From 6a4160bcc4c147153464dd52eb010d1d93297a2d Mon Sep 17 00:00:00 2001
From: Kerey Roper <kereyroper@users.noreply.github.com>
Date: Thu, 9 Jan 2025 04:07:24 -0800
Subject: [PATCH] add support for dimming/brightening X10 lamps (#130196)

Co-authored-by: Joost Lekkerkerker <joostlek@outlook.com>
---
 homeassistant/components/x10/light.py | 44 ++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 5 deletions(-)

diff --git a/homeassistant/components/x10/light.py b/homeassistant/components/x10/light.py
index 23343cb0f8dfdc..d98f1f51d5438b 100644
--- a/homeassistant/components/x10/light.py
+++ b/homeassistant/components/x10/light.py
@@ -81,9 +81,16 @@ def name(self):
 
     @property
     def brightness(self):
-        """Return the brightness of the light."""
+        """Return the brightness of the light, scaled to base class 0..255.
+
+        This needs to be scaled from 0..x for use with X10 dimmers.
+        """
         return self._brightness
 
+    def normalize_x10_brightness(self, brightness: float) -> float:
+        """Return calculated brightness values."""
+        return int((brightness / 255) * 32)
+
     @property
     def is_on(self):
         """Return true if light is on."""
@@ -91,11 +98,37 @@ def is_on(self):
 
     def turn_on(self, **kwargs: Any) -> None:
         """Instruct the light to turn on."""
-        if self._is_cm11a:
-            x10_command(f"on {self._id}")
-        else:
-            x10_command(f"fon {self._id}")
+        old_brightness = self._brightness
+        if old_brightness == 0:
+            # Dim down from max if applicable, also avoids a "dim" command if an "on" is more appropriate
+            old_brightness = 255
         self._brightness = kwargs.get(ATTR_BRIGHTNESS, 255)
+        brightness_diff = self.normalize_x10_brightness(
+            self._brightness
+        ) - self.normalize_x10_brightness(old_brightness)
+        command_suffix = ""
+        # heyu has quite a messy command structure - we'll just deal with it here
+        if brightness_diff == 0:
+            if self._is_cm11a:
+                command_prefix = "on"
+            else:
+                command_prefix = "fon"
+        elif brightness_diff > 0:
+            if self._is_cm11a:
+                command_prefix = "bright"
+            else:
+                command_prefix = "fbright"
+            command_suffix = f" {brightness_diff}"
+        else:
+            if self._is_cm11a:
+                if self._state:
+                    command_prefix = "dim"
+                else:
+                    command_prefix = "dimb"
+            else:
+                command_prefix = "fdim"
+            command_suffix = f" {-brightness_diff}"
+        x10_command(f"{command_prefix} {self._id}{command_suffix}")
         self._state = True
 
     def turn_off(self, **kwargs: Any) -> None:
@@ -104,6 +137,7 @@ def turn_off(self, **kwargs: Any) -> None:
             x10_command(f"off {self._id}")
         else:
             x10_command(f"foff {self._id}")
+        self._brightness = 0
         self._state = False
 
     def update(self) -> None: