import 'dart:async';
import 'dart:io';
import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:image/image.dart' as img;
import 'package:window_manager/window_manager.dart';
import 'package:desktop_drop/desktop_drop.dart';
import 'package:pdf/pdf.dart';
import 'package:pdf/widgets.dart' as pw;
import 'package:printing/printing.dart';
import '../services/image_manager.dart';
import '../services/file_handler.dart';
import '../services/crop_save_service.dart';
import '../widgets/custom_title_bar.dart';
import '../widgets/image_canvas.dart';
import '../widgets/window_resize_zones.dart';
import '../shortcuts/app_shortcuts.dart';
import '../services/window_persistence.dart';
import '../l10n/app_localizations.dart';

const appVersion = '1.7.0';

class ViewerScreen extends StatefulWidget {
  final List<String> initialFiles;
  const ViewerScreen({super.key, this.initialFiles = const []});
  @override
  State<ViewerScreen> createState() => _ViewerScreenState();
}

class _ViewerScreenState extends State<ViewerScreen> with WindowListener {
  bool _hasImages = false;
  bool _isDragging = false;
  bool _controlsVisible = false;
  Timer? _saveDebounce;
  Rect _lastBounds = Rect.zero;
  final GlobalKey<ImageCanvasState> _canvasKey = GlobalKey<ImageCanvasState>();

  @override
  void initState() {
    super.initState();
    windowManager.addListener(this);
    ImageManager.instance.addListener(_onImageManagerChanged);

    if (widget.initialFiles.isNotEmpty) {
      WidgetsBinding.instance.addPostFrameCallback((_) {
        FileHandler.loadImagesFromPaths(widget.initialFiles);
      });
    }
  }

  @override
  void dispose() {
    windowManager.removeListener(this);
    ImageManager.instance.removeListener(_onImageManagerChanged);
    _saveDebounce?.cancel();
    super.dispose();
  }

  /// Universal event handler
  @override
  void onWindowEvent(String eventName) {
    switch (eventName) {
      case 'close':
        // Senkron kayıt — async çağrı kapanışta tamamlanmayabilir
        if (_lastBounds != Rect.zero) {
          WindowPersistence.saveSync(
            position: _lastBounds.topLeft,
            size: _lastBounds.size,
          );
        }
        break;
      case 'resize':
      case 'move':
        // Son bilinen konumu hemen güncelle (kapanış senkron kaydı için)
        windowManager.getBounds().then((b) => _lastBounds = b).catchError((_) => _lastBounds);
        _saveDebounce?.cancel();
        _saveDebounce = Timer(const Duration(milliseconds: 300), () {
          _doSave();
        });
        break;
    }
  }

  void _onImageManagerChanged() {
    setState(() => _hasImages = ImageManager.instance.images.isNotEmpty);
  }

  Future<void> _doSave() async {
    try {
      final pos = await windowManager.getPosition();
      final size = await windowManager.getSize();
      _lastBounds = Rect.fromLTWH(pos.dx, pos.dy, size.width, size.height);
      WindowPersistence.saveSync(position: pos, size: size);
    } catch (_) {
      // Silently ignore save errors
    }
  }

