import 'dart:async';
import 'dart:math' as math;
import 'dart:typed_data';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_colorpicker/flutter_colorpicker.dart';
import 'package:image/image.dart' as img;
import 'package:image_picker/image_picker.dart';

void main() {
  runApp(const KorkenMosaicApp());
}

class KorkenMosaicApp extends StatelessWidget {
  const KorkenMosaicApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Korken Mosaic',
      theme: ThemeData(colorSchemeSeed: Colors.teal, useMaterial3: true),
      home: const MosaicHomePage(),
    );
  }
}

class MosaicHomePage extends StatefulWidget {
  const MosaicHomePage({super.key});

  @override
  State<MosaicHomePage> createState() => _MosaicHomePageState();
}

class _MosaicHomePageState extends State<MosaicHomePage> {
  final ImagePicker _picker = ImagePicker();
  final TextEditingController _gridWidthCtrl =
      TextEditingController(text: '40');
  final TextEditingController _gridHeightCtrl =
      TextEditingController(text: '30');
  final TextEditingController _capSizeCtrl = TextEditingController(text: '12');

  Uint8List? _sourceImageBytes;
  MosaicResult? _result;
  bool _useCapSize = false;
  bool _isGenerating = false;
  Timer? _debounceTimer;
  int _generationToken = 0;

  final List<CapColor> _palette = [
    CapColor(name: 'White', color: const Color(0xFFF2F2F2)),
    CapColor(name: 'Black', color: const Color(0xFF222222)),
    CapColor(name: 'Red', color: const Color(0xFFD84343)),
    CapColor(name: 'Blue', color: const Color(0xFF3F6FD8)),
    CapColor(name: 'Green', color: const Color(0xFF4FAE63)),
  ];

  @override
  void initState() {
    super.initState();
    _gridWidthCtrl.addListener(_scheduleRegenerate);
    _gridHeightCtrl.addListener(_scheduleRegenerate);
    _capSizeCtrl.addListener(_scheduleRegenerate);
  }

  @override
  void dispose() {
    _debounceTimer?.cancel();
    _gridWidthCtrl.dispose();
    _gridHeightCtrl.dispose();
    _capSizeCtrl.dispose();
    super.dispose();
  }

  Future<void> _pickImage() async {
    final XFile? picked = await _picker.pickImage(source: ImageSource.gallery);
    if (picked == null) return;
    final bytes = await picked.readAsBytes();
    setState(() {
      _sourceImageBytes = bytes;
      _result = null;
    });
  }

  void _scheduleRegenerate() {
    if (_sourceImageBytes == null || _result == null) return;
    _debounceTimer?.cancel();
    _debounceTimer = Timer(const Duration(milliseconds: 300), _generate);
  }

  void _addCapDialog() {
    Color selected = Colors.orange;
    final nameCtrl = TextEditingController();
    final hexCtrl = TextEditingController(
      text:
          '#${selected.toARGB32().toRadixString(16).substring(2).toUpperCase()}',
    );

    showDialog<void>(
      context: context,
      builder: (ctx) {
        return AlertDialog(
          title: const Text('Add Bottle Cap Color'),
          content: SingleChildScrollView(
            child: Column(
              mainAxisSize: MainAxisSize.min,
              children: [
                TextField(
                  controller: nameCtrl,
                  decoration: const InputDecoration(labelText: 'Name'),
                ),
                const SizedBox(height: 8),
                TextField(
                  controller: hexCtrl,
                  decoration: const InputDecoration(labelText: 'Hex (#RRGGBB)'),
                  onChanged: (value) {
                    final parsed = _parseHex(value);
                    if (parsed != null) selected = parsed;
                  },
                ),
                const SizedBox(height: 12),
                ColorPicker(
                  pickerColor: selected,
                  onColorChanged: (c) {
                    selected = c;
                    hexCtrl.text =
                        '#${c.toARGB32().toRadixString(16).substring(2).toUpperCase()}';
                  },
                ),
              ],
            ),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(ctx),
              child: const Text('Cancel'),
            ),
            FilledButton(
              onPressed: () {
                final name = nameCtrl.text.trim();
                if (name.isEmpty) return;
                setState(() {
                  _palette.add(
                    CapColor(
                        name: name, color: _parseHex(hexCtrl.text) ?? selected),
                  );
                });
                Navigator.pop(ctx);
                _scheduleRegenerate();
              },
              child: const Text('Add'),
            ),
          ],
        );
      },
    );
  }

