Change Eufy brightness handling (#14111)

Eufy device state isn't reported if the bulb is off, so avoid stamping on
the previous values if the bulb isn't going to give us useful information.
In addition, improve handling of bulb turn on if we aren't provided with a
brightness - this should avoid the bulb tending to end up with a brightness of
1 after power cycling.

homeassistant/components/light/eufy.py

@@ -61,13 +61,14 @@ class EufyLight(Light):
     def update(self):
         """Synchronise state from the bulb."""
         self._bulb.update()
-        self._brightness = self._bulb.brightness
-        self._temp = self._bulb.temperature
-        if self._bulb.colors:
-            self._colormode = True
-            self._hs = color_util.color_RGB_to_hs(*self._bulb.colors)
-        else:
-            self._colormode = False
+        if self._bulb.power:
+            self._brightness = self._bulb.brightness
+            self._temp = self._bulb.temperature
+            if self._bulb.colors:
+                self._colormode = True
+                self._hs = color_util.color_RGB_to_hs(*self._bulb.colors)
+            else:
+                self._colormode = False
         self._state = self._bulb.power
 
     @property
@@ -130,7 +131,9 @@ class EufyLight(Light):
         if brightness is not None:
             brightness = int(brightness * 100 / 255)
         else:
-            brightness = max(1, self._brightness)
+            if self._brightness is None:
+                self._brightness = 100
+            brightness = self._brightness
 
         if colortemp is not None:
             self._colormode = False