import 'dart:async';
import 'dart:typed_data';

import 'package:flutter_bluetooth_serial/flutter_bluetooth_serial.dart';

import '../logging/app_log.dart';

/// Wraps flutter_bluetooth_serial for SPP/RFCOMM Classic BT.
///
/// Every platform call is wrapped in a timeout and try/catch: the plugin is
/// old and some Android builds throw (or never answer) on connect/close.
class BtService {
  BluetoothConnection? _connection;
  StreamSubscription<Uint8List>? _inputSub;
  bool _connecting = false;

  final StreamController<Uint8List> _rawFrameController =
      StreamController<Uint8List>.broadcast();

  bool get isConnected {
    try {
      return _connection?.isConnected ?? false;
    } catch (_) {
      return false;
    }
  }

  Stream<Uint8List> get rawStream => _rawFrameController.stream;

  Future<List<BluetoothDevice>> getPairedDevices() async {
    return FlutterBluetoothSerial.instance.getBondedDevices();
  }

  Future<void> connect(BluetoothDevice device) async {
    if (_connecting) {
      throw StateError('A connection attempt is already in progress');
    }
    _connecting = true;
    try {
      if (_connection != null) {
        await disconnect();
      }
      AppLog.i('Connecting to ${device.name ?? '?'} (${device.address})');
      final conn = await BluetoothConnection.toAddress(device.address)
          .timeout(const Duration(seconds: 15));
      _connection = conn;
      _inputSub = conn.input?.listen(
        (Uint8List data) {
          if (!_rawFrameController.isClosed) _rawFrameController.add(data);
        },
        onDone: () {
          AppLog.w('BT input stream closed by remote/OS');
          if (!_rawFrameController.isClosed && identical(_connection, conn)) {
            _rawFrameController.addError('BT connection closed');
          }
        },
        onError: (Object e) {
          AppLog.w('BT input error: $e');
          if (!_rawFrameController.isClosed) _rawFrameController.addError(e);
        },
        cancelOnError: false,
      );
      AppLog.i('Connected');
    } on TimeoutException {
      AppLog.w('Connect timed out');
      throw Exception('Connection timed out — is the adapter powered and '
          'not connected to another phone?');
    } finally {
      _connecting = false;
    }
  }

  Future<void> write(Uint8List data) async {
    final conn = _connection;
    if (conn == null || !isConnected) {
      throw StateError('Not connected');
    }
    conn.output.add(data);
    await conn.output.allSent;
  }

  Future<void> disconnect() async {
    final conn = _connection;
    _connection = null;
    await _inputSub?.cancel();
    _inputSub = null;
    if (conn == null) return;
    try {
      await conn.close().timeout(const Duration(seconds: 3));
    } catch (e) {
      AppLog.w('BT close error (ignored): $e');
    }
  }

  void dispose() {
    disconnect();
    _rawFrameController.close();
  }
}