import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:flutter_easyloading/flutter_easyloading.dart';
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';
import 'package:uuid/uuid.dart';

/// 自定义相机预览 + 拍照队列
/// 对应 Android CheckPhotoActivity（多张拍照取证）
class CameraView extends StatefulWidget {
  final void Function(String path) onCaptured;
  const CameraView({super.key, required this.onCaptured});

  @override
  State<CameraView> createState() => _CameraViewState();
}

class _CameraViewState extends State<CameraView>
    with WidgetsBindingObserver {
  CameraController? _controller;
  List<CameraDescription> _cameras = [];
  int _cameraIdx = 0;
  bool _initializing = true;
  String? _error;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _setup();
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    _controller?.dispose();
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final c = _controller;
    if (c == null || !c.value.isInitialized) return;
    if (state == AppLifecycleState.inactive ||
        state == AppLifecycleState.paused) {
      c.dispose();
    } else if (state == AppLifecycleState.resumed) {
      _setup();
    }
  }

  Future<void> _setup() async {
    setState(() {
      _initializing = true;
      _error = null;
    });
    try {
      final cam = await Permission.camera.request();
      if (!cam.isGranted) {
        setState(() {
          _initializing = false;
          _error = '未授予相机权限';
        });
        return;
      }
      _cameras = await availableCameras();
      if (_cameras.isEmpty) {
        setState(() {
          _initializing = false;
          _error = '未检测到摄像头';
        });
        return;
      }
      _cameraIdx = _cameras.indexWhere(
        (c) => c.lensDirection == CameraLensDirection.back,
      );
      if (_cameraIdx < 0) _cameraIdx = 0;
      await _initController();
    } catch (e) {
      setState(() {
        _initializing = false;
        _error = '相机初始化失败: $e';
      });
    }
  }

  Future<void> _initController() async {
    final c = CameraController(
      _cameras[_cameraIdx],
      ResolutionPreset.high,
      enableAudio: false,
    );
    await c.initialize();
    if (!mounted) {
      await c.dispose();
      return;
    }
    setState(() {
      _controller = c;
      _initializing = false;
    });
  }

  Future<void> _switchCamera() async {
    if (_cameras.length < 2) return;
    _cameraIdx = (_cameraIdx + 1) % _cameras.length;
    await _controller?.dispose();
    await _initController();
  }

  Future<void> _takePicture() async {
    final c = _controller;
    if (c == null || !c.value.isInitialized) return;
    if (c.value.isTakingPicture) return;
    try {
      EasyLoading.show(status: '拍照中…');
      final xfile = await c.takePicture();
      EasyLoading.dismiss();
      // 复制到应用缓存目录（防止临时文件被清理）
      final dir = await getTemporaryDirectory();
      final out =
          '${dir.photos_cache_path()}/${const Uuid().v4()}.jpg';
      await File(xfile.path).copy(out);
      widget.onCaptured(out);
    } catch (e) {
      EasyLoading.dismiss();
      EasyLoading.showError('拍照失败: $e');
    }
  }

  @override
  Widget build(BuildContext context) {
    if (_error != null) {
      return Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            const Icon(Icons.no_photography, size: 64, color: Colors.white),
            const SizedBox(height: 8),
            Text(_error!, style: const TextStyle(color: Colors.white)),
            TextButton(onPressed: _setup, child: const Text('重试')),
          ],
        ),
      );
    }
    if (_initializing || _controller == null) {
      return const Center(
        child: CircularProgressIndicator(color: Colors.white),
      );
    }
    return Stack(
      fit: StackFit.expand,
      children: [
        CameraPreview(_controller!),
        // 顶部切换镜头
        Positioned(
          top: 16,
          right: 16,
          child: SafeArea(
            child: IconButton(
              icon: const Icon(Icons.cameraswitch, color: Colors.white),
              onPressed: _switchCamera,
            ),
          ),
        ),
        // 底部拍照按钮
        Positioned(
          left: 0,
          right: 0,
          bottom: 32,
          child: Center(
            child: GestureDetector(
              onTap: _takePicture,
              child: Container(
                width: 72,
                height: 72,
                decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  border: Border.all(color: Colors.white, width: 4),
                ),
                child: const Center(
                  child: Icon(Icons.circle, color: Colors.white, size: 56),
                ),
              ),
            ),
          ),
        ),
      ],
    );
  }
}

extension _DirPath on Directory {
  String photos_cache_path() {
    final p = path;
    if (p.endsWith('/')) return '${p}photos';
    return '$p/photos';
  }
}

/// 底部照片缩略图横排（可删除）
class PhotoThumbStrip extends StatelessWidget {
  final List<String> paths;
  final ValueChanged<int> onRemove;
  final VoidCallback? onAdd;
  const PhotoThumbStrip({
    super.key,
    required this.paths,
    required this.onRemove,
    this.onAdd,
  });

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: 88,
      child: ListView.separated(
        scrollDirection: Axis.horizontal,
        padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
        itemCount: paths.length + 1,
        separatorBuilder: (_, __) => const SizedBox(width: 8),
        itemBuilder: (ctx, i) {
          if (i == paths.length) {
            return InkWell(
              onTap: onAdd,
              child: Container(
                width: 72,
                height: 72,
                decoration: BoxDecoration(
                  color: Colors.black12,
                  borderRadius: BorderRadius.circular(6),
                ),
                child: const Icon(Icons.add_a_photo, color: Colors.white70),
              ),
            );
          }
          return Stack(
            children: [
              ClipRRect(
                borderRadius: BorderRadius.circular(6),
                child: Image.file(
                  File(paths[i]),
                  width: 72,
                  height: 72,
                  fit: BoxFit.cover,
                ),
              ),
              Positioned(
                top: 0,
                right: 0,
                child: GestureDetector(
                  onTap: () => onRemove(i),
                  child: Container(
                    decoration: const BoxDecoration(
                      color: Colors.black54,
                      shape: BoxShape.circle,
                    ),
                    padding: const EdgeInsets.all(2),
                    child: const Icon(
                      Icons.close,
                      size: 14,
                      color: Colors.white,
                    ),
                  ),
                ),
              ),
            ],
          );
        },
      ),
    );
  }
}

/// 备选：从相册选择（用 image_picker）
class AlbumPicker {
  static final _picker = ImagePicker();

  static Future<List<String>> pick({int max = 9}) async {
    final files = await _picker.pickMultiImage(
      imageQuality: 85,
      maxWidth: 1920,
    );
    if (files.isEmpty) return const [];
    return files.take(max).map((f) => f.path).toList();
  }
}