"""
homeassistant.components.binary_sensor.command_sensor
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allows to configure custom shell commands to turn a value into a logical value for a binary sensor.
"""
import logging
import subprocess
from datetime import timedelta

from homeassistant.const import CONF_VALUE_TEMPLATE
from homeassistant.components.binary_sensor import BinarySensorDevice
from homeassistant.util import template, Throttle

_LOGGER = logging.getLogger(__name__)

DEFAULT_NAME = "Binary Command Sensor"
DEFAULT_PAYLOAD_ON = 'ON'
DEFAULT_PAYLOAD_OFF = 'OFF'

# Return cached results if last scan was less then this time ago
MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=60)


# pylint: disable=unused-argument
def setup_platform(hass, config, add_devices, discovery_info=None):
    """ Add the Command Sensor. """

    if config.get('command') is None:
        _LOGGER.error('Missing required variable: "command"')
        return False

    data = CommandSensorData(config.get('command'))

    add_devices([CommandBinarySensor(
        hass,
        data,
        config.get('name', DEFAULT_NAME),
        config.get('payload_on', DEFAULT_PAYLOAD_ON),
        config.get('payload_off', DEFAULT_PAYLOAD_OFF),
        config.get(CONF_VALUE_TEMPLATE)
    )])


# pylint: disable=too-many-arguments
class CommandBinarySensor(BinarySensorDevice):
    """ Represents a binary sensor that is returning a value of a shell commands. """
    def __init__(self, hass, data, name, payload_on, payload_off, value_template):
        self._hass = hass
        self.data = data
        self._name = name
        self._state = False
        self._payload_on = payload_on
        self._payload_off = payload_off
        self._value_template = value_template
        self.update()

    @property
    def name(self):
        """ The name of the sensor. """
        return self._name

    @property
    def is_on(self):
        """ True if the binary sensor is on. """
        return self._state

    def update(self):
        """ Gets the latest data and updates the state. """
        self.data.update()
        value = self.data.value

        if self._value_template is not None:
            value = template.render_with_possible_json_value(
                self._hass, self.value_template, value, False)
        if value == self._payload_on:
            self._state = True
        elif value == self._payload_off:
            self._state = False


# pylint: disable=too-few-public-methods
class CommandSensorData(object):
    """ Class for handling the data retrieval. """

    def __init__(self, command):
        self.command = command
        self.value = None

    @Throttle(MIN_TIME_BETWEEN_UPDATES)
    def update(self):
        """ Gets the latest data with a shell command. """
        _LOGGER.info('Running command: %s', self.command)

        try:
            return_value = subprocess.check_output(self.command, shell=True)
            self.value = return_value.strip().decode('utf-8')
        except subprocess.CalledProcessError:
            _LOGGER.error('Command failed: %s', self.command)