"""Handle connecting to the HUE Eventstream and distribute events."""

import asyncio
from asyncio.coroutines import iscoroutinefunction
from collections import deque
from collections.abc import Callable
from enum import Enum
import json
import random
import string
from typing import TYPE_CHECKING, NoReturn, TypedDict

from aiohttp import ClientTimeout
from aiohttp.client_exceptions import ClientError

from aiohue.errors import AiohueException, InvalidAPIVersion, InvalidEvent, Unauthorized
from aiohue.util import NoneType
from aiohue.v2.models.geofence_client import GeofenceClientPost, GeofenceClientPut
from aiohue.v2.models.resource import ResourceTypes

if TYPE_CHECKING:
    from aiohue.v2 import HueBridgeV2


CONNECTION_TIMEOUT = 90  # 90 seconds
KEEPALIVE_INTERVAL = 60  # every minute


class EventStreamStatus(Enum):
    """Status options of EventStream."""

    CONNECTING = 0
    CONNECTED = 1
    DISCONNECTED = 2


class HueEvent(TypedDict):
    """Hue Event message as emitted by the EventStream."""

    id: str  # UUID
    creationtime: str
    type: str  # = EventType (add, update, delete)
    # data contains a list with (partial) resource objects
    # in case of add or update this is a full or partial resource object
    # in case of delete this will include only the
    # ResourceIndentifier (type and id) of the deleted object
    data: list[dict]


class EventType(Enum):
    """Enum with possible Events."""

    # resource events match those emitted by Hue eventstream
    RESOURCE_ADDED = "add"
    RESOURCE_UPDATED = "update"
    RESOURCE_DELETED = "delete"
    # connection events emitted by (this) events controller
    CONNECTED = "connected"
    DISCONNECTED = "disconnected"
    RECONNECTED = "reconnected"


EventCallBackType = Callable[[EventType, dict | None], None]
EventSubscriptionType = tuple[
    EventCallBackType,
    "tuple[EventType] | None",
    "tuple[ResourceTypes] | None",
]


class EventStream:
    """Holds the connection to the HUE Clip EventStream."""

    def __init__(self, bridge: "HueBridgeV2") -> None:
        """Initialize instance."""
        self._bridge = bridge
        self._listeners = set()
        self._event_queue = asyncio.Queue()
        self._last_event_id = ""
        self._status = EventStreamStatus.DISCONNECTED
        self._bg_tasks: list[asyncio.Task] = []
        self._subscribers: list[EventSubscriptionType] = []
        self._logger = bridge.logger.getChild("events")
        self._event_history = deque(maxlen=25)

    @property
    def connected(self) -> bool:
        """Return bool if we're connected."""
        return self._status == EventStreamStatus.CONNECTED

    @property
    def status(self) -> bool:
        """Return connection status."""
        return self._status

    @property
    def last_events(self) -> list[dict]:
        """Return a list with the previous X messages."""
        return self._event_history

    async def initialize(self) -> None:
        """
        Start listening for events.

        Starts the connection to the Hue Eventstream and collect events.
        Connection will be auto-reconnected if it gets lost.
        """
        assert len(self._bg_tasks) == 0
        self._bg_tasks.append(asyncio.create_task(self.__event_reader()))
        self._bg_tasks.append(asyncio.create_task(self.__event_processor()))
        self._bg_tasks.append(asyncio.create_task(self.__keepalive_workaround()))

    async def stop(self) -> None:
        """Stop listening for events."""
        for task in self._bg_tasks:
            task.cancel()
        self._bg_tasks = []

    def subscribe(
        self,
        callback: EventCallBackType,
        event_filter: EventType | tuple[EventType] | None = None,
        resource_filter: ResourceTypes | tuple[ResourceTypes] | None = None,
    ) -> Callable:
        """
        Subscribe to events emitted by the Hue bridge for resources.

        Parameters:
            - `callback` - callback function to call when an event emits.
            - `event_filter` - Optionally provide an EventType as filter.
            - `resource_filter` - Optionally provide a ResourceType as filter.

        Returns:
            function to unsubscribe.
        """
        if not isinstance(event_filter, NoneType | tuple):
            event_filter = (event_filter,)
        if not isinstance(resource_filter, NoneType | tuple):
            resource_filter = (resource_filter,)
        subscription = (callback, event_filter, resource_filter)

        def unsubscribe():
            self._subscribers.remove(subscription)

        self._subscribers.append(subscription)
        return unsubscribe

    def emit(self, event_type: EventType, data: dict | None = None) -> None:
        """Emit event to all listeners."""
        for callback, event_filter, resource_filter in self._subscribers:
            if event_filter is not None and event_type not in event_filter:
                continue
            if (
                data is not None
                and resource_filter is not None
                and ResourceTypes(data.get("type")) not in resource_filter
            ):
                continue
            if iscoroutinefunction(callback):
                asyncio.create_task(callback(event_type, data))
            else:
                callback(event_type, data)

    async def __event_reader(self) -> None:
        """

        Read incoming SSE messages and put them in a Queue to be processed.

