From 845d81bdae20243d03e88f47f5dd5ef193debe9b Mon Sep 17 00:00:00 2001
From: Richard Mitchell <mitchellrj@users.noreply.github.com>
Date: Tue, 23 Apr 2019 05:28:40 +0100
Subject: [PATCH] Correct calculation and units of light level values. (#23309)

---
 homeassistant/components/hue/sensor.py   |  9 +++++++--
 tests/components/hue/test_sensor_base.py | 10 +++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/homeassistant/components/hue/sensor.py b/homeassistant/components/hue/sensor.py
index 555c16a0be7..30a439f92e9 100644
--- a/homeassistant/components/hue/sensor.py
+++ b/homeassistant/components/hue/sensor.py
@@ -27,12 +27,17 @@ class HueLightLevel(GenericHueGaugeSensorEntity):
     """The light level sensor entity for a Hue motion sensor device."""
 
     device_class = DEVICE_CLASS_ILLUMINANCE
-    unit_of_measurement = "Lux"
+    unit_of_measurement = "lx"
 
     @property
     def state(self):
         """Return the state of the device."""
-        return self.sensor.lightlevel
+        # https://developers.meethue.com/develop/hue-api/supported-devices/#clip_zll_lightlevel
+        # Light level in 10000 log10 (lux) +1 measured by sensor. Logarithm
+        # scale used because the human eye adjusts to light levels and small
+        # changes at low lux levels are more noticeable than at high lux
+        # levels.
+        return 10 ** ((self.sensor.lightlevel - 1) / 10000)
 
     @property
     def device_state_attributes(self):
diff --git a/tests/components/hue/test_sensor_base.py b/tests/components/hue/test_sensor_base.py
index 38eb3d8c55b..6259921dcfb 100644
--- a/tests/components/hue/test_sensor_base.py
+++ b/tests/components/hue/test_sensor_base.py
@@ -48,7 +48,7 @@ PRESENCE_SENSOR_1_PRESENT = {
 }
 LIGHT_LEVEL_SENSOR_1 = {
     "state": {
-        "lightlevel": 0,
+        "lightlevel": 1,
         "dark": True,
         "daylight": True,
         "lastupdated": "2019-01-01T01:00:00"
@@ -141,7 +141,7 @@ PRESENCE_SENSOR_2_NOT_PRESENT = {
 }
 LIGHT_LEVEL_SENSOR_2 = {
     "state": {
-        "lightlevel": 100,
+        "lightlevel": 10001,
         "dark": True,
         "daylight": True,
         "lastupdated": "2019-01-01T01:00:00"
@@ -234,7 +234,7 @@ PRESENCE_SENSOR_3_PRESENT = {
 }
 LIGHT_LEVEL_SENSOR_3 = {
     "state": {
-        "lightlevel": 0,
+        "lightlevel": 1,
         "dark": True,
         "daylight": True,
         "lastupdated": "2019-01-01T01:00:00"
@@ -399,7 +399,7 @@ async def test_sensors(hass, mock_bridge):
     assert presence_sensor_1 is not None
     assert presence_sensor_1.state == 'on'
     assert light_level_sensor_1 is not None
-    assert light_level_sensor_1.state == '0'
+    assert light_level_sensor_1.state == '1.0'
     assert light_level_sensor_1.name == 'Living room sensor light level'
     assert temperature_sensor_1 is not None
     assert temperature_sensor_1.state == '17.75'
@@ -414,7 +414,7 @@ async def test_sensors(hass, mock_bridge):
     assert presence_sensor_2 is not None
     assert presence_sensor_2.state == 'off'
     assert light_level_sensor_2 is not None
-    assert light_level_sensor_2.state == '100'
+    assert light_level_sensor_2.state == '10.0'
     assert light_level_sensor_2.name == 'Kitchen sensor light level'
     assert temperature_sensor_2 is not None
     assert temperature_sensor_2.state == '18.75'