"""Config flow to configure homekit_controller."""
from __future__ import annotations

import logging
import re
from typing import Any

import aiohomekit
from aiohomekit.exceptions import AuthenticationError
from aiohomekit.model import Accessories, CharacteristicsTypes, ServicesTypes
import voluptuous as vol

from homeassistant import config_entries
from homeassistant.components import zeroconf
from homeassistant.core import callback
from homeassistant.data_entry_flow import AbortFlow, FlowResult
from homeassistant.helpers.device_registry import (
    CONNECTION_NETWORK_MAC,
    async_get_registry as async_get_device_registry,
)

from .const import DOMAIN, KNOWN_DEVICES
from .utils import async_get_controller

HOMEKIT_DIR = ".homekit"
HOMEKIT_BRIDGE_DOMAIN = "homekit"

HOMEKIT_IGNORE = [
    # eufy Indoor Cam 2K and 2K Pan & Tilt
    # https://github.com/home-assistant/core/issues/42307
    "T8400",
    "T8410",
    # Hive Hub - vendor does not give user a pairing code
    "HHKBridge1,1",
]

PAIRING_FILE = "pairing.json"

PIN_FORMAT = re.compile(r"^(\d{3})-{0,1}(\d{2})-{0,1}(\d{3})$")

_LOGGER = logging.getLogger(__name__)


INSECURE_CODES = {
    "00000000",
    "11111111",
    "22222222",
    "33333333",
    "44444444",
    "55555555",
    "66666666",
    "77777777",
    "88888888",
    "99999999",
    "12345678",
    "87654321",
}


def normalize_hkid(hkid: str) -> str:
    """Normalize a hkid so that it is safe to compare with other normalized hkids."""
    return hkid.lower()


@callback
def find_existing_host(hass, serial: str) -> config_entries.ConfigEntry | None:
    """Return a set of the configured hosts."""
    for entry in hass.config_entries.async_entries(DOMAIN):
        if entry.data.get("AccessoryPairingID") == serial:
            return entry
    return None


def ensure_pin_format(pin: str, allow_insecure_setup_codes: Any = None) -> str:
    """
    Ensure a pin code is correctly formatted.

    Ensures a pin code is in the format 111-11-111. Handles codes with and without dashes.

    If incorrect code is entered, an exception is raised.
    """
    if not (match := PIN_FORMAT.search(pin.strip())):
        raise aiohomekit.exceptions.MalformedPinError(f"Invalid PIN code f{pin}")
    pin_without_dashes = "".join(match.groups())
    if not allow_insecure_setup_codes and pin_without_dashes in INSECURE_CODES:
        raise InsecureSetupCode(f"Invalid PIN code f{pin}")
    return "-".join(match.groups())


class HomekitControllerFlowHandler(config_entries.ConfigFlow, domain=DOMAIN):
    """Handle a HomeKit config flow."""

    VERSION = 1

    def __init__(self):
        """Initialize the homekit_controller flow."""
        self.model = None
        self.hkid = None
        self.name = None
        self.devices = {}
        self.controller = None
        self.finish_pairing = None

    async def _async_setup_controller(self):
        """Create the controller."""
        self.controller = await async_get_controller(self.hass)

    async def async_step_user(self, user_input=None):
        """Handle a flow start."""
        errors = {}

        if user_input is not None:
            key = user_input["device"]
            self.hkid = self.devices[key].description.id
            self.model = self.devices[key].description.model
            self.name = self.devices[key].description.name

            await self.async_set_unique_id(
                normalize_hkid(self.hkid), raise_on_progress=False
            )

            return await self.async_step_pair()

        if self.controller is None:
            await self._async_setup_controller()

        self.devices = {}

        async for discovery in self.controller.async_discover():
            if discovery.paired:
                continue
            self.devices[discovery.description.name] = discovery

        if not self.devices:
            return self.async_abort(reason="no_devices")

        return self.async_show_form(
            step_id="user",
            errors=errors,
            data_schema=vol.Schema(
                {vol.Required("device"): vol.In(self.devices.keys())}
            ),
        )

