/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.tools.math.function.window;

import java.lang.reflect.InvocationTargetException;


/**
 * A window function applies weights to the data points in a series window.
 * Left, right or center justification allows to adjust which data points
 * should get the highest weights. In case of center justification the window
 * function is symmetric.
 * 
 * @author Tobias Malbrecht
 */
public abstract class WindowFunction {
	public static final Class[] FUNCTIONS = {
		RectangularWindowFunction.class,
		TriangularWindowFunction.class,
		GaussianWindowFunction.class,
		HannWindowFunction.class,
		HammingWindowFunction.class,
		BlackmanWindowFunction.class,
		BlackmanHarrisWindowFunction.class,
		BartlettWindowFunction.class
	}; 
	
	public static final String[] FUNCTION_NAMES = {
		"Rectangular",
		"Triangular",
		"Gaussian",
		"Hann",
		"Hamming",
		"Blackman",
		"Blackman-Harris",
		"Bartlett"
	};
	
	public static final int RECTANGULAR = 0;
	
	public static final int TRIANGULAR = 1;
	
	public static final int GAUSSIAN = 2;
	
	public static final int HANN = 3;
	
	public static final int HAMMING = 4;
	
	public static final int BLACKMAN = 5;
	
	public static final int BLACKMAN_HARRIS = 6;
	
	public static final int BARTLETT = 7;
	
	public static final int JUSTIFY_CENTER = 0;
	
	public static final int JUSTIFY_LEFT = 1;
	
	public static final int JUSTIFY_RIGHT = 2;
	
	private int width;
	
	private int justifiedWidth;
	
	private int justifiedOffset;
	
    public static WindowFunction createWindowFunction(String functionName, int justification, int width) throws InstantiationException, IllegalAccessException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException {
        int typeIndex = -1;
        for (int i = 0; i < FUNCTION_NAMES.length; i++) {
            if (FUNCTION_NAMES[i].equals(functionName)) {
                typeIndex = i;
                break;
            }
        }
        Class<?> clazz = null;
        if (typeIndex < 0) {
            clazz = Class.forName(functionName);
        } else {
            clazz = FUNCTIONS[typeIndex];
        }
        return (WindowFunction) clazz.getConstructor(new Class[] { Integer.class, Integer.class }).newInstance(width, justification);
    }
    
    public static WindowFunction createWindowFunction(String functionName, int width) throws InstantiationException, IllegalAccessException, ClassNotFoundException, NoSuchMethodException, InvocationTargetException {
    	return createWindowFunction(functionName, JUSTIFY_CENTER, width);
    }
    
    public static WindowFunction createWindowFunction(int typeIndex, int justification, int width) throws InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
    	if (typeIndex >= 0 && typeIndex < FUNCTION_NAMES.length) {
    		Class<?> clazz = FUNCTIONS[typeIndex];
            return (WindowFunction) clazz.getConstructor(new Class[] { Integer.class, Integer.class }).newInstance(width, justification);
    	} else {
    		throw new InstantiationException();
    	}
    }
    
    public static WindowFunction createWindowFunction(int typeIndex, int width) throws InstantiationException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
    	return createWindowFunction(typeIndex, JUSTIFY_CENTER, width);
    }
	
	public WindowFunction(int width) {
		this(width, JUSTIFY_CENTER);
	}
	
	public WindowFunction(int width, int justification) {
		this.width = width;
		switch (justification) {
		case JUSTIFY_CENTER:
			this.justifiedWidth = width;
			this.justifiedOffset = 0;
			break;
		case JUSTIFY_LEFT:
			this.justifiedWidth = width * 2;
			this.justifiedOffset = width;
			break;
		case JUSTIFY_RIGHT:
			this.justifiedWidth = width * 2;
			this.justifiedOffset = 0;
			break;
		}
	}
	
	public double[] getWeights() {
		double[] weights = new double[width];
		for (int i = 0; i < width; i++) {
			weights[i] = getValue(justifiedWidth, justifiedOffset + i);
		}
		return weights;
	}

	protected abstract double getValue(int width, int n);
	
	public double getValue(int n) {
		return getValue(width, n);
	}
}