import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import 'package:mini_tias/providers/camera_provider.dart';
import 'package:mini_tias/widgets/camera_preview.dart';

/// 撮影画面．カメラプレビューとシャッターボタンを表示する．
class CaptureScreen extends StatefulWidget {
  const CaptureScreen({super.key});

  @override
  State<CaptureScreen> createState() => _CaptureScreenState();
}

class _CaptureScreenState extends State<CaptureScreen>
    with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    WidgetsBinding.instance.addPostFrameCallback((_) {
      context.read<CameraProvider>().initialize();
    });
  }

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

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    final cameraProvider = context.read<CameraProvider>();
    if (state == AppLifecycleState.paused) {
      cameraProvider.disposeCamera();
    } else if (state == AppLifecycleState.resumed) {
      cameraProvider.initialize();
    }
  }

  @override
  Widget build(BuildContext context) {
    final cameraProvider = context.watch<CameraProvider>();

    if (cameraProvider.permissionDenied) {
      return _buildPermissionDenied(cameraProvider);
    }

    if (cameraProvider.errorMessage != null && !cameraProvider.isInitialized) {
      return Center(child: Text(cameraProvider.errorMessage!));
    }

    if (!cameraProvider.isInitialized) {
      return const Center(child: CircularProgressIndicator());
    }

    return CameraPreviewWidget(controller: cameraProvider.controller!);
  }

  Widget _buildPermissionDenied(CameraProvider cameraProvider) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text(cameraProvider.errorMessage ?? 'カメラの権限が必要です'),
          const SizedBox(height: 16),
          if (cameraProvider.permissionPermanentlyDenied)
            ElevatedButton(
              onPressed: () => cameraProvider.openSettings(),
              child: const Text('設定画面を開く'),
            )
          else
            ElevatedButton(
              onPressed: () => cameraProvider.initialize(),
              child: const Text('権限を許可する'),
            ),
        ],
      ),
    );
  }
}