Fix binary sensor in Ambient PWS (#20801)

* Fix binary sensor in Ambient PWS

* Correctly load entities

* Corrected what on and off means for existing sensor

* Make sure to return a boolean

* Member comments

* Binary sensor doesn't need state property

homeassistant/components/ambient_station/binary_sensor.py

@@ -0,0 +1,71 @@
+"""
+Support for Ambient Weather Station binary sensors.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/binary_sensor.ambient_station/
+"""
+import logging
+
+from homeassistant.components.ambient_station import (
+    SENSOR_TYPES, TYPE_BATTOUT, AmbientWeatherEntity)
+from homeassistant.components.binary_sensor import BinarySensorDevice
+from homeassistant.const import ATTR_NAME
+
+from .const import ATTR_LAST_DATA, DATA_CLIENT, DOMAIN, TYPE_BINARY_SENSOR
+
+DEPENDENCIES = ['ambient_station']
+_LOGGER = logging.getLogger(__name__)
+
+
+async def async_setup_platform(
+        hass, config, async_add_entities, discovery_info=None):
+    """Set up Ambient PWS binary sensors based on the old way."""
+    pass
+
+
+async def async_setup_entry(hass, entry, async_add_entities):
+    """Set up Ambient PWS binary sensors based on a config entry."""
+    ambient = hass.data[DOMAIN][DATA_CLIENT][entry.entry_id]
+
+    binary_sensor_list = []
+    for mac_address, station in ambient.stations.items():
+        for condition in ambient.monitored_conditions:
+            name, _, kind, device_class = SENSOR_TYPES[condition]
+            if kind == TYPE_BINARY_SENSOR:
+                binary_sensor_list.append(
+                    AmbientWeatherBinarySensor(
+                        ambient, mac_address, station[ATTR_NAME], condition,
+                        name, device_class))
+
+    async_add_entities(binary_sensor_list, True)
+
+
+class AmbientWeatherBinarySensor(AmbientWeatherEntity, BinarySensorDevice):
+    """Define an Ambient binary sensor."""
+
+    def __init__(
+            self, ambient, mac_address, station_name, sensor_type, sensor_name,
+            device_class):
+        """Initialize the sensor."""
+        super().__init__(
+            ambient, mac_address, station_name, sensor_type, sensor_name)
+
+        self._device_class = device_class
+
+    @property
+    def device_class(self):
+        """Return the device class."""
+        return self._device_class
+
+    @property
+    def is_on(self):
+        """Return the status of the sensor."""
+        if self._sensor_type == TYPE_BATTOUT:
+            return self._state == 0
+
+        return self._state == 1
+
+    async def async_update(self):
+        """Fetch new state data for the entity."""
+        self._state = self._ambient.stations[
+            self._mac_address][ATTR_LAST_DATA].get(self._sensor_type)