"""Shared pizone discovery lifecycle for iZone.

Lazy: ``create_discovery`` runs only when HomeKit discovery or user-initiated
setup needs it (then reused for config-entry ``create_controller``). Not started
from bare domain ``async_setup``.

The library 1.4 path does not run a scan loop; this module owns a slow shared
``discovery.scan()`` timer so new bridges still surface (parity with the old
~5 minute discovery broadcast).
"""

import asyncio
from collections.abc import Callable
from dataclasses import dataclass
from datetime import datetime
import logging

import pizone

from homeassistant import config_entries
from homeassistant.const import CONF_EXCLUDE, CONF_HOST, EVENT_HOMEASSISTANT_STOP
from homeassistant.core import Event, HomeAssistant, callback
from homeassistant.helpers import aiohttp_client, discovery_flow
from homeassistant.helpers.event import async_track_time_interval
from homeassistant.helpers.typing import ConfigType
from homeassistant.util.hass_dict import HassKey

from .const import DATA_CONFIG, DISCOVERY_IDLE_SECONDS, DISCOVERY_SCAN_INTERVAL, DOMAIN

_LOGGER = logging.getLogger(__name__)


@dataclass(slots=True)
class DiscoveryRuntime:
    """HA-owned handles for a running pizone discovery service."""

    service: pizone.DiscoveryService
    unsub_scan: Callable[[], None]
    unsub_stop: Callable[[], None]
    cancel_idle_stop: Callable[[], None] | None = None


@dataclass(slots=True)
class DiscoveryServiceState:
    """Shared discovery slot stored in ``hass.data``.

    ``runtime`` is set while the service is running. ``starting`` is set while
    ``create_discovery`` is in flight so concurrent ensure callers share one
    Future (same idea as ``helpers.singleton``). That covers the common case
    (startup / several callers hitting ensure together). Stop pops the slot then
    awaits ``close()``; a concurrent ensure during that await is possible but
    unlikely (idle-stop overlapping a new discovery). Serializing that
    open-during-close edge is left for a follow-up if needed.
    """

    runtime: DiscoveryRuntime | None = None
    starting: asyncio.Future[pizone.DiscoveryService] | None = None


DATA_DISCOVERY_SERVICE: HassKey[DiscoveryServiceState] = HassKey("izone_discovery")


def yaml_excluded_uids(hass: HomeAssistant) -> set[str]:
    """Return controller UIDs listed in deprecated YAML ``exclude``."""
    conf: ConfigType | None = hass.data.get(DATA_CONFIG)
    if not conf:
        return set()
    return set(conf.get(CONF_EXCLUDE, ()))


@callback
def async_note_integration_discovery(
    hass: HomeAssistant, endpoint: pizone.ControllerEndpoint
) -> None:
    """Start a config flow when discovery reports an unclaimed endpoint."""
    if endpoint.uid in yaml_excluded_uids(hass):
        return
    if _async_blocks_runtime_integration_discovery(hass):
        return
    discovery_flow.async_create_flow(
        hass,
        DOMAIN,
        context={
            "source": config_entries.SOURCE_INTEGRATION_DISCOVERY,
            "unique_id": endpoint.uid,
        },
        data={CONF_HOST: endpoint.host},
    )


@callback
def _async_blocks_runtime_integration_discovery(hass: HomeAssistant) -> bool:
    """Return True when an interactive setup flow should own the UI."""
    for flw in hass.config_entries.flow.async_progress_by_handler(
        DOMAIN, include_uninitialized=True
    ):
        src = flw["context"].get("source")
        if src == config_entries.SOURCE_USER:
            return True
    return False


@callback
def async_schedule_idle_stop(hass: HomeAssistant) -> None:
    """Schedule a delayed shutdown check for the shared discovery service."""
    state = hass.data.get(DATA_DISCOVERY_SERVICE)
    if state is None or state.runtime is None:
        return

    runtime = state.runtime
    if runtime.cancel_idle_stop is not None:
        runtime.cancel_idle_stop()

    def _fire_idle_stop() -> None:
        runtime.cancel_idle_stop = None
        hass.async_create_task(async_maybe_stop_discovery(hass))

    runtime.cancel_idle_stop = hass.loop.call_later(
        DISCOVERY_IDLE_SECONDS, _fire_idle_stop
    ).cancel


async def async_ensure_discovery(hass: HomeAssistant) -> pizone.DiscoveryService:
    """Create and start the shared discovery service if needed.

    Call from HomeKit / user-initiated setup (and later from entry setup for
    ``create_controller``). Do not call from bare domain ``async_setup``.

    Concurrent callers share one create via ``DiscoveryServiceState.starting``.

