", 27018),
                         ("208.64.200.202", 27019), ("208.64.200.203", 27017),
                         ("208.64.200.203", 27018), ("208.64.200.203", 27019),
                         ("208.64.200.204", 27017), ("208.64.200.204", 27018),
                         ("208.64.200.204", 27019), ("208.64.200.205", 27017),
                         ("208.64.200.205", 27018), ("208.64.200.205", 27019),
                         ("208.78.164.9", 27017), ("208.78.164.9", 27018),
                         ("208.78.164.9", 27019), ("208.78.164.10", 27017),
                         ("208.78.164.10", 27018), ("208.78.164.10", 27019),
                         ("208.78.164.11", 27017), ("208.78.164.11", 27018),
                         ("208.78.164.11", 27019), ("208.78.164.12", 27017),
                         ("208.78.164.12", 27018), ("208.78.164.12", 27019),
                         ("208.78.164.13", 27017), ("208.78.164.13", 27018),
                         ("208.78.164.13", 27019), ("208.78.164.14", 27017),
                         ("208.78.164.14", 27018), ("208.78.164.14", 27019),
                         ])

    def __iter__(self):
        def genfunc():
            while True:
                good_servers = filter(lambda x: x[1]['quality'] == CMServerList.Good, self.list.items())

                if len(good_servers) == 0:
                    self.reset_all()
                    continue

                shuffle(good_servers)

                for server_addr, meta in good_servers:
                    yield server_addr

        return genfunc()

    def reset_all(self):
        self._log.debug("Marking all CMs as Good.")

        for key in self.list:
            self.mark_good(key)

    def mark_good(self, server_addr):
        self.list[server_addr].update({'quality': CMServerList.Good, 'timestamp': time()})

    def mark_bad(self, server_addr):
        self._log.debug("Marking %s as Bad." % repr(server_addr))
        self.list[server_addr].update({'quality': CMServerList.Bad, 'timestamp': time()})

    def merge_list(self, new_list):
        total = len(self.list)

        for ip, port in new_list:
            self.mark_good((ip, port))

        if total:
            self._log.debug("Added %d new CM addresses." % (len(self.list) - total))