package de.intevation.flys.exports;

import java.awt.Color;
import java.awt.Font;

import java.io.IOException;
import java.io.OutputStream;

import java.util.ArrayList;
import java.util.List;
import java.util.Locale;

import javax.xml.xpath.XPathConstants;

import org.apache.log4j.Logger;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

import org.jfree.chart.JFreeChart;
import org.jfree.chart.LegendItem;
import org.jfree.chart.axis.NumberAxis;
import org.jfree.data.Range;

import de.intevation.artifacts.Artifact;
import de.intevation.artifacts.CallContext;
import de.intevation.artifacts.CallMeta;
import de.intevation.artifacts.PreferredLocale;

import de.intevation.artifacts.ArtifactNamespaceContext;
import de.intevation.artifacts.common.utils.XMLUtils;

import de.intevation.artifactdatabase.state.ArtifactAndFacet;
import de.intevation.artifactdatabase.state.Settings;

import de.intevation.flys.model.River;

import de.intevation.flys.artifacts.FLYSArtifact;
import de.intevation.flys.artifacts.resources.Resources;
import de.intevation.flys.utils.FLYSUtils;
import de.intevation.flys.utils.ThemeAccess;


/**
 * The base class for chart creation. It should provide some basic things that
 * equal in all chart types.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public abstract class ChartGenerator implements OutGenerator {

    private static Logger logger = Logger.getLogger(ChartGenerator.class);

    public static final int    DEFAULT_CHART_WIDTH     = 600;
    public static final int    DEFAULT_CHART_HEIGHT    = 400;
    public static final String DEFAULT_CHART_FORMAT    = "png";
    public static final Color  DEFAULT_GRID_COLOR      = Color.GRAY;
    public static final float  DEFAULT_GRID_LINE_WIDTH = 0.3f;
    public static final int    DEFAULT_FONT_SIZE       = 12;
    public static final String DEFAULT_FONT_NAME       = "Tahoma";


    public static final String XPATH_CHART_SIZE =
        "/art:action/art:attributes/art:size";

    public static final String XPATH_CHART_FORMAT =
        "/art:action/art:attributes/art:format/@art:value";

    public static final String XPATH_CHART_X_RANGE =
        "/art:action/art:attributes/art:xrange";

    public static final String XPATH_CHART_Y_RANGE =
        "/art:action/art:attributes/art:yrange";


    /** The document of the incoming out() request.*/
    protected Document request;

    /** The output stream where the data should be written to.*/
    protected OutputStream out;

    /** The CallContext object.*/
    protected CallContext context;

    /** The artifact that is used to decorate the chart with meta information.*/
    protected Artifact master;

    /** The settings that should be used during output creation.*/
    protected Settings settings;


    /**
     * A mini interface that allows to walk over the YAXIS enums defined in
     * subclasses.
     */
    public interface YAxisWalker {
        int length();
        String getId(int idx);
    }


    /**
     * This method needs to be implemented by concrete subclasses to create new
     * instances of JFreeChart.
     *
     * @return a new instance of a JFreeChart.
     */
    public abstract JFreeChart generateChart();


    public abstract void doOut(
        ArtifactAndFacet bundle,
        Document         attr,
        boolean          visible);


    protected abstract YAxisWalker getYAxisWalker();


    /**
     * Returns the default title of a chart.
     *
     * @return the default title of a chart.
     */
    protected abstract String getDefaultChartTitle();


    /**
     * Returns the default X-Axis label of a chart.
     *
     * @return the default X-Axis label of a chart.
     */
    protected abstract String getDefaultXAxisLabel();


    /**
     * This method is called to retrieve the default label for an Y axis at
     * position <i>pos</i>.
     *
     * @param pos The position of an Y axis.
     *
     * @return the default Y axis label at position <i>pos</i>.
     */
    protected abstract String getDefaultYAxisLabel(int pos);


    /**
     * This method should be used by concrete subclasses to add subtitle to
     * <i>chart</i>. <b>The method in this implementation is empty</b>.
     *
     * @param chart The JFreeChart chart object.
     */
    protected void addSubtitles(JFreeChart chart) {
        // do nothing
    }


