Add a Zoneminder availability sensor (#20184)

* Embed zoneminder platforms into component

* Add a binary sensor for ZoneMinder availability

* Lint

* Add missing docstrings

homeassistant/components/zoneminder/__init__.py

@@ -12,6 +12,7 @@ import homeassistant.helpers.config_validation as cv
 from homeassistant.const import (
     CONF_HOST, CONF_PASSWORD, CONF_PATH, CONF_SSL, CONF_USERNAME,
     CONF_VERIFY_SSL, ATTR_NAME, ATTR_ID)
+from homeassistant.helpers.discovery import async_load_platform
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -93,4 +94,8 @@ def setup(hass, config):
         schema=SET_RUN_STATE_SCHEMA
     )
 
+    hass.async_create_task(
+        async_load_platform(hass, 'binary_sensor', DOMAIN, {}, config)
+    )
+
     return success

homeassistant/components/zoneminder/binary_sensor.py

@@ -0,0 +1,50 @@
+"""
+Support for ZoneMinder Binary Sensor.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/binary_sensor.zoneminder/
+"""
+from homeassistant.components.binary_sensor import BinarySensorDevice
+
+from homeassistant.components.zoneminder import DOMAIN as ZONEMINDER_DOMAIN
+
+DEPENDENCIES = ['zoneminder']
+
+
+async def async_setup_platform(hass, config, add_entities,
+                               discovery_info=None):
+    """Set up the ZoneMinder binary sensor platform."""
+    sensors = []
+    for host_name, zm_client in hass.data[ZONEMINDER_DOMAIN].items():
+        sensors.append(ZMAvailabilitySensor(host_name, zm_client))
+    add_entities(sensors)
+    return True
+
+
+class ZMAvailabilitySensor(BinarySensorDevice):
+    """Representation of the availability of ZoneMinder as a binary sensor."""
+
+    def __init__(self, host_name, client):
+        """Initialize availability sensor."""
+        self._state = None
+        self._name = host_name
+        self._client = client
+
+    @property
+    def name(self):
+        """Return the name of this binary sensor."""
+        return self._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 device, from component DEVICE_CLASSES."""
+        return 'connectivity'
+
+    def update(self):
+        """Update the state of this sensor (availability of ZoneMinder)."""
+        self._state = self._client.is_available