import 'package:camera/camera.dart';

import '../detection/detection_result.dart';
import '../detection/detector_worker.dart';
import 'camera_view_model.dart';

/// 抽帧节流 + 后台推理（对应 Kotlin FrameAnalyzer）。
/// 推理在后台 isolate（DetectorWorker）执行，主 isolate 只投递帧与收结果。
class FrameAnalyzer {
  /// 连续检测：100ms 一帧
  int intervalMs = 100;

  /// null = 模型加载失败，仅预览不分析
  final DetectorWorker? worker;
  final CameraViewModel viewModel;

  int _lastDetectMs = 0;

  /// 诊断计数：推理调用/异常次数
  int detectCalls = 0;
  int detectErrors = 0;
  String? lastError;

  /// 最近一次完整处理（预处理+推理+运动检测）耗时 ms（worker 侧）
  int lastProcessMs = 0;

  /// 图像流回调是否到达（诊断用）
  int framesReceived = 0;

  FrameAnalyzer({required this.worker, required this.viewModel}) {
    worker?.onResult = _onResult;
    worker?.onError = _onError;
  }

  void recordStreamError(String msg) {
    lastError = msg;
    detectErrors++;
  }

  void _onResult(
      List<DetectionResult> results,
      List<MotionRegion> motion,
      List<MotionRegion> novelty,
      int rotation,
      int width,
      int height,
      int processMs) {
    detectCalls++;
    lastProcessMs = processMs;
    viewModel.onFramesAnalyzed(
      results,
      rotation,
      width,
      height,
      motion,
      novelty,
      detectCalls: detectCalls,
      detectErrors: detectErrors,
      lastError: lastError,
      framesReceived: framesReceived,
      lastProcessMs: lastProcessMs,
    );
  }

  void _onError(String msg) {
    detectErrors++;
    lastError = msg;
    viewModel.onFramesAnalyzed(
      const [],
      90,
      0,
      0,
      const [],
      const [],
      detectCalls: detectCalls,
      detectErrors: detectErrors,
      lastError: lastError,
      framesReceived: framesReceived,
      lastProcessMs: lastProcessMs,
    );
  }

  void analyze(CameraImage image, int rotationDegrees) {
    framesReceived++;
    final w = worker;
    if (w == null) return;
    final now = DateTime.now().millisecondsSinceEpoch;
    if (now - _lastDetectMs < intervalMs) return;
    _lastDetectMs = now;
    if (w.busy) return; // 上一帧未返回则丢帧，避免在途积压
    w.analyze(image, rotationDegrees);
  }

  void reset() => _lastDetectMs = 0;

  void dispose() => worker?.dispose();
}