    async def async_step_unignore(self, user_input):
        """Rediscover a previously ignored discover."""
        unique_id = user_input["unique_id"]
        await self.async_set_unique_id(unique_id)

        if self.controller is None:
            await self._async_setup_controller()

        try:
            device = await self.controller.async_find(unique_id)
        except aiohomekit.AccessoryNotFoundError:
            return self.async_abort(reason="accessory_not_found_error")

        self.name = device.description.name
        self.model = device.description.model
        self.hkid = device.description.id

        return self._async_step_pair_show_form()

    async def _hkid_is_homekit(self, hkid):
        """Determine if the device is a homekit bridge or accessory."""
        dev_reg = await async_get_device_registry(self.hass)
        device = dev_reg.async_get_device(
            identifiers=set(), connections={(CONNECTION_NETWORK_MAC, hkid)}
        )

        if device is None:
            return False

        for entry_id in device.config_entries:
            entry = self.hass.config_entries.async_get_entry(entry_id)
            if entry and entry.domain == HOMEKIT_BRIDGE_DOMAIN:
                return True

        return False

    async def async_step_zeroconf(
        self, discovery_info: zeroconf.ZeroconfServiceInfo
    ) -> FlowResult:
        """Handle a discovered HomeKit accessory.

        This flow is triggered by the discovery component.
        """
        # Normalize properties from discovery
        # homekit_python has code to do this, but not in a form we can
        # easily use, so do the bare minimum ourselves here instead.
        properties = {
            key.lower(): value for (key, value) in discovery_info.properties.items()
        }

        if zeroconf.ATTR_PROPERTIES_ID not in properties:
            # This can happen if the TXT record is received after the PTR record
            # we will wait for the next update in this case
            _LOGGER.debug(
                "HomeKit device %s: id not exposed; TXT record may have not yet been received",
                properties,
            )
            return self.async_abort(reason="invalid_properties")

        # The hkid is a unique random number that looks like a pairing code.
        # It changes if a device is factory reset.
        hkid = properties[zeroconf.ATTR_PROPERTIES_ID]
        normalized_hkid = normalize_hkid(hkid)

        model = properties["md"]
        name = discovery_info.name.replace("._hap._tcp.local.", "")
        status_flags = int(properties["sf"])
        paired = not status_flags & 0x01

        # The configuration number increases every time the characteristic map
        # needs updating. Some devices use a slightly off-spec name so handle
        # both cases.
        try:
            config_num = int(properties["c#"])
        except KeyError:
            _LOGGER.warning(
                "HomeKit device %s: c# not exposed, in violation of spec", hkid
            )
            config_num = None

        # Set unique-id and error out if it's already configured
        existing_entry = await self.async_set_unique_id(
            normalized_hkid, raise_on_progress=False
        )
        updated_ip_port = {
            "AccessoryIP": discovery_info.host,
            "AccessoryPort": discovery_info.port,
        }

        # If the device is already paired and known to us we should monitor c#
        # (config_num) for changes. If it changes, we check for new entities
        if paired and hkid in self.hass.data.get(KNOWN_DEVICES, {}):
            if existing_entry:
                self.hass.config_entries.async_update_entry(
                    existing_entry, data={**existing_entry.data, **updated_ip_port}
                )
            conn = self.hass.data[KNOWN_DEVICES][hkid]
            # When we rediscover the device, let aiohomekit know
            # that the device is available and we should not wait
            # to retry connecting any longer. reconnect_soon
            # will do nothing if the device is already connected
            await conn.pairing.connection.reconnect_soon()
            if conn.config_num != config_num:
                _LOGGER.debug(
                    "HomeKit info %s: c# incremented, refreshing entities", hkid
                )
                self.hass.async_create_task(conn.async_refresh_entity_map(config_num))
            return self.async_abort(reason="already_configured")

        _LOGGER.debug("Discovered device %s (%s - %s)", name, model, hkid)

        # Device isn't paired with us or anyone else.
        # But we have a 'complete' config entry for it - that is probably
        # invalid. Remove it automatically.
        existing = find_existing_host(self.hass, hkid)
        if not paired and existing:
            if self.controller is None:
                await self._async_setup_controller()