    /**
     * Generate chart.
     */
    @Override
    public void generate()
    throws IOException
    {
        logger.debug("ChartGenerator.generate");

        JFreeChart chart = generateChart();

        String format = getFormat();
        int[]  size   = getSize();

        if (size == null) {
            size = getExportDimension();
        }

        context.putContextValue("chart.width",  size[0]);
        context.putContextValue("chart.height", size[1]);

        if (format.equals(ChartExportHelper.FORMAT_PNG)) {
            context.putContextValue("chart.image.format", "png");

            ChartExportHelper.exportImage(
                out,
                chart,
                context);
        }
        else if (format.equals(ChartExportHelper.FORMAT_PDF)) {
            preparePDFContext(context);

            ChartExportHelper.exportPDF(
                out,
                chart,
                context);
        }
        else if (format.equals(ChartExportHelper.FORMAT_SVG)) {
            prepareSVGContext(context);

            ChartExportHelper.exportSVG(
                out,
                chart,
                context);
        }
        else if (format.equals(ChartExportHelper.FORMAT_CSV)) {
            context.putContextValue("chart.image.format", "csv");

            ChartExportHelper.exportCSV(
                out,
                chart,
                context);
        }
    }


    @Override
    public void init(Document request, OutputStream out, CallContext context) {
        logger.debug("ChartGenerator.init");

        this.request = request;
        this.out     = out;
        this.context = context;
    }


    @Override
    public void setMasterArtifact(Artifact master) {
        this.master = master;
    }


    @Override
    public void setSettings(Settings settings) {
        this.settings = settings;
    }


    /**
     * Returns an instance of <i>ChartSettings</i> with a chart specific section
     * but with no axes settings.
     *
     * @return an instance of <i>ChartSettings</i>.
     */
    @Override
    public Settings getSettings() {
        if (this.settings != null) {
            return this.settings;
        }

        ChartSettings settings = new ChartSettings();

        ChartSection  chartSection  = buildChartSection();
        LegendSection legendSection = buildLegendSection();
        ExportSection exportSection = buildExportSection();

        settings.setChartSection(chartSection);
        settings.setLegendSection(legendSection);
        settings.setExportSection(exportSection);

        List<AxisSection> axisSections = buildAxisSections();
        for (AxisSection axisSection: axisSections) {
            settings.addAxisSection(axisSection);
        }

        return settings;
    }


    /**
     * Creates a new <i>ChartSection</i>.
     *
     * @return a new <i>ChartSection</i>.
     */
    protected ChartSection buildChartSection() {
        ChartSection chartSection = new ChartSection();
        chartSection.setTitle(getChartTitle());
        chartSection.setSubtitle(getChartSubtitle());
        chartSection.setDisplayGird(isGridVisible());
        return chartSection;
    }


    /**
     * Creates a new <i>LegendSection</i>.
     *
     * @return a new <i>LegendSection</i>.
     */
    protected LegendSection buildLegendSection() {
        LegendSection legendSection = new LegendSection();
        legendSection.setVisibility(isLegendVisible());
        legendSection.setFontSize(getLegendFontSize());
        return legendSection;
    }


    /**
     * Creates a new <i>ExportSection</i> with default values <b>WIDTH=600</b>
     * and <b>HEIGHT=400</b>.
     *
     * @return a new <i>ExportSection</i>.
     */
    protected ExportSection buildExportSection() {
        ExportSection exportSection = new ExportSection();
        exportSection.setWidth(600);
        exportSection.setHeight(400);
        return exportSection;
    }


    /**
     * Creates a list of Sections that contains all axes of the chart (including
     * X and Y axes).
     *
     * @return a list of Sections for each axis in this chart.
     */
    protected List<AxisSection> buildAxisSections() {
        List<AxisSection> axisSections = new ArrayList<AxisSection>();

        axisSections.addAll(buildXAxisSections());
        axisSections.addAll(buildYAxisSections());

        return axisSections;
    }


    /**
     * Creates a new Section for chart's X axis.
     *
     * @return a List that contains a Section for the X axis.
     */
    protected List<AxisSection> buildXAxisSections() {
        List<AxisSection> axisSections = new ArrayList<AxisSection>();

