"""
kombu.transport.pyredis
=======================

Redis transport.

:copyright: (c) 2009 - 2011 by Ask Solem.
:license: BSD, see LICENSE for more details.

"""

from Queue import Empty

from anyjson import serialize, deserialize

from kombu.exceptions import VersionMismatch
from kombu.transport import virtual
from kombu.utils import eventio
from kombu.utils import cached_property

DEFAULT_PORT = 6379
DEFAULT_DB = 0


# This implementation may seem overly complex, but I assure you there is
# a good reason for doing it this way.
#
# Consuming from several connections enables us to emulate channels,
# which means we can have different service guarantees for individual
# channels.
#
# So we need to consume messages from multiple connections simultaneously,
# and using epoll means we don't have to do so using multiple threads.
#
# Also it means we can easily use PUBLISH/SUBSCRIBE to do fanout
# exchanges (broadcast), as an alternative to pushing messages to fanout-bound
# queues manually.


class MultiChannelPoller(object):
    eventflags = eventio.POLL_READ | eventio.POLL_ERR

    def __init__(self):
        # active channels
        self._channels = set()
        # file descriptor -> channel map.
        self._fd_to_chan = {}
        # channel -> socket map
        self._chan_to_sock = {}
        # poll implementation (epoll/kqueue/select)
        self._poller = eventio.poll()

    def close(self):
        for fd in self._chan_to_sock.itervalues():
            try:
                self._poller.unregister(fd)
            except KeyError:
                pass
        self._channels.clear()
        self._fd_to_chan.clear()
        self._chan_to_sock.clear()
        self._poller = None

    def add(self, channel):
        self._channels.add(channel)

    def discard(self, channel):
        self._channels.discard(channel)

    def _register(self, channel, client, type):
        if (channel, client, type) in self._chan_to_sock:
            self._unregister(channel, client, type)
        if client.connection._sock is None:   # not connected yet.
            client.connection.connect()
        sock = client.connection._sock
        self._fd_to_chan[sock.fileno()] = (channel, type)
        self._chan_to_sock[(channel, client, type)] = sock
        self._poller.register(sock, self.eventflags)

    def _unregister(self, channel, client, type):
        self._poller.unregister(self._chan_to_sock[(channel, client, type)])

    def _register_BRPOP(self, channel):
        """enable BRPOP mode for channel."""
        ident = channel, channel.client, "BRPOP"
        if channel.client.connection._sock is None or \
                ident not in self._chan_to_sock:
            channel._in_poll = False
            self._register(*ident)

        if not channel._in_poll:  # send BRPOP
            channel._brpop_start()

    def _register_LISTEN(self, channel):
        """enable LISTEN mode for channel."""
        if channel.subclient.connection._sock is None:
            channel._in_listen = False
            self._register(channel, channel.subclient, "LISTEN")
        if not channel._in_listen:
            channel._subscribe()  # send SUBSCRIBE

    def get(self, timeout=None):
        for channel in self._channels:
            if channel.active_queues:           # BRPOP mode?
                if channel.qos.can_consume():
                    self._register_BRPOP(channel)
            if channel.active_fanout_queues:    # LISTEN mode?
                self._register_LISTEN(channel)

        events = self._poller.poll(timeout and timeout * 1000 or None)
        for fileno, event in events:
            if event & eventio.POLL_READ:
                chan, type = self._fd_to_chan[fileno]
                if chan.qos.can_consume():
                    return chan.handlers[type](), self
            elif event & eventio.POLL_HUP:
                chan, type = self._fd_to_chan[fileno]
                chan._poll_error(type)
                break
        raise Empty()


class Channel(virtual.Channel):
    _client = None
    _subclient = None
    supports_fanout = True
    keyprefix_queue = "_kombu.binding.%s"
    sep = '\x06\x16'
    _in_poll = False
    _in_listen = False
    _fanout_queues = {}

    def __init__(self, *args, **kwargs):
        super_ = super(Channel, self)
        super_.__init__(*args, **kwargs)

        self.Client = self._get_client()
        self.ResponseError = self._get_response_error()
        self.active_fanout_queues = set()
        self._fanout_to_queue = {}
        self.handlers = {"BRPOP": self._brpop_read, "LISTEN": self._receive}

