import 'dart:convert';

/// 串口奇偶校验
enum SerialParity { none, odd, even, mark, space }

/// 串口流控
enum SerialFlowControl { none, rtsCts, xonXoff, dtrDsr }

/// 串口配置
///
/// 持久化到 settings 表的 `serial_config` key 中；
/// 打开串口时根据此配置构造底层 `UsbConfig`。
class SerialConfig {
  /// 设备 Vendor ID（十六进制）
  final int vendorId;

  /// 设备 Product ID（十六进制），0 表示不指定
  final int productId;

  /// 波特率
  final int baudRate;

  /// 数据位 (5/6/7/8)
  final int dataBits;

  /// 停止位 (1/2)
  final int stopBits;

  /// 校验位
  final SerialParity parity;

  /// 流控
  final SerialFlowControl flowControl;

  /// 读超时（毫秒）
  final int readTimeoutMs;

  /// 写超时（毫秒）
  final int writeTimeoutMs;

  const SerialConfig({
    this.vendorId = 0x1A86,
    this.productId = 0x7523,
    this.baudRate = 9600,
    this.dataBits = 8,
    this.stopBits = 1,
    this.parity = SerialParity.none,
    this.flowControl = SerialFlowControl.none,
    this.readTimeoutMs = 2000,
    this.writeTimeoutMs = 2000,
  });

  /// 默认配置
  static const SerialConfig defaults = SerialConfig();

  /// 常用波特率
  static const List<int> commonBaudRates = [
    1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800,
  ];

  SerialConfig copyWith({
    int? vendorId,
    int? productId,
    int? baudRate,
    int? dataBits,
    int? stopBits,
    SerialParity? parity,
    SerialFlowControl? flowControl,
    int? readTimeoutMs,
    int? writeTimeoutMs,
  }) {
    return SerialConfig(
      vendorId: vendorId ?? this.vendorId,
      productId: productId ?? this.productId,
      baudRate: baudRate ?? this.baudRate,
      dataBits: dataBits ?? this.dataBits,
      stopBits: stopBits ?? this.stopBits,
      parity: parity ?? this.parity,
      flowControl: flowControl ?? this.flowControl,
      readTimeoutMs: readTimeoutMs ?? this.readTimeoutMs,
      writeTimeoutMs: writeTimeoutMs ?? this.writeTimeoutMs,
    );
  }

  /// 编码为 JSON 字符串（用于持久化）
  String toJsonString() => jsonEncode({
        'vendorId': vendorId,
        'productId': productId,
        'baudRate': baudRate,
        'dataBits': dataBits,
        'stopBits': stopBits,
        'parity': parity.name,
        'flowControl': flowControl.name,
        'readTimeoutMs': readTimeoutMs,
        'writeTimeoutMs': writeTimeoutMs,
      });

  /// 从 JSON 字符串解码；解析失败时返回默认值
  factory SerialConfig.fromJsonString(String? raw) {
    if (raw == null || raw.isEmpty) return defaults;
    try {
      final map = jsonDecode(raw) as Map<String, dynamic>;
      return SerialConfig(
        vendorId: (map['vendorId'] as num?)?.toInt() ?? defaults.vendorId,
        productId: (map['productId'] as num?)?.toInt() ?? defaults.productId,
        baudRate: (map['baudRate'] as num?)?.toInt() ?? defaults.baudRate,
        dataBits: (map['dataBits'] as num?)?.toInt() ?? defaults.dataBits,
        stopBits: (map['stopBits'] as num?)?.toInt() ?? defaults.stopBits,
        parity: SerialParity.values.firstWhere(
          (e) => e.name == map['parity'],
          orElse: () => defaults.parity,
        ),
        flowControl: SerialFlowControl.values.firstWhere(
          (e) => e.name == map['flowControl'],
          orElse: () => defaults.flowControl,
        ),
        readTimeoutMs:
            (map['readTimeoutMs'] as num?)?.toInt() ?? defaults.readTimeoutMs,
        writeTimeoutMs:
            (map['writeTimeoutMs'] as num?)?.toInt() ?? defaults.writeTimeoutMs,
      );
    } catch (_) {
      return defaults;
    }
  }
}