pySwitchbot/switchbot/devices/lock.py

"""Library to handle connection with Switchbot Lock."""
from __future__ import annotations

import base64
import hashlib
import hmac
import json
import logging
import time
from typing import Any

import boto3
import requests
from bleak.backends.device import BLEDevice
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes

from ..api_config import SWITCHBOT_APP_API_BASE_URL, SWITCHBOT_APP_COGNITO_POOL
from ..const import (
    LockStatus,
    SwitchbotAccountConnectionError,
    SwitchbotAuthenticationError,
)
from .device import SwitchbotDevice, SwitchbotOperationError

COMMAND_HEADER = "57"
COMMAND_GET_CK_IV = f"{COMMAND_HEADER}0f2103"
COMMAND_LOCK_INFO = f"{COMMAND_HEADER}0f4f8101"
COMMAND_UNLOCK = f"{COMMAND_HEADER}0f4e01011080"
COMMAND_LOCK = f"{COMMAND_HEADER}0f4e01011000"
COMMAND_ENABLE_NOTIFICATIONS = f"{COMMAND_HEADER}0e01001e00008101"
COMMAND_DISABLE_NOTIFICATIONS = f"{COMMAND_HEADER}0e00"

MOVING_STATUSES = {LockStatus.LOCKING, LockStatus.UNLOCKING}
BLOCKED_STATUSES = {LockStatus.LOCKING_STOP, LockStatus.UNLOCKING_STOP}
REST_STATUSES = {LockStatus.LOCKED, LockStatus.UNLOCKED, LockStatus.NOT_FULLY_LOCKED}

_LOGGER = logging.getLogger(__name__)


COMMAND_RESULT_EXPECTED_VALUES = {1, 6}
# The return value of the command is 1 when the command is successful.
# The return value of the command is 6 when the command is successful but the battery is low.


class SwitchbotLock(SwitchbotDevice):
    """Representation of a Switchbot Lock."""

    def __init__(
        self,
        device: BLEDevice,
        key_id: str,
        encryption_key: str,
        interface: int = 0,
        **kwargs: Any,
    ) -> None:
        if len(key_id) == 0:
            raise ValueError("key_id is missing")
        elif len(key_id) != 2:
            raise ValueError("key_id is invalid")
        if len(encryption_key) == 0:
            raise ValueError("encryption_key is missing")
        elif len(encryption_key) != 32:
            raise ValueError("encryption_key is invalid")
        self._iv = None
        self._cipher = None
        self._key_id = key_id
        self._encryption_key = bytearray.fromhex(encryption_key)
        self._notifications_enabled: bool = False
        super().__init__(device, None, interface, **kwargs)

    @staticmethod
    async def verify_encryption_key(
        device: BLEDevice, key_id: str, encryption_key: str
    ) -> bool:
        try:
            lock = SwitchbotLock(
                device=device, key_id=key_id, encryption_key=encryption_key
            )
        except ValueError:
            return False
        try:
            lock_info = await lock.get_basic_info()
        except SwitchbotOperationError:
            return False

        return lock_info is not None

    @staticmethod
    def retrieve_encryption_key(device_mac: str, username: str, password: str):
        """Retrieve lock key from internal SwitchBot API."""
        device_mac = device_mac.replace(":", "").replace("-", "").upper()
        msg = bytes(username + SWITCHBOT_APP_COGNITO_POOL["AppClientId"], "utf-8")
        secret_hash = base64.b64encode(
            hmac.new(
                SWITCHBOT_APP_COGNITO_POOL["AppClientSecret"].encode(),
                msg,
                digestmod=hashlib.sha256,
            ).digest()
        ).decode()

