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

/// 强制更新页：检测到新版本时的全屏阻塞页。
/// PopScope 禁返回（Android 系统返回 / iOS 边缘滑动均不可退出），
/// 仅「立即更新」跳转系统浏览器下载 APK。
/// 点击更新时回调 onUpdateAccepted（调用方持久化服务器版本号，
/// 使 APK 版本号不递增时也不反复提示）。
class UpdateScreen extends StatelessWidget {
  final String version;
  final String url;
  final String notes;
  final VoidCallback? onUpdateAccepted;

  const UpdateScreen({
    super.key,
    required this.version,
    required this.url,
    this.notes = '',
    this.onUpdateAccepted,
  });

  Future<void> _launch() async {
    onUpdateAccepted?.call();
    final uri = Uri.tryParse(url);
    if (uri == null) return;
    try {
      await launchUrl(uri, mode: LaunchMode.externalApplication);
    } catch (_) {
      // 跳转失败保持页面，用户可重试
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    return PopScope(
      canPop: false,
      child: Scaffold(
        body: Center(
          child: Padding(
            padding: const EdgeInsets.all(32),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                Icon(Icons.system_update_alt,
                    size: 64, color: theme.colorScheme.primary),
                const SizedBox(height: 16),
                Text('发现新版本 $version',
                    style: theme.textTheme.headlineSmall),
                const SizedBox(height: 12),
                if (notes.isNotEmpty)
                  Text(notes,
                      textAlign: TextAlign.center,
                      style: const TextStyle(height: 1.6)),
                const SizedBox(height: 24),
                FilledButton.icon(
                  onPressed: _launch,
                  icon: const Icon(Icons.download),
                  label: const Text('立即更新'),
                  style: FilledButton.styleFrom(
                    minimumSize: const Size(200, 48),
                    textStyle: const TextStyle(fontSize: 16),
                  ),
                ),
                const SizedBox(height: 12),
                Text('不更新将无法继续使用',
                    style: theme.textTheme.bodySmall
                        ?.copyWith(color: theme.colorScheme.error)),
              ],
            ),
          ),
        ),
      ),
    );
  }
}