feat: Implement basic general folder support (#2051)

- Related: #1748

src/ha/brands-url.ts

@@ -0,0 +1,24 @@
+// Small set of utility functions to transform brand URLs. This is a fairly
+// hacky approach used by the HA frontend to transform logos (which may be wide
+// and not fit well in thumbnails, or may not respect the users themes) into
+// icons. In order to ensure consistency of iconography across the card and Home
+// Assistant, this is mirrored here.
+//
+// See: https://github.com/home-assistant/frontend/blob/dev/src/util/brands-url.ts
+interface BrandsOptions {
+  domain: string;
+  type: 'icon' | 'logo' | 'icon@2x' | 'logo@2x';
+  useFallback?: boolean;
+  darkOptimized?: boolean;
+  brand?: boolean;
+}
+
+export const brandsUrl = (options: BrandsOptions): string =>
+  `https://brands.home-assistant.io/${options.brand ? 'brands/' : ''}${
+    options.useFallback ? '_/' : ''
+  }${options.domain}/${options.darkOptimized ? 'dark_' : ''}${options.type}.png`;
+
+export const extractDomainFromBrandUrl = (url: string) => url.split('/')[4];
+
+export const isBrandUrl = (thumbnail?: string | null): boolean =>
+  !!thumbnail?.startsWith('https://brands.home-assistant.io/');