"""Support for UK Met Office weather service."""
from datetime import timedelta
import logging

import datapoint as dp
import voluptuous as vol

from homeassistant.components.sensor import PLATFORM_SCHEMA
from homeassistant.const import (
    ATTR_ATTRIBUTION,
    CONF_API_KEY,
    CONF_LATITUDE,
    CONF_LONGITUDE,
    CONF_MONITORED_CONDITIONS,
    CONF_NAME,
    TEMP_CELSIUS,
)
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.entity import Entity
from homeassistant.util import Throttle

_LOGGER = logging.getLogger(__name__)

ATTR_LAST_UPDATE = "last_update"
ATTR_SENSOR_ID = "sensor_id"
ATTR_SITE_ID = "site_id"
ATTR_SITE_NAME = "site_name"

ATTRIBUTION = "Data provided by the Met Office"

CONDITION_CLASSES = {
    "cloudy": ["7", "8"],
    "fog": ["5", "6"],
    "hail": ["19", "20", "21"],
    "lightning": ["30"],
    "lightning-rainy": ["28", "29"],
    "partlycloudy": ["2", "3"],
    "pouring": ["13", "14", "15"],
    "rainy": ["9", "10", "11", "12"],
    "snowy": ["22", "23", "24", "25", "26", "27"],
    "snowy-rainy": ["16", "17", "18"],
    "sunny": ["0", "1"],
    "windy": [],
    "windy-variant": [],
    "exceptional": [],
}

DEFAULT_NAME = "Met Office"

VISIBILITY_CLASSES = {
    "VP": "<1",
    "PO": "1-4",
    "MO": "4-10",
    "GO": "10-20",
    "VG": "20-40",
    "EX": ">40",
}

MIN_TIME_BETWEEN_UPDATES = timedelta(minutes=35)

# Sensor types are defined like: Name, units
SENSOR_TYPES = {
    "name": ["Station Name", None],
    "weather": ["Weather", None],
    "temperature": ["Temperature", TEMP_CELSIUS],
    "feels_like_temperature": ["Feels Like Temperature", TEMP_CELSIUS],
    "wind_speed": ["Wind Speed", "mph"],
    "wind_direction": ["Wind Direction", None],
    "wind_gust": ["Wind Gust", "mph"],
    "visibility": ["Visibility", None],
    "visibility_distance": ["Visibility Distance", "km"],
    "uv": ["UV", None],
    "precipitation": ["Probability of Precipitation", "%"],
    "humidity": ["Humidity", "%"],
}

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(
    {
        vol.Required(CONF_API_KEY): cv.string,
        vol.Required(CONF_MONITORED_CONDITIONS, default=[]): vol.All(
            cv.ensure_list, [vol.In(SENSOR_TYPES)]
        ),
        vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
        vol.Inclusive(
            CONF_LATITUDE, "coordinates", "Latitude and longitude must exist together"
        ): cv.latitude,
        vol.Inclusive(
            CONF_LONGITUDE, "coordinates", "Latitude and longitude must exist together"
        ): cv.longitude,
    }
)


def setup_platform(hass, config, add_entities, discovery_info=None):
    """Set up the Met Office sensor platform."""
    api_key = config.get(CONF_API_KEY)
    latitude = config.get(CONF_LATITUDE, hass.config.latitude)
    longitude = config.get(CONF_LONGITUDE, hass.config.longitude)
    name = config.get(CONF_NAME)

    datapoint = dp.connection(api_key=api_key)

    if None in (latitude, longitude):
        _LOGGER.error("Latitude or longitude not set in Home Assistant config")
        return

    try:
        site = datapoint.get_nearest_site(latitude=latitude, longitude=longitude)
    except dp.exceptions.APIException as err:
        _LOGGER.error("Received error from Met Office Datapoint: %s", err)
        return

    if not site:
        _LOGGER.error("Unable to get nearest Met Office forecast site")
        return

    data = MetOfficeCurrentData(hass, datapoint, site)
    data.update()
    if data.data is None:
        return

    sensors = []
    for variable in config[CONF_MONITORED_CONDITIONS]:
        sensors.append(MetOfficeCurrentSensor(site, data, variable, name))

    add_entities(sensors, True)


class MetOfficeCurrentSensor(Entity):
    """Implementation of a Met Office current sensor."""

    def __init__(self, site, data, condition, name):
        """Initialize the sensor."""
        self._condition = condition
        self.data = data
        self._name = name
        self.site = site

    @property
    def name(self):
        """Return the name of the sensor."""
        return "{} {}".format(self._name, SENSOR_TYPES[self._condition][0])

    @property
    def state(self):
        """Return the state of the sensor."""
        if self._condition == "visibility_distance" and hasattr(
            self.data.data, "visibility"
        ):
            return VISIBILITY_CLASSES.get(self.data.data.visibility.value)
        if hasattr(self.data.data, self._condition):
            variable = getattr(self.data.data, self._condition)
            if self._condition == "weather":
                return [
                    k
                    for k, v in CONDITION_CLASSES.items()
                    if self.data.data.weather.value in v
                ][0]
            return variable.value
        return None

    @property
    def unit_of_measurement(self):
        """Return the unit of measurement."""
        return SENSOR_TYPES[self._condition][1]

    @property
    def device_state_attributes(self):
        """Return the state attributes of the device."""
        attr = {}
        attr[ATTR_ATTRIBUTION] = ATTRIBUTION
        attr[ATTR_LAST_UPDATE] = self.data.data.date
        attr[ATTR_SENSOR_ID] = self._condition
        attr[ATTR_SITE_ID] = self.site.id
        attr[ATTR_SITE_NAME] = self.site.name
        return attr

    def update(self):
        """Update current conditions."""
        self.data.update()


class MetOfficeCurrentData:
    """Get data from Datapoint."""

    def __init__(self, hass, datapoint, site):
        """Initialize the data object."""
        self._datapoint = datapoint
        self._site = site
        self.data = None

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update(self):
        """Get the latest data from Datapoint."""
        try:
            forecast = self._datapoint.get_forecast_for_site(self._site.id, "3hourly")
            self.data = forecast.now()
        except (ValueError, dp.exceptions.APIException) as err:
            _LOGGER.error("Check Met Office %s", err.args)
            self.data = None
