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

import 'package:ch934x_serial/ch934x_serial.dart';
import 'package:flutter/material.dart';

/// CH934X 插件示例应用,演示:
/// 1. 设备查找;
/// 2. 串口打开/关闭;
/// 3. 数据发送与接收(GPIO/Modem 控制以按钮形式呈现)。
void main() {
  runApp(const Ch934xSerialExampleApp());
}

class Ch934xSerialExampleApp extends StatelessWidget {
  const Ch934xSerialExampleApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'CH934X Serial Example',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.indigo),
        useMaterial3: true,
      ),
      home: const Ch934xSerialExamplePage(),
    );
  }
}

class Ch934xSerialExamplePage extends StatefulWidget {
  const Ch934xSerialExamplePage({super.key});

  @override
  State<Ch934xSerialExamplePage> createState() =>
      _Ch934xSerialExamplePageState();
}

class _Ch934xSerialExamplePageState extends State<Ch934xSerialExamplePage> {
  final Ch934xSerial _plugin = Ch934xSerial();
  final TextEditingController _commandController =
      TextEditingController(text: '*IDN?\n');

  List<Ch934xDeviceInfo> _devices = const <Ch934xDeviceInfo>[];
  Ch934xDeviceInfo? _selectedDevice;
  /// 当前选中设备的可用串口索引集合(由 SDK getSerialCount 决定)。
  List<int> _availablePortIndices = const <int>[];
  int? _selectedPortIndex;
  StreamSubscription<Ch934xException>? _exceptionSubscription;
  StreamSubscription<Uint8List>? _dataSubscription;

  String _status = '未连接';
  String _receivedBuffer = '';
  bool _portOpened = false;

  @override
  void initState() {
    super.initState();
    _bindExceptionCallback();
    _refreshDeviceList();
  }

  @override
  void dispose() {
    _exceptionSubscription?.cancel();
    _dataSubscription?.cancel();
    if (_portOpened) {
      // 关闭串口,保证释放 USB 接口。
      _plugin.closePort();
    }
    _commandController.dispose();
    super.dispose();
  }

  /// 注册异常回调(对应 7.3.1)。
  Future<void> _bindExceptionCallback() async {
    _exceptionSubscription = await _plugin.setExceptionCallback((event) {
      if (!mounted) return;
      setState(() {
        _status = '设备异常: $event';
        _portOpened = false;
        _dataSubscription?.cancel();
        _dataSubscription = null;
      });
    });
  }

  /// 触发设备列表刷新(对应 4.1.4)。
  Future<void> _refreshDeviceList() async {
    try {
      final devices = await _plugin.getDeviceList();
      if (!mounted) return;
      setState(() {
        _devices = devices;
        // 清理已不再列表中的旧选项,避免 DropdownButton value 不在 items 中报错。
        final selected = _selectedDevice;
        if (selected != null && !devices.contains(selected)) {
          _selectedDevice = null;
          _availablePortIndices = const <int>[];
          _selectedPortIndex = null;
        } else if (selected != null) {
          _availablePortIndices = _resolvePortIndices(selected);
          final current = _selectedPortIndex;
          if (current == null || !_availablePortIndices.contains(current)) {
            _selectedPortIndex = _availablePortIndices.isNotEmpty
                ? _availablePortIndices.first
                : null;
          }
        }
        _status = '已扫描到 ${devices.length} 台 CH934X 设备';
      });
    } on Exception catch (e) {
      if (!mounted) return;
      setState(() => _status = '设备扫描失败: $e');
    }
  }

  /// 把设备的串口描述转换为可用索引列表。
  ///
  /// 优先使用 SDK 返回的 [Ch934xSerialPortInfo.portIndex],缺
  /// 失时回退到 0..N-1,确保 UI 始终有可选项。
  List<int> _resolvePortIndices(Ch934xDeviceInfo device) {
    if (device.serialPorts.isNotEmpty) {
      return device.serialPorts.map((p) => p.portIndex).toList()..sort();
    }
    if (device.interfaceCount > 0) {
      return List<int>.generate(device.interfaceCount, (i) => i);
    }
    // 最坏情况下,允许打开串口 0;用户可通过业务调用切换。
    return const <int>[0];
  }

  Future<void> _openPort() async {
    final device = _selectedDevice;
    final portIndex = _selectedPortIndex;
    if (device == null || portIndex == null) {
      setState(() => _status = '请先选择设备与串口');
      return;
    }
    final target = Ch934xPortTarget(
      deviceId: device.deviceId,
      interfaceNumber: 0,
      serialPortIndex: portIndex,
    );
    final ok = await _plugin.openPort(target);
    if (!ok) {
      setState(() => _status = '打开串口失败,请确认已授予 USB 权限');
      return;
    }
    setState(() {
      _portOpened = true;
      _status = '串口 $portIndex 已打开';
    });
    _startReceiving();
  }

  Future<void> _closePort() async {
    await _dataSubscription?.cancel();
    _dataSubscription = null;
    final ok = await _plugin.closePort();
    setState(() {
      _portOpened = false;
      _status = ok ? '串口已关闭' : '关闭串口失败';
    });
  }

  /// 启动数据流订阅(基于 [Ch934xSerial.dataStream])。
  void _startReceiving() {
    _dataSubscription?.cancel();
    _dataSubscription = _plugin.dataStream().listen((chunk) {
      final text = String.fromCharCodes(chunk);
      setState(() => _receivedBuffer = '$_receivedBuffer$text');
    });
  }