  void _showSettings() {
    showDialog(
      context: context,
      builder: (context) => StatefulBuilder(
        builder: (context, setDialogState) => AlertDialog(
          backgroundColor: const Color(0xFF2a2a2a),
          title: Text(AppLocalizations.of(context)!.settingsTitle,
              style: const TextStyle(color: Colors.white, fontSize: 18)),
          content: SingleChildScrollView(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(AppLocalizations.of(context)!.sortBy,
                    style: const TextStyle(color: Colors.white70, fontSize: 13)),
                RadioListTile<bool>(
                  value: false,
                  groupValue: ImageManager.instance.sortByName,
                  dense: true,
                  activeColor: Colors.blueAccent,
                  title: Text(AppLocalizations.of(context)!.sortByTime,
                      style: const TextStyle(color: Colors.white, fontSize: 14)),
                  onChanged: (v) {
                    ImageManager.instance.setSortByName(v!);
                    setDialogState(() {});
                  },
                ),
                RadioListTile<bool>(
                  value: true,
                  groupValue: ImageManager.instance.sortByName,
                  dense: true,
                  activeColor: Colors.blueAccent,
                  title: Text(AppLocalizations.of(context)!.sortByName,
                      style: const TextStyle(color: Colors.white, fontSize: 14)),
                  onChanged: (v) {
                    ImageManager.instance.setSortByName(v!);
                    setDialogState(() {});
                  },
                ),
                const Divider(color: Colors.white24, height: 24),
                if (_hasImages) ...[
                  Text(AppLocalizations.of(context)!.fileProperties,
                      style: const TextStyle(color: Colors.white70, fontSize: 13)),
                  const SizedBox(height: 4),
                  FutureBuilder<List<(String, String)>>(
                    future: _fileProperties(ImageManager.instance.currentImagePath),
                    builder: (context, snap) {
                      if (!snap.hasData) return const SizedBox(height: 20);
                      return Column(
                        children: snap.data!.map((r) => Padding(
                          padding: const EdgeInsets.only(bottom: 2),
                          child: Text.rich(
                            TextSpan(children: [
                              TextSpan(text: '${r.$1}: ', style: const TextStyle(color: Colors.white70, fontSize: 13)),
                              TextSpan(text: r.$2, style: const TextStyle(color: Colors.white, fontSize: 13)),
                            ]),
                          ),
                        )).toList(),
                      );
                    },
                  ),
                  const SizedBox(height: 12),
                ],
                Text('imajViewer $appVersion',
                    style: const TextStyle(color: Colors.white, fontSize: 15)),
                const SizedBox(height: 4),
                Text(
                  AppLocalizations.of(context)!.appDescription,
                  style: const TextStyle(color: Colors.white70, fontSize: 13, height: 1.5),
                ),
                const SizedBox(height: 12),
                Text(AppLocalizations.of(context)!.shortcuts,
                    style: const TextStyle(color: Colors.white70, fontSize: 13)),
                const SizedBox(height: 4),
                Text(
                  AppLocalizations.of(context)!.shortcutsList,
                  style: const TextStyle(color: Colors.white70, fontSize: 13, height: 1.6),
                ),
              ],
            ),
          ),
          actions: [
            TextButton.icon(
              onPressed: () {
                Navigator.pop(context);
                _printImage();
              },
              icon: const Icon(Icons.print, color: Colors.white70, size: 18),
              label: Text(AppLocalizations.of(context)!.print,
                  style: const TextStyle(color: Colors.white70)),
            ),
            TextButton(
              onPressed: () => Navigator.pop(context),
              child: Text(AppLocalizations.of(context)!.close, style: const TextStyle(color: Colors.white70)),
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _printImage() async {
    final path = ImageManager.instance.currentImagePath;
    if (path.isEmpty) return;
    final bytes = await File(path).readAsBytes();
    final image = pw.MemoryImage(bytes);
    await Printing.layoutPdf(
      onLayout: (format) async {
        final doc = pw.Document();
        doc.addPage(
          pw.Page(
            pageFormat: PdfPageFormat.a4,
            build: (context) => pw.Center(
              child: pw.Image(image, fit: pw.BoxFit.contain),
            ),
          ),
        );
        return doc.save();
      },
    );
  }

  Future<List<(String, String)>> _fileProperties(String path) async {
    final l10n = AppLocalizations.of(context)!;
    final file = File(path);
    final rows = <(String, String)>[];
    Size? size;
    try {
      final stat = file.statSync();
      const maxHead = 512 * 1024;
      final raf = file.openSync();
      final header = raf.readSync(stat.size < maxHead ? stat.size : maxHead);
      raf.closeSync();
      size = _headerPixelSize(header);
    } catch (_) {}
    rows.add((l10n.propResolution, size == null ? '—' : '${size!.width.toInt()} × ${size!.height.toInt()}'));
    try {
      rows.add((l10n.propFileSize, _fmtSize(file.statSync().size)));
    } catch (_) {
      rows.add((l10n.propFileSize, '—'));
    }
    rows.add((l10n.propFormat, path.toLowerCase().split('.').last.toUpperCase()));
    try {
      rows.add((l10n.propModified, _fmtDate(file.statSync().modified)));
    } catch (_) {
      rows.add((l10n.propModified, '—'));
    }
    rows.add((l10n.propPath, path));
    return rows;
  }

