import 'dart:convert';
import 'dart:io';
import 'dart:typed_data';

class PathHelper {
  String pth = "";
  PathHelper({required this.pth});

  static String combine(String path1, String path2) {
    return path1 + Platform.pathSeparator + path2;
  }

  static PathHelper builder(String startPath) {
    return PathHelper(pth: startPath);
  }

  bool exists() {
    File fi = File(build());
    Directory dir = Directory(build());

    return fi.existsSync() || dir.existsSync();
  }

  PathHelper clone() {
    return PathHelper.builder(build());
  }

  PathHelper resolve(String path2) {
    pth += Platform.pathSeparator + path2;
    return this;
  }

  PathHelper conditionalResolve(bool flag, String path) {
    if (flag) pth += Platform.pathSeparator + path;
    return this;
  }

  bool deleteDirectory({bool recursive = false}) {
    Directory dir = new Directory(build());
    try {
      dir.deleteSync(recursive: recursive);

      return true;
    } catch (E) {
      return false;
    }
  }

  bool deleteFile() {
    File file = new File(build());
    try {
      file.deleteSync(recursive: true);

      return true;
    } catch (E) {
      return false;
    }
  }

  PathHelper removeDir() {
    deleteDirectory(recursive: true);
    return this;
  }

  PathHelper removeFile() {
    deleteFile();
    return this;
  }

  PathHelper mkdir() {
    Directory dir = new Directory(build());
    dir.createSync(recursive: true);

    return this;
  }

  String build() {
    return pth;
  }
}

Stream<List<int>> tail(final File file) async* {
  final randomAccess = await file.open(mode: FileMode.read);
  var pos = await randomAccess.position();
  var len = await randomAccess.length();
  // Increase/decrease buffer size as needed.
  var buf = Uint8List(8192);

  Stream<Uint8List> _read() async* {
    while (pos < len) {
      try {
        final bytesRead = await randomAccess.readInto(buf);
        pos += bytesRead;

        yield buf.sublist(0, bytesRead);
      } catch (E) {}
    }
  }

  // Step 1: read whole file
  yield* _read();

  // Step 2: wait for modify events and read more bytes from file
  await for (final event in file.watch(events: FileSystemEvent.modify)) {
    if ((event as FileSystemModifyEvent).contentChanged) {
      try {
        len = await (randomAccess.length());
        yield* _read();
      } catch (E) {}
    }
  }
}

void tailAndPrint(File file) {
  try {
    tail(file)
        .transform(utf8.decoder)
        .transform(LineSplitter())
        .forEach((line) {
      // Do something with the line that has been read, e.g. print it out...
      print(line);
    });
  } catch (E) {}
}