package edu.hws.eck.umb.palette;

import java.awt.Color;
import java.util.ArrayList;

import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

/**
 * Represents a palette, that is a sequence of colors.  A palette assigns
 * a color to each real number in the range 0 through 1, inclusive.  The color
 * is specified at several points in this range (including at least 0 and 1).
 * These points are referred to as "division points."
 * Between these points, the color is determined by linear interpolation.  A palette
 * can have color type HSB or RGB.  For HSB colors, the interpolation is done in
 * the HSB color space; for RGB colors, the interpolation is done in the RGB color
 * space.
 */
public class Palette implements Cloneable {
	
	/**
	 * The colorType for a palette in which colors are specified as Red/Green/Blue values.
	 */
	public final static int COLOR_TYPE_RGB = 0;

	/**
	 * The colorType for a palette in which colors are specified as Hue/Saturation/Brightness values.
	 */
	public final static int COLOR_TYPE_HSB = 1;
		
	private int colorType;
	private boolean mirrorOutOfRangeComponents;

	private ArrayList<Double> divisionPoints;  // First element is always 0; last value is always 1
	private ArrayList<float[]> divisionPointColors; // Size is divisionPoints.size() + 1
	
	private final ChangeEvent changeEvent = new ChangeEvent(this);
	private ArrayList<ChangeListener> changeListeners;
	
	/**
	 * Creates a palette of HSB color type, showing a rainbow spectrum.
	 */
	public Palette() {
		this(COLOR_TYPE_HSB);
	}

	/**
	 * Create a palette of specified color type.  For HSB color type, the palette
	 * is a rainbow spectrum.  For the RGB color type, the palette is a grayscale
	 * from white to black.
	 * @param colorType One of the constants Palette.COLOR_TYPE_HSB or Palette.COLOR_TYPE_RGB.
	 * @throws IllegalArgumentException if the parameter is not one of the two valid color type constants.
	 */
	public Palette(int colorType) {
		this.colorType = colorType;
		mirrorOutOfRangeComponents = true;
		divisionPoints = new ArrayList<Double>();
		divisionPointColors = new ArrayList<float[]>();
		divisionPoints.add(0.0);
		divisionPoints.add(1.0);
		if (colorType == COLOR_TYPE_HSB) { // spectrum
			divisionPointColors.add(new float[] {0, 1, 1});
			divisionPointColors.add(new float[] {1, 1, 1});
		}
		else if (colorType == COLOR_TYPE_RGB){ // grayscale
			divisionPointColors.add(new float[] {1, 1, 1});
			divisionPointColors.add(new float[] {0, 0, 0});
		}
		else 
			throw new IllegalArgumentException("Palette color type must be TYPE_COLOR_RGB or TYPE_COLOR_HSB");
	}
	
	Palette(int colorType, boolean mirrored, ArrayList<Double> divisionPoints, ArrayList<float[]> colorComponents) {
		   // For use by the PaletteIO and PaletteEditDialog classes in the same package; no error checking done here.
		this.colorType = colorType;
		this.mirrorOutOfRangeComponents = mirrored;
		this.divisionPoints = divisionPoints;
		this.divisionPointColors = colorComponents;
	}
	
