package ie.dcu.image.binary;

import ie.dcu.image.dt.DistanceTransform;
import ie.dcu.matrix.*;
import ie.dcu.matrix.Matrix.Type;

/**
 * Implementation of the Medial Axis Transform (MAT).
 * 
 * Computes the MAT by finding the Laplace of the square distance transform.
 * 
 * @author Kevin McGuinness
 */
public class MedialAxisTransformOp extends AbstractBinaryImageOp {
	private boolean simpleLaplace = false;

	@Override
	protected Matrix processImage(ByteMatrix input) {
		DistanceTransform transform = new DistanceTransform();
		transform.init(input, foregroundValue);
		IntMatrix dt = transform.computeSquareTransform();
		return laplace(dt).clamp(0, Integer.MAX_VALUE);
	}
	

	private IntMatrix laplace(IntMatrix m) {
		return simpleLaplace ? laplace4(m) : laplace8(m);
	}
	
	private IntMatrix laplace4(IntMatrix m) {
		
		IntMatrix result = new IntMatrix(m.rows, m.cols);
		
		int n0, n1, n2, n3;
		for (int i = 0; i < m.rows; i++) {
			
			n0 = (i != 0) ? 1 : 0;
			n3 = (i != m.rows - 1) ? 1 : 0;
			
			for (int j = 0; j < m.cols; j++) {
				
				 n1 = (j != 0) ? 1 : 0;
				 n2 = (j != m.cols-1) ? 1 : 0;
				 
				 int value = (n0 + n1 + n2 + n3) * m.intAt(i, j);
				 value -= (n0 != 0) ? m.intAt(i-1, j) : 0;
				 value -= (n1 != 0) ? m.intAt(i, j-1) : 0;
				 value -= (n2 != 0) ? m.intAt(i, j+1) : 0;
				 value -= (n3 != 0) ? m.intAt(i+1, j) : 0;
				 result.setIntAt(i, j, value);
			}
		}
		
		return result;
	}
	
	private IntMatrix laplace8(IntMatrix m) {
		IntMatrix result = new IntMatrix(m.rows, m.cols);
		
		int a = m.rows - 1;
		int b = m.cols - 1;
		
		int n0, n1, n2, n3, n4, n5, n6, n7;
		for (int i = 0; i < m.rows; i++) {
			
			for (int j = 0; j < m.cols; j++) {
				
				n0 = (i != 0 && j != 0) ? 1 : 0;
				n1 = (i != 0) ? 1 : 0;
				n2 = (i != 0 && j != b) ? 1 : 0;
				n3 = (j != 0) ? 1 : 0;
				n4 = (j != b) ? 1 : 0;
				n5 = (i != a && j != 0) ? 1 : 0;
				n6 = (i != a) ? 1 : 0;
				n7 = (i != a && j != b) ? 1 : 0;
				
				int w = (n0 + n1 + n2 + n3 + n4 + n5 + n6 + n7);
				int v = w * m.intAt(i, j);
				
				v -= (n0 != 0) ? m.intAt(i-1, j-1) : 0;
				v -= (n1 != 0) ? m.intAt(i-1, j  ) : 0;
				v -= (n2 != 0) ? m.intAt(i-1, j+1) : 0;
				v -= (n3 != 0) ? m.intAt(i  , j-1) : 0;
				v -= (n4 != 0) ? m.intAt(i  , j+1) : 0;
				v -= (n5 != 0) ? m.intAt(i+1, j-1) : 0;
				v -= (n6 != 0) ? m.intAt(i+1, j  ) : 0;
				v -= (n7 != 0) ? m.intAt(i+1, j+1) : 0;
				
				result.setIntAt(i, j, v);
			}
		}
		return result;
	}

	public Type getDefaultMatrixType() {
		return Matrix.Type.Int;
	}
}