/*
 * Copyright (c) 2010 by Intevation GmbH
 *
 * This program is free software under the LGPL (>=v2.1)
 * Read the file LGPL.txt coming with the software for details
 * or visit http://www.gnu.org/licenses/ if it does not exist.
 */

package de.intevation.gnv.chart;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;

import org.jfree.data.general.DatasetChangeEvent;
import org.jfree.data.xy.AbstractIntervalXYDataset;
import org.jfree.data.xy.IntervalXYDataset;

import org.jfree.data.statistics.HistogramType;
import org.jfree.data.statistics.HistogramBin;

import org.jfree.util.ObjectUtilities;
import org.jfree.util.PublicCloneable;

/**
 * This class extends the functionality of the internal JFreeChart class
 * <code>HistogramDataset</code>. <code>AdvancedHistogramDataset</code> takes
 * the number of bins OR a bin width. It is mainly a copy of this class. The
 * reason why there is no inheritance from JFreeChart's internal class is,
 * that basic attributes have private access there.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class AdvancedHistogramDataset
extends      AbstractIntervalXYDataset
implements   IntervalXYDataset, Cloneable, PublicCloneable, Serializable
{
    /** A list of maps. */
    protected List list;

    /** The histogram type. */
    protected HistogramType type;

    /** The width of a single bin. */
    protected double binWidth = -1;

    /** The number of bins. */
    protected int bins = -1;

    /** The logger */
    private static Logger logger =
        Logger.getLogger(AdvancedHistogramDataset.class);


    /**
     * Creates a new (empty) dataset with a default type of
     * {@link HistogramType}.FREQUENCY.
     */
    public AdvancedHistogramDataset() {
        this.list = new ArrayList();
        this.type = HistogramType.FREQUENCY;
    }

    /**
     * Creates a new (empty) dataset with a default type of
     * {@link HistogramType}.FREQUENCY.
     */
    public AdvancedHistogramDataset(int bins, double binWidth) {
        this.list     = new ArrayList();
        this.type     = HistogramType.FREQUENCY;
        this.bins     = bins;
        this.binWidth = binWidth;
    }

    /**
     * Returns the histogram type.
     *
     * @return The type (never <code>null</code>).
     */
    public HistogramType getType() {
        return this.type;
    }

    /**
     * Sets the histogram type and sends a {@link DatasetChangeEvent} to all
     * registered listeners.
     *
     * @param type  the type (<code>null</code> not permitted).
     */
    public void setType(HistogramType type) {
        if (type == null) {
            throw new IllegalArgumentException("Null 'type' argument");
        }
        this.type = type;
        notifyListeners(new DatasetChangeEvent(this, this));
    }

    /**
     * Adds a series to the dataset, using the specified number of bins.
     *
     * @param key  the series key (<code>null</code> not permitted).
     * @param values the values (<code>null</code> not permitted).
     */
    public void addSeries(Comparable key, double[] values) {
        double minimum = getMinimum(values);
        double maximum = getMaximum(values);
        addSeries(key, values, minimum, maximum);
    }

    /**
     * Adds a series to the dataset. Any data value less than minimum will be
     * assigned to the first bin, and any data value greater than maximum will
     * be assigned to the last bin.  Values falling on the boundary of
     * adjacent bins will be assigned to the higher indexed bin.
     *
     * @param key  the series key (<code>null</code> not permitted).
     * @param values  the raw observations.
     * @param bins  the number of bins (must be at least 1).
     * @param minimum  the lower bound of the bin range.
     * @param maximum  the upper bound of the bin range.
     */
    public void addSeries(Comparable key,
                          double[] values,
                          double minimum,
                          double maximum) {

        if (key == null) {
            throw new IllegalArgumentException("Null 'key' argument.");
        }
        if (values == null) {
            throw new IllegalArgumentException("Null 'values' argument.");
        }
        if (bins <= 0 && binWidth <= 0) {
            throw new IllegalArgumentException(
                "We need at least a bin width or the number of bins.");
        }

