/*
*

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package railo.runtime.img.filter;import java.awt.Rectangle;
import java.awt.image.BufferedImage;

import railo.runtime.engine.ThreadLocalPageContext;
import railo.runtime.exp.FunctionException;
import railo.runtime.exp.PageException;
import railo.runtime.img.ImageUtil;
import railo.runtime.type.Struct;
import railo.runtime.type.util.CollectionUtil;

/**
 * A filter to perform auto-equalization on an image.
 */
public class EqualizeFilter extends WholeImageFilter  implements DynFiltering {

    private int[][] lut;

	public EqualizeFilter() {
	}

	protected int[] filterPixels( int width, int height, int[] inPixels, Rectangle transformedSpace ) {
		Histogram histogram = new Histogram(inPixels, width, height, 0, width);

		int i, j;

		if (histogram.getNumSamples() > 0) {
			float scale = 255.0f / histogram.getNumSamples();
			lut = new int[3][256];
			for (i = 0; i < 3; i++) {
				lut[i][0] = histogram.getFrequency(i, 0);
				for (j = 1; j < 256; j++)
					lut[i][j] = lut[i][j-1] + histogram.getFrequency(i, j);
				for (j = 0; j < 256; j++)
					lut[i][j] = Math.round(lut[i][j]*scale);
			}
		} else
			lut = null;

		i = 0;
		for (int y = 0; y < height; y++)
			for (int x = 0; x < width; x++) {
				inPixels[i] = filterRGB(x, y, inPixels[i]);
				i++;
			}
		lut = null;
		
		return inPixels;
	}

	private int filterRGB(int x, int y, int rgb) {
		if (lut != null) {
			int a = rgb & 0xff000000;
			int r = lut[Histogram.RED][(rgb >> 16) & 0xff];
			int g = lut[Histogram.GREEN][(rgb >> 8) & 0xff];
			int b = lut[Histogram.BLUE][rgb & 0xff];

			return a | (r << 16) | (g << 8) | b;
		}
		return rgb;
	}

	public String toString() {
		return "Colors/Equalize";
	}
	public BufferedImage filter(BufferedImage src, Struct parameters) throws PageException {BufferedImage dst=ImageUtil.createBufferedImage(src);
		//Object o;

		// check for arguments not supported
		if(parameters.size()>0) {
			throw new FunctionException(ThreadLocalPageContext.get(), "ImageFilter", 3, "parameters", "the parameter"+(parameters.size()>1?"s":"")+" ["+CollectionUtil.getKeyList(parameters,", ")+"] "+(parameters.size()>1?"are":"is")+" not allowed, only the following parameters are supported []");
		}

		return filter(src, dst);
	}
}