"""
Support for Nest Thermostat Sensors.

For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/sensor.nest/
"""
import logging

from homeassistant.components.nest import DATA_NEST, NestSensorDevice
from homeassistant.const import (
    TEMP_CELSIUS, TEMP_FAHRENHEIT, CONF_MONITORED_CONDITIONS,
    DEVICE_CLASS_TEMPERATURE, DEVICE_CLASS_HUMIDITY)

DEPENDENCIES = ['nest']

SENSOR_TYPES = ['humidity', 'operation_mode', 'hvac_state']

TEMP_SENSOR_TYPES = ['temperature', 'target']

PROTECT_SENSOR_TYPES = ['co_status', 'smoke_status', 'battery_health']

STRUCTURE_SENSOR_TYPES = ['eta']

_VALID_SENSOR_TYPES = SENSOR_TYPES + TEMP_SENSOR_TYPES + PROTECT_SENSOR_TYPES \
                      + STRUCTURE_SENSOR_TYPES

SENSOR_UNITS = {'humidity': '%'}

SENSOR_DEVICE_CLASSES = {'humidity': DEVICE_CLASS_HUMIDITY}

VARIABLE_NAME_MAPPING = {'eta': 'eta_begin', 'operation_mode': 'mode'}

SENSOR_TYPES_DEPRECATED = ['last_ip',
                           'local_ip',
                           'last_connection',
                           'battery_level']

DEPRECATED_WEATHER_VARS = ['weather_humidity',
                           'weather_temperature',
                           'weather_condition',
                           'wind_speed',
                           'wind_direction']

_SENSOR_TYPES_DEPRECATED = SENSOR_TYPES_DEPRECATED + DEPRECATED_WEATHER_VARS

_LOGGER = logging.getLogger(__name__)


def setup_platform(hass, config, add_devices, discovery_info=None):
    """Set up the Nest Sensor."""
    if discovery_info is None:
        return

    nest = hass.data[DATA_NEST]

    # Add all available sensors if no Nest sensor config is set
    if discovery_info == {}:
        conditions = _VALID_SENSOR_TYPES
    else:
        conditions = discovery_info.get(CONF_MONITORED_CONDITIONS, {})

    for variable in conditions:
        if variable in _SENSOR_TYPES_DEPRECATED:
            if variable in DEPRECATED_WEATHER_VARS:
                wstr = ("Nest no longer provides weather data like %s. See "
                        "https://home-assistant.io/components/#weather "
                        "for a list of other weather components to use." %
                        variable)
            else:
                wstr = (variable + " is no a longer supported "
                        "monitored_conditions. See "
                        "https://home-assistant.io/components/"
                        "binary_sensor.nest/ for valid options.")
            _LOGGER.error(wstr)

    all_sensors = []
    for structure in nest.structures():
        all_sensors += [NestBasicSensor(structure, None, variable)
                        for variable in conditions
                        if variable in STRUCTURE_SENSOR_TYPES]

    for structure, device in nest.thermostats():
        all_sensors += [NestBasicSensor(structure, device, variable)
                        for variable in conditions
                        if variable in SENSOR_TYPES]
        all_sensors += [NestTempSensor(structure, device, variable)
                        for variable in conditions
                        if variable in TEMP_SENSOR_TYPES]

    for structure, device in nest.smoke_co_alarms():
        all_sensors += [NestBasicSensor(structure, device, variable)
                        for variable in conditions
                        if variable in PROTECT_SENSOR_TYPES]

    add_devices(all_sensors, True)


class NestBasicSensor(NestSensorDevice):
    """Representation a basic Nest sensor."""

    @property
    def state(self):
        """Return the state of the sensor."""
        return self._state

    @property
    def device_class(self):
        """Return the device class of the sensor."""
        return SENSOR_DEVICE_CLASSES.get(self.variable)

    def update(self):
        """Retrieve latest state."""
        self._unit = SENSOR_UNITS.get(self.variable)

        if self.variable in VARIABLE_NAME_MAPPING:
            self._state = getattr(self.device,
                                  VARIABLE_NAME_MAPPING[self.variable])
        elif self.variable in PROTECT_SENSOR_TYPES:
            # keep backward compatibility
            self._state = getattr(self.device, self.variable).capitalize()
        else:
            self._state = getattr(self.device, self.variable)


class NestTempSensor(NestSensorDevice):
    """Representation of a Nest Temperature sensor."""

    @property
    def state(self):
        """Return the state of the sensor."""
        return self._state

    @property
    def device_class(self):
        """Return the device class of the sensor."""
        return DEVICE_CLASS_TEMPERATURE

    def update(self):
        """Retrieve latest state."""
        if self.device.temperature_scale == 'C':
            self._unit = TEMP_CELSIUS
        else:
            self._unit = TEMP_FAHRENHEIT

        temp = getattr(self.device, self.variable)
        if temp is None:
            self._state = None

        if isinstance(temp, tuple):
            low, high = temp
            self._state = "%s-%s" % (int(low), int(high))
        else:
            self._state = round(temp, 1)