        // There is a binWidth given to calculate the number of bins in this
        // case
        if (bins <= 0) {
            double tmp = (maximum - minimum) / binWidth;
            bins       = (int) tmp;
            bins       = tmp % 1 > 0 ? bins + 1 : bins;

            double overlap = minimum + bins * binWidth - maximum;
            tmp            = minimum;
            minimum -= overlap / 2;

            logger.debug("There is an overlap of " + overlap);
            logger.info("The lower bound is moved left from "
                + tmp + " to " + minimum);

            tmp      = maximum;
            maximum += overlap / 2;
            logger.info("The upper bound is moved right from "
                + tmp + " to " + maximum);
        }

        if (bins <= 0) {
            bins = 1;
        }

        // in this case, there is a number of bins given, so we need to
        // calculate the width of a single bin
        if (binWidth <= 0)
            binWidth = (maximum - minimum) / bins;

        logger.info("bin width: " + binWidth);
        logger.info("number of bins: " + bins);

        double lower = minimum;
        double upper;
        List binList = new ArrayList(bins);
        for (int i = 0; i < bins; i++) {
            HistogramBin bin;
            // make sure bins[bins.length]'s upper boundary ends at maximum
            // to avoid the rounding issue. the bins[0] lower boundary is
            // guaranteed start from min
            if (i == bins - 1) {
                bin = new HistogramBin(lower, maximum);
            }
            else {
                upper = minimum + (i + 1) * binWidth;
                bin = new HistogramBin(lower, upper);
                lower = upper;
            }
            binList.add(bin);
        }
        // fill the bins
        for (int i = 0; i < values.length; i++) {
            int binIndex = bins - 1;
            if (values[i] < maximum) {
                double fraction = (values[i] - minimum) / (maximum - minimum);
                if (fraction < 0.0) {
                    fraction = 0.0;
                }
                binIndex = (int) (fraction * bins);
                // rounding could result in binIndex being equal to bins
                // which will cause an IndexOutOfBoundsException - see bug
                // report 1553088
                if (binIndex >= bins) {
                    binIndex = bins - 1;
                }
            }
            HistogramBin bin = (HistogramBin) binList.get(binIndex);
            bin.incrementCount();
        }
        // generic map for each series
        Map map = new HashMap();
        map.put("key", key);
        map.put("bins", binList);
        map.put("values.length", new Integer(values.length));
        map.put("bin width", new Double(binWidth));
        this.list.add(map);
    }

    /**
     * Returns the minimum value in an array of values.
     *
     * @param values  the values (<code>null</code> not permitted and
     *                zero-length array not permitted).
     *
     * @return The minimum value.
     */
    private double getMinimum(double[] values) {
        if (values == null || values.length < 1) {
            throw new IllegalArgumentException(
                    "Null or zero length 'values' argument.");
        }
        double min = Double.MAX_VALUE;
        for (int i = 0; i < values.length; i++) {
            if (values[i] < min) {
                min = values[i];
            }
        }
        return min;
    }

    /**
     * Returns the maximum value in an array of values.
     *
     * @param values  the values (<code>null</code> not permitted and
     *                zero-length array not permitted).
     *
     * @return The maximum value.
     */
    private double getMaximum(double[] values) {
        if (values == null || values.length < 1) {
            throw new IllegalArgumentException(
                    "Null or zero length 'values' argument.");
        }
        double max = -Double.MAX_VALUE;
        for (int i = 0; i < values.length; i++) {
            if (values[i] > max) {
                max = values[i];
            }
        }
        return max;
    }

    /**
     * Returns the bins for a series.
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     *
     * @return A list of bins.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    List getBins(int series) {
        Map map = (Map) this.list.get(series);
        return (List) map.get("bins");
    }

    /**
     * Returns the total number of observations for a series.
     *
     * @param series  the series index.
     *
     * @return The total.
     */
    private int getTotal(int series) {
        Map map = (Map) this.list.get(series);
        return ((Integer) map.get("values.length")).intValue();
    }

    /**
     * Returns the bin width for a series.
     *
     * @param series  the series index (zero based).
     *
     * @return The bin width.
     */
    private double getBinWidth(int series) {
        if (binWidth > 0)
            return binWidth;

