feat: add xiami crypto & have a working decryption workflow (#2, #9)

src/decrypt-worker/worker.ts

@@ -1,12 +1,27 @@
 import { WorkerServerBus } from '~/util/WorkerEventBus';
 import { DECRYPTION_WORKER_ACTION_NAME } from './constants';
 
+import type { CryptoFactory } from './crypto/CryptoBase';
+import { XiamiCrypto } from './crypto/xiami/xiami';
+
 const bus = new WorkerServerBus();
 onmessage = bus.onmessage;
 
+const decryptorFactories: CryptoFactory[] = [
+  // Xiami (*.xm)
+  () => new XiamiCrypto(),
+];
+
 bus.addEventHandler(DECRYPTION_WORKER_ACTION_NAME.DECRYPT, async (blobURI) => {
-  const blob = await fetch(blobURI).then((r) => r.arrayBuffer());
-  // TODO: Implement decryptor for blob received here.
-  console.log(blob);
-  return { hello: true };
+  const blob = await fetch(blobURI).then((r) => r.blob());
+
+  for (const factory of decryptorFactories) {
+    const decryptor = factory();
+    if (await decryptor.isSupported(blob)) {
+      const decrypted = await decryptor.decrypt(blob);
+      return { decrypted: URL.createObjectURL(decrypted) };
+    }
+  }
+
+  throw new Error('could not decrypt file: no working decryptor found');
 });