import 'dart:io';
import 'dart:ui' show Rect;
import 'package:image/image.dart' as img;
import 'package:path/path.dart' as p;

class CropSaveError implements Exception {
  final String code;
  const CropSaveError(this.code);

  @override
  String toString() => 'CropSaveError($code)';
}

class CropSaveService {
  /// Tam çözünürlükte decode + EXIF yönünü gömme (engine görüntüsüyle tutarlı).
  static Future<img.Image> load(String srcPath) async {
    final bytes = await File(srcPath).readAsBytes();
    final src = img.decodeImage(bytes);
    if (src == null) throw const CropSaveError('decode');
    return img.bakeOrientation(src);
  }

  /// Hedef yol: `resim.jpg` -> `resim_143025.jpg` (çakışmada null).
  static String? buildOutputPath(String srcPath) {
    final ext = p.extension(srcPath);
    final base = p.basenameWithoutExtension(srcPath);
    final dir = p.dirname(srcPath);
    final now = DateTime.now();
    final hh = now.hour.toString().padLeft(2, '0');
    final mm = now.minute.toString().padLeft(2, '0');
    final ss = now.second.toString().padLeft(2, '0');
    final candidate = p.join(dir, '${base}_$hh$mm$ss$ext');
    return File(candidate).existsSync() ? null : candidate;
  }

  /// Crop + aktif renk matrisi + JPEG q90.
  /// [matrix] 4x5 row-major renk matrisi (image_canvas ile aynı form, 0-255 alanı);
  /// null = gömme yok.
  static Future<String> saveCrop({
    required String srcPath,
    required img.Image source,
    required Rect rect,
    List<double>? matrix,
  }) async {
    final outPath = buildOutputPath(srcPath);
    if (outPath == null) throw const CropSaveError('file_exists');

    final iw = source.width, ih = source.height;
    final x = rect.left.round().clamp(0, iw - 1);
    final y = rect.top.round().clamp(0, ih - 1);
    final w = rect.right.round().clamp(x + 1, iw) - x;
    final h = rect.bottom.round().clamp(y + 1, ih) - y;
    if (w <= 0 || h <= 0) throw const CropSaveError('empty_rect');

    final crop = img.copyCrop(source, x: x, y: y, width: w, height: h);
    // Çıktıda yön fiziksel — EXIF tag'ini temizle (çift dönüşü önler).
    crop.exif.imageIfd.orientation = null;

    if (matrix != null) _applyMatrix(crop, matrix);

    final jpeg = img.JpegEncoder(quality: 90).encode(crop);
    await File(outPath).writeAsBytes(jpeg);
    return outPath;
  }

  /// Flutter'la aynı 0-255 alan/semantiğindeki 4x5 matrisi uygular.
  static void _applyMatrix(img.Image image, List<double> m) {
    for (final pixel in image) {
      final r = pixel.r.toDouble(), g = pixel.g.toDouble(), b = pixel.b.toDouble();
      pixel.r = (m[0] * r + m[1] * g + m[2] * b + m[4]).clamp(0, 255).round();
      pixel.g = (m[5] * r + m[6] * g + m[7] * b + m[9]).clamp(0, 255).round();
      pixel.b = (m[10] * r + m[11] * g + m[12] * b + m[13]).clamp(0, 255).round();
    }
  }
}