        cognito_idp_client = boto3.client(
            "cognito-idp", region_name=SWITCHBOT_APP_COGNITO_POOL["Region"]
        )
        try:
            auth_response = cognito_idp_client.initiate_auth(
                ClientId=SWITCHBOT_APP_COGNITO_POOL["AppClientId"],
                AuthFlow="USER_PASSWORD_AUTH",
                AuthParameters={
                    "USERNAME": username,
                    "PASSWORD": password,
                    "SECRET_HASH": secret_hash,
                },
            )
        except cognito_idp_client.exceptions.NotAuthorizedException as err:
            raise SwitchbotAuthenticationError(
                f"Failed to authenticate: {err}"
            ) from err
        except Exception as err:
            raise SwitchbotAuthenticationError(
                f"Unexpected error during authentication: {err}"
            ) from err

        if (
            auth_response is None
            or "AuthenticationResult" not in auth_response
            or "AccessToken" not in auth_response["AuthenticationResult"]
        ):
            raise SwitchbotAuthenticationError("Unexpected authentication response")

        access_token = auth_response["AuthenticationResult"]["AccessToken"]
        try:
            key_response = requests.post(
                url=SWITCHBOT_APP_API_BASE_URL + "/developStage/keys/v1/communicate",
                headers={"authorization": access_token},
                json={
                    "device_mac": device_mac,
                    "keyType": "user",
                },
                timeout=10,
            )
        except requests.exceptions.RequestException as err:
            raise SwitchbotAccountConnectionError(
                f"Failed to retrieve encryption key from SwitchBot Account: {err}"
            ) from err
        if key_response.status_code > 299:
            raise SwitchbotAuthenticationError(
                f"Unexpected status code returned by SwitchBot Account API: {key_response.status_code}"
            )
        key_response_content = json.loads(key_response.content)
        if key_response_content["statusCode"] != 100:
            raise SwitchbotAuthenticationError(
                f"Unexpected status code returned by SwitchBot API: {key_response_content['statusCode']}"
            )

        return {
            "key_id": key_response_content["body"]["communicationKey"]["keyId"],
            "encryption_key": key_response_content["body"]["communicationKey"]["key"],
        }

    async def lock(self) -> bool:
        """Send lock command."""
        return await self._lock_unlock(
            COMMAND_LOCK, {LockStatus.LOCKED, LockStatus.LOCKING}
        )

    async def unlock(self) -> bool:
        """Send unlock command."""
        return await self._lock_unlock(
            COMMAND_UNLOCK, {LockStatus.UNLOCKED, LockStatus.UNLOCKING}
        )

    def _parse_basic_data(self, basic_data: bytes) -> dict[str, Any]:
        """Parse basic data from lock."""
        return {
            "battery": basic_data[1],
            "firmware": basic_data[2] / 10.0,
        }

    async def _lock_unlock(
        self, command: str, ignore_statuses: set[LockStatus]
    ) -> bool:
        status = self.get_lock_status()
        if status is None:
            await self.update()
            status = self.get_lock_status()
        if status in ignore_statuses:
            return True

        await self._enable_notifications()
        result = await self._send_command(command)
        status = self._check_command_result(result, 0, COMMAND_RESULT_EXPECTED_VALUES)

        # Also update the battery and firmware version
        if basic_data := await self._get_basic_info():
            self._last_full_update = time.monotonic()
            self._update_parsed_data(self._parse_basic_data(basic_data))
            self._fire_callbacks()

        return status

    async def get_basic_info(self) -> dict[str, Any] | None:
        """Get device basic status."""
        lock_raw_data = await self._get_lock_info()
        if not lock_raw_data:
            return None

        basic_data = await self._get_basic_info()
        if not basic_data:
            return None

        return self._parse_lock_data(lock_raw_data[1:]) | self._parse_basic_data(
            basic_data
        )

    def is_calibrated(self) -> Any:
        """Return True if lock is calibrated."""
        return self._get_adv_value("calibration")

    def get_lock_status(self) -> LockStatus:
        """Return lock status."""
        return self._get_adv_value("status")

    def is_door_open(self) -> bool:
        """Return True if door is open."""
        return self._get_adv_value("door_open")

    def is_unclosed_alarm_on(self) -> bool:
        """Return True if unclosed door alarm is on."""
        return self._get_adv_value("unclosed_alarm")

    def is_unlocked_alarm_on(self) -> bool:
        """Return True if lock unlocked alarm is on."""
        return self._get_adv_value("unlocked_alarm")

