text: """
  Support for MQTT binary sensors.
  
  For more details about this platform, please refer to the documentation at
  https://home-assistant.io/components/binary_sensor.mqtt/
  """
  import logging
  
  import voluptuous as vol
  
  from homeassistant.core import callback
  from homeassistant.components import mqtt, binary_sensor
  from homeassistant.components.binary_sensor import (
      BinarySensorDevice, DEVICE_CLASSES_SCHEMA)
  from homeassistant.const import (
      CONF_FORCE_UPDATE, CONF_NAME, CONF_VALUE_TEMPLATE, CONF_PAYLOAD_ON,
      CONF_PAYLOAD_OFF, CONF_DEVICE_CLASS, CONF_DEVICE)
  from homeassistant.components.mqtt import (
      ATTR_DISCOVERY_HASH, CONF_AVAILABILITY_TOPIC, CONF_STATE_TOPIC,
      CONF_PAYLOAD_AVAILABLE, CONF_PAYLOAD_NOT_AVAILABLE, CONF_QOS,
      MqttAttributes, MqttAvailability, MqttDiscoveryUpdate,
      MqttEntityDeviceInfo, subscription)
  from homeassistant.components.mqtt.discovery import MQTT_DISCOVERY_NEW
  import homeassistant.helpers.config_validation as cv
  from homeassistant.helpers.dispatcher import async_dispatcher_connect
  import homeassistant.helpers.event as evt
  from homeassistant.helpers.typing import HomeAssistantType, ConfigType
  
  _LOGGER = logging.getLogger(__name__)
  
  DEFAULT_NAME = 'MQTT Binary sensor'
  CONF_OFF_DELAY = 'off_delay'
  CONF_UNIQUE_ID = 'unique_id'
  DEFAULT_PAYLOAD_OFF = 'OFF'
  DEFAULT_PAYLOAD_ON = 'ON'
  DEFAULT_FORCE_UPDATE = False
  
  DEPENDENCIES = ['mqtt']
  
  PLATFORM_SCHEMA = mqtt.MQTT_RO_PLATFORM_SCHEMA.extend({
      vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
      vol.Optional(CONF_PAYLOAD_OFF, default=DEFAULT_PAYLOAD_OFF): cv.string,
      vol.Optional(CONF_PAYLOAD_ON, default=DEFAULT_PAYLOAD_ON): cv.string,
      vol.Optional(CONF_DEVICE_CLASS): DEVICE_CLASSES_SCHEMA,
      vol.Optional(CONF_FORCE_UPDATE, default=DEFAULT_FORCE_UPDATE): cv.boolean,
      vol.Optional(CONF_OFF_DELAY):
          vol.All(vol.Coerce(int), vol.Range(min=0)),
      # Integrations should never expose unique_id through configuration.
      # This is an exception because MQTT is a message transport, not a protocol
      vol.Optional(CONF_UNIQUE_ID): cv.string,
      vol.Optional(CONF_DEVICE): mqtt.MQTT_ENTITY_DEVICE_INFO_SCHEMA,
  }).extend(mqtt.MQTT_AVAILABILITY_SCHEMA.schema).extend(
      mqtt.MQTT_JSON_ATTRS_SCHEMA.schema)
  
  
  async def async_setup_platform(hass: HomeAssistantType, config: ConfigType,
                                 async_add_entities, discovery_info=None):
      """Set up MQTT binary sensor through configuration.yaml."""
      await _async_setup_entity(config, async_add_entities)
  
  
  async def async_setup_entry(hass, config_entry, async_add_entities):
      """Set up MQTT binary sensor dynamically through MQTT discovery."""
      async def async_discover(discovery_payload):
          """Discover and add a MQTT binary sensor."""
          config = PLATFORM_SCHEMA(discovery_payload)
          await _async_setup_entity(config, async_add_entities,
                                    discovery_payload[ATTR_DISCOVERY_HASH])
  
      async_dispatcher_connect(
          hass, MQTT_DISCOVERY_NEW.format(binary_sensor.DOMAIN, 'mqtt'),
          async_discover)
  
  
  async def _async_setup_entity(config, async_add_entities, discovery_hash=None):
      """Set up the MQTT binary sensor."""
      async_add_entities([MqttBinarySensor(config, discovery_hash)])
  
  
  class MqttBinarySensor(MqttAttributes, MqttAvailability, MqttDiscoveryUpdate,
                         MqttEntityDeviceInfo, BinarySensorDevice):
      """Representation a binary sensor that is updated by MQTT."""
  
