text: """Device tracker platform that adds support for OwnTracks over MQTT."""
  from homeassistant.components.device_tracker import (
      ATTR_BATTERY,
      ATTR_GPS,
      ATTR_GPS_ACCURACY,
      ATTR_LOCATION_NAME,
  )
  from homeassistant.components.device_tracker.config_entry import TrackerEntity
  from homeassistant.components.device_tracker.const import SOURCE_TYPE_GPS
  from homeassistant.const import ATTR_BATTERY_LEVEL, ATTR_LATITUDE, ATTR_LONGITUDE
  from homeassistant.core import callback
  from homeassistant.helpers.restore_state import RestoreEntity
  
  from .const import (
      ATTR_ALTITUDE,
      ATTR_COURSE,
      ATTR_DEVICE_ID,
      ATTR_DEVICE_NAME,
      ATTR_SPEED,
      ATTR_VERTICAL_ACCURACY,
      SIGNAL_LOCATION_UPDATE,
  )
  from .helpers import device_info
  
  ATTR_KEYS = (ATTR_ALTITUDE, ATTR_COURSE, ATTR_SPEED, ATTR_VERTICAL_ACCURACY)
  
  
  async def async_setup_entry(hass, entry, async_add_entities):
      """Set up OwnTracks based off an entry."""
      entity = MobileAppEntity(entry)
      async_add_entities([entity])
      return True
  
  
  class MobileAppEntity(TrackerEntity, RestoreEntity):
      """Represent a tracked device."""
  
      def __init__(self, entry, data=None):
          """Set up OwnTracks entity."""
          self._entry = entry
          self._data = data
          self._dispatch_unsub = None
  
      @property
      def unique_id(self):
          """Return the unique ID."""
          return self._entry.data[ATTR_DEVICE_ID]
  
      @property
      def battery_level(self):
          """Return the battery level of the device."""
          return self._data.get(ATTR_BATTERY)
  
      @property
      def device_state_attributes(self):
          """Return device specific attributes."""
          attrs = {}
          for key in ATTR_KEYS:
              value = self._data.get(key)
              if value is not None:
                  attrs[key] = value
  
          return attrs
  
      @property
      def location_accuracy(self):
          """Return the gps accuracy of the device."""
          return self._data.get(ATTR_GPS_ACCURACY)
  
      @property
      def latitude(self):
          """Return latitude value of the device."""
          gps = self._data.get(ATTR_GPS)
  
          if gps is None:
              return None
  
          return gps[0]
  
      @property
      def longitude(self):
          """Return longitude value of the device."""
          gps = self._data.get(ATTR_GPS)
  
          if gps is None:
              return None
  
          return gps[1]
  
      @property
      def location_name(self):
          """Return a location name for the current location of the device."""
          return self._data.get(ATTR_LOCATION_NAME)
  
      @property
      def name(self):
          """Return the name of the device."""
          return self._entry.data[ATTR_DEVICE_NAME]
  
      @property
      def source_type(self):
          """Return the source type, eg gps or router, of the device."""
          return SOURCE_TYPE_GPS
  
      @property
      def device_info(self):
          """Return the device info."""
          return device_info(self._entry.data)
  
      async def async_added_to_hass(self):
          """Call when entity about to be added to Home Assistant."""
          await super().async_added_to_hass()
          self._dispatch_unsub = self.hass.helpers.dispatcher.async_dispatcher_connect(
              SIGNAL_LOCATION_UPDATE.format(self._entry.entry_id), self.update_data
          )
  
          # Don't restore if we got set up with data.
          if self._data is not None:
              return
  
          state = await self.async_get_last_state()
  
          if state is None:
              self._data = {}
              return
  
          attr = state.attributes
          data = {
              ATTR_GPS: (attr.get(ATTR_LATITUDE), attr.get(ATTR_LONGITUDE)),
              ATTR_GPS_ACCURACY: attr.get(ATTR_GPS_ACCURACY),
              ATTR_BATTERY: attr.get(ATTR_BATTERY_LEVEL),
          }
          data.update({key: attr[key] for key in attr if key in ATTR_KEYS})
          self._data = data
  
      async def async_will_remove_from_hass(self):
          """Call when entity is being removed from hass."""
          await super().async_will_remove_from_hass()
  
          if self._dispatch_unsub:
              self._dispatch_unsub()
              self._dispatch_unsub = None
  
      @callback
      def update_data(self, data):
          """Mark the device as seen."""
          self._data = data
          self.async_write_ha_state()
  