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。
/// DLL 与非托管指针都不跨 isolate（闭包内自建自释放）。
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(_statusSync);

  PrinterStatus _statusSync() {
    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');
    }
  }

  @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;
    // 只把 data URL 字符串与份数传进 isolate；图层转换与 ffi 调用全部在子 isolate 内完成
    final frontColor = front.color;
    final frontK = front.k;
    final backColor = back?.color;
    final backK = back?.k;
    final copies = request.copies;
    return Isolate.run(() 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;
        if (frontK != null && frontK.isNotEmpty) {
          frontKGray = CardImage.fromDataUrl(frontK).toGray8();
        } else {
          frontKGray = 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);
      }
    });
  }
}