        Map map = (Map) this.list.get(series);
        return ((Double) map.get("bin width")).doubleValue();
    }

    /**
     * Returns the number of series in the dataset.
     *
     * @return The series count.
     */
    public int getSeriesCount() {
        return this.list.size();
    }

    /**
     * Returns the key for a series.
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     *
     * @return The series key.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Comparable getSeriesKey(int series) {
        Map map = (Map) this.list.get(series);
        return (Comparable) map.get("key");
    }

    /**
     * Returns the number of data items for a series.
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     *
     * @return The item count.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public int getItemCount(int series) {
        return getBins(series).size();
    }

    /**
     * Returns the X value for a bin.  This value won't be used for plotting
     * histograms, since the renderer will ignore it.  But other renderers can
     * use it (for example, you could use the dataset to create a line
     * chart).
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The start value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getX(int series, int item) {
        List bins        = getBins(series);
        HistogramBin bin = (HistogramBin) bins.get(item);
        double x         = (bin.getStartBoundary() + bin.getEndBoundary()) / 2.;
        return new Double(x);
    }

    /**
     * Returns the y-value for a bin (calculated to take into account the
     * histogram type).
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The y-value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getY(int series, int item) {
        List bins        = getBins(series);
        HistogramBin bin = (HistogramBin) bins.get(item);
        double total     = getTotal(series);
        double binWidth  = getBinWidth(series);

        if (this.type == HistogramType.FREQUENCY) {
            return new Double(bin.getCount());
        }
        else if (this.type == HistogramType.RELATIVE_FREQUENCY) {
            return new Double(bin.getCount() / total);
        }
        else if (this.type == HistogramType.SCALE_AREA_TO_1) {
            return new Double(bin.getCount() / (binWidth * total));
        }
        else { // pretty sure this shouldn't ever happen
            throw new IllegalStateException();
        }
    }

    /**
     * Returns the start value for a bin.
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The start value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getStartX(int series, int item) {
        List bins = getBins(series);
        HistogramBin bin = (HistogramBin) bins.get(item);
        return new Double(bin.getStartBoundary());
    }

    /**
     * Returns the end value for a bin.
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The end value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getEndX(int series, int item) {
        List bins = getBins(series);
        HistogramBin bin = (HistogramBin) bins.get(item);
        return new Double(bin.getEndBoundary());
    }

    /**
     * Returns the start y-value for a bin (which is the same as the y-value,
     * this method exists only to support the general form of the
     * {@link IntervalXYDataset} interface).
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The y-value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getStartY(int series, int item) {
        return getY(series, item);
    }

    /**
     * Returns the end y-value for a bin (which is the same as the y-value,
     * this method exists only to support the general form of the
     * {@link IntervalXYDataset} interface).
     *
     * @param series  the series index (in the range <code>0</code> to
     *     <code>getSeriesCount() - 1</code>).
     * @param item  the item index (zero based).
     *
     * @return The Y value.
     *
     * @throws IndexOutOfBoundsException if <code>series</code> is outside the
     *     specified range.
     */
    public Number getEndY(int series, int item) {
        return getY(series, item);
    }

    /**
     * Tests this dataset for equality with an arbitrary object.
     *
     * @param obj  the object to test against (<code>null</code> permitted).
     *
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof AdvancedHistogramDataset)) {
            return false;
        }
        AdvancedHistogramDataset that = (AdvancedHistogramDataset) obj;
        if (!ObjectUtilities.equal(this.type, that.type)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.list, that.list)) {
            return false;
        }
        return true;
    }

    /**
     * Returns a clone of the dataset.
     *
     * @return A clone of the dataset.
     *
     * @throws CloneNotSupportedException if the object cannot be cloned.
     */
    public Object clone() throws CloneNotSupportedException {
        AdvancedHistogramDataset clone = (AdvancedHistogramDataset) super.clone();
        int seriesCount = getSeriesCount();
        clone.list = new java.util.ArrayList(seriesCount);
        for (int i = 0; i < seriesCount; i++) {
            clone.list.add(new HashMap((Map) this.list.get(i)));
        }
        return clone;
    }
}
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