/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-present, by David Gilbert and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
 * Other names may be trademarks of their respective owners.]
 *
 * -----------------------
 * GradientBarPainter.java
 * -----------------------
 * (C) Copyright 2008-present, by David Gilbert.
 *
 * Original Author:  David Gilbert;
 * Contributor(s):   -;
 *
 */

package org.jfree.chart.renderer.category;

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.Paint;
import java.awt.Stroke;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RectangularShape;
import java.io.Serializable;

import org.jfree.chart.HashUtils;
import org.jfree.chart.ui.RectangleEdge;

/**
 * An implementation of the {@link BarPainter} interface that uses several
 * gradient fills to enrich the appearance of the bars.
 */
public class GradientBarPainter implements BarPainter, Serializable {

    /** The division point between the first and second gradient regions. */
    private double g1;

    /** The division point between the second and third gradient regions. */
    private double g2;

    /** The division point between the third and fourth gradient regions. */
    private double g3;

    /**
     * Creates a new instance.
     */
    public GradientBarPainter() {
        this(0.10, 0.20, 0.80);
    }

    /**
     * Creates a new instance.
     *
     * @param g1  percentage value defining the line between regions 1 and 2.
     * @param g2  percentage value defining the line between regions 2 and 3.
     * @param g3  percentage value defining the line between regions 3 and 4.
     */
    public GradientBarPainter(double g1, double g2, double g3) {
        this.g1 = g1;
        this.g2 = g2;
        this.g3 = g3;
    }

    /**
     * Paints a single bar instance.
     *
     * @param g2  the graphics target.
     * @param renderer  the renderer.
     * @param row  the row index.
     * @param column  the column index.
     * @param bar  the bar
     * @param base  indicates which side of the rectangle is the base of the
     *              bar.
     */
    @Override
    public void paintBar(Graphics2D g2, BarRenderer renderer, int row,
            int column, RectangularShape bar, RectangleEdge base) {

        Paint itemPaint = renderer.getItemPaint(row, column);

        Color c0, c1;
        if (itemPaint instanceof Color) {
            c0 = (Color) itemPaint;
            c1 = c0.brighter();
        }
        else if (itemPaint instanceof GradientPaint) {
            GradientPaint gp = (GradientPaint) itemPaint;
            c0 = gp.getColor1();
            c1 = gp.getColor2();
        }
        else {
            c0 = Color.BLUE;
            c1 = Color.BLUE.brighter();
        }

        // as a special case, if the bar colour has alpha == 0, we draw
        // nothing.
        if (c0.getAlpha() == 0) {
            return;
        }

        if (base == RectangleEdge.TOP || base == RectangleEdge.BOTTOM) {
            Rectangle2D[] regions = splitVerticalBar(bar, this.g1, this.g2,
                    this.g3);
            GradientPaint gp = new GradientPaint((float) regions[0].getMinX(),
                    0.0f, c0, (float) regions[0].getMaxX(), 0.0f, Color.WHITE);
            g2.setPaint(gp);
            g2.fill(regions[0]);

            gp = new GradientPaint((float) regions[1].getMinX(), 0.0f,
                    Color.WHITE, (float) regions[1].getMaxX(), 0.0f, c0);
            g2.setPaint(gp);
            g2.fill(regions[1]);

            gp = new GradientPaint((float) regions[2].getMinX(), 0.0f, c0,
                    (float) regions[2].getMaxX(), 0.0f, c1);
            g2.setPaint(gp);
            g2.fill(regions[2]);

            gp = new GradientPaint((float) regions[3].getMinX(), 0.0f, c1,
                     (float) regions[3].getMaxX(), 0.0f, c0);
            g2.setPaint(gp);
            g2.fill(regions[3]);
        }
        else if (base == RectangleEdge.LEFT || base == RectangleEdge.RIGHT) {
            Rectangle2D[] regions = splitHorizontalBar(bar, this.g1, this.g2,
                    this.g3);
            GradientPaint gp = new GradientPaint(0.0f,
                    (float) regions[0].getMinY(), c0, 0.0f,
                    (float) regions[0].getMaxY(), Color.WHITE);
            g2.setPaint(gp);
            g2.fill(regions[0]);

            gp = new GradientPaint(0.0f, (float) regions[1].getMinY(),
                    Color.WHITE, 0.0f, (float) regions[1].getMaxY(), c0);
            g2.setPaint(gp);
            g2.fill(regions[1]);

            gp = new GradientPaint(0.0f, (float) regions[2].getMinY(), c0,
                    0.0f, (float) regions[2].getMaxY(), c1);
            g2.setPaint(gp);
            g2.fill(regions[2]);

            gp = new GradientPaint(0.0f, (float) regions[3].getMinY(), c1,
                     0.0f, (float) regions[3].getMaxY(), c0);
            g2.setPaint(gp);
            g2.fill(regions[3]);

        }

        // draw the outline...
        if (renderer.isDrawBarOutline()
            /*&& state.getBarWidth() > renderer.BAR_OUTLINE_WIDTH_THRESHOLD*/) {
            Stroke stroke = renderer.getItemOutlineStroke(row, column);
            Paint paint = renderer.getItemOutlinePaint(row, column);
            if (stroke != null && paint != null) {
                g2.setStroke(stroke);
                g2.setPaint(paint);
                g2.draw(bar);
            }
        }

    }

    /**
     * Paints a single bar instance.
     *
     * @param g2  the graphics target.
     * @param renderer  the renderer.
     * @param row  the row index.
     * @param column  the column index.
     * @param bar  the bar
     * @param base  indicates which side of the rectangle is the base of the
     *              bar.
     * @param pegShadow  peg the shadow to the base of the bar?
     */
    @Override
    public void paintBarShadow(Graphics2D g2, BarRenderer renderer, int row,
            int column, RectangularShape bar, RectangleEdge base,
            boolean pegShadow) {