        # Evaluate connection.
        self.client.info()

        self.connection.cycle.add(self)  # add to channel poller.

    def basic_consume(self, queue, *args, **kwargs):
        if queue in self._fanout_queues:
            exchange = self._fanout_queues[queue]
            self.active_fanout_queues.add(queue)
            self._fanout_to_queue[exchange] = queue
        return super(Channel, self).basic_consume(queue, *args, **kwargs)

    def basic_cancel(self, consumer_tag):
        try:
            queue = self._tag_to_queue[consumer_tag]
        except KeyError:
            return
        try:
            self.active_fanout_queues.discard(queue)
            self._fanout_to_queue.pop(self._fanout_queues[queue])
        except KeyError:
            pass
        return super(Channel, self).basic_cancel(consumer_tag)

    def _subscribe(self):
        keys = [self._fanout_queues[queue]
                    for queue in self.active_fanout_queues]
        if not keys:
            return
        c = self.subclient
        if c.connection._sock is None:
            c.connection.connect()
        self.subclient.subscribe(keys)
        self._in_listen = True

    def _handle_message(self, client, r):
        if r[0] == "unsubscribe" and r[2] == 0:
            client.subscribed = False
        elif r[0] == "pmessage":
            return {"type":    r[0], "pattern": r[1],
                    "channel": r[2], "data":    r[3]}
        else:
            return {"type":    r[0], "pattern": None,
                    "channel": r[1], "data":    r[2]}

    def _receive(self):
        c = self.subclient
        response = None
        try:
            response = c.parse_response()
        except self.connection.connection_errors:
            self._in_listen = False
        if response is not None:
            payload = self._handle_message(c, response)
            if payload["type"] == "message":
                return (deserialize(payload["data"]),
                        self._fanout_to_queue[payload["channel"]])
        raise Empty()

    def _brpop_start(self, timeout=1):
        queues = self.active_queues
        if not queues:
            return
        keys = list(queues) + [timeout or 0]
        self.client.connection.send_command("BRPOP", *keys)
        self._in_poll = True

    def _brpop_read(self, **options):
        try:
            try:
                dest__item = self.client.parse_response(self.client.connection,
                                                        "BRPOP",
                                                        **options)
            except self.connection.connection_errors:
                # if there's a ConnectionError, disconnect so the next
                # iteration will reconnect automatically.
                self.client.connection.disconnect()
                raise Empty()
            if dest__item:
                dest, item = dest__item
                return deserialize(item), dest
            else:
                raise Empty()
        finally:
            self._in_poll = False

    def _poll_error(self, type, **options):
        try:
            self.client.parse_response(type)
        except self.connection.connection_errors:
            pass

    def _get(self, queue):
        """basic.get

        .. note::

            Implies ``no_ack=True``

        """
        item = self._avail_client.rpop(queue)
        if item:
            return deserialize(item)
        raise Empty()

    def _size(self, queue):
        return self._avail_client.llen(queue)

    def _put(self, queue, message, **kwargs):
        """Deliver message."""
        self._avail_client.lpush(queue, serialize(message))

    def _put_fanout(self, exchange, message, **kwargs):
        """Deliver fanout message."""
        self._avail_client.publish(exchange, serialize(message))

    def _queue_bind(self, exchange, routing_key, pattern, queue):
        if self.typeof(exchange).type == "fanout":
            # Mark exchange as fanout.
            self._fanout_queues[queue] = exchange
        self._avail_client.sadd(self.keyprefix_queue % (exchange, ),
                            self.sep.join([routing_key or "",
                                           pattern or "",
                                           queue or ""]))