	/**
	 * Creates one of the built-in palettes used in the Mandelbrot program.
	 * @param paletteName The name of the palette.  Must be one of "Spectrum",
	 * "PaleSpectrum", "Grayscale", "CyclicGrayscale", "CyclicRedCyan",
	 * "EarthSky", "HotCold", or "Fire".
	 * @throws IllegalArgumentException if the parameter is not one of the valid
	 * built-in palette names.
	 */
	public static Palette makeDefaultPalette(String paletteName) {
		Palette palette;
		if (paletteName.equals("Spectrum")) {
			palette = new Palette();
		}
		else if (paletteName.equals("PaleSpectrum")) {
			palette = new Palette();
			palette.setDivisionPointColorComponents(0, 0, 0.5f, 1);
			palette.setDivisionPointColorComponents(1, 1, 0.5f, 1);
		}
		else if (paletteName.equals("Grayscale")) {
			palette =new Palette(Palette.COLOR_TYPE_RGB);
		}
		else if (paletteName.equals("CyclicGrayscale")) {
			palette = new Palette(Palette.COLOR_TYPE_RGB);
			palette.split(0.5);
			palette.setDivisionPointColorComponents(1, 0, 0, 0);
			palette.setDivisionPointColorComponents(2, 1, 1, 1);
		}
		else if (paletteName.equals("CyclicRedCyan")) {
			palette = new Palette(Palette.COLOR_TYPE_RGB);
			palette.split(0.5);
			palette.setDivisionPointColorComponents(0, 1, 0, 0);
			palette.setDivisionPointColorComponents(1, 0, 1, 1);
			palette.setDivisionPointColorComponents(2, 1, 0, 0);
		}
		else if (paletteName.equals("EarthSky")) {
			palette = new Palette(Palette.COLOR_TYPE_RGB);
			palette.split(0.15);
			palette.split(0.33);
			palette.split(0.67);
			palette.split(0.85);
			palette.setDivisionPointColorComponents(0, 1, 1, 1);
			palette.setDivisionPointColorComponents(1, 1, 0.8f, 0);
			palette.setDivisionPointColorComponents(2, 0.53f, 0.12f, 0.075f);
			palette.setDivisionPointColorComponents(3, 0, 0, 0.6f);
			palette.setDivisionPointColorComponents(4, 0, 0.4f, 1);
			palette.setDivisionPointColorComponents(5, 1, 1, 1);
		}
		else if (paletteName.equals("HotCold")) {
			palette = new Palette(Palette.COLOR_TYPE_RGB);
			palette.split(0.16);
			palette.split(0.5);
			palette.split(0.84);
			palette.setDivisionPointColorComponents(0, 1, 1, 1);
			palette.setDivisionPointColorComponents(1, 0, 0.4f, 1);
			palette.setDivisionPointColorComponents(2, 0.2f, 0.2f, 0.2f);
			palette.setDivisionPointColorComponents(3, 1, 0, 0.8f);
			palette.setDivisionPointColorComponents(4, 1, 1, 1);
		}
		else if (paletteName.equals("Fire")) {
			palette = new Palette(Palette.COLOR_TYPE_RGB);
			palette.split(0.17);
			palette.split(0.83);
			palette.setDivisionPointColorComponents(0, 0, 0, 0);
			palette.setDivisionPointColorComponents(1, 1, 0, 0);
			palette.setDivisionPointColorComponents(2, 1, 1, 0);
			palette.setDivisionPointColorComponents(3, 1, 1, 1);
		}
		else
			throw new IllegalArgumentException("Unknown palette: " + paletteName);
		return palette;
	}
	
	public boolean equals(Object obj) {
		if (obj == null || !(obj instanceof Palette))
			return false;
		Palette that = (Palette)obj;
		if (that.colorType != colorType)
			return false;
		if (that.mirrorOutOfRangeComponents != mirrorOutOfRangeComponents)
			return false;
		if (that.divisionPoints.size() != divisionPoints.size())
			return false;
		for (int i = 0; i < divisionPoints.size(); i++) {
			if (that.divisionPoints.get(i) != divisionPoints.get(i))
				return false;
			float[] a = that.divisionPointColors.get(i);
			float[] b = divisionPointColors.get(i);
			if (a[0] != b[0] || a[1] != b[1] || a[2] != b[2])
				return false;
		}
		return true;
	}
	
	public Palette clone() {
		Palette that = new Palette(this.colorType);
		that.mirrorOutOfRangeComponents = this.mirrorOutOfRangeComponents;
		that.divisionPoints = new ArrayList<Double>();
		that.divisionPoints.addAll(this.divisionPoints);
		that.divisionPointColors = new ArrayList<float[]>();
		for (float[] c : this.divisionPointColors)
			that.divisionPointColors.add(c.clone());
		that.changed();
		return that;
	}
	
