"""Support for HTU21D temperature and humidity sensor."""
from __future__ import annotations

from datetime import timedelta
from functools import partial
import logging

from i2csense.htu21d import HTU21D  # pylint: disable=import-error
import smbus
import voluptuous as vol

from homeassistant.components.sensor import (
    PLATFORM_SCHEMA,
    SensorEntity,
    SensorEntityDescription,
)
from homeassistant.const import (
    CONF_NAME,
    DEVICE_CLASS_HUMIDITY,
    DEVICE_CLASS_TEMPERATURE,
    PERCENTAGE,
    TEMP_CELSIUS,
)
import homeassistant.helpers.config_validation as cv
from homeassistant.util import Throttle

_LOGGER = logging.getLogger(__name__)

CONF_I2C_BUS = "i2c_bus"
DEFAULT_I2C_BUS = 1

MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=5)

DEFAULT_NAME = "HTU21D Sensor"

SENSOR_TEMPERATURE = "temperature"
SENSOR_HUMIDITY = "humidity"

SENSOR_TYPES: tuple[SensorEntityDescription, ...] = (
    SensorEntityDescription(
        key=SENSOR_TEMPERATURE,
        native_unit_of_measurement=TEMP_CELSIUS,
        device_class=DEVICE_CLASS_TEMPERATURE,
    ),
    SensorEntityDescription(
        key=SENSOR_HUMIDITY,
        native_unit_of_measurement=PERCENTAGE,
        device_class=DEVICE_CLASS_HUMIDITY,
    ),
)

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
        vol.Optional(CONF_I2C_BUS, default=DEFAULT_I2C_BUS): vol.Coerce(int),
    }
)


async def async_setup_platform(hass, config, async_add_entities, discovery_info=None):
    """Set up the HTU21D sensor."""
    name = config.get(CONF_NAME)
    bus_number = config.get(CONF_I2C_BUS)

    bus = smbus.SMBus(config.get(CONF_I2C_BUS))
    sensor = await hass.async_add_executor_job(partial(HTU21D, bus, logger=_LOGGER))
    if not sensor.sample_ok:
        _LOGGER.error("HTU21D sensor not detected in bus %s", bus_number)
        return False

    sensor_handler = await hass.async_add_executor_job(HTU21DHandler, sensor)

    entities = [
        HTU21DSensor(sensor_handler, name, description) for description in SENSOR_TYPES
    ]

    async_add_entities(entities)


class HTU21DHandler:
    """Implement HTU21D communication."""

    def __init__(self, sensor):
        """Initialize the sensor handler."""
        self.sensor = sensor
        self.sensor.update()

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update(self):
        """Read raw data and calculate temperature and humidity."""
        self.sensor.update()


class HTU21DSensor(SensorEntity):
    """Implementation of the HTU21D sensor."""

    def __init__(self, htu21d_client, name, description: SensorEntityDescription):
        """Initialize the sensor."""
        self.entity_description = description
        self._client = htu21d_client

        self._attr_name = f"{name}_{description.key}"

    async def async_update(self):
        """Get the latest data from the HTU21D sensor and update the state."""
        await self.hass.async_add_executor_job(self._client.update)
        if self._client.sensor.sample_ok:
            if self.entity_description.key == SENSOR_TEMPERATURE:
                value = round(self._client.sensor.temperature, 1)
            else:
                value = round(self._client.sensor.humidity, 1)
            self._attr_native_value = value
        else:
            _LOGGER.warning("Bad sample")