    def is_auto_lock_paused(self) -> bool:
        """Return True if auto lock is paused."""
        return self._get_adv_value("auto_lock_paused")

    async def _get_lock_info(self) -> bytes | None:
        """Return lock info of device."""
        _data = await self._send_command(key=COMMAND_LOCK_INFO, retry=self._retry_count)

        if not self._check_command_result(_data, 0, COMMAND_RESULT_EXPECTED_VALUES):
            _LOGGER.error("Unsuccessful, please try again")
            return None

        return _data

    async def _enable_notifications(self) -> bool:
        if self._notifications_enabled:
            return True
        result = await self._send_command(COMMAND_ENABLE_NOTIFICATIONS)
        if self._check_command_result(result, 0, COMMAND_RESULT_EXPECTED_VALUES):
            self._notifications_enabled = True
        return self._notifications_enabled

    async def _disable_notifications(self) -> bool:
        if not self._notifications_enabled:
            return True
        result = await self._send_command(COMMAND_DISABLE_NOTIFICATIONS)
        if self._check_command_result(result, 0, COMMAND_RESULT_EXPECTED_VALUES):
            self._notifications_enabled = False
        return not self._notifications_enabled

    def _notification_handler(self, _sender: int, data: bytearray) -> None:
        if self._notifications_enabled and self._check_command_result(data, 0, {0xF}):
            self._update_lock_status(data)
        else:
            super()._notification_handler(_sender, data)

    def _update_lock_status(self, data: bytearray) -> None:
        lock_data = self._parse_lock_data(self._decrypt(data[4:]))
        if self._update_parsed_data(lock_data):
            # We leave notifications enabled in case
            # the lock is operated manually before we
            # disconnect.
            self._reset_disconnect_timer()
            self._fire_callbacks()

    @staticmethod
    def _parse_lock_data(data: bytes) -> dict[str, Any]:
        return {
            "calibration": bool(data[0] & 0b10000000),
            "status": LockStatus((data[0] & 0b01110000) >> 4),
            "door_open": bool(data[0] & 0b00000100),
            "unclosed_alarm": bool(data[1] & 0b00100000),
            "unlocked_alarm": bool(data[1] & 0b00010000),
        }

    async def _send_command(
        self, key: str, retry: int | None = None, encrypt: bool = True
    ) -> bytes | None:
        if not encrypt:
            return await super()._send_command(key[:2] + "000000" + key[2:], retry)

        result = await self._ensure_encryption_initialized()
        if not result:
            _LOGGER.error("Failed to initialize encryption")
            return None

        encrypted = (
            key[:2] + self._key_id + self._iv[0:2].hex() + self._encrypt(key[2:])
        )
        result = await super()._send_command(encrypted, retry)
        return result[:1] + self._decrypt(result[4:])

    async def _ensure_encryption_initialized(self) -> bool:
        if self._iv is not None:
            return True

        result = await self._send_command(
            COMMAND_GET_CK_IV + self._key_id, encrypt=False
        )
        ok = self._check_command_result(result, 0, COMMAND_RESULT_EXPECTED_VALUES)
        if ok:
            self._iv = result[4:]

        return ok

    async def _execute_disconnect(self) -> None:
        await super()._execute_disconnect()
        self._iv = None
        self._cipher = None
        self._notifications_enabled = False

    def _get_cipher(self) -> Cipher:
        if self._cipher is None:
            self._cipher = Cipher(
                algorithms.AES128(self._encryption_key), modes.CTR(self._iv)
            )
        return self._cipher

    def _encrypt(self, data: str) -> str:
        if len(data) == 0:
            return ""
        encryptor = self._get_cipher().encryptor()
        return (encryptor.update(bytearray.fromhex(data)) + encryptor.finalize()).hex()

    def _decrypt(self, data: bytearray) -> bytes:
        if len(data) == 0:
            return b""
        decryptor = self._get_cipher().decryptor()
        return decryptor.update(data) + decryptor.finalize()