	/**
	 * Copies all properties from a specified palette, making this
	 * palette equal to the specified palette.
	 * @param that the palette whose properties are to be copied
	 */
	public void copyFrom(Palette that) {
		this.colorType = that.colorType;
		this.mirrorOutOfRangeComponents = that.mirrorOutOfRangeComponents;
		this.divisionPoints = new ArrayList<Double>();
		this.divisionPoints.addAll(that.divisionPoints);
		this.divisionPointColors = new ArrayList<float[]>();
		for (float[] c : that.divisionPointColors)
			this.divisionPointColors.add(c.clone());
		this.changed();
	}
	
	/**
	 * Removes a specified division point, one of the points where the color is specified explicitly.
	 * @param divisionPointIndex the number of the division point to be removed, which much be
	 * in the range 1 through ct-2, where ct is the number of division points.  It is not possible
	 * to remove the first division point (which is 0.0) or the last division point (which is 1.0).
	 */
	public void join(int divisionPointIndex) {
		if (divisionPointIndex <= 0 || divisionPointIndex >= divisionPoints.size() - 1)
			throw new IllegalArgumentException("Division point index out of range: " + divisionPointIndex);
		divisionPoints.remove(divisionPointIndex);
		divisionPointColors.remove(divisionPointIndex);
		changed();
	}
	
	/**
	 * Adds a division point to the palette.  The color associated to the point is obtained by
	 * interpolating between the colors of the points that neighbor the new point.
	 * @param divisionPoint The number between 0.0 and 1.0 where the new division point is to
	 * be added.  The value cannot be the same as an existing point.
	 * @return The index of the new division point, this is, its position number in the list of division points.
	 * @throws IllegalArgumentException if the parameter is less than 0.0 or greater than 1.0, or if
	 * a division point already exists at the specified value.
	 */
	public int split(double divisionPoint) {  // Return value is index of divisionPoint/color that are inserted, or -1 if exact number already exists as a divisionPoint
		if (divisionPoint <= 0 || divisionPoint >= 1 || Double.isNaN(divisionPoint))
			throw new IllegalArgumentException("Division point out of range: " + divisionPoint);
		int index = 0;
		while (divisionPoint > divisionPoints.get(index))
			index++;
		if (Math.abs(divisionPoint - divisionPoints.get(index)) < 1e-15)
			return -1;
		float ratio = (float)( (divisionPoint - divisionPoints.get(index-1)) 
				/ (divisionPoints.get(index) - divisionPoints.get(index-1)) );
		float[] c1 = divisionPointColors.get(index-1);
		float[] c2 = divisionPointColors.get(index);
		float a = c1[0] + ratio*(c2[0] - c1[0]);
		float b = c1[1] + ratio*(c2[1] - c1[1]);
		float c = c1[2] + ratio*(c2[2] - c1[2]);
		float[] color = new float[] { a, b, c };
		divisionPoints.add(index, divisionPoint);
		divisionPointColors.add(index, color);
		changed();
		return index;
	}
	
	/**
	 * Get the color that this palette assigns to a specified number.
	 * @param position the number between 0.0 and 1.0, inclusive, for which the corresponding
	 * color is to be returned.
	 * @throws IllegalArgumentException if the position is outside the range 0.0 to 1.0.
	 */
	public Color getColor(double position) {
		if (position < 0 || position > 1)
			throw new IllegalArgumentException("Position " + position + " is out of range.");
		int pt = 1;
		while (position > divisionPoints.get(pt))
			pt++;
		float ratio = (float)( (position - divisionPoints.get(pt-1)) 
				/ (divisionPoints.get(pt) - divisionPoints.get(pt-1)) );
		float[] c1 = divisionPointColors.get(pt-1);
		float[] c2 = divisionPointColors.get(pt);
		float a = clamp1(c1[0] + ratio*(c2[0] - c1[0]));
		float b = clamp2(c1[1] + ratio*(c2[1] - c1[1]));
		float c = clamp2(c1[2] + ratio*(c2[2] - c1[2]));
		Color color;
		if (colorType == COLOR_TYPE_HSB)
			color = Color.getHSBColor(a, b, c);
		else
			color = new Color(a, b, c);
		return color;
	}
		