        String identifier = "X";

        AxisSection axisSection = new AxisSection();
        axisSection.setIdentifier(identifier);
        axisSection.setLabel(getXAxisLabel());
        axisSection.setFontSize(14);
        axisSection.setFixed(false);

        // XXX We are able to find better default ranges that [0,0], but the Y
        // axes currently have no better ranges set.
        axisSection.setUpperRange(0d);
        axisSection.setLowerRange(0d);

        axisSections.add(axisSection);

        return axisSections;
    }


    /**
     * Creates a list of Section for the chart's Y axes. This method makes use
     * of <i>getYAxisWalker</i> to be able to access all Y axes defined in
     * subclasses.
     *
     * @return a list of Y axis sections.
     */
    protected List<AxisSection> buildYAxisSections() {
        List<AxisSection> axisSections = new ArrayList<AxisSection>();

        YAxisWalker walker = getYAxisWalker();
        for (int i = 0, n = walker.length(); i < n; i++) {
            AxisSection ySection = new AxisSection();
            ySection.setIdentifier(walker.getId(i));
            ySection.setLabel(getYAxisLabel(i));
            ySection.setFontSize(14);
            ySection.setFixed(false);

            // XXX We are able to find better default ranges that [0,0], the
            // only problem is, that we do NOT have a better range than [0,0]
            // for each axis, because the initial chart will not have a dataset
            // for each axis set!
            ySection.setUpperRange(0d);
            ySection.setLowerRange(0d);

            axisSections.add(ySection);
        }

        return axisSections;
    }


    /**
     * Returns the <i>settings</i> as <i>ChartSettings</i>.
     *
     * @return the <i>settings</i> as <i>ChartSettings</i> or null, if
     * <i>settings</i> is not an instance of <i>ChartSettings</i>.
     */
    public ChartSettings getChartSettings() {
        if (settings instanceof ChartSettings) {
            return (ChartSettings) settings;
        }

        return null;
    }


    /**
     * Returns the chart title provided by <i>settings</i>.
     *
     * @param settings A ChartSettings object.
     *
     * @return the title provided by <i>settings</i> or null if no
     * <i>ChartSection</i> is provided by <i>settings</i>.
     *
     * @throws NullPointerException if <i>settings</i> is null.
     */
    public String getChartTitle(ChartSettings settings) {
        ChartSection cs = settings.getChartSection();
        return cs != null ? cs.getTitle() : null;
    }


    /**
     * Returns the chart subtitle provided by <i>settings</i>.
     *
     * @param settings A ChartSettings object.
     *
     * @return the subtitle provided by <i>settings</i> or null if no
     * <i>ChartSection</i> is provided by <i>settings</i>.
     *
     * @throws NullPointerException if <i>settings</i> is null.
     */
    public String getChartSubtitle(ChartSettings settings) {
        ChartSection cs = settings.getChartSection();
        return cs != null ? cs.getSubtitle() : null;
    }


    /**
     * Returns a boolean object that determines if the chart grid should be
     * visible or not. This information needs to be provided by <i>settings</i>,
     * otherweise the default is true.
     *
     * @param settings A ChartSettings object.
     *
     * @return true, if the chart grid should be visible otherwise false.
     *
     * @throws NullPointerException if <i>settings</i> is null.
     */
    public boolean isGridVisible(ChartSettings settings) {
        ChartSection     cs = settings.getChartSection();
        Boolean displayGrid = cs.getDisplayGrid();

        return displayGrid != null ? displayGrid : true;
    }


    /**
     * Returns a boolean object that determines if the chart legend should be
     * visible or not. This information needs to be provided by <i>settings</i>,
     * otherwise the default is true.
     *
     * @param settings A ChartSettings object.
     *
     * @return true, if the chart legend should be visible otherwise false.
     *
     * @throws NullPointerException if <i>settings</i> is null.
     */
    public boolean isLegendVisible(ChartSettings settings) {
        LegendSection      ls = settings.getLegendSection();
        Boolean displayLegend = ls.getVisibility();

        return displayLegend != null ? displayLegend : true;
    }


    /**
     * Returns the legend font size specified in <i>settings</i> or null if no
     * <i>LegendSection</i> is provided by <i>settings</i>.
     *
     * @param settings A ChartSettings object.
     *
     * @return the legend font size or null.
     *
     * @throws NullPointerException if <i>settings</i> is null.
     */
    public Integer getLegendFontSize(ChartSettings settings) {
        LegendSection ls = settings.getLegendSection();
        return ls != null ? ls.getFontSize() : null;
    }


