feat: mark entities as unavailable on disconnect, shutdown & crash

This implementation makes the HA availability a bit more robust. In
comparison to the previous version it makes use of the last will message
to also mark entities available if the connection is lost or the
application doesn't exit gracefully. It also extends availability
support to distributed entities with the exception of the state-unlocked
ones.

Closes #181, closes #348

src/integrations/home-assistant/entity-config.ts

@@ -1,5 +1,25 @@
 import { Device } from './device';
 
+export const PROPERTY_DENYLIST = [
+  'component',
+  'configTopic',
+  'commandStore',
+  '_instanceStatusTopic',
+  '_entityStatusTopic',
+  'distributed',
+  'stateLocked',
+];
+
+export type AvailabilityStatus = 'online' | 'offline';
+type AvailabilityMode = 'all' | 'any' | 'latest';
+
+export class Availability {
+  payloadAvailable: AvailabilityStatus = 'online';
+  payloadNotAvailable: AvailabilityStatus = 'offline';
+
+  constructor(public topic: string) {}
+}
+
 export abstract class EntityConfig {
   uniqueId: string;
   component: string;
@@ -10,9 +30,13 @@ export abstract class EntityConfig {
   configTopic: string;
   stateTopic: string;
   jsonAttributesTopic: string;
-  availabilityTopic: string;
-  payloadAvailable = 'online';
-  payloadNotAvailable = 'offline';
+  availabilityMode: AvailabilityMode = 'all';
+
+  distributed = false;
+  stateLocked = true;
+
+  private _instanceStatusTopic: string;
+  private readonly _entityStatusTopic: string;
 
   protected constructor(
     component: string,
@@ -28,6 +52,30 @@ export abstract class EntityConfig {
     this.configTopic = `${this.component}/room-assistant/${id}/config`;
     this.stateTopic = `room-assistant/${this.component}/${id}/state`;
     this.jsonAttributesTopic = `room-assistant/${this.component}/${id}/attributes`;
-    this.availabilityTopic = `room-assistant/${this.component}/${id}/status`;
+    this._entityStatusTopic = `room-assistant/${this.component}/${id}/status`;
+  }
+
+  get availability(): Array<Availability> {
+    if (this.distributed && !this.stateLocked) {
+      return [];
+    } else {
+      return [
+        new Availability(this._entityStatusTopic),
+        new Availability(this._instanceStatusTopic),
+      ];
+    }
+  }
+
+  setInstanceStatusTopic(topic: string): void {
+    this._instanceStatusTopic = topic;
+  }
+
+  shallowClone(): Record<string, unknown> {
+    const clone: Record<string, unknown> = Object.assign({}, this) as Record<
+      string,
+      unknown
+    >;
+    clone.availability = this.availability;
+    return clone;
   }
 }

src/integrations/home-assistant/home-assistant.module.ts

@@ -5,13 +5,20 @@ import { EntitiesModule } from '../../entities/entities.module';
 import { StatusModule } from '../../status/status.module';
 import { HomeAssistantHealthIndicator } from './home-assistant.health';
 import { ClusterModule } from '../../cluster/cluster.module';
+import { ScheduleModule } from '@nestjs/schedule';
 
 @Module({})
 export default class HomeAssistantModule {
   static forRoot(): DynamicModule {
     return {
       module: HomeAssistantModule,
-      imports: [ConfigModule, EntitiesModule, ClusterModule, StatusModule],
+      imports: [
+        ConfigModule,
+        EntitiesModule,
+        ClusterModule,
+        StatusModule,
+        ScheduleModule.forRoot(),
+      ],
       providers: [HomeAssistantService, HomeAssistantHealthIndicator],
     };
   }