	/**
	 * Get an array of RGB color values corresponding to equally spaced points in the
	 * range 0.0 to 1.0.
	 * @param paletteLength The number of points for which colors will be returned.
	 * @param offset the color values are "rotated" by this amount within the array.
	 * That is, the color value corresponding to 0.0 is in the array at index = offset
	 * (or, more exactly, paletteLength % offset).
	 */
	public int[] makeRGBs(int paletteLength, int offset) {
		int[] rgb;
		rgb = new int[paletteLength];
		rgb[offset % paletteLength] = getDivisionPointColor(0).getRGB();
		int ct = 1;
		double dx = 1.0 / (paletteLength-1);
		int pt = 1;
		while (ct < paletteLength-1) {
			double position = dx*ct;
			while (position > divisionPoints.get(pt))
				pt++;
			float ratio = (float)( (position - divisionPoints.get(pt-1)) 
					/ (divisionPoints.get(pt) - divisionPoints.get(pt-1)) );
			float[] c1 = divisionPointColors.get(pt-1);
			float[] c2 = divisionPointColors.get(pt);
			float a = clamp1(c1[0] + ratio*(c2[0] - c1[0]));
			float b = clamp2(c1[1] + ratio*(c2[1] - c1[1]));
			float c = clamp2(c1[2] + ratio*(c2[2] - c1[2]));
			Color color;
			if (colorType == COLOR_TYPE_HSB)
				color = Color.getHSBColor(a, b, c);
			else
				color = new Color(a, b, c);
			rgb[(ct + offset) % paletteLength] = color.getRGB();
			ct++;
		}
		rgb[(offset + paletteLength-1) % paletteLength] = getDivisionPointColor(divisionPoints.size()-1).getRGB();
		return rgb;
	}

	/**
	 * Returns the number of division points in the palette, always two or more.
	 */
	public int getDivisionPointCount() {
		return divisionPoints.size();
	}
	
	/**
	 * Returns a specified division points.  The return value is the range 0.0 to 1.0.  Divsion points
	 * are stored in strictly increasing order.
	 * @param index The index of the desired division point in the list of division points.
	 */
	public double getDivisionPoint(int index) {
		return divisionPoints.get(index);
	}
	
	/**
	 * Sets the value of a specified division point.  Does not apply to the first or last points,
	 * which always have values 0.0 and 1.0.  The new value must be strictly between the positions
	 * the neighboring division points.
	 * @param index The index of the division point whose position is to be set.
	 * @param position The new position for the specified division point.
	 * @throws IllegalArgumentException if the index or position is not valid.
	 */
	public void setDivisionPoint(int index, double position) {
		if (index <= 0 || index >= divisionPoints.size() - 1)
			throw new IllegalArgumentException("Index out of legal range");
		if (position <= divisionPoints.get(index-1) || position >= divisionPoints.get(index+1))
			throw new IllegalArgumentException("Division point position outside of legal range.");
		if (position != divisionPoints.get(index)) {
			divisionPoints.set(index, position);
			changed();
		}
	}
	
	/**
	 * Get the color associated with a given division point.
	 * @param index The index of the division point in the list of points.
	 */
	public Color getDivisionPointColor(int index) {
		float[] components = divisionPointColors.get(index);
		float a = clamp1(components[0]);
		float b = clamp2(components[1]);
		float c = clamp2(components[2]);
		if (colorType == COLOR_TYPE_RGB)
			return new Color(a,b,c);
		else
			return Color.getHSBColor(a,b,c);
	}
	
