Add state attribute for computing end time

README.md

@@ -211,7 +211,15 @@ duration:
   units: minutes # Since the slider state is a number like 10.0
 ```
 
-#### 7. If your entity doesn't meet these criteria...
+#### 7. My end time comes from the entity's state
+
+End times and durations can use any of the types `attribute`, `fixed`, `entity` (you've seen these 3 before) and `state`! The `state` type uses the entity's current state. Let's say we have a timer who's state is the time it will go off, like `2021-09-07T20:24:13+00:00`! Here's how to configure the card:
+
+```yaml
+end_time: { state: true }
+```
+
+#### 8. If your entity doesn't meet these criteria...
 
 🧡 please create an issue and tell me the entity so I can improve these instructions! ❤️️
 

src/helpers.ts

@@ -101,6 +101,7 @@ export const attribute = (hass: HomeAssistant, stateObj: HassEntity, attrib: Att
   if (!attrib) throw new Error('One of duration, start_time, or end_time was not fully specified. Make sure you set entity, fixed, or attribute');
   if ('fixed' in attrib) return attrib.fixed;
   if ('entity' in attrib) return hass.states[attrib.entity].state;
+  if ('state' in attrib) return stateObj.state;
   return stateObj.attributes[attrib.attribute];
 }
 

src/types.ts

@@ -37,6 +37,7 @@ interface modsConfig extends styleConfig {
 type AttributeType =
   | { attribute: string }
   | { entity: string }
+  | { state: any }
   | { fixed: number };
 export type AttributeConfig = AttributeType & {
   units?: "duration" | "hours" | "minutes" | "seconds";