do a better job at filling out light metadata

brightness, rgb and color temp are now conditionally enabled
based on available metadata.

But: if we don't have any http metadata, we'll report no
capabilities at all. There's not much we can do about this
without having some kind of offline device metadata database
to consult.

src/platform_api.rs

@@ -458,6 +458,26 @@ impl HttpDeviceInfo {
     pub fn capability_by_instance(&self, instance: &str) -> Option<&DeviceCapability> {
         self.capabilities.iter().find(|c| c.instance == instance)
     }
+
+    pub fn supports_rgb(&self) -> bool {
+        self.capability_by_instance("colorRgb").is_some()
+    }
+
+    pub fn supports_brightness(&self) -> bool {
+        self.capability_by_instance("brightness").is_some()
+    }
+
+    pub fn get_color_temperature_range(&self) -> Option<(u32, u32)> {
+        let cap = self.capability_by_instance("colorTemperatureK")?;
+
+        match cap.parameters {
+            DeviceParameters::Integer {
+                range: IntegerRange { min, max, .. },
+                ..
+            } => Some((min, max)),
+            _ => None,
+        }
+    }
 }
 
 #[derive(Deserialize, Serialize, Debug, Default, Clone, Copy)]

src/service/hass.rs

@@ -225,6 +225,9 @@ pub struct LightConfig {
     #[serde(skip_serializing_if = "Vec::is_empty")]
     pub effect_list: Vec<String>,
 
+    pub min_mireds: Option<u32>,
+    pub max_mireds: Option<u32>,
+
     pub payload_available: String,
 }
 
@@ -237,6 +240,39 @@ impl LightConfig {
 
         let effect_list = state.device_list_scenes(device).await?;
 
+        let mut supported_color_modes = vec![];
+        let mut color_mode = false;
+
+        if device
+            .http_device_info
+            .as_ref()
+            .map(|info| info.supports_rgb())
+            .unwrap_or(false)
+        {
+            supported_color_modes.push("rgb".to_string());
+            color_mode = true;
+        }
+
+        let (min_mireds, max_mireds) = if let Some((min, max)) = device
+            .http_device_info
+            .as_ref()
+            .and_then(|info| info.get_color_temperature_range())
+        {
+            supported_color_modes.push("color_temp".to_string());
+            color_mode = true;
+            // Note that min and max are swapped by the translation
+            // from kelvin to mired
+            (Some(kelvin_to_mired(max)), Some(kelvin_to_mired(min)))
+        } else {
+            (None, None)
+        };
+
+        let brightness = device
+            .http_device_info
+            .as_ref()
+            .map(|info| info.supports_brightness())
+            .unwrap_or(false);
+
         Ok(Self {
             base: EntityConfig {
                 availability_topic,
@@ -251,17 +287,15 @@ impl LightConfig {
             schema: "json".to_string(),
             command_topic,
             state_topic,
-            supported_color_modes: vec![
-                "rgb".to_string(),
-                "color_temp".to_string(),
-                //"white".to_string(),
-            ],
-            color_mode: true,
-            brightness: true,
+            supported_color_modes,
+            color_mode,
+            brightness,
             brightness_scale: 100,
             effect: true,
             effect_list,
             payload_available: "online".to_string(),
+            max_mireds,
+            min_mireds,
         })
     }