add askar scan

lib/askar/askar_wrapper.dart

@@ -1198,21 +1198,15 @@ Future<AskarResult<EntryListHandle>> askarScanNext(ScanHandle handle) async {
       completedResult.errorCode, EntryListHandle(completedResult.value));
 }
 
-Future<AskarResult<ScanHandle>> askarScanStart(
-  StoreHandle handle,
-  String profile,
-  String category,
-  Map tagFilter,
-  int offset,
-  int limit,
-) async {
+Future<AskarResult<ScanHandle>> askarScanStart(StoreHandle handle,
+    {String? profile, String? category, Map? tagFilter, int? offset, int? limit}) async {
   Pointer<Utf8> profilePointer = nullptr;
   Pointer<Utf8> categoryPointer = nullptr;
   Pointer<Utf8> tagFilterPointer = nullptr;
 
   try {
-    profilePointer = profile.toNativeUtf8();
-    categoryPointer = category.toNativeUtf8();
+    profilePointer = (profile ?? "").toNativeUtf8();
+    categoryPointer = (category ?? "").toNativeUtf8();
     tagFilterPointer = jsonEncode(tagFilter).toNativeUtf8();
 
     final callback = newCallbackWithHandle();
@@ -1222,8 +1216,8 @@ Future<AskarResult<ScanHandle>> askarScanStart(
       profilePointer,
       categoryPointer,
       tagFilterPointer,
-      offset,
-      limit,
+      (offset ?? 0),
+      (limit ?? 0),
       callback.nativeCallable.nativeFunction,
       callback.id,
     );

lib/askar/store/scan.dart

@@ -0,0 +1,82 @@
+import 'package:askar_flutter_sdk/askar/askar_wrapper.dart';
+import 'package:askar_flutter_sdk/askar/crypto/handles.dart';
+import 'package:askar_flutter_sdk/askar/exceptions/exceptions.dart';
+
+import 'entry.dart';
+import 'entry_list.dart';
+import 'store.dart';
+
+class Scan {
+  ScanHandle? handle;
+  final Store store;
+  final String? profile;
+  final String category;
+  final Map<String, dynamic>? tagFilter;
+  final int? offset;
+  final int? limit;
+  final String? orderBy;
+  final bool? descending;
+
+  Scan({
+    required this.store,
+    required this.category,
+    this.profile,
+    this.tagFilter,
+    this.offset,
+    this.limit,
+    this.orderBy,
+    this.descending,
+  });
+
+  Future<List<EntryObject>> fetchAll() async {
+    final rows = <EntryObject>[];
+    await _forEachRow((row, _) => rows.add(row.toJson()));
+    return rows;
+  }
+
+  Future<void> _forEachRow(void Function(Entry row, int? index) cb) async {
+    _initHandle();
+
+    try {
+      int recordCount = 0;
+
+      while (limit == null || recordCount < limit!) {
+        final scanResult = await askarScanNext(handle!);
+
+        if (!scanResult.errorCode.isSuccess()) {
+          break;
+        }
+
+        final list = EntryList(handle: scanResult.value);
+
+        recordCount += list.length;
+        for (int i = 0; i < list.length; i++) {
+          final entry = list.getEntryByIndex(i);
+          cb(entry, i);
+        }
+
+        askarEntryListFree(list.handle);
+      }
+    } catch (e) {
+      AskarScanException('Failed to scan: $e');
+    } finally {
+      if (handle != null) {
+        askarScanFree(handle!);
+      }
+    }
+  }
+
+  Future<void> _initHandle() async {
+    try {
+      handle ??= (await askarScanStart(store.handle,
+              profile: profile,
+              category: category,
+              limit: limit,
+              offset: offset,
+              tagFilter: tagFilter))
+          .getValueOrException();
+    } catch (e) {
+      AskarScanException('Failed to start scan: $e');
+    }
+  }
+}

test/askar_test.dart

@@ -650,8 +650,14 @@ Future<AskarResult<ScanHandle>> scanStartTest(
   final int offset = 0;
   final int limit = 2;
 
-  final result =
-      await askarScanStart(handle, profile, category, tagFilter, offset, limit);
+  final result = await askarScanStart(
+    handle,
+    profile: profile,
+    category: category,
+    tagFilter: tagFilter,
+    offset: offset,
+    limit: limit,
+  );
 
   printAskarResult('ScanStart', result);