  Future<void> _generate() async {
    if (_sourceImageBytes == null || _palette.isEmpty) return;

    final int gridW = math.max(1, int.tryParse(_gridWidthCtrl.text) ?? 40);
    final int gridH = math.max(1, int.tryParse(_gridHeightCtrl.text) ?? 30);
    final int capSize = math.max(1, int.tryParse(_capSizeCtrl.text) ?? 12);

    final token = ++_generationToken;
    setState(() => _isGenerating = true);

    final payload = <String, dynamic>{
      'source': _sourceImageBytes!,
      'useCapSize': _useCapSize,
      'gridW': gridW,
      'gridH': gridH,
      'capSize': capSize,
      'palette': _palette
          .map((p) =>
              <String, dynamic>{'name': p.name, 'value': p.color.toARGB32()})
          .toList(growable: false),
    };

    final out = await compute(_generateMosaicIsolate, payload);
    if (!mounted || token != _generationToken) return;

    final palette = (out['palette'] as List)
        .map(
          (e) => CapColor(
              name: e['name'] as String, color: Color(e['value'] as int)),
        )
        .toList(growable: false);

    final countsList = (out['counts'] as List).cast<int>();
    final counts = <CapColor, int>{};
    for (int i = 0; i < palette.length; i++) {
      counts[palette[i]] = countsList[i];
    }

    final sortedCounts = counts.entries.toList()
      ..sort((a, b) => b.value.compareTo(a.value));

