feat: Implement basic general folder support (#2051)

- Related: #1748

src/ha/registry/device/index.ts

@@ -0,0 +1,51 @@
+import { errorToConsole } from '../../../utils/basic';
+import { HomeAssistant } from '../../types';
+import { homeAssistantWSRequest } from '../../ws-request';
+import { Device, DeviceCache, DeviceList, deviceListSchema } from './types';
+
+export class DeviceRegistryManager {
+  protected _cache: DeviceCache;
+  protected _fetchedDeviceList = false;
+
+  constructor(cache: DeviceCache) {
+    this._cache = cache;
+  }
+
+  public async getDevice(hass: HomeAssistant, deviceID: string): Promise<Device | null> {
+    if (this._cache.has(deviceID)) {
+      return this._cache.get(deviceID);
+    }
+
+    // There is currently no way to fetch a single device.
+    await this._fetchDeviceList(hass);
+    return this._cache.get(deviceID) ?? null;
+  }
+
+  public async getMatchingDevices(
+    hass: HomeAssistant,
+    func: (arg: Device) => boolean,
+  ): Promise<Device[]> {
+    await this._fetchDeviceList(hass);
+    return this._cache.getMatches(func);
+  }
+
+  protected async _fetchDeviceList(hass: HomeAssistant): Promise<void> {
+    if (this._fetchedDeviceList) {
+      return;
+    }
+
+    let deviceList: DeviceList | null = null;
+    try {
+      deviceList = await homeAssistantWSRequest<DeviceList>(hass, deviceListSchema, {
+        type: 'config/device_registry/list',
+      });
+    } catch (e) {
+      errorToConsole(e as Error);
+      return;
+    }
+    deviceList.forEach((device) => {
+      this._cache.set(device.id, device);
+    });
+    this._fetchedDeviceList = true;
+  }
+}