package dokumenty;

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

public class SzybkiFiltrKrawedziowyPoziomy implements IOperator1P<IImageChannel, IImageChannel> {

	private IImageChannel imageChannel;
	private IImageChannel result;
	private int maskSize;
	private int fullSize;

	private float [] cached;

	public SzybkiFiltrKrawedziowyPoziomy(int maskSize) {
		this.maskSize = maskSize;
		this.fullSize = this.maskSize * 2 + 1;
	}

	private int getStartIndex(int coord) {
		if (coord - this.maskSize < 0) {
			return -(coord - this.maskSize);
		}
		return 0;
	}

	private int getEndIndex(int coord, int maxCoord) {
		if (coord + this.fullSize - this.maskSize >= maxCoord) {
			return maxCoord - (coord - this.maskSize);
		}
		return this.fullSize;
	}

	private void cacheValues(int x) {
		for (int y = 0; y < this.imageChannel.getYSize(); y++) {
			this.cached[y] = 0;
			int maxMx = this.getEndIndex(x, this.imageChannel.getXSize());
			for (int mx = this.getStartIndex(x); mx < maxMx; mx++) {
				int px = x + mx - this.maskSize;
				int index = this.imageChannel.getIndex(px, y);
				float value = this.imageChannel.getValue(index);
				this.cached[y] += value;
			}
		}
	}

	private void processSinglePixel(int x, int y) {
		float mean = 0;
		int maxMy = this.getEndIndex(y, this.imageChannel.getYSize());
		for (int my = this.getStartIndex(y); my < maxMy; my++) {
			int py = y + my - this.maskSize;
			if (my == this.maskSize) {
				mean += this.cached[py];
			} else {
				mean -= this.cached[py];
			}
		}
		this.result.setValue(x, y, mean);
	}

	public IImageChannel apply(IImageChannel imageChannel) {
		this.imageChannel = imageChannel;
		this.cached = new float[this.imageChannel.getYSize()];
		this.result = new ImageChannelFactory(this.imageChannel).apply();
		for (int x = 0; x < this.imageChannel.getXSize(); x++) {
			this.cacheValues(x);
			for (int y = 0; y < this.imageChannel.getYSize(); y++) {
				this.processSinglePixel(x, y);
			}
		}
		return this.result;
	}
}