Fix longstanding architectural issues

ext/src/lib/chromecastConfigApi.ts

@@ -0,0 +1,60 @@
+import logger from "./logger";
+import { TypedStorageArea } from "./TypedStorageArea";
+
+const ENDPOINT = "https://clients3.google.com/cast/chromecast/device";
+
+export interface BaseConfig {
+    app_tags: Array<{
+        supports_audio_only: boolean;
+        suports_video: boolean;
+        app_id: number;
+    }>;
+}
+
+export const baseConfigStorage = new TypedStorageArea<{
+    baseConfig: BaseConfig;
+    baseConfigUpdated: number;
+}>(browser.storage.local);
+
+/**
+ * Fetches Chromecast base config data subset.
+ */
+export async function fetchBaseConfig(): Promise<BaseConfig | null> {
+    try {
+        const res = await fetch(`${ENDPOINT}/baseconfig`);
+        const baseConfig = JSON.parse((await res.text()).slice(4));
+
+        // Strip other properties
+        return { app_tags: baseConfig.app_tags };
+    } catch (err) {
+        logger.error("Failed to fetch Chromecast base config!");
+        return null;
+    }
+}
+
+/**
+ * Get app tag from base config.
+ * @param baseConfig Base config data.
+ * @param appId Chromecast app ID.
+ */
+export function getAppTag(baseConfig: BaseConfig, appId: string) {
+    // App tag IDs are represented as 32-bit signed integers
+    const signedAppId = (parseInt(appId, 16) << 32) >> 32;
+    return baseConfig.app_tags.find(tag => tag.app_id === signedAppId);
+}
+
+/**
+ * Fetches Chromecast app config.
+ *
+ * @param appId Chromecast app ID
+ * @returns
+ */
+export async function fetchAppConfig(appId: string) {
+    try {
+        const res = await fetch(`${ENDPOINT}/app?a=${appId}`);
+        return JSON.parse((await res.text()).slice(4));
+    } catch (err) {
+        logger.error("Failed to fetch Chromecast app config!", { appId });
+        return null;
+    }
+}