import 'package:camera/camera.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';

import 'frame_analyzer.dart';

/// camera 插件封装：后摄图像流（对应 Kotlin CameraController）。
class AppCameraController {
  final List<CameraDescription> cameras;
  CameraController? controller;

  /// 图像流回调实际触发次数（诊断用，与 analyzer 帧计数区分）
  int streamCallbacks = 0;

  AppCameraController._(this.cameras);

  static Future<AppCameraController?> create() async {
    final cameras = await availableCameras();
    if (cameras.isEmpty) return null;
    return AppCameraController._(cameras);
  }

  bool get isInitialized => controller?.value.isInitialized ?? false;

  CameraController get currentController =>
      controller ?? (throw StateError('camera not initialized'));

  /// 图像流送达时的旋转角（传感器 → 竖屏显示所需的顺时针旋转）。
  /// 与 CameraX rotationDegrees 同公式；预览本身由平台旋转，检测框 overlay
  /// 用同一角度映射即可对齐。
  int get rotationDegrees {
    final c = controller;
    if (c == null) return 0;
    final deviceDegrees = switch (c.value.deviceOrientation) {
      DeviceOrientation.portraitUp => 0,
      DeviceOrientation.landscapeLeft => 90,
      DeviceOrientation.portraitDown => 180,
      DeviceOrientation.landscapeRight => 270,
    };
    final sensor = c.description.sensorOrientation;
    final isFront =
        c.description.lensDirection == CameraLensDirection.front;
    final degrees = (isFront ? sensor + deviceDegrees : sensor - deviceDegrees) % 360;
    return degrees < 0 ? degrees + 360 : degrees;
  }

  Future<void> start(FrameAnalyzer analyzer) async {
    await stop();
    final desc = cameras.firstWhere(
        (c) => c.lensDirection == CameraLensDirection.back,
        orElse: () => cameras.first);
    // iOS 用默认 bgra8888（420v 在部分 iOS 版本上视频输出静默不送帧），
    // Android 用 yuv420 多平面。
    final fmt = defaultTargetPlatform == TargetPlatform.iOS
        ? ImageFormatGroup.bgra8888
        : ImageFormatGroup.yuv420;
    final c = CameraController(desc, ResolutionPreset.high,
        enableAudio: false, imageFormatGroup: fmt);
    controller = c;
    await c.initialize();
    // 相机（重新）启动后重置运动/背景参考与抽帧节流，避免旧场景残留
    analyzer.reset();
    analyzer.worker?.reset();
    debugPrint('[camera] initialized, starting image stream');
    try {
      await c.startImageStream((image) {
        streamCallbacks++;
        try {
          analyzer.analyze(image, rotationDegrees);
        } catch (e, st) {
          debugPrint('[camera] analyze error: $e\n$st');
          analyzer.recordStreamError('analyze: $e');
        }
      });
      debugPrint('[camera] startImageStream ok');
    } catch (e, st) {
      debugPrint('[camera] startImageStream FAILED: $e\n$st');
      analyzer.recordStreamError('startImageStream: $e');
      rethrow;
    }
  }

  Future<void> stop() async {
    final c = controller;
    if (c == null) return;
    controller = null;
    try {
      await c.stopImageStream();
    } catch (_) {}
    await c.dispose();
  }
}