	/**
	 * Returns the color components for the division point at a specified index.
	 */
	public float[] getDivisionPointColorComponents(int index) {
		return divisionPointColors.get(index).clone();
	}
	
	/**
	 * Set the color components for the division point at a s specified index in the list of
	 * division points.  These components are the color data that is stored for each division
	 * point and that are used for interpolation between division points.  Note that when a color
	 * is actually computed, the component values must be in the range 0.0 to 1.0.  However, the
	 * values specified here do NOT have to be in this range.  Values given here are used for
	 * interpolation, and then the resulting values are transformed into the range 0.0 to 1.0
	 * just before the color is computed.  This means that the value can effectively oscillate
	 * several times between two division points.
	 * @param index
	 * @param c1 The Red color component for an RGB palette, or the Hue component for an HSB palette.
	 * @param c2 The Green color component for an RGB palette, or the Saturation component for an HSB palette.
	 * @param c3 The Blue color component for an RGB palette, or the Brightness component for an HSB palette.
	 */
	public void setDivisionPointColorComponents(int index, float c1, float c2, float c3) {
		float[] c = divisionPointColors.get(index);
		if (c1 == c[0] && c2 == c[1] && c3 == c[2])
			return;
		c[0] = c1;
		c[1] = c2;
		c[2] = c3;
		changed();
	}

	/**
	 * Return the color type of this palette, which is one of the constants Palette.COLOR_TYPE_RGB
	 * or Palette.COLOR_TYPE_HSB.
	 */
	public int getColorType() {
		return colorType;
	}

	public boolean getMirrorOutOfRangeComponents() {
		return mirrorOutOfRangeComponents;
	}

	/**
	 * Sets the value of the confusing mirrorOutOfRangeComponents property.  This only has
	 * an effect when a floating-point color component value that is outside the range
	 * 0.0 to 1.0 has to be transformed to a value within that range.  For a Hue, the whole-number
	 * part is simply discarded.  For the other components however, the transformation depends
	 * on the value of the mirrorOutOfRangeComponents property.  If the property is false,
	 * the whole-number part is discarded, but this results in a discontinuity at integer values.
	 * If the property is true, this discontinuity is avoided by having the value oscillate with
	 * period 2 instead of cycle with period 1.  The default value is true, and this is never 
	 * changed in the Mandelbrot application.  So, really, you shouldn't even be reading this.
	 */
	public void setMirrorOutOfRangeComponents(boolean mirrorOutOfRangeComponents) {
		if (this.mirrorOutOfRangeComponents == mirrorOutOfRangeComponents)
			return;
		this.mirrorOutOfRangeComponents = mirrorOutOfRangeComponents;
		changed();
	}
	
	/**
	 * Add a listener that will be notified whenever the palette changes in any way.
	 */
	public void addChangeListener(ChangeListener listener) {
		if (listener == null)
			return;
		if (changeListeners == null)
			changeListeners = new ArrayList<ChangeListener>();
		if (!changeListeners.contains(listener))
			changeListeners.add(listener);
	}

	/**
	 * Remove a listener (if present in the list of listeners).
	 */
	public void removeChangeListener(ChangeListener listener) {
		if (changeListeners == null)
			return;
		changeListeners.remove(listener);
		if (changeListeners.size() == 0)
			changeListeners = null;
	}
	
	private float clamp1(float x) {
		if (colorType == COLOR_TYPE_HSB || !mirrorOutOfRangeComponents)
			return x - (float)Math.floor(x);
		else 
			return clamp2(x);
	}
	
	private float clamp2(float x) {
		if (!mirrorOutOfRangeComponents)
			return x - (float)Math.floor(x);
		x = 2*(x/2 - (float)Math.floor(x/2));
		if (x > 1)
			x = 2 - x;
		return x;
	}
		
	private void changed() {
		if (changeListeners != null)
			for (ChangeListener lst : changeListeners)
				lst.stateChanged(changeEvent);
	}
}