    setState(() {
      _result = MosaicResult(
        width: out['width'] as int,
        height: out['height'] as int,
        assignments: (out['assignments'] as List).cast<int>(),
        palette: palette,
        counts: counts,
        sortedCounts: sortedCounts,
        previewPng: out['previewPng'] as Uint8List,
      );
      _isGenerating = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Bottle-Cap Mosaic Prototype')),
      floatingActionButton: FloatingActionButton.extended(
        onPressed: _isGenerating ? null : _generate,
        icon: _isGenerating
            ? const SizedBox(
                width: 18,
                height: 18,
                child: CircularProgressIndicator(strokeWidth: 2),
              )
            : const Icon(Icons.auto_fix_high),
        label: Text(_isGenerating ? 'Generating…' : 'Generate Mosaic'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(12),
        child: ListView(
          children: [
            Wrap(
              runSpacing: 8,
              spacing: 8,
              crossAxisAlignment: WrapCrossAlignment.center,
              children: [
                FilledButton.icon(
                  onPressed: _pickImage,
                  icon: const Icon(Icons.image_outlined),
                  label: const Text('Import target image'),
                ),
                if (_sourceImageBytes != null) const Text('Image loaded ✅'),
              ],
            ),
            const SizedBox(height: 12),
            SegmentedButton<bool>(
              segments: const [
                ButtonSegment(value: false, label: Text('Grid W x H')),
                ButtonSegment(value: true, label: Text('Cap size (px)')),
              ],
              selected: {_useCapSize},
              onSelectionChanged: (s) {
                setState(() => _useCapSize = s.first);
                _scheduleRegenerate();
              },
            ),
            const SizedBox(height: 8),
            if (!_useCapSize)
              Row(
                children: [
                  Expanded(
                    child: TextField(
                      controller: _gridWidthCtrl,
                      keyboardType: TextInputType.number,
                      decoration:
                          const InputDecoration(labelText: 'Grid Width'),
                    ),
                  ),
                  const SizedBox(width: 8),
                  Expanded(
                    child: TextField(
                      controller: _gridHeightCtrl,
                      keyboardType: TextInputType.number,
                      decoration:
                          const InputDecoration(labelText: 'Grid Height'),
                    ),
                  ),
                ],
              )
            else
              TextField(
                controller: _capSizeCtrl,
                keyboardType: TextInputType.number,
                decoration: const InputDecoration(
                  labelText: 'Approx cap size in source image (pixels)',
                ),
              ),
            const SizedBox(height: 16),
            Row(
              children: [
                const Expanded(
                  child: Text(
                    'Cap Palette',
                    style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
                  ),
                ),
                IconButton(
                  onPressed: _addCapDialog,
                  icon: const Icon(Icons.add_circle_outline),
                ),
              ],
            ),
            Wrap(
              spacing: 8,
              runSpacing: 8,
              children: [
                for (int i = 0; i < _palette.length; i++)
                  Chip(
                    avatar: CircleAvatar(backgroundColor: _palette[i].color),
                    label: Text(_palette[i].name),
                    onDeleted: _palette.length <= 1
                        ? null
                        : () {
                            setState(() => _palette.removeAt(i));
                            _scheduleRegenerate();
                          },
                  ),
              ],
            ),
            const SizedBox(height: 16),
            if (_result != null) ...[
              Text(
                'Preview (${_result!.width} x ${_result!.height})',
                style:
                    const TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              const SizedBox(height: 8),
              RepaintBoundary(
                child: AspectRatio(
                  aspectRatio: _result!.width / _result!.height,
                  child: Image.memory(
                    _result!.previewPng,
                    fit: BoxFit.fill,
                    filterQuality: FilterQuality.none,
                    gaplessPlayback: true,
                  ),
                ),
              ),
              const SizedBox(height: 16),
              const Text(
                'Bill of Materials',
                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
              ),
              ..._result!.sortedCounts.map(
                (e) => ListTile(
                  dense: true,
                  leading: CircleAvatar(backgroundColor: e.key.color),
                  title: Text(e.key.name),
                  trailing: Text('${e.value} caps'),
                ),
              ),
            ],
          ],
        ),
      ),
    );
  }

  Color? _parseHex(String raw) {
    final hex = raw.trim().replaceFirst('#', '');
    if (hex.length != 6) return null;
    final value = int.tryParse(hex, radix: 16);
    if (value == null) return null;
    return Color(0xFF000000 | value);
  }
}

class CapColor {
  final String name;
  final Color color;

  const CapColor({required this.name, required this.color});
}

class MosaicResult {
  final int width;
  final int height;
  final List<int> assignments;
  final List<CapColor> palette;
  final Map<CapColor, int> counts;
  final List<MapEntry<CapColor, int>> sortedCounts;
  final Uint8List previewPng;

  MosaicResult({
    required this.width,
    required this.height,
    required this.assignments,
    required this.palette,
    required this.counts,
    required this.sortedCounts,
    required this.previewPng,
  });
}

Map<String, dynamic> _generateMosaicIsolate(Map<String, dynamic> request) {
  final source = request['source'] as Uint8List;
  final useCapSize = request['useCapSize'] as bool;
  final defaultGridW = request['gridW'] as int;
  final defaultGridH = request['gridH'] as int;
  final capSize = request['capSize'] as int;
  final paletteRaw = (request['palette'] as List).cast<Map>();

  final decoded = img.decodeImage(source);
  if (decoded == null) {
    return <String, dynamic>{
      'width': 1,
      'height': 1,
      'assignments': <int>[0],
      'counts': <int>[1],
      'palette': paletteRaw,
      'previewPng': Uint8List.fromList(
        img.encodePng(img.Image(width: 1, height: 1)),
      ),
    };
  }

  final gridW = useCapSize
      ? math.max(1, (decoded.width / capSize).round())
      : defaultGridW;
  final gridH = useCapSize
      ? math.max(1, (decoded.height / capSize).round())
      : defaultGridH;