  /// İlk 512 KB'dan çözünürlük (piksel decode yok).
  /// PNG/GIF/BMP/WebP: boyut ilk 33 baytta → elle parse.
  /// JPEG: SOF büyük APP/EXIF segmentlerinin ardından gelebilir → package:image startDecode.
  Size? _headerPixelSize(Uint8List b) {
    try {
      if (b.length >= 24 && b[0] == 0x89 && b[1] == 0x50) {
        // PNG
        final w = (b[16] << 24) | (b[17] << 16) | (b[18] << 8) | b[19];
        final h = (b[20] << 24) | (b[21] << 16) | (b[22] << 8) | b[23];
        return Size(w.toDouble(), h.toDouble());
      }
      if (b.length >= 10 && b[0] == 0x47 && b[1] == 0x49 && b[2] == 0x46) {
        // GIF (WBMP da GIF tabanlı olabilir)
        final w = b[6] | (b[7] << 8);
        final h = b[8] | (b[9] << 8);
        return Size(w.toDouble(), h.toDouble());
      }
      if (b.length >= 26 && b[0] == 0x42 && b[1] == 0x4D) {
        // BMP
        final w = b[18] | (b[19] << 8) | (b[20] << 16) | (b[21] << 24);
        final h = b[22] | (b[23] << 8) | (b[24] << 16) | (b[25] << 24);
        return Size(w.toDouble(), h.abs().toDouble());
      }
      if (b.length >= 30 && b[0] == 0x52 && b[1] == 0x49 && b[2] == 0x46 && b[3] == 0x46 &&
          b[8] == 0x57 && b[9] == 0x45 && b[10] == 0x42 && b[11] == 0x50) {
        // WebP
        if (b[12] == 0x56 && b[13] == 0x50 && b[15] == 0x58) {
          // VP8X
          final w = b[24] | (b[25] << 8) | (b[26] << 16);
          final h = b[27] | (b[28] << 8) | (b[29] << 16);
          return Size((w + 1).toDouble(), (h + 1).toDouble());
        }
        if (b.length >= 25 && b[12] == 0x56 && b[13] == 0x50 && b[15] == 0x4C && b[20] == 0x2F) {
          // VP8L
          final w = (b[21] & 0x3F) | ((b[22] & 0x0F) << 6);
          final h = (b[23] & 0x3F) | ((b[24] & 0x0F) << 6);
          return Size((w + 1).toDouble(), (h + 1).toDouble());
        }
        if (b[12] == 0x56 && b[13] == 0x50 && b[15] == 0x20) {
          // VP8 (lossy)
          final w = (b[26] | (b[27] << 8)) & 0x3FFF;
          final h = (b[28] | (b[29] << 8)) & 0x3FFF;
          return Size(w.toDouble(), h.toDouble());
        }
      }
    } catch (_) {}
    try {
      // JPEG
      final info = img.JpegDecoder().startDecode(b);
      if (info != null) return Size(info.width.toDouble(), info.height.toDouble());
    } catch (_) {}
    return null;
  }

  String _fmtSize(int bytes) {
    if (bytes < 1024) return '$bytes B';
    const units = ['KB', 'MB', 'GB', 'TB'];
    double v = bytes / 1024;
    var i = 0;
    while (v >= 1024 && i < units.length - 1) {
      v /= 1024;
      i++;
    }
    return '${v.toStringAsFixed(v >= 100 ? 0 : 1)} ${units[i]}';
  }

  String _fmtDate(DateTime t) {
    String two(int n) => n.toString().padLeft(2, '0');
    return '${t.year}-${two(t.month)}-${two(t.day)} ${two(t.hour)}:${two(t.minute)}';
  }

  void _flipHorizontal() => _canvasKey.currentState?.toggleFlipH();

  Future<void> _cropSave() async {
    final path = ImageManager.instance.currentImagePath;
    final state = _canvasKey.currentState;
    if (path.isEmpty || state == null) return;
    final l10n = AppLocalizations.of(context)!;
    String? message;
    try {
      final source = await CropSaveService.load(path);
      final vp = state.cropViewParams(source.width, source.height);
      if (vp == null) {
        message = l10n.cropFailed;
      } else {
        final outPath = await CropSaveService.saveCrop(
          srcPath: path,
          source: source,
          vp: vp,
          matrix: state.activeColorMatrix,
        );
        message = l10n.cropSaved(outPath);
      }
    } on CropSaveError catch (e) {
      switch (e.code) {
        case 'file_exists':
          message = l10n.cropFileExists;
        case 'decode':
          message = l10n.cropUnsupported;
        default:
          message = l10n.cropFailed;
      }
    } catch (_) {
      message = l10n.cropFailed;
    }
    if (!mounted) return;
    ScaffoldMessenger.of(context)
      ..hideCurrentSnackBar()
      ..showSnackBar(SnackBar(
        content: Text(message, style: const TextStyle(fontSize: 13)),
        duration: const Duration(seconds: 2),
        behavior: SnackBarBehavior.floating,
        width: 520,
      ));
  }

