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）。
/// 2026-09-03 改为浏览器下载：App 内 PackageInstaller 会话安装在小米等
/// ROM 上点系统确认框后失败（下载/写入正常但最终安装被拒），而系统浏览器
/// 下载 APK 后经通知栏走 ROM 自己的安装器可正常完成，故下载链接改由浏览器
/// 打开，不再 App 内下载/安装。仅点「立即更新」按钮时打开浏览器，不自动
/// 跳转；安装完成（versionName 追上服务器）后下次启动不再提示。
class UpdateScreen extends StatefulWidget {
  final String version;
  final String url;
  final String notes;

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

  @override
  State<UpdateScreen> createState() => _UpdateScreenState();
}

class _UpdateScreenState extends State<UpdateScreen> {
  String? _message;

  Future<void> _openBrowser() async {
    final uri = Uri.tryParse(widget.url);
    if (uri == null) {
      setState(() => _message = '下载链接无效，请联系管理员');
      return;
    }
    try {
      final ok = await launchUrl(uri, mode: LaunchMode.externalApplication);
      if (!mounted) return;
      setState(() {
        _message = ok ? '已打开浏览器下载，完成后点击通知栏的安装提示即可更新' : '打开浏览器失败，请点「立即更新」重试';
      });
    } catch (_) {
      if (!mounted) return;
      setState(() => _message = '打开浏览器失败，请点「立即更新」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 ${widget.version}',
                    style: theme.textTheme.headlineSmall),
                const SizedBox(height: 12),
                if (widget.notes.isNotEmpty)
                  Text(widget.notes,
                      textAlign: TextAlign.center,
                      style: const TextStyle(height: 1.6)),
                const SizedBox(height: 24),
                FilledButton.icon(
                  onPressed: _openBrowser,
                  icon: const Icon(Icons.open_in_browser),
                  label: const Text('立即更新'),
                  style: FilledButton.styleFrom(
                    minimumSize: const Size(200, 48),
                    textStyle: const TextStyle(fontSize: 16),
                  ),
                ),
                const SizedBox(height: 16),
                Text(
                  '新版本需在浏览器下载 APK 后手动安装\n安装完成后请重新打开应用',
                  textAlign: TextAlign.center,
                  style: theme.textTheme.bodySmall
                      ?.copyWith(color: theme.colorScheme.error),
                ),
                if (_message != null) ...[
                  const SizedBox(height: 12),
                  Text(
                    _message!,
                    textAlign: TextAlign.center,
                    style: TextStyle(
                      height: 1.5,
                      color: _message!.startsWith('已打开')
                          ? Colors.green
                          : theme.colorScheme.error,
                    ),
                  ),
                ],
              ],
            ),
          ),
        ),
      ),
    );
  }
}