"""Support for PCA 301 smart switch."""
import logging

import voluptuous as vol

from homeassistant.components.switch import (
    SwitchDevice, PLATFORM_SCHEMA, ATTR_CURRENT_POWER_W)
from homeassistant.const import (
    CONF_NAME, CONF_DEVICE, EVENT_HOMEASSISTANT_STOP)
import homeassistant.helpers.config_validation as cv

_LOGGER = logging.getLogger(__name__)

ATTR_TOTAL_ENERGY_KWH = 'total_energy_kwh'

DEFAULT_NAME = 'PCA 301'

PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
    vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
    vol.Required(CONF_DEVICE): cv.string
})


def setup_platform(hass, config, add_entities, discovery_info=None):
    """Set up the PCA switch platform."""
    import pypca
    from serial import SerialException

    name = config[CONF_NAME]
    usb_device = config[CONF_DEVICE]

    try:
        pca = pypca.PCA(usb_device)
        pca.open()
        entities = [SmartPlugSwitch(pca, device, name)
                    for device in pca.get_devices()]
        add_entities(entities, True)

    except SerialException as exc:
        _LOGGER.warning("Unable to open serial port: %s", exc)
        return

    hass.bus.listen_once(EVENT_HOMEASSISTANT_STOP, pca.close)

    pca.start_scan()


class SmartPlugSwitch(SwitchDevice):
    """Representation of a PCA Smart Plug switch."""

    def __init__(self, pca, device_id, name):
        """Initialize the switch."""
        self._device_id = device_id
        self._name = name
        self._state = None
        self._available = True
        self._emeter_params = {}
        self._pca = pca

    @property
    def name(self):
        """Return the name of the Smart Plug, if any."""
        return self._name

    @property
    def available(self) -> bool:
        """Return if switch is available."""
        return self._available

    @property
    def is_on(self):
        """Return true if switch is on."""
        return self._state

    def turn_on(self, **kwargs):
        """Turn the switch on."""
        self._pca.turn_on(self._device_id)

    def turn_off(self, **kwargs):
        """Turn the switch off."""
        self._pca.turn_off(self._device_id)

    @property
    def device_state_attributes(self):
        """Return the state attributes of the device."""
        return self._emeter_params

    def update(self):
        """Update the PCA switch's state."""
        try:
            self._emeter_params[ATTR_CURRENT_POWER_W] = "{:.1f}".format(
                self._pca.get_current_power(self._device_id))
            self._emeter_params[ATTR_TOTAL_ENERGY_KWH] = "{:.2f}".format(
                self._pca.get_total_consumption(self._device_id))

            self._available = True
            self._state = self._pca.get_state(self._device_id)

        except (OSError) as ex:
            if self._available:
                _LOGGER.warning(
                    "Could not read state for %s: %s", self.name, ex)
                self._available = False
