cake_wallet/cw_core/lib/root_dir.dart

import 'dart:io';
import 'package:path_provider/path_provider.dart';

String? _rootDirPath;

void setRootDirFromEnv() => _rootDirPath = Platform.environment['CAKE_WALLET_DIR'];

Future<Directory> getAppDir({String appName = 'cake_wallet'}) async {
  Directory dir;

  if (_rootDirPath != null && _rootDirPath!.isNotEmpty) {
    dir = Directory.fromUri(Uri.file(_rootDirPath!));
    dir.create(recursive: true);
  } else {
    if (Platform.isWindows) {
      dir = await getApplicationSupportDirectory();
    } else if (Platform.isLinux) {
      String appDirPath;

      try {
        dir = await getApplicationDocumentsDirectory();
        appDirPath = '${dir.path}/$appName';
      } catch (e) {
        appDirPath = '/home/${Platform.environment['USER']}/.$appName';
      }

      dir = Directory.fromUri(Uri.file(appDirPath));
      await dir.create(recursive: true);
    } else {
      dir = await getApplicationDocumentsDirectory();
    }
  }

  return dir;
}