feat: task file manage (#196)

1. support view task file list
2. support share file on android and iOS

ui/flutter/lib/app/modules/task/controllers/task_files_controller.dart

@@ -0,0 +1,86 @@
+import 'package:get/get.dart';
+import '../../../../api/api.dart';
+import '../../../../api/model/resource.dart';
+import '../../../../api/model/task.dart';
+
+class FileItem {
+  final bool isDirectory;
+  final String path;
+  final String name;
+  final int size;
+
+  FileItem(this.isDirectory, this.path, this.name, this.size);
+
+  String get fullPath => "${path == "/" ? path : "$path/"}$name";
+}
+
+class TaskFilesController extends GetxController {
+  final Map<String, List<FileItem>> _dirMap = {};
+
+  final task = Rx<Task?>(null);
+  final fileList = <FileItem>[].obs;
+
+  @override
+  void onInit() async {
+    super.onInit();
+
+    final taskId = Get.rootDelegate.parameters['id'];
+    final tasks = await getTasks([]);
+    task.value = tasks.firstWhere((element) => element.id == taskId);
+    parseDirMap(task.value!.meta.res.files);
+    toDir("/");
+  }
+
+  void parseDirMap(List<FileInfo> fileList) {
+    for (final file in fileList) {
+      String dir = file.path;
+      if (!dir.startsWith("/")) {
+        dir = "/$dir";
+      }
+      if (!_dirMap.containsKey(dir)) {
+        _dirMap[dir] = [];
+      }
+
+      _dirMap[dir]!.add(FileItem(false, dir, file.name, file.size));
+
+      void findParent(String dir) {
+        final parentDirIndex = dir.lastIndexOf("/");
+        String parentDir =
+            parentDirIndex == 0 ? "/" : dir.substring(0, parentDirIndex);
+        if (!_dirMap.containsKey(parentDir)) {
+          _dirMap[parentDir] = [];
+        }
+        String dirName = dir.substring(dir.lastIndexOf("/") + 1);
+        if (!_dirMap[parentDir]!.any((element) => element.name == dirName)) {
+          _dirMap[parentDir]!.add(FileItem(true, parentDir, dirName, 0));
+        }
+      }
+
+      while (dir != "/" && dir != "") {
+        findParent(dir);
+        dir = dir.substring(0, dir.lastIndexOf("/"));
+      }
+    }
+
+    // sort children, directories first then files, alphabetically
+    _dirMap.forEach((key, value) {
+      value.sort((a, b) {
+        if (a.isDirectory && !b.isDirectory) {
+          return -1;
+        } else if (!a.isDirectory && b.isDirectory) {
+          return 1;
+        } else {
+          return a.name.compareTo(b.name);
+        }
+      });
+    });
+  }
+
+  void toDir(String dir) {
+    fileList.value = _dirMap[dir]?.toList() ?? [];
+  }
+
+  int dirItemCount(String dir) {
+    return _dirMap[dir]?.length ?? 0;
+  }
+}