add method to fetch all assets in an assetPath

lib/utils/file_sync_util.dart

@@ -7,6 +7,7 @@ import 'package:photos/models/file.dart';
 
 final _logger = Logger("FileSyncUtil");
 final ignoreSizeConstraint = SizeConstraint(ignoreSize: true);
+final assetFetchPageSize = 2000;
 Future<List<File>> getDeviceFiles(
     int fromTime, int toTime, Computer computer) async {
   final pathEntities = await _getGalleryList(fromTime, toTime);
@@ -41,8 +42,7 @@ Future<List<LocalAsset>> getAllLocalAssets() async {
   );
   final List<LocalAsset> assets = [];
   for (final assetPath in assetPaths) {
-    for (final asset
-        in await assetPath.getAssetListPaged(page: 0, size: 10000)) {
+    for (final asset in await _getAllAssetLists(assetPath)) {
       assets.add(LocalAsset(asset.id, assetPath.name));
     }
   }
@@ -134,12 +134,25 @@ Future<List<File>> _computeFiles(AssetPathEntity pathEntity, int fromTime,
     List<File> files, Computer computer) async {
   final args = Map<String, dynamic>();
   args["pathEntity"] = pathEntity;
-  args["assetList"] = await pathEntity.getAssetListPaged(page: 0, size: 10000);
+  args["assetList"] = await _getAllAssetLists(pathEntity);
   args["fromTime"] = fromTime;
   args["files"] = files;
   return await computer.compute(_getFiles, param: args);
 }
 
+Future<List<AssetEntity>> _getAllAssetLists(AssetPathEntity pathEntity) async {
+  List<AssetEntity> result = [];
+  int currentPage = 0;
+  List<AssetEntity> currentPageResult = [];
+  do {
+    currentPageResult = await pathEntity.getAssetListPaged(
+        page: currentPage, size: assetFetchPageSize);
+    result.addAll(currentPageResult);
+    currentPage = currentPage + 1;
+  } while (currentPageResult.length >= assetFetchPageSize);
+  return result;
+}
+
 Future<List<File>> _getFiles(Map<String, dynamic> args) async {
   final pathEntity = args["pathEntity"];
   final assetList = args["assetList"];