        // handle a special case - if the bar colour has alpha == 0, it is
        // invisible so we shouldn't draw any shadow
        Paint itemPaint = renderer.getItemPaint(row, column);
        if (itemPaint instanceof Color) {
            Color c = (Color) itemPaint;
            if (c.getAlpha() == 0) {
                return;
            }
        }

        RectangularShape shadow = createShadow(bar, renderer.getShadowXOffset(),
                renderer.getShadowYOffset(), base, pegShadow);
        g2.setPaint(renderer.getShadowPaint());
        g2.fill(shadow);

    }

    /**
     * Creates a shadow for the bar.
     *
     * @param bar  the bar shape.
     * @param xOffset  the x-offset for the shadow.
     * @param yOffset  the y-offset for the shadow.
     * @param base  the edge that is the base of the bar.
     * @param pegShadow  peg the shadow to the base?
     *
     * @return A rectangle for the shadow.
     */
    private Rectangle2D createShadow(RectangularShape bar, double xOffset,
            double yOffset, RectangleEdge base, boolean pegShadow) {
        double x0 = bar.getMinX();
        double x1 = bar.getMaxX();
        double y0 = bar.getMinY();
        double y1 = bar.getMaxY();
        if (base == RectangleEdge.TOP) {
            x0 += xOffset;
            x1 += xOffset;
            if (!pegShadow) {
                y0 += yOffset;
            }
            y1 += yOffset;
        }
        else if (base == RectangleEdge.BOTTOM) {
            x0 += xOffset;
            x1 += xOffset;
            y0 += yOffset;
            if (!pegShadow) {
                y1 += yOffset;
            }
        }
        else if (base == RectangleEdge.LEFT) {
            if (!pegShadow) {
                x0 += xOffset;
            }
            x1 += xOffset;
            y0 += yOffset;
            y1 += yOffset;
        }
        else if (base == RectangleEdge.RIGHT) {
            x0 += xOffset;
            if (!pegShadow) {
                x1 += xOffset;
            }
            y0 += yOffset;
            y1 += yOffset;
        }
        return new Rectangle2D.Double(x0, y0, (x1 - x0), (y1 - y0));
    }

    /**
     * Splits a bar into subregions (elsewhere, these subregions will have
     * different gradients applied to them).
     *
     * @param bar  the bar shape.
     * @param a  the first division.
     * @param b  the second division.
     * @param c  the third division.
     *
     * @return An array containing four subregions.
     */
    private Rectangle2D[] splitVerticalBar(RectangularShape bar, double a,
            double b, double c) {
        Rectangle2D[] result = new Rectangle2D[4];
        double x0 = bar.getMinX();
        double x1 = Math.rint(x0 + (bar.getWidth() * a));
        double x2 = Math.rint(x0 + (bar.getWidth() * b));
        double x3 = Math.rint(x0 + (bar.getWidth() * c));
        result[0] = new Rectangle2D.Double(bar.getMinX(), bar.getMinY(),
                x1 - x0, bar.getHeight());
        result[1] = new Rectangle2D.Double(x1, bar.getMinY(), x2 - x1,
                bar.getHeight());
        result[2] = new Rectangle2D.Double(x2, bar.getMinY(), x3 - x2,
                bar.getHeight());
        result[3] = new Rectangle2D.Double(x3, bar.getMinY(),
                bar.getMaxX() - x3, bar.getHeight());
        return result;
    }

    /**
     * Splits a bar into subregions (elsewhere, these subregions will have
     * different gradients applied to them).
     *
     * @param bar  the bar shape.
     * @param a  the first division.
     * @param b  the second division.
     * @param c  the third division.
     *
     * @return An array containing four subregions.
     */
    private Rectangle2D[] splitHorizontalBar(RectangularShape bar, double a,
            double b, double c) {
        Rectangle2D[] result = new Rectangle2D[4];
        double y0 = bar.getMinY();
        double y1 = Math.rint(y0 + (bar.getHeight() * a));
        double y2 = Math.rint(y0 + (bar.getHeight() * b));
        double y3 = Math.rint(y0 + (bar.getHeight() * c));
        result[0] = new Rectangle2D.Double(bar.getMinX(), bar.getMinY(),
                bar.getWidth(), y1 - y0);
        result[1] = new Rectangle2D.Double(bar.getMinX(), y1, bar.getWidth(),
                y2 - y1);
        result[2] = new Rectangle2D.Double(bar.getMinX(), y2, bar.getWidth(),
                y3 - y2);
        result[3] = new Rectangle2D.Double(bar.getMinX(), y3, bar.getWidth(),
                bar.getMaxY() - y3);
        return result;
    }

    /**
     * Tests this instance for equality with an arbitrary object.
     *
     * @param obj  the obj ({@code null} permitted).
     *
     * @return A boolean.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof GradientBarPainter)) {
            return false;
        }
        GradientBarPainter that = (GradientBarPainter) obj;
        if (this.g1 != that.g1) {
            return false;
        }
        if (this.g2 != that.g2) {
            return false;
        }
        if (this.g3 != that.g3) {
            return false;
        }
        return true;
    }

    /**
     * Returns a hash code for this instance.
     *
     * @return A hash code.
     */
    @Override
    public int hashCode() {
        int hash = 37;
        hash = HashUtils.hashCode(hash, this.g1);
        hash = HashUtils.hashCode(hash, this.g2);
        hash = HashUtils.hashCode(hash, this.g3);
        return hash;
    }

}