      def __init__(self, config, discovery_hash):
          """Initialize the MQTT binary sensor."""
          self._config = config
          self._unique_id = config.get(CONF_UNIQUE_ID)
          self._state = None
          self._sub_state = None
          self._delay_listener = None
  
          availability_topic = config.get(CONF_AVAILABILITY_TOPIC)
          payload_available = config.get(CONF_PAYLOAD_AVAILABLE)
          payload_not_available = config.get(CONF_PAYLOAD_NOT_AVAILABLE)
          qos = config.get(CONF_QOS)
          device_config = config.get(CONF_DEVICE)
  
          MqttAttributes.__init__(self, config)
          MqttAvailability.__init__(self, availability_topic, qos,
                                    payload_available, payload_not_available)
          MqttDiscoveryUpdate.__init__(self, discovery_hash,
                                       self.discovery_update)
          MqttEntityDeviceInfo.__init__(self, device_config)
  
      async def async_added_to_hass(self):
          """Subscribe mqtt events."""
          await super().async_added_to_hass()
          await self._subscribe_topics()
  
      async def discovery_update(self, discovery_payload):
          """Handle updated discovery message."""
          config = PLATFORM_SCHEMA(discovery_payload)
          self._config = config
          await self.attributes_discovery_update(config)
          await self.availability_discovery_update(config)
          await self._subscribe_topics()
          self.async_schedule_update_ha_state()
  
      async def _subscribe_topics(self):
          """(Re)Subscribe to topics."""
          value_template = self._config.get(CONF_VALUE_TEMPLATE)
          if value_template is not None:
              value_template.hass = self.hass
  
          @callback
          def off_delay_listener(now):
              """Switch device off after a delay."""
              self._delay_listener = None
              self._state = False
              self.async_schedule_update_ha_state()
  
          @callback
          def state_message_received(_topic, payload, _qos):
              """Handle a new received MQTT state message."""
              value_template = self._config.get(CONF_VALUE_TEMPLATE)
              if value_template is not None:
                  payload = value_template.async_render_with_possible_json_value(
                      payload)
              if payload == self._config.get(CONF_PAYLOAD_ON):
                  self._state = True
              elif payload == self._config.get(CONF_PAYLOAD_OFF):
                  self._state = False
              else:  # Payload is not for this entity
                  _LOGGER.warning('No matching payload found'
                                  ' for entity: %s with state_topic: %s',
                                  self._config.get(CONF_NAME),
                                  self._config.get(CONF_STATE_TOPIC))
                  return
  
              if self._delay_listener is not None:
                  self._delay_listener()
                  self._delay_listener = None
  
              off_delay = self._config.get(CONF_OFF_DELAY)
              if (self._state and off_delay is not None):
                  self._delay_listener = evt.async_call_later(
                      self.hass, off_delay, off_delay_listener)
  
              self.async_schedule_update_ha_state()
  
          self._sub_state = await subscription.async_subscribe_topics(
              self.hass, self._sub_state,
              {'state_topic': {'topic': self._config.get(CONF_STATE_TOPIC),
                               'msg_callback': state_message_received,
                               'qos': self._config.get(CONF_QOS)}})
  
      async def async_will_remove_from_hass(self):
          """Unsubscribe when removed."""
          await subscription.async_unsubscribe_topics(self.hass, self._sub_state)
          await MqttAttributes.async_will_remove_from_hass(self)
          await MqttAvailability.async_will_remove_from_hass(self)
  
      @property
      def should_poll(self):
          """Return the polling state."""
          return False
  
      @property
      def name(self):
          """Return the name of the binary sensor."""
          return self._config.get(CONF_NAME)
  
      @property
      def is_on(self):
          """Return true if the binary sensor is on."""
          return self._state
  
      @property
      def device_class(self):
          """Return the class of this sensor."""
          return self._config.get(CONF_DEVICE_CLASS)
  
      @property
      def force_update(self):
          """Force update."""
          return self._config.get(CONF_FORCE_UPDATE)
  
      @property
      def unique_id(self):
          """Return a unique ID."""
          return self._unique_id
  