implemented dirty tracking, modification updates, etc.

lib/src/internal/async_utils.dart

@@ -0,0 +1,29 @@
+import 'dart:async';
+
+/// Base class which can be used as a mixin directly, but you have to call `cancelSubscriptions`.
+/// If used inside a [State], use [StreamSubscriberMixin].
+mixin StreamSubscriberBase {
+  final List<StreamSubscription<dynamic>> _subscriptions = <StreamSubscription<dynamic>>[];
+
+  /// Listens to a stream and saves it to the list of subscriptions.
+  void listen(Stream<dynamic> stream, void onData(dynamic data), {Function onError}) {
+    if (stream != null) {
+      _subscriptions.add(stream.listen(onData, onError: onError));
+    }
+  }
+
+  void handle(StreamSubscription<dynamic> subscription) {
+    _subscriptions.add(subscription);
+  }
+
+  /// Cancels all streams that were previously added with listen().
+  void cancelSubscriptions() {
+    _subscriptions.forEach(_cancelSubscription);
+    _subscriptions.clear();
+  }
+
+  Future<void> _cancelSubscription(StreamSubscription<dynamic> subscription) =>
+      subscription.cancel();
+}
+
+class StreamSubscriptions with StreamSubscriberBase {}

lib/src/kdbx_format.dart

@@ -6,6 +6,7 @@ import 'package:convert/convert.dart' as convert;
 import 'package:crypto/crypto.dart' as crypto;
 import 'package:kdbx/src/crypto/protected_salt_generator.dart';
 import 'package:kdbx/src/crypto/protected_value.dart';
+import 'package:kdbx/src/internal/async_utils.dart';
 import 'package:kdbx/src/internal/byte_utils.dart';
 import 'package:kdbx/src/internal/crypto_utils.dart';
 import 'package:kdbx/src/kdbx_group.dart';
@@ -34,8 +35,10 @@ class Credentials {
   }
 }
 
-class KdbxFile {
+class KdbxFile with Changeable<KdbxFile> {
-  KdbxFile(this.credentials, this.header, this.body);
+  KdbxFile(this.credentials, this.header, this.body) {
+    _subscribeToChildren();
+  }
 
   static final protectedValues = Expando<ProtectedValue>();
 
@@ -43,23 +46,57 @@ class KdbxFile {
     return protectedValues[node];
   }
 
-  static void setProtectedValueForNode(xml.XmlElement node, ProtectedValue value) {
+  static void setProtectedValueForNode(
+      xml.XmlElement node, ProtectedValue value) {
     protectedValues[node] = value;
   }
 
+  final StreamSubscriptions _subscriptions = StreamSubscriptions();
+
   final Credentials credentials;
   final KdbxHeader header;
   final KdbxBody body;
 
   Uint8List save() {
+    assert(header.versionMajor == 3);
     final output = BytesBuilder();
     final writer = WriterHelper(output);
     header.generateSalts();
     header.write(writer);
-    body.write(writer, this);
+
+    final streamKey =
+        header.fields[HeaderFields.ProtectedStreamKey].bytes.asUint8List();
+    final gen = ProtectedSaltGenerator(streamKey);
+
+    body.meta.headerHash.set(
+        (crypto.sha256.convert(writer.output.toBytes()).bytes as Uint8List)
+            .buffer);
+    body.writeV3(writer, this, gen);
     return output.toBytes();
   }
 
+  Iterable<KdbxObject> get _allObjects => body.rootGroup
+      .getAllGroups()
+      .cast<KdbxObject>()
+      .followedBy(body.rootGroup.getAllEntries());
+
+  void _subscribeToChildren() {
+    final allObjects = _allObjects;
+    for (final obj in allObjects) {
+      _subscriptions.handle(obj.changes.listen((event) {
+        if (event.isDirty) {
+          isDirty = true;
+          if (event.object is KdbxGroup) {
+            Future(() {
+              // resubscribe, just in case some child groups/entries have changed.
+              _subscriptions.cancelSubscriptions();
+              _subscribeToChildren();
+            });
+          }
+        }
+      }));
+    }
+  }
 }
 
 class KdbxBody extends KdbxNode {
@@ -77,35 +114,32 @@ class KdbxBody extends KdbxNode {
   final KdbxMeta meta;
   final KdbxGroup rootGroup;
 
