Implement KNX dimming functionality (#8371)

* Implement KNX dimming functionality

* Formatting

* Formatting

* Formatting

homeassistant/components/light/knx.py

@@ -4,15 +4,22 @@ Support KNX Lighting actuators.
 For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/Light.knx/
 """
+import logging
 import voluptuous as vol
 
-from homeassistant.components.knx import (KNXConfig, KNXGroupAddress)
-from homeassistant.components.light import (Light, PLATFORM_SCHEMA)
+from homeassistant.components.knx import (KNXConfig, KNXMultiAddressDevice)
+from homeassistant.components.light import (Light, PLATFORM_SCHEMA,
+                                            SUPPORT_BRIGHTNESS,
+                                            ATTR_BRIGHTNESS)
 from homeassistant.const import CONF_NAME
 import homeassistant.helpers.config_validation as cv
 
 CONF_ADDRESS = 'address'
 CONF_STATE_ADDRESS = 'state_address'
+CONF_BRIGHTNESS_ADDRESS = 'brightness_address'
+CONF_BRIGHTNESS_STATE_ADDRESS = 'brightness_state_address'
+
+_LOGGER = logging.getLogger(__name__)
 
 DEFAULT_NAME = 'KNX Light'
 DEPENDENCIES = ['knx']
@@ -21,6 +28,8 @@ PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend({
     vol.Required(CONF_ADDRESS): cv.string,
     vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
     vol.Optional(CONF_STATE_ADDRESS): cv.string,
+    vol.Optional(CONF_BRIGHTNESS_ADDRESS): cv.string,
+    vol.Optional(CONF_BRIGHTNESS_STATE_ADDRESS): cv.string,
 })
 
 
@@ -29,16 +38,41 @@ def setup_platform(hass, config, add_devices, discovery_info=None):
     add_devices([KNXLight(hass, KNXConfig(config))])
 
 
-class KNXLight(KNXGroupAddress, Light):
+class KNXLight(KNXMultiAddressDevice, Light):
     """Representation of a KNX Light device."""
 
+    def __init__(self, hass, config):
+        """Initialize the cover."""
+        KNXMultiAddressDevice.__init__(
+            self, hass, config,
+            [],  # required
+            optional=['state', 'brightness', 'brightness_state']
+        )
+        self._hass = hass
+        self._supported_features = 0
+
+        if CONF_BRIGHTNESS_ADDRESS in config.config:
+            _LOGGER.debug("%s is dimmable", self.name)
+            self._supported_features = self._supported_features | \
+                SUPPORT_BRIGHTNESS
+            self._brightness = None
+
     def turn_on(self, **kwargs):
         """Turn the switch on.
 
         This sends a value 1 to the group address of the device
         """
-        self.group_write(1)
-        self._state = [1]
+        _LOGGER.debug("%s: turn on", self.name)
+        self.set_value('base', [1])
+        self._state = 1
+
+        if ATTR_BRIGHTNESS in kwargs:
+            self._brightness = kwargs[ATTR_BRIGHTNESS]
+            _LOGGER.debug("turn_on requested brightness for light: %s is: %s ",
+                          self.name, self._brightness)
+            assert self._brightness <= 255
+            self.set_value("brightness", [self._brightness])
+
         if not self.should_poll:
             self.schedule_update_ha_state()
 
@@ -47,7 +81,36 @@ class KNXLight(KNXGroupAddress, Light):
 
         This sends a value 1 to the group address of the device
         """
-        self.group_write(0)
-        self._state = [0]
+        _LOGGER.debug("%s: turn off", self.name)
+        self.set_value('base', [0])
+        self._state = 0
         if not self.should_poll:
             self.schedule_update_ha_state()
+
+    @property
+    def is_on(self):
+        """Return True if the value is not 0 is on, else False."""
+        return self._state != 0
+
+    @property
+    def supported_features(self):
+        """Flag supported features."""
+        return self._supported_features
+
+    def update(self):
+        """Update device state."""
+        super().update()
+        if self.has_attribute('brightness_state'):
+            value = self.value('brightness_state')
+            if value is not None:
+                self._brightness = int.from_bytes(value, byteorder='little')
+                _LOGGER.debug("%s: brightness = %d",
+                              self.name, self._brightness)
+
+        if self.has_attribute('state'):
+            self._state = self.value("state")[0]
+            _LOGGER.debug("%s: state = %d", self.name, self._state)
+
+    def should_poll(self):
+        """No polling needed for a KNX light."""
+        return False