feat: isolates for compute heavy tasks

packages/amber/lib/data_layer/repositories/signers/amber_event_signer.dart

@@ -1,7 +1,6 @@
 import 'dart:convert';
 
 import 'package:ndk/ndk.dart';
-import 'package:ndk/shared/nips/nip19/nip19.dart';
 
 import '../../data_sources/amber_flutter.dart';
 
@@ -18,13 +17,15 @@ class AmberEventSigner implements EventSigner {
   });
 
   @override
-  Future<void> sign(Nip01Event event) async {
+  Future<Nip01Event> sign(Nip01Event event) async {
     final npub = publicKey.startsWith('npub')
         ? publicKey
         : Nip19.encodePubKey(publicKey);
     Map<dynamic, dynamic> map = await amberFlutterDS.amber.signEvent(
-        currentUser: npub, eventJson: jsonEncode(event.toJson()), id: event.id);
-    event.sig = map['signature'];
+        currentUser: npub,
+        eventJson: Nip01EventModel.fromEntity(event).toJsonString(),
+        id: event.id);
+    return event.copyWith(sig: map['signature']);
   }
 
   @override

packages/isar/lib/data_layer/models/db/db_event.dart

@@ -42,7 +42,7 @@ class DbEvent extends Nip01Event {
   String get content => super.content;
 
   @override
-  String get sig => super.sig;
+  String? get sig => super.sig;
 
   @override
   bool? get validSig => super.validSig;
@@ -56,12 +56,9 @@ class DbEvent extends Nip01Event {
       required super.tags,
       required super.content,
       super.createdAt,
-      required String sig,
+      String? sig,
       bool? validSig,
       required List<String> sources}) {
-    super.sig = sig;
-    super.validSig = validSig;
-    super.sources = sources;
   }
 
   static DbEvent fromNip01Event(Nip01Event event) {

packages/ndk/example/bunkers_example.dart

@@ -22,9 +22,9 @@ Future<void> main() async {
       tags: [],
     );
 
-    await ndk.accounts.sign(event);
+    final signedEvent = await ndk.accounts.sign(event);
     log('Event signed successfully!');
-    log('Event ID: ${event.id}');
+    log('Event ID: ${signedEvent.id}');
   } catch (e) {
     log('Error: $e');
   }

packages/ndk/example/nip13_pow_example.dart

@@ -1,21 +1,30 @@
 import 'dart:developer';
 
-import 'package:ndk/domain_layer/entities/nip_01_event.dart';
+import 'package:ndk/ndk.dart';
 import 'package:ndk/shared/nips/nip01/bip340.dart';
 
 void main() async {
   final keyPair = Bip340.generatePrivateKey();
 
-  final minedEvent = Nip01Event(
+  final event = Nip01Event(
     pubKey: keyPair.publicKey,
     kind: 1,
     tags: [],
     content: 'message',
-  ).minePoW(12);
+  );
 
-  log(minedEvent.id); // the id will start with "000"
+  /// your global NDK instance
+  final ndk = Ndk.emptyBootstrapRelaysConfig();
 
-  if (minedEvent.checkPoWDifficulty(10)) {
+  /// pass your event to the proof of work usecase
+  final minedEvent =
+      await ndk.proofOfWork.minePoW(event: event, targetDifficulty: 10);
+
+  /// the id will start with "000"
+  log(minedEvent.id);
+
+  /// check the difficulty
+  if (ndk.proofOfWork.checkPoWDifficulty(event: event, targetDifficulty: 10)) {
     log('Event has difficulty >= 10');
   }
 }

packages/ndk/example/nostrconnect_example.dart

@@ -28,9 +28,9 @@ Future<void> main() async {
       tags: [],
     );
 
-    await ndk.accounts.sign(event);
+    final signedEvent = await ndk.accounts.sign(event);
     log('Event signed successfully!');
-    log('Event ID: ${event.id}');
+    log('Event ID: ${signedEvent.id}');
   } catch (e) {
     log('Error: $e');
   }

packages/ndk/lib/data_layer/data_sources/websocket_client.dart

@@ -26,8 +26,8 @@ class WebsocketDSClient {
   }
 
   bool isOpen() {
-    return ws.connection.state == Connected() ||
-        ws.connection.state == Reconnected();
+    final state = ws.connection.state;
+    return state is Connected || state is Reconnected;
   }
 
   bool isConnecting() {
@@ -36,15 +36,13 @@ class WebsocketDSClient {
   }
 
   int? closeCode() {
-    return ws.connection.state == Disconnected()
-        ? (ws.connection.state as Disconnected).code
-        : null;
+    final state = ws.connection.state;
+    return state is Disconnected ? state.code : null;
   }
 
