"""View to accept incoming websocket connection."""
from __future__ import annotations

import asyncio
from collections.abc import Callable
from contextlib import suppress
import datetime as dt
import logging
from typing import Any, Final

from aiohttp import WSMsgType, web
import async_timeout

from homeassistant.components.http import HomeAssistantView
from homeassistant.const import EVENT_HOMEASSISTANT_STOP
from homeassistant.core import Event, HomeAssistant, callback
from homeassistant.helpers.event import async_call_later

from .auth import AuthPhase, auth_required_message
from .const import (
    CANCELLATION_ERRORS,
    DATA_CONNECTIONS,
    MAX_PENDING_MSG,
    PENDING_MSG_PEAK,
    PENDING_MSG_PEAK_TIME,
    SIGNAL_WEBSOCKET_CONNECTED,
    SIGNAL_WEBSOCKET_DISCONNECTED,
    URL,
)
from .error import Disconnect
from .messages import message_to_json

_WS_LOGGER: Final = logging.getLogger(f"{__name__}.connection")


class WebsocketAPIView(HomeAssistantView):
    """View to serve a websockets endpoint."""

    name: str = "websocketapi"
    url: str = URL
    requires_auth: bool = False

    async def get(self, request: web.Request) -> web.WebSocketResponse:
        """Handle an incoming websocket connection."""
        return await WebSocketHandler(request.app["hass"], request).async_handle()


class WebSocketAdapter(logging.LoggerAdapter):
    """Add connection id to websocket messages."""

    def process(self, msg: str, kwargs: Any) -> tuple[str, Any]:
        """Add connid to websocket log messages."""
        return f'[{self.extra["connid"]}] {msg}', kwargs


class WebSocketHandler:
    """Handle an active websocket client connection."""

    def __init__(self, hass: HomeAssistant, request: web.Request) -> None:
        """Initialize an active connection."""
        self.hass = hass
        self.request = request
        self.wsock: web.WebSocketResponse | None = None
        self._to_write: asyncio.Queue = asyncio.Queue(maxsize=MAX_PENDING_MSG)
        self._handle_task: asyncio.Task | None = None
        self._writer_task: asyncio.Task | None = None
        self._logger = WebSocketAdapter(_WS_LOGGER, {"connid": id(self)})
        self._peak_checker_unsub: Callable[[], None] | None = None

    async def _writer(self) -> None:
        """Write outgoing messages."""
        # Exceptions if Socket disconnected or cancelled by connection handler
        assert self.wsock is not None
        with suppress(RuntimeError, ConnectionResetError, *CANCELLATION_ERRORS):
            while not self.wsock.closed:
                message = await self._to_write.get()
                if message is None:
                    break

                self._logger.debug("Sending %s", message)
                await self.wsock.send_str(message)

        # Clean up the peaker checker when we shut down the writer
        if self._peak_checker_unsub is not None:
            self._peak_checker_unsub()
            self._peak_checker_unsub = None

    @callback
    def _send_message(self, message: str | dict[str, Any]) -> None:
        """Send a message to the client.

        Closes connection if the client is not reading the messages.

        Async friendly.
        """
        if not isinstance(message, str):
            message = message_to_json(message)

        try:
            self._to_write.put_nowait(message)
        except asyncio.QueueFull:
            self._logger.error(
                "Client exceeded max pending messages [2]: %s", MAX_PENDING_MSG
            )

            self._cancel()

        if self._to_write.qsize() < PENDING_MSG_PEAK:
            if self._peak_checker_unsub:
                self._peak_checker_unsub()
                self._peak_checker_unsub = None
            return

        if self._peak_checker_unsub is None:
            self._peak_checker_unsub = async_call_later(
                self.hass, PENDING_MSG_PEAK_TIME, self._check_write_peak
            )

