import 'dart:io';
import 'dart:math' as math;
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)';
}

/// Viewport -> tam cozunurluk kaynak eslemesi (image_canvas'tan gelir).
class CropViewParams {
  final int w, h; // kaynak dosya boyutu
  final double vw, vh; // viewport boyutu
  final double tx, ty, sc; // pan/zoom
  final double angleDeg; // donus (derece)
  final bool flipH; // yatay aynalama (goruntunun kendisi degil, gorunum)
  final double cx, cy; // donus merkezi (viewport ortasi)
  final double k; // kaynak -> layout olcegi
  final double ox, oy; // layout offset
  const CropViewParams({
    required this.w,
    required this.h,
    required this.vw,
    required this.vh,
    required this.tx,
    required this.ty,
    required this.sc,
    required this.angleDeg,
    this.flipH = false,
    required this.cx,
    required this.cy,
    required this.k,
    required this.ox,
    required this.oy,
  });
}

class CropSaveService {
  /// Tam cozunurlukte decode + EXIF yonunu gomme (engine goruntusuyle tutarli).
  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.png` -> `resim_143025.jpg` (hep JPEG; cakismada null).
  static String? buildOutputPath(String 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.jpg');
    return File(candidate).existsSync() ? null : candidate;
  }

  /// Ekranda gorunen bolgeyi birebir (donus dahil) tam cozunurlukte kaydedir.
  /// Duzlem: viewport -> (tx,ty,sc) -> (vp ortasi etrafinda donus) -> (k,ox,oy) -> kaynak px.
  static Future<String> saveCrop({
    required String srcPath,
    required img.Image source,
    required CropViewParams vp,
    List<double>? matrix,
    int jpegQuality = 93,
  }) async {
    final outPath = buildOutputPath(srcPath);
    if (outPath == null) throw const CropSaveError('file_exists');

    final out = vp.angleDeg == 0
        ? _cropAxisAligned(source, vp)
        : _cropRotated(source, vp);
    // Ekranda yatay aynalama acikken cikti da aynalanir (cikti = viewport'un birebir eslemesi).
    if (vp.flipH) img.flipHorizontal(out);
    // Çıktıda yön fiziksel — EXIF tag'ini temizle (çift dönüşü önler).
    out.exif.imageIfd.orientation = null;

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

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

  /// Donus yok: gorulen dikdortgeni birebir kes (hizli yol).
  static img.Image _cropAxisAligned(img.Image src, CropViewParams vp) {
    double toX(double vx) => ((vx - vp.tx) / vp.sc - vp.ox) / vp.k;
    double toY(double vy) => ((vy - vp.ty) / vp.sc - vp.oy) / vp.k;
    final x0 = toX(0), x1 = toX(vp.vw), y0 = toY(0), y1 = toY(vp.vh);
    final x = x0.round().clamp(0, src.width - 1);
    final y = y0.round().clamp(0, src.height - 1);
    final xr = x1.round().clamp(x + 1, src.width);
    final yr = y1.round().clamp(y + 1, src.height);
    return img.copyCrop(src, x: x, y: y, width: xr - x, height: yr - y);
  }

  /// Donus var: ekran grid'ini kaynaga birebir ornekler (bilinear).
  static img.Image _cropRotated(img.Image src, CropViewParams vp) {
    final step = vp.sc * vp.k; // ekran px basina kaynak px
    if (step <= 0) throw const CropSaveError('empty_rect');
    final ow = (vp.vw / step).round().clamp(1, 1 << 14);
    final oh = (vp.vh / step).round().clamp(1, 1 << 14);
    final angle = vp.angleDeg * math.pi / 180;
    final cos = math.cos(-angle), sin = math.sin(-angle);

    (double, double) toSrc(double vx, double vy) {
      final x = (vx - vp.tx) / vp.sc - vp.cx;
      final y = (vy - vp.ty) / vp.sc - vp.cy;
      return ((cos * x - sin * y + vp.cx - vp.ox) / vp.k,
          (sin * x + cos * y + vp.cy - vp.oy) / vp.k);
    }

    final out = img.Image(width: ow, height: oh);
    for (var y = 0; y < oh; y++) {
      final vy = (y + 0.5) * step;
      for (var x = 0; x < ow; x++) {
        final s = toSrc((x + 0.5) * step, vy);
        final c = _sampleBilinear(src, s.$1, s.$2);
        out.setPixelRgb(x, y, c.$1, c.$2, c.$3);
      }
    }
    return out;
  }

  /// Manuel bilinear ornekleme (package:image 4.x API'si).
  static (int, int, int) _sampleBilinear(img.Image src, double fx, double fy) {
    final x0 = fx.floor(), y0 = fy.floor();
    final tx = (fx - x0).clamp(0.0, 1.0), ty = (fy - y0).clamp(0.0, 1.0);
    final c00 = src.getPixelClamped(x0, y0), c10 = src.getPixelClamped(x0 + 1, y0),
          c01 = src.getPixelClamped(x0, y0 + 1), c11 = src.getPixelClamped(x0 + 1, y0 + 1);
    int lerp(num a, num b, double t) => (a + (b - a) * t).toInt();
    return (
      lerp(lerp(c00.r, c10.r, tx), lerp(c01.r, c11.r, tx), ty),
      lerp(lerp(c00.g, c10.g, tx), lerp(c01.g, c11.g, tx), ty),
      lerp(lerp(c00.b, c10.b, tx), lerp(c01.b, c11.b, tx), ty),
    );
  }

  /// Flutter'la ayni 0-255 alan/semantigindaki 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[14]).clamp(0, 255).round();
    }
  }
}