  /// 发送命令,展示 [Ch934xSerial.write] 的用法。
  Future<void> _sendCommand() async {
    if (!_portOpened) {
      setState(() => _status = '请先打开串口');
      return;
    }
    final data = Uint8List.fromList(_commandController.text.codeUnits);
    final written = await _plugin.write(data);
    setState(() => _status = '已写入 $written 字节');
  }

  /// 查询 Modem 状态,展示 7.2.2 接口。
  Future<void> _queryModemStatus() async {
    if (!_portOpened) return;
    final status = await _plugin.getModemStatus();
    setState(() {
      _status = 'Modem 状态位: 0x${status.toRadixString(16).padLeft(2, '0')} '
          '(CTS=${ModemStatus.isSet(status, ModemStatus.cts)}, '
          'DSR=${ModemStatus.isSet(status, ModemStatus.dsr)})';
    });
  }

  /// 控制 DTR/RTS,展示 7.2.1 接口。
  Future<void> _toggleModem() async {
    if (!_portOpened) return;
    final ok = await _plugin.setModemControl(dtr: 1, rts: 1);
    setState(() => _status = ok ? 'DTR/RTS 置高' : 'Modem 控制失败');
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('CH934X Serial Example'),
        actions: [
          IconButton(
            tooltip: '刷新设备列表',
            icon: const Icon(Icons.refresh),
            onPressed: _refreshDeviceList,
          ),
        ],
      ),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: ListView(
          children: [
            Text('状态: $_status'),
            const SizedBox(height: 8),
            if (_devices.isEmpty)
              const Card(
                child: ListTile(
                  leading: Icon(Icons.usb_off),
                  title: Text('未发现 CH934X 设备'),
                  subtitle: Text('请确认 OTG 已连接,并授予 USB 权限'),
                ),
              )
            else
              DropdownButton<Ch934xDeviceInfo>(
                isExpanded: true,
                value: _selectedDevice,
                hint: const Text('选择 CH934X 设备'),
                items: _devices
                    .map(
                      (d) => DropdownMenuItem<Ch934xDeviceInfo>(
                        value: d,
                        child: Text(
                          'VID=0x${d.vendorId.toRadixString(16)} '
                          'PID=0x${d.productId.toRadixString(16)} '
                          'SN=${d.serialNumber ?? "-"}',
                        ),
                      ),
                    )
                    .toList(),
                onChanged: (device) {
                  setState(() {
                    _selectedDevice = device;
                    if (device == null) {
                      _availablePortIndices = const <int>[];
                      _selectedPortIndex = null;
                    } else {
                      _availablePortIndices = _resolvePortIndices(device);
                      _selectedPortIndex = _availablePortIndices.isNotEmpty
                          ? _availablePortIndices.first
                          : null;
                    }
                  });
                },
              ),
            if (_selectedDevice != null) ...[
              const SizedBox(height: 8),
              DropdownButton<int>(
                isExpanded: true,
                value: _selectedPortIndex,
                hint: const Text('选择串口'),
                items: _availablePortIndices
                    .map(
                      (idx) => DropdownMenuItem<int>(
                        value: idx,
                        child: Text('port #$idx'),
                      ),
                    )
                    .toList(),
                onChanged: (idx) => setState(() => _selectedPortIndex = idx),
              ),
            ],
            const SizedBox(height: 16),
            Row(
              children: [
                Expanded(
                  child: FilledButton.icon(
                    onPressed: _portOpened ? null : _openPort,
                    icon: const Icon(Icons.power_settings_new),
                    label: const Text('打开'),
                  ),
                ),
                const SizedBox(width: 8),
                Expanded(
                  child: OutlinedButton.icon(
                    onPressed: _portOpened ? _closePort : null,
                    icon: const Icon(Icons.close),
                    label: const Text('关闭'),
                  ),
                ),
              ],
            ),
            const SizedBox(height: 16),
            TextField(
              controller: _commandController,
              decoration: const InputDecoration(
                labelText: '发送数据',
                border: OutlineInputBorder(),
              ),
              maxLines: 3,
            ),
            const SizedBox(height: 8),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                FilledButton.icon(
                  onPressed: _sendCommand,
                  icon: const Icon(Icons.send),
                  label: const Text('写入'),
                ),
                OutlinedButton.icon(
                  onPressed: _queryModemStatus,
                  icon: const Icon(Icons.info_outline),
                  label: const Text('查询 Modem'),
                ),
                OutlinedButton.icon(
                  onPressed: _toggleModem,
                  icon: const Icon(Icons.cable),
                  label: const Text('DTR/RTS=1'),
                ),
                OutlinedButton.icon(
                  onPressed: () async {
                    if (!_portOpened) return;
                    final v = await _plugin.getGpioInput(0);
                    if (!mounted) return;
                    setState(() => _status = 'GPIO0 = $v');
                  },
                  icon: const Icon(Icons.input),
                  label: const Text('读取 GPIO0'),
                ),
              ],
            ),
            const SizedBox(height: 16),
            Text(
              '接收缓冲区:\n$_receivedBuffer',
              style: const TextStyle(fontFamily: 'monospace'),
            ),
          ],
        ),
      ),
    );
  }
}