import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:flutter_quill/flutter_quill.dart' as quill;

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 _realProgress = 0.0;
  bool _downloading = false;
  bool _failed = false;
  List<dynamic>? _notesDelta;
  String? _notesPlain;
  quill.QuillController? _notesController;
  final FocusNode _notesFocusNode = FocusNode();
  final ScrollController _notesScrollController = ScrollController();

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

    try {
      await AppUpdateService.instance.downloadAndInstallApk(
        widget.info.latestVersion!.downloadUrl,
        onProgress: (p) => setState(() => _realProgress = 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 ?? '';

    // parse release notes into a Quill delta list if possible
    if ((_notesDelta == null && _notesPlain == null) && notes.isNotEmpty) {
      try {
        final parsed = jsonDecode(notes);
        if (parsed is List) {
          _notesDelta = parsed;
          _notesController = quill.QuillController(
            document: quill.Document.fromJson(parsed),
            selection: const TextSelection.collapsed(offset: 0),
            readOnly: true,
          );

          // Prevent keyboard focus while still allowing text selection + copy.
          _notesFocusNode.canRequestFocus = false;
        } else {
          _notesPlain = notes;
        }
      } catch (_) {
        _notesPlain = notes;
      }
    }

    // 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: [
            // Show current + new versions
            if (widget.info.latestVersion != null)
              Padding(
                padding: const EdgeInsets.only(bottom: 12),
                child: Text(
                  'Version: ${widget.info.currentBuildNumber} → ${widget.info.latestVersion!.versionCode}',
                  style: Theme.of(context).textTheme.bodyMedium,
                ),
              ),
            // Render release notes: prefer Quill delta if available
            if (_notesController != null)
              SizedBox(
                height: 250,
                child: quill.QuillEditor.basic(
                  controller: _notesController!,
                  focusNode: _notesFocusNode,
                  scrollController: _notesScrollController,
                  config: const quill.QuillEditorConfig(
                    // Keep the editor readable/copyable but avoid showing the
                    // selection toolbar or receiving keyboard focus.
                    autoFocus: false,
                    showCursor: false,
                    enableInteractiveSelection: true,
                    enableSelectionToolbar: false,
                    // Prevent the context menu / selection toolbar from showing.
                    contextMenuBuilder: _noContextMenu,
                  ),
                ),
              ),
            if (_notesController == null &&
                _notesPlain != null &&
                _notesPlain!.isNotEmpty)
              SizedBox(
                height: 250,
                child: SingleChildScrollView(
                  child: SelectableText(_notesPlain!),
                ),
              ),
            const SizedBox(height: 12),
            if (_downloading) ...[
              SizedBox(
                width: double.infinity,
                child: const LinearProgressIndicator(value: null),
              ),
              const SizedBox(height: 8),
              TweenAnimationBuilder<double>(
                tween: Tween(begin: 0.0, end: _realProgress),
                duration: const Duration(milliseconds: 300),
                builder: (context, value, child) {
                  return Text(
                    '${(value * 100).toStringAsFixed(value * 100 >= 10 ? 0 : 1)}%',
                  );
                },
              ),
            ],
            if (_failed)
              Padding(
                padding: const EdgeInsets.only(top: 8.0),
                child: Text(
                  'An error occurred while downloading. Please try again.',
                  style: TextStyle(
                    color: Theme.of(context).colorScheme.error,
                  ),
                ),
              ),
          ],
        ),
        actions: _buildActions(),
      ),
    );
  }

  List<Widget> _buildActions() {
    final actions = <Widget>[];

    if (!widget.info.isForceUpdate && !_downloading) {
      actions.add(
        TextButton(
          onPressed: () => Navigator.of(context).pop(),
          child: const Text('Later'),
        ),
      );
    }

    actions.add(
      FilledButton(
        onPressed: _downloading ? null : _startDownload,
        child: _downloading
            ? const CircularProgressIndicator()
            : const Text('Update Now'),
      ),
    );

    return actions;
  }

  @override
  void initState() {
    super.initState();
    // Pre-parse release notes so heavy JSON parsing doesn't block UI later
    final notes = widget.info.latestVersion?.releaseNotes ?? '';
    if (notes.isNotEmpty) {
      try {
        final parsed = jsonDecode(notes);
        if (parsed is List) {
          _notesDelta = parsed;
          _notesController = quill.QuillController(
            document: quill.Document.fromJson(parsed),
            selection: const TextSelection.collapsed(offset: 0),
            readOnly: true,
          );

          // Prevent keyboard focus while still allowing text selection + copy.
          _notesFocusNode.canRequestFocus = false;
        } else {
          _notesPlain = notes;
        }
      } catch (_) {
        _notesPlain = notes;
      }
    }
  }

  @override
  void dispose() {
    _notesFocusNode.dispose();
    _notesScrollController.dispose();
    super.dispose();
  }

  static Widget _noContextMenu(BuildContext context, Object state) =>
      const SizedBox.shrink();
}