New: Add brightness support for backlight/ambilight

bulbs/backlight/brightness.js

@@ -0,0 +1,56 @@
+const BacklightBrightness = (Device) =>
+  class extends Device {
+    constructor(props, platform) {
+      super(props, platform);
+      this.backlightBright = props['bg_bright'];
+
+      const { Brightness } = global.Characteristic;
+
+      (
+        this.backlightService.getCharacteristic(Brightness) ||
+        this.backlightService.addCharacteristic(Brightness)
+      )
+        .on('set', async (value, callback) => {
+          try {
+            await this.setBacklightBrightness(value);
+            callback(null);
+          } catch (err) {
+            callback(err);
+          }
+        })
+        .updateValue(this.backlightBright);
+    }
+
+    get backlightBright() {
+      return this._backlightBright;
+    }
+
+    set backlightBright(brightness) {
+      this._backlightBright = Number(brightness);
+    }
+
+    async setBacklightBrightness(brightness) {
+      const { brightness: transition = 400 } = this.config.transitions || {};
+      await this.setBacklightPower(true);
+      const req = {
+        method: 'bg_set_bright',
+        params: [Math.max(brightness, 1), 'smooth', transition],
+      };
+      return this.sendCmd(req).then(() => {
+        this._backlightBright = brightness;
+      });
+    }
+
+    updateStateFromProp(prop, value) {
+      if (prop === 'bg_bright') {
+        this.backlightBright = value;
+        this.backlightService
+          .getCharacteristic(global.Characteristic.Brightness)
+          .updateValue(this.backlightBright);
+        return;
+      }
+      super.updateStateFromProp(prop, value);
+    }
+  };
+
+module.exports = BacklightBrightness;

platform.js

@@ -6,6 +6,7 @@ const MoonlightMode = require('./bulbs/moonlight');
 const Color = require('./bulbs/color');
 const Temperature = require('./bulbs/temperature');
 const Backlight = require('./bulbs/backlight/bulb');
+const BacklightBrightness = require('./bulbs/backlight/brightness');
 const { getDeviceId, getName, blacklist, sleep, pipe } = require('./utils');
 
 class YeePlatform {
@@ -152,6 +153,11 @@ class YeePlatform {
       mixins.push(Backlight);
     }
 
+    if (features.includes('bg_set_bright')) {
+      this.log(`Device ${name} supports backlight brightness`);
+      mixins.push(BacklightBrightness);
+    }
+
     const Bulb = class extends pipe(...mixins)(YeeBulb) {};
     return new Bulb({ id, model, endpoint, accessory, limits, ...props }, this);
   }