#
# Copyright 2022 aiohomekit team
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

from __future__ import annotations

import asyncio
import logging
import uuid
from typing import TYPE_CHECKING

from bleak.backends.device import BLEDevice
from bleak.backends.scanner import AdvertisementData
from bleak.exc import BleakError
from bleak_retry_connector import retry_bluetooth_connection_error

from aiohomekit.controller.abstract import AbstractDiscovery, FinishPairing
from aiohomekit.model import CharacteristicsTypes, ServicesTypes
from aiohomekit.model.feature_flags import FeatureFlags
from aiohomekit.protocol import perform_pair_setup_part1, perform_pair_setup_part2
from aiohomekit.utils import check_pin_format, pair_with_auth

from .bleak import AIOHomeKitBleakClient
from .client import (
    char_read,
    char_write,
    disconnect_on_missing_services,
    drive_pairing_state_machine,
)
from .connection import establish_connection
from .manufacturer_data import HomeKitAdvertisement
from .pairing import BlePairing

if TYPE_CHECKING:
    from aiohomekit.controller.ble.controller import BleController


logger = logging.getLogger(__name__)


class BleDiscovery(AbstractDiscovery):
    """
    A discovered BLE HAP device that is unpaired.
    """

    description: HomeKitAdvertisement

    def __init__(
        self,
        controller: BleController,
        device: BLEDevice,
        description: HomeKitAdvertisement,
        ble_advertisement: AdvertisementData,
    ) -> None:
        self.description = description
        self.controller = controller
        self.device = device
        self.ble_advertisement = ble_advertisement
        self.client: AIOHomeKitBleakClient | None = None
        self._connection_lock = asyncio.Lock()

    @property
    def name(self) -> str:
        return f"{self.description.name} ({self.description.address})"

    @property
    def rssi(self) -> int | None:
        return self.ble_advertisement.rssi if self.ble_advertisement else None

    async def _ensure_connected(self):
        logger.debug(
            "%s: Ensure connected with device %s; rssi=%s",
            self.name,
            self.device,
            self.rssi,
        )
        if self.client and self.client.is_connected:
            return
        async with self._connection_lock:
            # Check again while holding the lock
            if self.client and self.client.is_connected:
                return
            self.client = await establish_connection(
                self.device,
                self.name,
                self._async_disconnected,
                ble_device_callback=lambda: self.device,
                use_services_cache=True,
            )

    def _async_disconnected(self, client: AIOHomeKitBleakClient) -> None:
        logger.debug("%s: Session closed callback; rssi=%s", self.name, self.rssi)

    async def _close(self):
        if not self.client:
            return
        async with self._connection_lock:
            if not self.client or not self.client.is_connected:
                return
            logger.debug("%s: Disconnecting: %s", self.name, self.rssi)
            try:
                await self.client.disconnect()
            except BleakError:
                logger.debug(
                    "%s: Failed to close connection, client may have already closed it",
                    self.name,
                )
            finally:
                self.client = None

    async def _async_start_pairing(self, alias: str) -> tuple[bytearray, bytearray]:
        await self._ensure_connected()

        try:
            ff_char = await self.client.get_characteristic(
                ServicesTypes.PAIRING,
                CharacteristicsTypes.PAIRING_FEATURES,
            )
        except ValueError:
            # If the device closed the connection while reading the services
            # we need to reconnect since our client is now invalid.
            await self._close()
            await self._ensure_connected()
            ff_char = await self.client.get_characteristic(
                ServicesTypes.PAIRING,
                CharacteristicsTypes.PAIRING_FEATURES,
            )

        ff_iid = await self.client.get_characteristic_iid(ff_char)
        ff_raw = await char_read(self.client, None, None, ff_char, ff_iid)
        ff = FeatureFlags(ff_raw[0])
        logger.debug("%s: starting pairing; rssi=%s", self.name, self.rssi)
        return await drive_pairing_state_machine(
            self.client,
            CharacteristicsTypes.PAIR_SETUP,
            perform_pair_setup_part1(
                with_auth=pair_with_auth(ff),
            ),
        )

    @retry_bluetooth_connection_error()
    @disconnect_on_missing_services
    async def async_start_pairing(self, alias: str) -> FinishPairing:
        salt, pub_key = await self._async_start_pairing(alias)
        attempt = 0

        @retry_bluetooth_connection_error()
        @disconnect_on_missing_services
        async def finish_pairing(pin: str) -> BlePairing:
            logger.debug("%s: finish pairing; rssi=%s", self.name, self.rssi)

            nonlocal attempt
            nonlocal salt
            nonlocal pub_key

            check_pin_format(pin)

            attempt += 1

            if attempt > 1:
                # We've already tried to pair, if
                # the retry gets us here again, we
                # need to disconnect and restart
                # the pairing process.
                await self._close()
                salt, pub_key = await self._async_start_pairing(alias)

            pairing = await drive_pairing_state_machine(
                self.client,
                CharacteristicsTypes.PAIR_SETUP,
                perform_pair_setup_part2(
                    pin,
                    str(uuid.uuid4()),
                    salt,
                    pub_key,
                ),
            )

            pairing["AccessoryAddress"] = self.description.address
            pairing["Connection"] = "BLE"

            obj = self.controller.pairings[alias] = BlePairing(
                self.controller,
                pairing,
                device=self.device,
                client=self.client,
                description=self.description,
            )
            return obj

        return finish_pairing

    async def async_identify(self) -> None:
        if self.paired:
            raise RuntimeError(f"{self.name}: Cannot anonymously identify a paired accessory")

        await self._ensure_connected()

        char = await self.client.get_characteristic(
            ServicesTypes.ACCESSORY_INFORMATION,
            CharacteristicsTypes.IDENTIFY,
        )
        iid = await self.client.get_characteristic_iid(char)

        await char_write(self.client, None, None, char, iid, b"\x01")

    def _async_process_advertisement(
        self,
        device: BLEDevice,
        description: HomeKitAdvertisement,
        ble_advertisement: AdvertisementData,
    ):
        """Update the device and description so we connect to the right place."""
        self.device = device
        self.ble_advertisement = ble_advertisement
        self.description = description