feat: makes NDK parameter optional

packages/file_transfer_sdk/lib/src/functions/fetch_blob.dart

@@ -7,10 +7,20 @@ import 'decrypt_blob.dart';
 import 'package:ndk/ndk.dart';
 
 Future<Uint8List> fetchBlob({
-  required Ndk ndk,
   required FileMetadata fileMetadata,
+  Ndk? ndk,
 }) async {
-  final blobResponse = await ndk.blossom.getBlob(
+  final ndk0 =
+      ndk ??
+      Ndk(
+        NdkConfig(
+          eventVerifier: Bip340EventVerifier(),
+          cache: MemCacheManager(),
+          bootstrapRelays: [],
+        ),
+      );
+
+  final blobResponse = await ndk0.blossom.getBlob(
     sha256: fileMetadata.x,
     serverUrls: Constants.blossomServers,
   );
@@ -21,5 +31,7 @@ Future<Uint8List> fetchBlob({
     nonce: fileMetadata.nonce,
   );
 
+  if (ndk == null) await ndk0.destroy();
+
   return decryptedBytes;
 }

packages/file_transfer_sdk/lib/src/functions/fetch_file_metdata.dart

@@ -1,17 +1,29 @@
 import 'dart:convert';
 
 import 'package:file_transfer_sdk/file_transfer_sdk.dart';
+import 'package:file_transfer_sdk/src/constants.dart';
 import 'package:ndk/ndk.dart';
 import 'package:ndk/shared/nips/nip01/bip340.dart';
 
 Future<FileMetadata> fetchFileMetadata({
-  required Ndk ndk,
   required SharedFile sharedFile,
+  Ndk? ndk,
 }) async {
+  final ndk0 =
+      ndk ??
+      Ndk(
+        NdkConfig(
+          eventVerifier: Bip340EventVerifier(),
+          cache: MemCacheManager(),
+          bootstrapRelays: [],
+        ),
+      );
+
   final decodedNevent = Nip19.decodeNevent(sharedFile.nevent);
 
-  final query = ndk.requests.query(
+  final query = ndk0.requests.query(
     filter: Filter(ids: [decodedNevent.eventId]),
+    explicitRelays: Constants.relays,
   );
 
   Nip01Event? event;
@@ -39,5 +51,7 @@ Future<FileMetadata> fetchFileMetadata({
       .map((tag) => List<String>.from(tag as List))
       .toList();
 
+  if (ndk == null) await ndk0.destroy();
+
   return FileMetadata.fromTags(tags);
 }

packages/file_transfer_sdk/lib/src/functions/share_file.dart

@@ -10,23 +10,41 @@ import 'package:ndk/ndk.dart';
 import 'package:ndk/shared/nips/nip01/bip340.dart';
 
 Future<SharedFile> shareFile({
-  required Ndk ndk,
   required Uint8List bytes,
   String? contentType,
   String? filename,
+  Ndk? ndk,
 }) async {
+  final ndk0 =
+      ndk ??
+      Ndk(
+        NdkConfig(
+          eventVerifier: Bip340EventVerifier(),
+          cache: MemCacheManager(),
+          bootstrapRelays: [],
+        ),
+      );
+
+  if (ndk == null) {
+    final keyPair = Bip340.generatePrivateKey();
+    ndk0.accounts.loginPrivateKey(
+      pubkey: keyPair.publicKey,
+      privkey: keyPair.privateKey!,
+    );
+  }
+
   final recipientKeyPair = Bip340.generatePrivateKey();
 
   final encryptedBlob = await encryptBlob(bytes);
 
   final blobDescriptor = await uploadBlob(
-    ndk: ndk,
+    ndk: ndk0,
     data: encryptedBlob.bytes,
     contentType: contentType,
   );
 
   final event = await createEvent(
-    ndk: ndk,
+    ndk: ndk0,
     descriptor: blobDescriptor!,
     recipientPubkey: recipientKeyPair.publicKey,
     key: encryptedBlob.key,
@@ -34,7 +52,7 @@ Future<SharedFile> shareFile({
     filename: filename,
   );
 
-  await ndk.broadcast
+  await ndk0.broadcast
       .broadcast(nostrEvent: event, specificRelays: Constants.relays)
       .broadcastDoneFuture;
 
@@ -45,5 +63,7 @@ Future<SharedFile> shareFile({
 
   final nsec = Nip19.encodePrivateKey(recipientKeyPair.privateKey!);
 
+  if (ndk == null) await ndk0.destroy();
+
   return SharedFile(nevent: nevent, encodedPrivateKey: nsec);
 }

packages/file_transfer_sdk/test/file_transfer_sdk_test.dart

@@ -8,13 +8,21 @@ import 'package:ndk/shared/nips/nip01/bip340.dart';
 import 'package:test/test.dart';
 
 void main() {
-  test("First test", () async {
+  test("Test without shared NDK instance", () async {
+    final originalData = Uint8List.fromList('Hello, World!'.codeUnits);
+
+    final share = await shareFile(bytes: originalData);
+    final fileMetadata = await fetchFileMetadata(sharedFile: share);
+    final fetchedData = await fetchBlob(fileMetadata: fileMetadata);
+
+    expect(fetchedData, originalData);
+  });
+
+  test("Test with shared NDK instance", () async {
     final ndk = Ndk(
       NdkConfig(eventVerifier: Bip340EventVerifier(), cache: MemCacheManager()),
     );
-
     final keyPair = Bip340.generatePrivateKey();
-
     ndk.accounts.loginPrivateKey(
       pubkey: keyPair.publicKey,
       privkey: keyPair.privateKey!,