    def _delete(self, queue, exchange, routing_key, pattern, *args):
        self._avail_client.srem(self.keyprefix_queue % (exchange, ),
                                self.sep.join([routing_key or "",
                                               pattern or "",
                                               queue or ""]))
        self._avail_client.delete(queue)

    def _has_queue(self, queue, **kwargs):
        return self._avail_client.exists(queue)

    def get_table(self, exchange):
        return [tuple(val.split(self.sep))
                    for val in self._avail_client.smembers(
                            self.keyprefix_queue % exchange)]

    def _purge(self, queue):
        size, _ = self._avail_client.pipeline().llen(queue) \
                                        .delete(queue).execute()
        return size

    def close(self):
        if not self.closed:
            # remove from channel poller.
            self.connection.cycle.discard(self)

            # Close connections
            for attr in "client", "subclient":
                try:
                    delattr(self, attr)
                except (AttributeError, self.ResponseError):
                    pass
        super(Channel, self).close()

    def _create_client(self):
        conninfo = self.connection.client
        database = conninfo.virtual_host
        if not isinstance(database, int):
            if not database or database == "/":
                database = DEFAULT_DB
            elif database.startswith("/"):
                database = database[1:]
            try:
                database = int(database)
            except ValueError:
                raise ValueError(
                    "Database name must be int between 0 and limit - 1")

        return self.Client(host=conninfo.hostname,
                           port=conninfo.port or DEFAULT_PORT,
                           db=database,
                           password=conninfo.password)

    def _get_client(self):
        import redis

        version = getattr(redis, "__version__", (0, 0, 0))
        if version:
            version = tuple(version.split("."))
        if version < (2, 4, 4):
            raise VersionMismatch(
                "Redis transport requires redis-py versions 2.4.4 or later. "
                "You have %r" % (".".join(version), ))

        # KombuRedis maintains a connection attribute on it's instance and
        # uses that when executing commands
        class KombuRedis(redis.Redis):

            def __init__(self, *args, **kwargs):
                super(KombuRedis, self).__init__(*args, **kwargs)
                self.connection = self.connection_pool.get_connection('_')

            def execute_command(self, *args, **options):
                conn = self.connection
                command_name = args[0]
                try:
                    conn.send_command(*args)
                    return self.parse_response(conn, command_name, **options)
                except redis.ConnectionError:
                    conn.disconnect()
                    conn.send_command(*args)
                    return self.parse_response(conn, command_name, **options)

        return KombuRedis

    def _get_response_error(self):
        from redis import exceptions
        return exceptions.ResponseError

    @property
    def _avail_client(self):
        if self._in_poll:
            return self._create_client()
        return self.client

    @cached_property
    def client(self):
        return self._create_client()

    @client.deleter     # noqa
    def client(self, client):
        client.connection.disconnect()

    @cached_property
    def subclient(self):
        client = self._create_client()
        pubsub = client.pubsub()
        pool = pubsub.connection_pool
        pubsub.connection = pool.get_connection("pubsub", pubsub.shard_hint)
        return pubsub

    @subclient.deleter  # noqa
    def subclient(self, client):
        client.connection.disconnect()

    @property
    def active_queues(self):
        return set(queue for queue in self._active_queues
                            if queue not in self.active_fanout_queues)


class Transport(virtual.Transport):
    Channel = Channel

    interval = 1
    default_port = DEFAULT_PORT
    # poller is global for all Redis BrokerConnection's

    def __init__(self, *args, **kwargs):
        super(Transport, self).__init__(*args, **kwargs)
        self.connection_errors, self.channel_errors = self._get_errors()
        self.cycle = MultiChannelPoller()

    def _get_errors(self):
        from redis import exceptions
        # This exception suddenly changed name between redis-py versions
        if hasattr(exceptions, "InvalidData"):
            DataError = exceptions.InvalidData
        else:
            DataError = exceptions.DataError
        return ((exceptions.ConnectionError,
                 exceptions.AuthenticationError),
                (exceptions.ConnectionError,
                 DataError,
                 exceptions.InvalidResponse,
                 exceptions.ResponseError))
