package pl.wroc.pwr.imagechannel.edges;

import pl.wroc.pwr.IOperator1P;
import pl.wroc.pwr.imagechannel.IImageChannel;
import pl.wroc.pwr.imagechannel.factory.ImageChannelFactory;

public class Sobel implements IOperator1P<IImageChannel, IImageChannel> {
	private float threshold;

	public Sobel(float threshold) {
		this.threshold = threshold;
	}

	public IImageChannel apply(IImageChannel inputChannel) {
		IImageChannel outputChannel = new ImageChannelFactory( inputChannel ).apply();

		final int ySize = inputChannel.getYSize();
		for (int x = 1; x < inputChannel.getXSize() - 1; x++) {
			for ( int y = 1; y < ySize - 1; y++ ) {
				float a = inputChannel.getValue(x - 1, y - 1);
				float b = inputChannel.getValue(x + 0, y - 1);
				float c = inputChannel.getValue(x + 1, y - 1);
				float d = inputChannel.getValue(x - 1, y + 0);
				float e = inputChannel.getValue(x + 1, y + 0);
				float f = inputChannel.getValue(x - 1, y + 1);
				float g = inputChannel.getValue(x + 0, y + 1);
				float h = inputChannel.getValue(x + 1, y + 1);

				float hor = Math.abs((a + d + f) - (c + e + h));
				float vert = Math.abs((a + b + c) - (f + g + h));

				float result = hor + vert;
				if (result > this.threshold) {
					outputChannel.setValue(x, y, 1);
				}
			}
		}
		return outputChannel;
	}
}