    @callback
    def _check_write_peak(self, _utc_time: dt.datetime) -> None:
        """Check that we are no longer above the write peak."""
        self._peak_checker_unsub = None

        if self._to_write.qsize() < PENDING_MSG_PEAK:
            return

        self._logger.error(
            "Client unable to keep up with pending messages. Stayed over %s for %s seconds",
            PENDING_MSG_PEAK,
            PENDING_MSG_PEAK_TIME,
        )
        self._cancel()

    @callback
    def _cancel(self) -> None:
        """Cancel the connection."""
        if self._handle_task is not None:
            self._handle_task.cancel()
        if self._writer_task is not None:
            self._writer_task.cancel()

    async def async_handle(self) -> web.WebSocketResponse:
        """Handle a websocket response."""
        request = self.request
        wsock = self.wsock = web.WebSocketResponse(heartbeat=55)
        await wsock.prepare(request)
        self._logger.debug("Connected from %s", request.remote)
        self._handle_task = asyncio.current_task()

        @callback
        def handle_hass_stop(event: Event) -> None:
            """Cancel this connection."""
            self._cancel()

        unsub_stop = self.hass.bus.async_listen(
            EVENT_HOMEASSISTANT_STOP, handle_hass_stop
        )

        # As the webserver is now started before the start
        # event we do not want to block for websocket responses
        self._writer_task = asyncio.create_task(self._writer())

        auth = AuthPhase(self._logger, self.hass, self._send_message, request)
        connection = None
        disconnect_warn = None

        try:
            self._send_message(auth_required_message())

            # Auth Phase
            try:
                with async_timeout.timeout(10):
                    msg = await wsock.receive()
            except asyncio.TimeoutError as err:
                disconnect_warn = "Did not receive auth message within 10 seconds"
                raise Disconnect from err

            if msg.type in (WSMsgType.CLOSE, WSMsgType.CLOSING):
                raise Disconnect

            if msg.type != WSMsgType.TEXT:
                disconnect_warn = "Received non-Text message."
                raise Disconnect

            try:
                msg_data = msg.json()
            except ValueError as err:
                disconnect_warn = "Received invalid JSON."
                raise Disconnect from err

            self._logger.debug("Received %s", msg_data)
            connection = await auth.async_handle(msg_data)
            self.hass.data[DATA_CONNECTIONS] = (
                self.hass.data.get(DATA_CONNECTIONS, 0) + 1
            )
            self.hass.helpers.dispatcher.async_dispatcher_send(
                SIGNAL_WEBSOCKET_CONNECTED
            )

            # Command phase
            while not wsock.closed:
                msg = await wsock.receive()

                if msg.type in (WSMsgType.CLOSE, WSMsgType.CLOSING):
                    break

                if msg.type != WSMsgType.TEXT:
                    disconnect_warn = "Received non-Text message."
                    break

                try:
                    msg_data = msg.json()
                except ValueError:
                    disconnect_warn = "Received invalid JSON."
                    break

                self._logger.debug("Received %s", msg_data)
                connection.async_handle(msg_data)

        except asyncio.CancelledError:
            self._logger.info("Connection closed by client")

        except Disconnect:
            pass

        except Exception:  # pylint: disable=broad-except
            self._logger.exception("Unexpected error inside websocket API")

        finally:
            unsub_stop()

            if connection is not None:
                connection.async_close()

            try:
                self._to_write.put_nowait(None)
                # Make sure all error messages are written before closing
                await self._writer_task
                await wsock.close()
            except asyncio.QueueFull:  # can be raised by put_nowait
                self._writer_task.cancel()

            finally:
                if disconnect_warn is None:
                    self._logger.debug("Disconnected")
                else:
                    self._logger.warning("Disconnected: %s", disconnect_warn)

                if connection is not None:
                    self.hass.data[DATA_CONNECTIONS] -= 1
                self.hass.helpers.dispatcher.async_dispatcher_send(
                    SIGNAL_WEBSOCKET_DISCONNECTED
                )

        return wsock
