"""Diagnosewerte eines ninstrip."""

from __future__ import annotations

from collections.abc import Callable
from dataclasses import dataclass
from datetime import datetime, timedelta
from typing import Any

from homeassistant.components.sensor import (
    SensorDeviceClass,
    SensorEntity,
    SensorEntityDescription,
    SensorStateClass,
)
from homeassistant.const import (
    SIGNAL_STRENGTH_DECIBELS_MILLIWATT,
    EntityCategory,
    UnitOfElectricCurrent,
    UnitOfInformation,
    UnitOfPower,
    UnitOfTime,
)
from homeassistant.core import HomeAssistant, callback
from homeassistant.helpers.entity_platform import AddConfigEntryEntitiesCallback
from homeassistant.util import dt as dt_util

from .coordinator import NinstripConfigEntry, NinstripCoordinator, NinstripData
from .entity import NinstripEntity

# Die Laufzeit springt bei jeder Abfrage um ein paar Sekunden; daraus eine
# Startzeit zu rechnen ergaebe sonst dauernd einen neuen Zeitstempel. Wie
# ha-ninlight.
BOOT_TIME_TOLERANCE = timedelta(seconds=30)


@dataclass(frozen=True, kw_only=True)
class NinstripSensorDescription(SensorEntityDescription):
    """Beschreibung samt Zugriff auf den Wert."""

    value: Callable[[NinstripData], Any]


def _wifi(data: NinstripData, key: str) -> Any:
    wifi = data.info.get("wifi")
    return wifi.get(key) if isinstance(wifi, dict) else None


def _strip(data: NinstripData, key: str) -> Any:
    strip = data.info.get("strip")
    return strip.get(key) if isinstance(strip, dict) else None


SENSORS: tuple[NinstripSensorDescription, ...] = (
    # Von Haus aus an: die Adresse ist das, was man im Alltag sucht - fuer die
    # Firmware-API, zum Anpingen oder um ein Geraet wiederzufinden. Wie in
    # ha-ninlight.
    NinstripSensorDescription(
        key="ip_address",
        translation_key="ip_address",
        entity_category=EntityCategory.DIAGNOSTIC,
        value=lambda d: _wifi(d, "ip"),
    ),
    NinstripSensorDescription(
        key="rssi",
        translation_key="rssi",
        device_class=SensorDeviceClass.SIGNAL_STRENGTH,
        native_unit_of_measurement=SIGNAL_STRENGTH_DECIBELS_MILLIWATT,
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        entity_registry_enabled_default=False,
        value=lambda d: _wifi(d, "rssi"),
    ),
    NinstripSensorDescription(
        key="uptime",
        translation_key="uptime",
        native_unit_of_measurement=UnitOfTime.SECONDS,
        device_class=SensorDeviceClass.DURATION,
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        entity_registry_enabled_default=False,
        value=lambda d: d.info.get("uptime"),
    ),
    NinstripSensorDescription(
        key="free_heap",
        translation_key="free_heap",
        native_unit_of_measurement=UnitOfInformation.BYTES,
        device_class=SensorDeviceClass.DATA_SIZE,
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        entity_registry_enabled_default=False,
        value=lambda d: d.info.get("free_heap"),
    ),
    # Sagt, ob die Strombegrenzung gerade herunterregelt. 100 heisst: nein.
    NinstripSensorDescription(
        key="power_scale",
        translation_key="power_scale",
        native_unit_of_measurement="%",
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        value=lambda d: _strip(d, "power_scale"),
    ),
    # 0 mA heisst entweder "zieht gerade nichts" oder "misst gar nicht" -
    # aeltere Firmware ohne Shunt meldet ebenfalls 0. Von aussen nicht zu
    # unterscheiden, und keine Heuristik dagegen: Schwaeche der Geraete-API.
    NinstripSensorDescription(
        key="current",
        translation_key="current",
        device_class=SensorDeviceClass.CURRENT,
        native_unit_of_measurement=UnitOfElectricCurrent.MILLIAMPERE,
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        value=lambda d: _strip(d, "current_ma"),
    ),
    NinstripSensorDescription(
        key="power",
        translation_key="power",
        device_class=SensorDeviceClass.POWER,
        native_unit_of_measurement=UnitOfPower.WATT,
        state_class=SensorStateClass.MEASUREMENT,
        entity_category=EntityCategory.DIAGNOSTIC,
        value=lambda d: _strip(d, "power_w"),
    ),
    # Was bei der letzten Aktualisierung schiefging - leer, solange nichts
    # schiefging. Aus der Ferne der einzige Hinweis darauf.
    NinstripSensorDescription(
        key="last_ota_error",
        translation_key="last_ota_error",
        entity_category=EntityCategory.DIAGNOSTIC,
        entity_registry_enabled_default=False,
        value=lambda d: d.info.get("last_ota_error"),
    ),
)


async def async_setup_entry(
    hass: HomeAssistant,
    entry: NinstripConfigEntry,
    async_add_entities: AddConfigEntryEntitiesCallback,
) -> None:
    coordinator = entry.runtime_data
    entitaeten: list[SensorEntity] = [NinstripSensor(coordinator, d) for d in SENSORS]
    entitaeten.append(NinstripBootTimeSensor(coordinator))
    async_add_entities(entitaeten)


class NinstripSensor(NinstripEntity, SensorEntity):
    entity_description: NinstripSensorDescription

    def __init__(
        self, coordinator: NinstripCoordinator, description: NinstripSensorDescription
    ) -> None:
        super().__init__(coordinator, description.key)
        self.entity_description = description

    @property
    def native_value(self) -> Any:
        return self.entity_description.value(self.coordinator.data)


class NinstripBootTimeSensor(NinstripEntity, SensorEntity):
    """Wann der Strip zuletzt gestartet ist - ein Zeitstempel statt einer
    Laufzeit, die jede Abfrage weiterlaeuft."""

    _attr_device_class = SensorDeviceClass.TIMESTAMP
    _attr_entity_category = EntityCategory.DIAGNOSTIC
    _attr_entity_registry_enabled_default = False
    _attr_translation_key = "boot_time"

    def __init__(self, coordinator: NinstripCoordinator) -> None:
        super().__init__(coordinator, "boot_time")
        self._boot: datetime | None = None
        self._boot_aktualisieren()

    def _boot_aktualisieren(self) -> None:
        uptime = self.coordinator.data.info.get("uptime")
        if not isinstance(uptime, (int, float)):
            return
        boot = dt_util.utcnow() - timedelta(seconds=uptime)
        # Nur uebernehmen, wenn er wirklich abweicht - sonst wandert der
        # Zeitstempel bei jeder Abfrage um die Messungenauigkeit.
        if self._boot is None or abs(boot - self._boot) > BOOT_TIME_TOLERANCE:
            self._boot = boot

    @callback
    def _handle_coordinator_update(self) -> None:
        self._boot_aktualisieren()
        super()._handle_coordinator_update()

    @property
    def native_value(self) -> datetime | None:
        return self._boot