-  void write(WriterHelper writer, KdbxFile kdbxFile) {
+  void writeV3(WriterHelper writer, KdbxFile kdbxFile,
-    assert(kdbxFile.header.versionMajor == 3);
-    final streamKey = kdbxFile
-        .header.fields[HeaderFields.ProtectedStreamKey].bytes
-        .asUint8List();
-    final gen = ProtectedSaltGenerator(streamKey);
-
-    _writeV3(writer, kdbxFile, gen);
-  }
-
-  void _writeV3(WriterHelper writer, KdbxFile kdbxFile,
       ProtectedSaltGenerator saltGenerator) {
-    meta.headerHash.set(
-        (crypto.sha256.convert(writer.output.toBytes()).bytes as Uint8List)
-            .buffer);
     final xml = generateXml(saltGenerator);
     final xmlBytes = utf8.encode(xml.toXmlString());
-    final Uint8List compressedBytes = (kdbxFile.header.compression == Compression.gzip ?
+    final Uint8List compressedBytes =
-      GZipCodec().encode(xmlBytes) : xmlBytes) as Uint8List;
+        (kdbxFile.header.compression == Compression.gzip
+            ? GZipCodec().encode(xmlBytes)
+            : xmlBytes) as Uint8List;
 
+    final encrypted = _encryptV3(kdbxFile, compressedBytes);
+    writer.writeBytes(encrypted);
+  }
+
+  Uint8List _encryptV3(KdbxFile kdbxFile, Uint8List compressedBytes) {
     final byteWriter = WriterHelper();
-    byteWriter.writeBytes(kdbxFile.header.fields[HeaderFields.StreamStartBytes].bytes.asUint8List());
+    byteWriter.writeBytes(kdbxFile
+        .header.fields[HeaderFields.StreamStartBytes].bytes
+        .asUint8List());
     HashedBlockReader.writeBlocks(ReaderHelper(compressedBytes), byteWriter);
     final bytes = byteWriter.output.toBytes();
 
-    final masterKey = KdbxFormat._generateMasterKeyV3(kdbxFile.header, kdbxFile.credentials);
+    final masterKey =
-    final encrypted = KdbxFormat._encryptDataAes(masterKey, bytes, kdbxFile.header.fields[HeaderFields.EncryptionIV].bytes.asUint8List());
+        KdbxFormat._generateMasterKeyV3(kdbxFile.header, kdbxFile.credentials);
-//    writer.writeBytes(kdbxFile.header.fields[HeaderFields.StreamStartBytes].bytes.asUint8List());
+    final encrypted = KdbxFormat._encryptDataAes(masterKey, bytes,
-    writer.writeBytes(encrypted);
+        kdbxFile.header.fields[HeaderFields.EncryptionIV].bytes.asUint8List());
+    return encrypted;
   }
 
   xml.XmlDocument generateXml(ProtectedSaltGenerator saltGenerator) {
@@ -124,12 +158,16 @@ class KdbxBody extends KdbxNode {
       }
     }
 
-
     final builder = xml.XmlBuilder();
-    builder.processing('xml', 'version="1.0" encoding="utf-8" standalone="yes"');
+    builder.processing(
-    builder.element('KeePassFile', nest: [
+        'xml', 'version="1.0" encoding="utf-8" standalone="yes"');
+    builder.element(
+      'KeePassFile',
+      nest: [
         meta.toXml(),
-      () => builder.element('Root', nest: rootGroupNode),],);
+        () => builder.element('Root', nest: rootGroupNode),
+      ],
+    );
 //    final doc = xml.XmlDocument();
 //    doc.children.add(xml.XmlProcessing(
 //        'xml', 'version="1.0" encoding="utf-8" standalone="yes"'));
@@ -224,7 +262,8 @@ class KdbxFormat {
     final decryptCipher = CBCBlockCipher(AESFastEngine());
     decryptCipher.init(false,
         ParametersWithIV(KeyParameter(masterKey), encryptionIv.asUint8List()));
-    final paddedDecrypted = AesHelper.processBlocks(decryptCipher, encryptedPayload);
+    final paddedDecrypted =
+        AesHelper.processBlocks(decryptCipher, encryptedPayload);
     final decrypted = AesHelper.unpad(paddedDecrypted);
 
     final streamStart = header.fields[HeaderFields.StreamStartBytes].bytes;
@@ -265,11 +304,12 @@ class KdbxFormat {
     return masterKey;
   }
 
-  static Uint8List _encryptDataAes(Uint8List masterKey, Uint8List payload, Uint8List encryptionIv) {
+  static Uint8List _encryptDataAes(
+      Uint8List masterKey, Uint8List payload, Uint8List encryptionIv) {
     final encryptCipher = CBCBlockCipher(AESFastEngine());
-    encryptCipher.init(true,
+    encryptCipher.init(
-        ParametersWithIV(KeyParameter(masterKey), encryptionIv));
+        true, ParametersWithIV(KeyParameter(masterKey), encryptionIv));
-    return AesHelper.processBlocks(encryptCipher, AesHelper.pad(payload, encryptCipher.blockSize));
+    return AesHelper.processBlocks(
-
+        encryptCipher, AesHelper.pad(payload, encryptCipher.blockSize));
   }
 }