            # mypy can't see that self._async_setup_controller() always sets self.controller or throws
            assert self.controller

            pairing = self.controller.load_pairing(
                existing.data["AccessoryPairingID"], dict(existing.data)
            )

            try:
                await pairing.list_accessories_and_characteristics()
            except AuthenticationError:
                _LOGGER.debug(
                    "%s (%s - %s) is unpaired. Removing invalid pairing for this device",
                    name,
                    model,
                    hkid,
                )
                await self.hass.config_entries.async_remove(existing.entry_id)
            else:
                _LOGGER.debug(
                    "%s (%s - %s) claims to be unpaired but isn't. "
                    "It's implementation of HomeKit is defective "
                    "or a zeroconf relay is broadcasting stale data",
                    name,
                    model,
                    hkid,
                )
                return self.async_abort(reason="already_paired")

        # Set unique-id and error out if it's already configured
        self._abort_if_unique_id_configured(updates=updated_ip_port)

        for progress in self._async_in_progress(include_uninitialized=True):
            context = progress["context"]
            if context.get("unique_id") == normalized_hkid and not context.get(
                "pairing"
            ):
                if paired:
                    # If the device gets paired, we want to dismiss
                    # an existing discovery since we can no longer
                    # pair with it
                    self.hass.config_entries.flow.async_abort(progress["flow_id"])
                else:
                    raise AbortFlow("already_in_progress")

        if paired:
            # Device is paired but not to us - ignore it
            _LOGGER.debug("HomeKit device %s ignored as already paired", hkid)
            return self.async_abort(reason="already_paired")

        # Devices in HOMEKIT_IGNORE have native local integrations - users
        # should be encouraged to use native integration and not confused
        # by alternative HK API.
        if model in HOMEKIT_IGNORE:
            return self.async_abort(reason="ignored_model")

        # If this is a HomeKit bridge/accessory exported by *this* HA instance ignore it.
        if await self._hkid_is_homekit(hkid):
            return self.async_abort(reason="ignored_model")

        self.name = name
        self.model = model
        self.hkid = hkid

        # We want to show the pairing form - but don't call async_step_pair
        # directly as it has side effects (will ask the device to show a
        # pairing code)
        return self._async_step_pair_show_form()

    async def async_step_pair(self, pair_info=None):
        """Pair with a new HomeKit accessory."""
        # If async_step_pair is called with no pairing code then we do the M1
        # phase of pairing. If this is successful the device enters pairing
        # mode.

        # If it doesn't have a screen then the pin is static.

        # If it has a display it will display a pin on that display. In
        # this case the code is random. So we have to call the async_start_pairing
        # API before the user can enter a pin. But equally we don't want to
        # call async_start_pairing when the device is discovered, only when they
        # click on 'Configure' in the UI.

        # async_start_pairing will make the device show its pin and return a
        # callable. We call the callable with the pin that the user has typed
        # in.

        errors = {}

        if self.controller is None:
            await self._async_setup_controller()

        if pair_info and self.finish_pairing:
            self.context["pairing"] = True
            code = pair_info["pairing_code"]
            try:
                code = ensure_pin_format(
                    code,
                    allow_insecure_setup_codes=pair_info.get(
                        "allow_insecure_setup_codes"
                    ),
                )
                pairing = await self.finish_pairing(code)
                return await self._entry_from_accessory(pairing)
            except aiohomekit.exceptions.MalformedPinError:
                # Library claimed pin was invalid before even making an API call
                errors["pairing_code"] = "authentication_error"
            except aiohomekit.AuthenticationError:
                # PairSetup M4 - SRP proof failed
                # PairSetup M6 - Ed25519 signature verification failed
                # PairVerify M4 - Decryption failed
                # PairVerify M4 - Device not recognised
                # PairVerify M4 - Ed25519 signature verification failed
                errors["pairing_code"] = "authentication_error"
                self.finish_pairing = None
            except aiohomekit.UnknownError:
                # An error occurred on the device whilst performing this
                # operation.
                errors["pairing_code"] = "unknown_error"
                self.finish_pairing = None
            except aiohomekit.MaxPeersError:
                # The device can't pair with any more accessories.
                errors["pairing_code"] = "max_peers_error"
                self.finish_pairing = None
            except aiohomekit.AccessoryNotFoundError:
                # Can no longer find the device on the network
                return self.async_abort(reason="accessory_not_found_error")
            except InsecureSetupCode:
                errors["pairing_code"] = "insecure_setup_code"
            except Exception:  # pylint: disable=broad-except
                _LOGGER.exception("Pairing attempt failed with an unhandled exception")
                self.finish_pairing = None
                errors["pairing_code"] = "pairing_failed"

