import 'package:opencv_dart/opencv_dart.dart' as cv;
import '../../domain/entities/quality_result.dart';

class QualityChecker {
  
  static double getBlurScore(cv.Mat mat) {
    final laplacian = cv.laplacian(mat, cv.MatType.CV_64F);
    final (_, stddev) = cv.meanStdDev(laplacian);
    laplacian.dispose();
    return stddev.val1 * stddev.val1;
  }

  static double checkIllumination(cv.Mat mat) {
    final meanScalar = cv.mean(mat);
    return meanScalar.val1;
  }

  static bool checkPosition(cv.Mat mat) {
    final (_, threshMat) = cv.threshold(mat, 0, 255, cv.THRESH_BINARY + cv.THRESH_OTSU);
    final (contours, hierarchy) = cv.findContours(threshMat, cv.RETR_EXTERNAL, cv.CHAIN_APPROX_SIMPLE);
    threshMat.dispose();
    hierarchy.dispose();

    if (contours.isEmpty) return false;

    double maxArea = 0;
    cv.Rect? maxRect;
    
    for (int i = 0; i < contours.length; i++) {
      final contour = contours[i];
      final area = cv.contourArea(contour);
      if (area > maxArea) {
        maxArea = area;
        maxRect = cv.boundingRect(contour);
      }
    }
    
    if (maxRect == null) return false;

    final imgW = mat.cols;
    final imgH = mat.rows;
    
    final guideX = imgW ~/ 4;
    final guideY = imgH ~/ 4;
    final guideW = imgW ~/ 2;
    final guideH = imgH ~/ 2;

    final objCx = maxRect.x + maxRect.width / 2;
    final objCy = maxRect.y + maxRect.height / 2;
    
    final bool isCentered = objCx >= guideX && objCx <= (guideX + guideW) &&
                            objCy >= guideY && objCy <= (guideY + guideH);
                            
    final bool isBigEnough = maxArea > (imgW * imgH * 0.25);

    return isCentered && isBigEnough;
  }

  static QualityResult analyze(cv.Mat mat) {
    final blur = getBlurScore(mat);
    final brightness = checkIllumination(mat);
    final positionValid = checkPosition(mat);

    final bool isSharp = blur > 100.0;
    final bool isLit = brightness > 40.0 && brightness < 220.0;
    
    final normBlur = (blur / 500.0).clamp(0.0, 1.0);
    final normBright = 1.0 - ((brightness - 128).abs() / 128.0).clamp(0.0, 1.0);
    
    final score = (normBlur * 0.6) + (normBright * 0.4);

    return QualityResult(
      passed: isSharp && isLit && positionValid,
      score: score,
      blurScore: blur,
      brightness: brightness,
      isPositionValid: positionValid,
    );
  }
}