   String? closeReason() {
-    return ws.connection.state == Disconnected()
-        ? (ws.connection.state as Disconnected).reason
-        : null;
+    final state = ws.connection.state;
+    return state is Disconnected ? state.reason : null;
   }
 }
 // coverage:ignore-end

packages/ndk/lib/data_layer/models/nip_01_event_model.dart

@@ -0,0 +1,181 @@
+import 'dart:convert';
+
+import '../../domain_layer/entities/nip_01_event.dart';
+import '../../shared/helpers/list_casting.dart';
+import '../../shared/nips/nip19/nip19.dart';
+
+/// Data model for NIP-01 Event
+/// Extends [Nip01Event] entity with serialization methods to/from JSON and other formats
+class Nip01EventModel extends Nip01Event {
+  /// creates a new [Nip01EventModel] instance
+  Nip01EventModel({
+    required super.id,
+    required super.pubKey,
+    required super.createdAt,
+    required super.kind,
+    required super.tags,
+    required super.content,
+    required super.sig,
+    super.validSig,
+    super.sources = const [],
+  });
+
+  /// creates a copy of this event with the given fields replaced by the new values \
+  /// needed so other packages depending on the extened nip01_event.dart can use copyWith
+  @override
+  Nip01EventModel copyWith({
+    String? id,
+    String? pubKey,
+    int? createdAt,
+    int? kind,
+    List<List<String>>? tags,
+    String? content,
+    String? sig,
+    bool? validSig,
+    List<String>? sources,
+  }) {
+    return Nip01EventModel(
+        id: id ?? this.id,
+        pubKey: pubKey ?? this.pubKey,
+        createdAt: createdAt ?? this.createdAt,
+        kind: kind ?? this.kind,
+        tags: tags ?? this.tags,
+        content: content ?? this.content,
+        sig: sig ?? this.sig,
+        validSig: validSig ?? this.validSig,
+        sources: sources ?? this.sources);
+  }
+
+  /**
+   * encoding/decoding methods
+   */
+
+  /// creates a new [Nip01EventModel] instance from a [Nip01Event] entity
+  factory Nip01EventModel.fromEntity(Nip01Event event) {
+    return Nip01EventModel(
+      id: event.id,
+      pubKey: event.pubKey,
+      createdAt: event.createdAt,
+      kind: event.kind,
+      tags: event.tags,
+      content: event.content,
+      sig: event.sig,
+      sources: event.sources,
+      validSig: event.validSig,
+    );
+  }
+
+  /// creates a new [Nip01EventModel] instance from a JSON object
+  factory Nip01EventModel.fromJson(Map<dynamic, dynamic> data) {
+    final id = data['id'] as String? ?? '';
+    final pubKey = data['pubkey'] as String? ?? '';
+    final createdAt = data['created_at'] as int;
+    final kind = data['kind'] as int;
+    final tags = castToListOfListOfString(data['tags']);
+    final content = data['content'] as String? ?? '';
+
+    /// '' to support rumor events
+    final sig = (data['sig'] as String?);
+
+    return Nip01EventModel(
+      id: id,
+      pubKey: pubKey,
+      createdAt: createdAt,
+      kind: kind,
+      tags: tags,
+      content: content,
+      sig: sig,
+    );
+  }
+
+  /// Returns the Event object as a JSON object
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'pubkey': pubKey,
+      'created_at': createdAt,
+      'kind': kind,
+      'tags': tags,
+      'content': content,
+      'sig': sig
+    };
+  }
+
+  /// Returns the Event object as a JSON string
+  String toJsonString() {
+    final jsonMap = toJson();
+    return json.encode(jsonMap);
+  }
+
+  /// Encode this event as a nevent (NIP-19 event reference)
+  ///
+  /// Returns a bech32-encoded nevent string that includes:
+  /// - Event ID (required)
+  /// - Author pubkey (included)
+  /// - Kind (included)
+  /// - Relay hints from event.sources (if available)
+  ///
+  /// Usage: `final nevent = event.nevent;`
+  String get nevent {
+    return Nip19.encodeNevent(
+      eventId: id,
+      author: pubKey,
+      kind: kind,
+      relays: sources.isEmpty ? null : sources,
+    );
+  }
+
+  /// Encode this event as an naddr (NIP-19 addressable event coordinate)
+  ///
+  /// Only works for addressable/replaceable events (kind >= 10000 or kind 0, 3, 41)
+  /// Requires a "d" tag to identify the event.
+  ///
+  /// Returns a bech32-encoded naddr string or null if:
+  /// - Event is not addressable/replaceable
+  /// - Event doesn't have a "d" tag
+  ///
+  /// Usage: `final naddr = event.naddr;`
+  String? get naddr {
+    // Check if this is an addressable event
+    if (!_isAddressableKind(kind)) {
+      return null;
+    }
+
+    // Get the "d" tag identifier
+    final identifier = getDtag();
+    if (identifier == null) {
+      return null;
+    }
+
+    return Nip19.encodeNaddr(
+      identifier: identifier,
+      pubkey: pubKey,
+      kind: kind,
+      relays: sources.isEmpty ? null : sources,
+    );
+  }
+
+  /// Returns the Event object as a base64-encoded JSON string
+  String toBase64() {
+    return base64Encode(utf8.encode(json.encode(toJson())));
+  }
+
+  /// Check if an event kind is addressable/replaceable
+  ///
+  /// According to NIP-01:
+  /// - Replaceable events: 0, 3, 41
+  /// - Parameterized replaceable events: 10000-19999, 30000-39999
+  bool _isAddressableKind(int kind) {
+    // Replaceable events
+    if (kind == 0 || kind == 3 || kind == 41) {
+      return true;
+    }
+
+    // Parameterized replaceable events
+    if ((kind >= 10000 && kind <= 19999) || (kind >= 30000 && kind <= 39999)) {
+      return true;
+    }
+
+    return false;
+  }
+}