lib/src/kdbx_group.dart

@@ -1,3 +1,4 @@
+import 'package:kdbx/src/internal/async_utils.dart';
 import 'package:kdbx/src/kdbx_consts.dart';
 import 'package:kdbx/src/kdbx_entry.dart';
 import 'package:kdbx/src/kdbx_xml.dart';
@@ -7,7 +8,8 @@ import 'package:xml/xml.dart';
 import 'kdbx_object.dart';
 
 class KdbxGroup extends KdbxObject {
-  KdbxGroup.create({@required this.parent, @required String name}) : super.create('Group') {
+  KdbxGroup.create({@required this.parent, @required String name})
+      : super.create('Group') {
     this.name.set(name);
     icon.set(KdbxIcon.Folder);
     expanded.set(true);
@@ -24,6 +26,8 @@ class KdbxGroup extends KdbxObject {
         .forEach(_entries.add);
   }
 
+  final StreamSubscriptions _subscriptions = StreamSubscriptions();
+
   @override
   XmlElement toXml() {
     final el = super.toXml();
@@ -46,18 +50,22 @@ class KdbxGroup extends KdbxObject {
   /// null if this is the root group.
   final KdbxGroup parent;
   final List<KdbxGroup> groups = [];
+
   List<KdbxEntry> get entries => List.unmodifiable(_entries);
   final List<KdbxEntry> _entries = [];
 
   void addEntry(KdbxEntry entry) {
     if (entry.parent != this) {
-      throw StateError('Invalid operation. Trying to add entry which is already in another group.');
+      throw StateError(
+          'Invalid operation. Trying to add entry which is already in another group.');
     }
     _entries.add(entry);
     node.children.add(entry.node);
+    isDirty = true;
   }
 
   StringNode get name => StringNode(this, 'Name');
+
 //  String get name => text('Name') ?? '';
   BooleanNode get expanded => BooleanNode(this, 'IsExpanded');
 }

lib/src/kdbx_object.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:typed_data';
 
@@ -8,8 +9,29 @@ import 'package:uuid/uuid.dart';
 import 'package:uuid/uuid_util.dart';
 import 'package:xml/xml.dart';
 
-abstract class KdbxNode {
+class ChangeEvent<T> {
-  KdbxNode.create(String nodeName) : node = XmlElement(XmlName(nodeName));
+  ChangeEvent({this.object, this.isDirty});
+
+  final T object;
+  final bool isDirty;
+}
+
+mixin Changeable<T> {
+  final _controller = StreamController<ChangeEvent<T>>.broadcast();
+  Stream<ChangeEvent<T>> get changes => _controller.stream;
+
+  bool _isDirty = false;
+  set isDirty(bool dirty) {
+    _isDirty = dirty;
+    _controller.add(ChangeEvent(object: this as T, isDirty: dirty));
+  }
+  bool get isDirty => _isDirty;
+}
+
+abstract class KdbxNode with Changeable<KdbxNode> {
+  KdbxNode.create(String nodeName) : node = XmlElement(XmlName(nodeName)) {
+    isDirty = true;
+  }
 
   KdbxNode.read(this.node);
 
@@ -18,8 +40,6 @@ abstract class KdbxNode {
 //  @protected
 //  String text(String nodeName) => _opt(nodeName)?.text;
 
-  KdbxSubTextNode textNode(String nodeName) => StringNode(this, nodeName);
-
   @mustCallSuper
   XmlElement toXml() {
     final el = node.copy() as XmlElement;
@@ -42,6 +62,12 @@ abstract class KdbxObject extends KdbxNode {
 
   IconNode get icon => IconNode(this, 'IconID');
 
+  @override
+  set isDirty(bool dirty) {
+    super.isDirty = dirty;
+    times.modifiedNow();
+  }
+
   @override
   XmlElement toXml() {
     final el = super.toXml();

lib/src/kdbx_times.dart

@@ -27,6 +27,11 @@ class KdbxTimes extends KdbxNode {
   DateTimeUtcNode get locationChanged => DateTimeUtcNode(this, 'LocationChanged');
 
   void accessedNow() {
-    lastAccessTime.set(clock.now());
+    lastAccessTime.set(clock.now().toUtc());
+  }
+
+  void modifiedNow() {
+    accessedNow();
+    lastModificationTime.set(clock.now().toUtc());
   }
 }

lib/src/kdbx_xml.dart

@@ -41,6 +41,7 @@ abstract class KdbxSubTextNode<T> extends KdbxSubNode<T> {
 
   @override
   void set(T value) {
+    node.isDirty = true;
     final el =
         node.node.findElements(name).singleWhere((x) => true, orElse: () {
       final el = XmlElement(XmlName(name));