import asyncio
from enum import Enum, unique
from logging import getLogger
from typing import Optional, Union

import aiormq

from .message import Message
from .types import TimeoutType


log = getLogger(__name__)


@unique
class ExchangeType(Enum):
    FANOUT = "fanout"
    DIRECT = "direct"
    TOPIC = "topic"
    HEADERS = "headers"
    X_DELAYED_MESSAGE = "x-delayed-message"
    X_CONSISTENT_HASH = "x-consistent-hash"
    X_MODULUS_HASH = "x-modulus-hash"


ExchangeParamType = Union["Exchange", str]


class Exchange:
    """ Exchange abstraction """

    def __init__(
        self,
        connection,
        channel: aiormq.Channel,
        name: str,
        type: Union[ExchangeType, str] = ExchangeType.DIRECT,
        *,
        auto_delete: Optional[bool],
        durable: Optional[bool],
        internal: Optional[bool],
        passive: Optional[bool],
        arguments: dict = None
    ):

        self.loop = connection.loop

        if not arguments:
            arguments = {}

        self._channel = channel
        self.__type = type.value if isinstance(type, ExchangeType) else type
        self.name = name
        self.auto_delete = auto_delete
        self.durable = durable
        self.internal = internal
        self.passive = passive
        self.arguments = arguments

    @property
    def channel(self) -> aiormq.Channel:
        if self._channel is None:
            raise RuntimeError("Channel not opened")

        return self._channel

    def __str__(self):
        return self.name

    def __repr__(self):
        return "<Exchange(%s): auto_delete=%s, durable=%s, arguments=%r)>" % (
            self,
            self.auto_delete,
            self.durable,
            self.arguments,
        )

    async def declare(
        self, timeout: TimeoutType = None
    ) -> aiormq.spec.Exchange.DeclareOk:
        return await asyncio.wait_for(
            self.channel.exchange_declare(
                self.name,
                exchange_type=self.__type,
                durable=self.durable,
                auto_delete=self.auto_delete,
                internal=self.internal,
                passive=self.passive,
                arguments=self.arguments,
            ),
            timeout=timeout,
        )

    @staticmethod
    def _get_exchange_name(exchange: ExchangeParamType):
        if isinstance(exchange, Exchange):
            return exchange.name
        elif isinstance(exchange, str):
            return exchange
        else:
            raise ValueError(
                "exchange argument must be an exchange instance or str",
            )

    async def bind(
        self,
        exchange: ExchangeParamType,
        routing_key: str = "",
        *,
        arguments: dict = None,
        timeout: TimeoutType = None
    ) -> aiormq.spec.Exchange.BindOk:

        """ A binding can also be a relationship between two exchanges.
        This can be simply read as: this exchange is interested in messages
        from another exchange.

        Bindings can take an extra routing_key parameter. To avoid the confusion
        with a basic_publish parameter we're going to call it a binding key.

        .. code-block:: python

            client = await connect()

            routing_key = 'simple_routing_key'
            src_exchange_name = "source_exchange"
            dest_exchange_name = "destination_exchange"

            channel = await client.channel()
            src_exchange = await channel.declare_exchange(
                src_exchange_name, auto_delete=True
            )
            dest_exchange = await channel.declare_exchange(
                dest_exchange_name, auto_delete=True
            )
            queue = await channel.declare_queue(auto_delete=True)

            await queue.bind(dest_exchange, routing_key)
            await dest_exchange.bind(src_exchange, routing_key)

        :param exchange: :class:`aio_pika.exchange.Exchange` instance
        :param routing_key: routing key
        :param arguments: additional arguments
        :param timeout: execution timeout
        :return: :class:`None`
        """

        log.debug(
            "Binding exchange %r to exchange %r, routing_key=%r, arguments=%r",
            self,
            exchange,
            routing_key,
            arguments,
        )

        return await asyncio.wait_for(
            self.channel.exchange_bind(
                arguments=arguments,
                destination=self.name,
                routing_key=routing_key,
                source=self._get_exchange_name(exchange),
            ),
            timeout=timeout,
        )

    async def unbind(
        self,
        exchange: ExchangeParamType,
        routing_key: str = "",
        arguments: dict = None,
        timeout: TimeoutType = None,
    ) -> aiormq.spec.Exchange.UnbindOk:

        """ Remove exchange-to-exchange binding for this
        :class:`Exchange` instance

        :param exchange: :class:`aio_pika.exchange.Exchange` instance
        :param routing_key: routing key
        :param arguments: additional arguments
        :param timeout: execution timeout
        :return: :class:`None`
        """

        log.debug(
            "Unbinding exchange %r from exchange %r, "
            "routing_key=%r, arguments=%r",
            self,
            exchange,
            routing_key,
            arguments,
        )

        return await asyncio.wait_for(
            self.channel.exchange_unbind(
                arguments=arguments,
                destination=self.name,
                routing_key=routing_key,
                source=self._get_exchange_name(exchange),
            ),
            timeout=timeout,
        )

    async def publish(
        self,
        message: Message,
        routing_key,
        *,
        mandatory: bool = True,
        immediate: bool = False,
        timeout: TimeoutType = None
    ) -> Optional[aiormq.types.ConfirmationFrameType]:

        """ Publish the message to the queue. `aio-pika` uses
        `publisher confirms`_ extension for message delivery.

        .. _publisher confirms: https://www.rabbitmq.com/confirms.html

        """

        log.debug(
            "Publishing message with routing key %r via exchange %r: %r",
            routing_key,
            self,
            message,
        )

        if self.internal:
            # Caught on the client side to prevent channel closure
            raise ValueError(
                "Can not publish to internal exchange: '%s'!" % self.name,
            )

        return await asyncio.wait_for(
            self.channel.basic_publish(
                exchange=self.name,
                routing_key=routing_key,
                body=message.body,
                properties=message.properties,
                mandatory=mandatory,
                immediate=immediate,
            ),
            timeout=timeout,
        )

    async def delete(
        self, if_unused: bool = False, timeout: TimeoutType = None
    ) -> aiormq.spec.Exchange.DeleteOk:

        """ Delete the queue

        :param timeout: operation timeout
        :param if_unused: perform deletion when queue has no bindings.
        """

        log.info("Deleting %r", self)
        return await asyncio.wait_for(
            self.channel.exchange_delete(self.name, if_unused=if_unused),
            timeout=timeout,
        )


__all__ = ("Exchange", "ExchangeType", "ExchangeParamType")