    Raises:
        OSError: Discovery UDP socket could not be bound.
        RuntimeError: A process-global discovery service already exists outside
            this Home Assistant instance's tracking.
    """
    state = hass.data.get(DATA_DISCOVERY_SERVICE)
    if state is not None and state.runtime is not None:
        return state.runtime.service

    if state is not None and state.starting is not None:
        return await state.starting

    starting: asyncio.Future[pizone.DiscoveryService] = hass.loop.create_future()
    state = DiscoveryServiceState(starting=starting)
    hass.data[DATA_DISCOVERY_SERVICE] = state
    _LOGGER.debug("Starting iZone discovery service")

    @callback
    def _on_endpoint_discovered(
        endpoint: pizone.ControllerEndpoint,
    ) -> None:
        async_note_integration_discovery(hass, endpoint)
        async_schedule_idle_stop(hass)

    session = aiohttp_client.async_get_clientsession(hass)
    try:
        service = await pizone.create_discovery(
            on_endpoint_discovered=_on_endpoint_discovered,
            session=session,
        )
    except BaseException as err:
        if hass.data.get(DATA_DISCOVERY_SERVICE) is state:
            hass.data.pop(DATA_DISCOVERY_SERVICE, None)
        if not starting.done():
            starting.set_exception(err)
            # Mark retrieved so an un-awaited failure does not log loudly.
            starting.exception()
        raise

    # Stopped while create was in flight — discard the orphaned service.
    if starting.done():
        await service.close()
        return await starting

    async def _async_scan(_now: datetime | None = None) -> None:
        try:
            await service.scan()
        except ConnectionError:
            _LOGGER.debug("iZone discovery scan skipped; transport not ready")

    unsub_scan = async_track_time_interval(
        hass, _async_scan, DISCOVERY_SCAN_INTERVAL, cancel_on_shutdown=True
    )

    async def _async_stop_on_shutdown(_event: Event) -> None:
        # listen_once removes itself before this runs; avoid a second unsub.
        if slot := hass.data.get(DATA_DISCOVERY_SERVICE):
            if slot.runtime is not None:
                slot.runtime.unsub_stop = lambda: None
        await async_stop_discovery(hass)

    unsub_stop = hass.bus.async_listen_once(
        EVENT_HOMEASSISTANT_STOP, _async_stop_on_shutdown
    )

    state.runtime = DiscoveryRuntime(
        service=service,
        unsub_scan=unsub_scan,
        unsub_stop=unsub_stop,
    )
    state.starting = None
    starting.set_result(service)

    # Initial broadcast — 1.4 create_discovery binds :7005 but does not scan.
    await _async_scan()
    async_schedule_idle_stop(hass)
    return service


async def async_discover_all_endpoints(
    hass: HomeAssistant,
) -> dict[str, pizone.ControllerEndpoint]:
    """Scan and return all verified endpoints for user / HomeKit setup.

    Starts shared discovery if needed.

    Raises:
        OSError: Discovery UDP socket could not be bound.
    """
    service = await async_ensure_discovery(hass)
    return {endpoint.uid: endpoint for endpoint in await service.discover_all()}


async def async_discover_endpoint(
    hass: HomeAssistant, uid: str
) -> pizone.ControllerEndpoint | None:
    """Resolve one endpoint by UID for confirm / targeted HomeKit lookup.

    Starts shared discovery if needed. Uses cache when the UID is already known.

    Raises:
        OSError: Discovery UDP socket could not be bound.
    """
    service = await async_ensure_discovery(hass)
    return await service.discover_by_uid(uid)


async def async_maybe_stop_discovery(hass: HomeAssistant) -> None:
    """Stop discovery when nothing actionable remains.

    Keeps the UDP listener while any entry is loaded, mid-setup, or in
    ``SETUP_RETRY``, or while an actionable config flow is in progress.
    """
    if DATA_DISCOVERY_SERVICE not in hass.data:
        return

    if (
        hass.config_entries.async_loaded_entries(DOMAIN)
        or any(
            entry.state
            in (
                config_entries.ConfigEntryState.SETUP_IN_PROGRESS,
                config_entries.ConfigEntryState.SETUP_RETRY,
            )
            for entry in hass.config_entries.async_entries(DOMAIN)
        )
        or any(
            flow["context"].get("source") != config_entries.SOURCE_IGNORE
            for flow in hass.config_entries.flow.async_progress_by_handler(
                DOMAIN, include_uninitialized=True
            )
        )
    ):
        async_schedule_idle_stop(hass)
        return

    await async_stop_discovery(hass)


async def async_stop_discovery(hass: HomeAssistant) -> None:
    """Stop the shared discovery service and clear HA tracking."""
    state = hass.data.pop(DATA_DISCOVERY_SERVICE, None)
    if state is None:
        return

    if state.starting is not None and not state.starting.done():
        state.starting.set_exception(
            RuntimeError("iZone discovery stopped before start completed")
        )
        state.starting.exception()

    if state.runtime is None:
        return

    runtime = state.runtime
    if runtime.cancel_idle_stop is not None:
        runtime.cancel_idle_stop()
        runtime.cancel_idle_stop = None

    runtime.unsub_scan()
    runtime.unsub_stop()
    await runtime.service.close()
    _LOGGER.debug("Stopped iZone discovery service")