  final scaled = img.copyResize(
    decoded,
    width: gridW,
    height: gridH,
    interpolation: img.Interpolation.average,
  );

  final paletteValues = paletteRaw.map((e) => e['value'] as int).toList();
  final paletteLab = paletteValues.map(_argbToLab).toList(growable: false);

  final assignments = List<int>.filled(gridW * gridH, 0);
  final counts = List<int>.filled(paletteValues.length, 0);

  final nearestCache = <int, int>{};
  final labCache = <int, List<double>>{};

  for (int y = 0; y < gridH; y++) {
    for (int x = 0; x < gridW; x++) {
      final pix = scaled.getPixel(x, y);
      final rgb = (pix.r.toInt() << 16) | (pix.g.toInt() << 8) | pix.b.toInt();

      final cached = nearestCache[rgb];
      if (cached != null) {
        assignments[y * gridW + x] = cached;
        counts[cached]++;
        continue;
      }

      final srcLab = labCache.putIfAbsent(rgb, () => _rgbToLab(rgb));

      int bestIdx = 0;
      double bestDistance = double.infinity;
      for (int i = 0; i < paletteLab.length; i++) {
        final d = _deltaE76(srcLab, paletteLab[i]);
        if (d < bestDistance) {
          bestDistance = d;
          bestIdx = i;
        }
      }

      nearestCache[rgb] = bestIdx;
      assignments[y * gridW + x] = bestIdx;
      counts[bestIdx]++;
    }
  }

  final preview = img.Image(width: gridW, height: gridH);
  for (int y = 0; y < gridH; y++) {
    for (int x = 0; x < gridW; x++) {
      final idx = assignments[y * gridW + x];
      final argb = paletteValues[idx];
      preview.setPixelRgba(
        x,
        y,
        (argb >> 16) & 0xFF,
        (argb >> 8) & 0xFF,
        argb & 0xFF,
        255,
      );
    }
  }

  return <String, dynamic>{
    'width': gridW,
    'height': gridH,
    'assignments': assignments,
    'counts': counts,
    'palette': paletteRaw,
    'previewPng': Uint8List.fromList(img.encodePng(preview, level: 1)),
  };
}

List<double> _argbToLab(int argb) {
  final rgb = argb & 0x00FFFFFF;
  return _rgbToLab(rgb);
}

List<double> _rgbToLab(int rgb) {
  double r = ((rgb >> 16) & 0xFF) / 255.0;
  double g = ((rgb >> 8) & 0xFF) / 255.0;
  double b = (rgb & 0xFF) / 255.0;

  r = r <= 0.04045 ? r / 12.92 : math.pow((r + 0.055) / 1.055, 2.4).toDouble();
  g = g <= 0.04045 ? g / 12.92 : math.pow((g + 0.055) / 1.055, 2.4).toDouble();
  b = b <= 0.04045 ? b / 12.92 : math.pow((b + 0.055) / 1.055, 2.4).toDouble();

  final x = (r * 0.4124 + g * 0.3576 + b * 0.1805) / 0.95047;
  final y = (r * 0.2126 + g * 0.7152 + b * 0.0722) / 1.00000;
  final z = (r * 0.0193 + g * 0.1192 + b * 0.9505) / 1.08883;

  double f(double t) => t > 0.008856
      ? math.pow(t, 1.0 / 3.0).toDouble()
      : (7.787 * t) + (16 / 116);

  final fx = f(x);
  final fy = f(y);
  final fz = f(z);

  final l = (116 * fy) - 16;
  final a = 500 * (fx - fy);
  final bStar = 200 * (fy - fz);

  return [l, a, bStar];
}

double _deltaE76(List<double> lab1, List<double> lab2) {
  final dl = lab1[0] - lab2[0];
  final da = lab1[1] - lab2[1];
  final db = lab1[2] - lab2[2];
  return math.sqrt(dl * dl + da * da + db * db);
}