desktop-plugin/lib/print/pavo/pavo_backend.dart

import 'dart:isolate';
import 'dart:typed_data';

import 'package:ffi/ffi.dart';

import '../../image/card_image.dart';
import '../../server/protocol.dart';
import '../backend.dart';
import '../cups_backend.dart' show noopLog;
import 'pavo_ffi.dart';
import 'pavo_printer.dart';

/// Windows 打印后端：HiTi PavoApi 直打（BGR/K 分层 BITMAP）。
///
/// 所有 ffi 调用（含像素转换的 CPU 密集计算）都放进 `Isolate.run`：
/// PavoApi 的同步调用最长可阻塞数秒（发送 2MB 像素）、打印轮询最长 3 分钟，
/// 放独立 isolate 保证主 isolate 的 HTTP 服务（任务状态轮询）不被卡住。
///
/// **重要**：传给 Isolate.run 的闭包/函数不得捕获任何实例状态（this 链会经
/// onLog→AgentLog→StreamController→UI 订阅链一路拽到 Timer 等 unsendable 对象，
/// isolate 消息序列化直接抛 "Illegal argument in isolate message"）——
/// 因此 isolate 入口全部是顶层函数，只以纯数据（字符串）进出。
class PavoPrintBackend implements PrintBackend {
  PavoPrintBackend({void Function(String line)? onLog}) : _log = onLog ?? noopLog;

  final void Function(String line) _log;

  @override
  String get name => 'pavo';

  @override
  Future<PrinterStatus> getStatus() => Isolate.run(pavoStatusSync);

  @override
  Future<void> printOneCard(PrintRequest request) {
    _log('Pavo 直打任务开始（份数 ${request.copies}，后端在子 isolate 执行）');
    final front = request.front!;
    final back = request.back;
    // 先解出纯数据再进闭包：闭包只捕获字符串/整数（最小捕获面，杜绝实例链）
    final frontColor = front.color;
    final frontK = front.k;
    final backColor = back?.color;
    final backK = back?.k;
    final copies = request.copies;
    return Isolate.run(() => pavoPrintSync(
          frontColor: frontColor,
          frontK: frontK,
          backColor: backColor,
          backK: backK,
          copies: copies,
        ));
  }
}

/// isolate 入口：查询打印机状态（顶层函数，不捕获任何实例状态）。
PrinterStatus pavoStatusSync() {
  try {
    final api = PavoApi();
    final printers = PavoPrinter.enumUsbPrinters(api);
    if (printers.isEmpty) {
      return PrinterStatus.offline('打印机未连接');
    }
    final printer = printers.first.toNativeUtf16();
    try {
      final status = PavoPrinter.getStatus(api, printer);
      final (ribbonType, remainCount) = PavoPrinter.getRibbonInfo(api, printer);
      final dto = PrinterStatus(
        online: true,
        model: PavoPrinter.getDeviceInfoText(api, printer, PavoApi.devinfoModelName),
        firmware: PavoPrinter.getDeviceInfoText(api, printer, PavoApi.devinfoFirmwareVersion),
        connection: 'USB',
        ribbon: RibbonInfo(
          type: PavoPrinter.ribbonTypeName(ribbonType),
          // 设备返回剩余张数，按常见 100 张装 YMCKO 色带折算百分比
          remain: ribbonType == PavoApi.ribbonMissing ? -1 : (remainCount > 100 ? 100 : remainCount),
          remainCount: remainCount,
        ),
        status: status,
        statusText: PavoPrinter.statusTextOf(status),
      );
      if (status == PavoApi.dsCardLow || status == PavoApi.dsCardOut) {
        dto.cardLow = true;
      }
      return dto;
    } finally {
      calloc.free(printer);
    }
  } catch (e) {
    return PrinterStatus.offline('状态读取失败：$e');
  }
}

/// isolate 入口：转换图层并直打（顶层函数，参数全部为可发送的纯数据）。
Future<void> pavoPrintSync({
  required String frontColor,
  String? frontK,
  String? backColor,
  String? backK,
  required int copies,
}) async {
  final api = PavoApi();
  final printers = PavoPrinter.enumUsbPrinters(api);
  if (printers.isEmpty) {
    throw StateError('未找到 USB 连接的 HiTi 证卡打印机');
  }
  final printer = printers.first.toNativeUtf16();
  try {
    final frontImg = CardImage.fromDataUrl(frontColor);
    final frontBgr = frontImg.toBgr24();
    final Uint8List? frontKGray =
        frontK != null && frontK.isNotEmpty ? CardImage.fromDataUrl(frontK).toGray8() : null;
    final Uint8List? backBgr;
    final Uint8List? backKGray;
    if (backColor != null && backColor.isNotEmpty) {
      final backImg = CardImage.fromDataUrl(backColor);
      backBgr = backImg.toBgr24();
      backKGray =
          backK != null && backK.isNotEmpty ? CardImage.fromDataUrl(backK).toGray8() : null;
    } else {
      backBgr = null;
      backKGray = null;
    }

    await PavoPrinter.printOneCard(
      api,
      printer,
      frontBgr: frontBgr,
      frontK: frontKGray,
      backBgr: backBgr,
      backK: backKGray,
      isLandscape: frontImg.isLandscape,
      copies: copies,
    );
  } finally {
    calloc.free(printer);
  }
}