import 'dart:async';
import 'dart:convert';
import 'dart:io';

import 'package:quasar_jet/services/singbox_runtime.dart';

final class SingBoxService {
  SingBoxService({SingBoxRuntime? runtime}) : _runtime = runtime ?? SingBoxRuntime();

  final SingBoxRuntime _runtime;
  final StreamController<String> _logController =
      StreamController<String>.broadcast();

  Process? _process;

  Stream<String> get logs => _logController.stream;
  bool get isRunning => _process != null;

  Future<void> prepare() async {
    await _runtime.ensureBinary();
  }

  Future<bool> start(String configJson) async {
    if (_process != null) {
      return true;
    }

    if (!Platform.isLinux) {
      throw UnsupportedError('SingBoxService supports Linux only');
    }

    try {
      jsonDecode(configJson);
    } catch (_) {
      _logController.add('Config is not valid JSON for sing-box');
      return false;
    }

    final String binaryPath = await _runtime.ensureBinary();
    final String configPath = await _runtime.configPath();
    await File(configPath).writeAsString(configJson, flush: true);

    final List<String> command = <String>[
      'pkexec',
      binaryPath,
      'run',
      '-c',
      configPath,
    ];

    try {
      _process = await Process.start(command.first, command.sublist(1));

      _process!.stdout
          .transform(utf8.decoder)
          .listen((String data) => _logController.add(data));
      _process!.stderr
          .transform(utf8.decoder)
          .listen((String data) => _logController.add('ERROR: $data'));

      _process!.exitCode.then((int code) {
        _logController.add('sing-box exited with code $code');
        _process = null;
      });
      return true;
    } catch (error) {
      _logController.add('Start failed: $error');
      _process = null;
      return false;
    }
  }

  Future<void> stop() async {
    final Process? process = _process;
    if (process == null) {
      return;
    }

    process.kill(ProcessSignal.sigterm);
    await process.exitCode.timeout(const Duration(seconds: 3), onTimeout: () {
      process.kill(ProcessSignal.sigkill);
      return -1;
    });
    _process = null;
  }

  Future<void> dispose() async {
    await stop();
    await _logController.close();
  }
}