        if not self.finish_pairing:
            # Its possible that the first try may have been busy so
            # we always check to see if self.finish_paring has been
            # set.
            try:
                discovery = await self.controller.async_find(self.hkid)
                self.finish_pairing = await discovery.async_start_pairing(self.hkid)

            except aiohomekit.BusyError:
                # Already performing a pair setup operation with a different
                # controller
                return await self.async_step_busy_error()
            except aiohomekit.MaxTriesError:
                # The accessory has received more than 100 unsuccessful auth
                # attempts.
                return await self.async_step_max_tries_error()
            except aiohomekit.UnavailableError:
                # The accessory is already paired - cannot try to pair again.
                return self.async_abort(reason="already_paired")
            except aiohomekit.AccessoryNotFoundError:
                # Can no longer find the device on the network
                return self.async_abort(reason="accessory_not_found_error")
            except IndexError:
                # TLV error, usually not in pairing mode
                _LOGGER.exception("Pairing communication failed")
                return await self.async_step_protocol_error()
            except Exception:  # pylint: disable=broad-except
                _LOGGER.exception("Pairing attempt failed with an unhandled exception")
                errors["pairing_code"] = "pairing_failed"

        return self._async_step_pair_show_form(errors)

    async def async_step_busy_error(self, user_input=None):
        """Retry pairing after the accessory is busy."""
        if user_input is not None:
            return await self.async_step_pair()

        return self.async_show_form(step_id="busy_error")

    async def async_step_max_tries_error(self, user_input=None):
        """Retry pairing after the accessory has reached max tries."""
        if user_input is not None:
            return await self.async_step_pair()

        return self.async_show_form(step_id="max_tries_error")

    async def async_step_protocol_error(self, user_input=None):
        """Retry pairing after the accessory has a protocol error."""
        if user_input is not None:
            return await self.async_step_pair()

        return self.async_show_form(step_id="protocol_error")

    @callback
    def _async_step_pair_show_form(self, errors=None):
        placeholders = {"name": self.name}
        self.context["title_placeholders"] = {"name": self.name}

        schema = {vol.Required("pairing_code"): vol.All(str, vol.Strip)}
        if errors and errors.get("pairing_code") == "insecure_setup_code":
            schema[vol.Optional("allow_insecure_setup_codes")] = bool

        return self.async_show_form(
            step_id="pair",
            errors=errors or {},
            description_placeholders=placeholders,
            data_schema=vol.Schema(schema),
        )

    async def _entry_from_accessory(self, pairing):
        """Return a config entry from an initialized bridge."""
        # The bulk of the pairing record is stored on the config entry.
        # A specific exception is the 'accessories' key. This is more
        # volatile. We do cache it, but not against the config entry.
        # So copy the pairing data and mutate the copy.
        pairing_data = pairing.pairing_data.copy()

        # Use the accessories data from the pairing operation if it is
        # available. Otherwise request a fresh copy from the API.
        # This removes the 'accessories' key from pairing_data at
        # the same time.
        if not (accessories := pairing_data.pop("accessories", None)):
            accessories = await pairing.list_accessories_and_characteristics()

        parsed = Accessories.from_list(accessories)
        accessory_info = parsed.aid(1).services.first(
            service_type=ServicesTypes.ACCESSORY_INFORMATION
        )
        name = accessory_info.value(CharacteristicsTypes.NAME, "")

        return self.async_create_entry(title=name, data=pairing_data)


class InsecureSetupCode(Exception):
    """An exception for insecure trivial setup codes."""