  @override
  Widget build(BuildContext context) {
    return AppShortcuts(
      onCropSave: _hasImages ? _cropSave : null,
      onFlipH: _hasImages ? _flipHorizontal : null,
      child: Scaffold(
        backgroundColor: Colors.transparent,
        body: WindowResizeZones(
          child: DropTarget(
            onDragEntered: (_) => setState(() => _isDragging = true),
            onDragExited: (_) => setState(() => _isDragging = false),
            onDragDone: (details) {
              setState(() => _isDragging = false);
              FileHandler.loadImagesFromPaths(
                  details.files.map((f) => f.path).toList());
            },
            child: MouseRegion(
              onEnter: (_) => setState(() => _controlsVisible = true),
              onExit: (_) => setState(() => _controlsVisible = false),
              child: Stack(
                children: [
                  Positioned(
                    top: 0,
                    left: 0,
                    right: 0,
                    bottom: 0,
                    child: Container(color: const Color(0xFF1a1a1a)),
                  ),
                  Positioned(
                    top: 0,
                    left: 0,
                    right: 0,
                    bottom: 0,
                    child: Container(
                      color: Colors.transparent,
                      child: _hasImages
                          ? ImageCanvas(
                              key: _canvasKey,
                              filePath: ImageManager.instance.currentImagePath,
                            )
                          : Center(
                              child: Column(
                                mainAxisSize: MainAxisSize.min,
                                children: [
                                  const Icon(Icons.image, size: 64, color: Colors.white24),
                                  const SizedBox(height: 16),
                                  Text(AppLocalizations.of(context)!.dragDropHint,
                                      key: const Key('dragDropHint'),
                                      textAlign: TextAlign.center,
                                      style: const TextStyle(color: Colors.white38, fontSize: 16)),
                                ],
                              ),
                            ),
                    ),
                  ),
                  CustomTitleBar(
                    onSettings: _showSettings,
                    onSaveCrop: _hasImages ? _cropSave : null,
                    visible: _controlsVisible,
                  ),
                  if (_hasImages && _controlsVisible) ...[
                  Positioned(
                    left: 8,
                    bottom: 8,
                    child: _NavButton(
                      icon: Icons.chevron_left,
                      onTap: () => ImageManager.instance.previousImage(),
                    ),
                  ),
                  Positioned(
                    right: 8,
                    bottom: 8,
                    child: _NavButton(
                      icon: Icons.chevron_right,
                      onTap: () => ImageManager.instance.nextImage(),
                    ),
                  ),
                ],
                if (_isDragging)
                  Positioned.fill(
                    child: Container(
                      color: Colors.blue.withValues(alpha: 0.1),
                      child: Center(
                        child: Container(
                          padding: const EdgeInsets.all(32),
                          decoration: BoxDecoration(
                            color: Colors.black87,
                            borderRadius: BorderRadius.circular(16),
                            border: Border.all(color: Colors.blueAccent, width: 2),
                          ),
                          child: Text(AppLocalizations.of(context)!.dropHere,
                              style: const TextStyle(color: Colors.white, fontSize: 24)),
                        ),
                      ),
                    ),
                  ),
              ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

class _NavButton extends StatefulWidget {
  final IconData icon;
  final VoidCallback onTap;

  const _NavButton({required this.icon, required this.onTap});

  @override
  State<_NavButton> createState() => _NavButtonState();
}

class _NavButtonState extends State<_NavButton> {
  bool _hovered = false;

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: widget.onTap,
      child: MouseRegion(
        cursor: SystemMouseCursors.click,
        onEnter: (_) => setState(() => _hovered = true),
        onExit: (_) => setState(() => _hovered = false),
        child: Container(
          width: 36,
          height: 36,
          decoration: BoxDecoration(
            color: _hovered
                ? Colors.red.withValues(alpha: 0.8)
                : Colors.black.withValues(alpha: 0.35),
            shape: BoxShape.circle,
          ),
          child: Icon(widget.icon, color: Colors.white, size: 22),
        ),
      ),
    );
  }
}