        Background task that keeps (re)connecting until stopped.

        https://html.spec.whatwg.org/multipage/server-sent-events.html#event-stream-interpretation
        """
        self._status = EventStreamStatus.CONNECTING
        connect_attempts = 0
        headers = {
            "Accept": "text/event-stream",
            "Cache-Control": "no-cache",
            "Connection": "close",
        }

        while True:
            connect_attempts += 1
            if self._last_event_id:
                headers["last-event-id"] = self._last_event_id
            # Messages come in line by line, according to EventStream/SSE specs
            # we iterate over the incoming lines in the streamreader.
            try:
                async with self._bridge.create_request(
                    "get",
                    "eventstream/clip/v2",
                    timeout=ClientTimeout(total=0, sock_read=CONNECTION_TIMEOUT),
                    headers=headers,
                ) as resp:
                    # update status to connected once we reach this point
                    self._status = EventStreamStatus.CONNECTED
                    if connect_attempts == 1:
                        self.emit(EventType.CONNECTED)
                    else:
                        self.emit(EventType.RECONNECTED)
                    connect_attempts = 1  # reset on successful connect
                    self._logger.debug("Connected to EventStream")
                    # read over incoming messages line by line
                    async for line in resp.content:
                        # process the message
                        self.__parse_message(line)
            except (ClientError, asyncio.TimeoutError) as err:
                # pass expected connection errors because we will auto retry
                status = getattr(err, "status", None)
                if status == 404:
                    raise InvalidAPIVersion from err
                if status == 403:
                    raise Unauthorized from err
                if status:
                    # for debugging purpose only
                    self._logger.debug(err)
            except Exception as err:
                # for debugging purpose only
                self._logger.exception(err)
                raise err

            # if we reach this point, the connection was lost
            self.emit(EventType.DISCONNECTED)

            reconnect_wait = min(2 * connect_attempts, 600)
            self._logger.debug(
                "Disconnected from EventStream"
                " - Reconnect will be attempted in %s seconds",
                reconnect_wait,
            )
            # every 10 failed connect attempts log warning
            if connect_attempts % 10 == 0:
                self._logger.warning(
                    "%s Attempts to (re)connect to bridge failed"
                    " - This might be an indication of connection issues.",
                    connect_attempts,
                )
            self._status = EventStreamStatus.CONNECTING
            await asyncio.sleep(reconnect_wait)

    async def __event_processor(self) -> None:
        """Process incoming Hue events on the Queue and distribute those."""
        while True:
            event: HueEvent = await self._event_queue.get()
            # each clip event has array of updated/added/deleted objects in data property
            # we fire an event for each object that was added/updated/deleted
            for item in event["data"]:
                self.emit(EventType(event["type"]), item)

    def __parse_message(self, msg: bytes) -> None:
        """Parse a plain message string as received from EventStream."""
        try:
            line = msg.decode().strip()
            if not line or ":" not in line:
                return
            key, value = line.split(":", 1)
            if not key:
                return
            if key == "id":
                self._last_event_id = value
                return
            if key == "data":
                # events is array with multiple events
                events: list[HueEvent] = json.loads(value)
                for event in events:
                    if event.get("type") not in ["add", "update", "delete"]:
                        raise InvalidEvent(f"Received invalid event {event}")
                    self._event_queue.put_nowait(event)
                    self._event_history.append(event)
                return
            if key != "data":
                self._logger.debug("Received unexpected message: %s - %s", key, value)
        except Exception as exc:  # pylint: disable=broad-except
            self._logger.warning(
                "Unable to parse Event message: %s", line, exc_info=exc
            )

    async def __keepalive_workaround(self) -> NoReturn:
        """Send keepalive command to bridge, abusing geofence client."""
        # Oh yeah, this is a major hack and hopefully it will only be temporary ;-)
        # Signify forgot to implement some sort of periodic keep alive message on the EventBus
        # so we have no way to determine if the connection is still alive.
        # To workaround this, we create a geofence client (with status not at home)
        # on the bridge for aiohue which will have its name updated every minute
        # this will result in an event on the eventstream and thus a way to figure out
        # if its still alive. It's not very pretty but at least it works.
        # Now let's contact Signify if this can be solved.
        # Update 2022-12-12: Still no solution and apparently no real need for signify to fix this
        # https://developers.meethue.com/forum/t/several-issues-and-questions-about-the-v2-api/6586/35
        prefix = "aiohue_"

        while True:
            await asyncio.sleep(KEEPALIVE_INTERVAL)

            try:
                for client in self._bridge.sensors.geofence_client.items:
                    if client.name.startswith(prefix):
                        hass_client = client
                        break
                else:
                    await self._bridge.sensors.geofence_client.create(
                        GeofenceClientPost(name=prefix, is_at_home=False)
                    )
                    continue

                # simply updating the name of the geofence client will result in an event message
                # the eventstream timeout will detect if our keepalive message was not received
                random_str = "".join(
                    (random.choice(string.ascii_lowercase)) for x in range(10)
                )
                await self._bridge.sensors.geofence_client.update(
                    hass_client.id,
                    GeofenceClientPut(name=f"{prefix}{random_str}", is_at_home=False),
                )
            except (ClientError, asyncio.TimeoutError, AiohueException) as err:
                # might happen on connection error, we don't want the retry logic to bail out
                self._logger.debug("Error while sending keepalive: %s", str(err))
