import 'package:flutter/material.dart';

import '../models/app_version.dart';
import '../services/app_update_service.dart';

/// A reusable dialog that can render both flexible and forced updates and
/// report download progress.  Callers should wrap this with `showDialog` and
/// control ``barrierDismissible`` according to ``info.isForceUpdate``.
class UpdateDialog extends StatefulWidget {
  final AppUpdateInfo info;

  const UpdateDialog({required this.info, super.key});

  @override
  State<UpdateDialog> createState() => _UpdateDialogState();
}

class _UpdateDialogState extends State<UpdateDialog> {
  double _progress = 0;
  bool _downloading = false;
  bool _failed = false;

  Future<void> _startDownload() async {
    setState(() {
      _downloading = true;
      _failed = false;
    });

    try {
      await AppUpdateService.instance.downloadAndInstallApk(
        widget.info.latestVersion!.downloadUrl,
        onProgress: (p) => setState(() => _progress = p),
      );
      // once the installer launches the app is likely to be stopped; we
      // don't pop the dialog explicitly.
    } catch (err) {
      if (!mounted) return;
      setState(() {
        _failed = true;
        _downloading = false;
      });
      ScaffoldMessenger.of(
        context,
      ).showSnackBar(SnackBar(content: Text('Download failed: $err')));
    }
  }

  @override
  Widget build(BuildContext context) {
    final notes = widget.info.latestVersion?.releaseNotes ?? '';

    // WillPopScope is deprecated in newer Flutter versions but PopScope
    // has a different API; to avoid breaking changes we continue to use the
    // old widget and suppress the warning.
    // ignore: deprecated_member_use
    return WillPopScope(
      onWillPop: () async {
        // prevent the user from dismissing when download is in progress or
        // when the dialog is forcing an update
        return !widget.info.isForceUpdate && !_downloading;
      },
      child: AlertDialog(
        title: const Text('Update Available'),
        content: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            if (notes.isNotEmpty) ...[Text(notes), const SizedBox(height: 12)],
            if (_downloading)
              Column(
                children: [
                  LinearProgressIndicator(value: _progress),
                  const SizedBox(height: 8),
                  Text('${(_progress * 100).toStringAsFixed(0)}%'),
                ],
              ),
            if (_failed)
              const Text(
                'An error occurred while downloading. Please try again.',
                style: TextStyle(color: Colors.red),
              ),
          ],
        ),
        actions: _buildActions(),
      ),
    );
  }

  List<Widget> _buildActions() {
    if (_downloading) {
      // don't show any actions while the apk is being fetched
      return <Widget>[];
    }

    if (widget.info.isForceUpdate) {
      return [
        FilledButton(
          onPressed: _startDownload,
          child: const Text('Update Now'),
        ),
      ];
    }

    return [
      TextButton(
        onPressed: () => Navigator.of(context).pop(),
        child: const Text('Later'),
      ),
      FilledButton(onPressed: _startDownload, child: const Text('Update Now')),
    ];
  }
}