    /**
     * Returns the title of a chart. The return value depends on the existence
     * of ChartSettings: if there are ChartSettings set, this method returns the
     * chart title provided by those settings. Otherwise, this method returns
     * getDefaultChartTitle().
     *
     * @return the title of a chart.
     */
    protected String getChartTitle() {
        ChartSettings chartSettings = getChartSettings();

        if (chartSettings != null) {
            return getChartTitle(chartSettings);
        }

        return getDefaultChartTitle();
    }


    /**
     * Returns the subtitle of a chart. The return value depends on the
     * existence of ChartSettings: if there are ChartSettings set, this method
     * returns the chart title provided by those settings. Otherwise, this
     * method returns getDefaultChartSubtitle().
     *
     * @return the subtitle of a chart.
     */
    protected String getChartSubtitle() {
        ChartSettings chartSettings = getChartSettings();

        if (chartSettings != null) {
            return getChartSubtitle(chartSettings);
        }

        return getDefaultChartSubtitle();
    }


    /**
     * This method always returns null. Override it in subclasses that require
     * subtitles.
     *
     * @return null.
     */
    protected String getDefaultChartSubtitle() {
        // Override this method in subclasses
        return null;
    }


    /**
     * This method is used to determine, if the chart's legend is visible or
     * not. If a <i>settings</i> instance is set, this instance determines the
     * visibility otherwise, this method returns true as default if no
     * <i>settings</i> is set.
     *
     * @return true, if the legend should be visible, otherwise false.
     */
    protected boolean isLegendVisible() {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings != null) {
            return isLegendVisible(chartSettings);
        }

        return true;
    }


    /**
     * This method is used to determine the font size of the chart's legend. If
     * a <i>settings</i> instance is set, this instance determines the font
     * size, otherwise this method returns 12 as default if no <i>settings</i>
     * is set or if it doesn't provide a legend font size.
     *
     * @return a legend font size.
     */
    protected int getLegendFontSize() {
        Integer fontSize = null;

        ChartSettings chartSettings = getChartSettings();
        if (chartSettings != null) {
            fontSize = getLegendFontSize(chartSettings);
        }

        return fontSize != null ? fontSize : DEFAULT_FONT_SIZE;
    }


    /**
     * This method is used to determine if the resulting chart should display
     * grid lines or not. <b>Note: this method always returns true!</b>
     *
     * @return true, if the chart should display grid lines, otherwise false.
     */
    protected boolean isGridVisible() {
        return true;
    }


    /**
     * Returns the X-Axis label of a chart.
     *
     * @return the X-Axis label of a chart.
     */
    protected String getXAxisLabel() {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return getDefaultXAxisLabel();
        }

        AxisSection as = chartSettings.getAxisSection("X");
        if (as != null) {
            String label = as.getLabel();

            if (label != null) {
                return label;
            }
        }

        return getDefaultXAxisLabel();
    }


    /**
     * This method returns the font size for the X axis. If the font size is
     * specified in ChartSettings (if <i>chartSettings</i> is set), this size is
     * returned. Otherwise the default font size 12 is returned.
     *
     * @return the font size for the x axis.
     */
    protected int getXAxisLabelFontSize() {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return DEFAULT_FONT_SIZE;
        }

        AxisSection   as = chartSettings.getAxisSection("X");
        Integer fontSize = as.getFontSize();

        return fontSize != null ? fontSize : DEFAULT_FONT_SIZE;
    }


    /**
     * This method returns the font size for an Y axis. If the font size is
     * specified in ChartSettings (if <i>chartSettings</i> is set), this size is
     * returned. Otherwise the default font size 12 is returned.
     *
     * @return the font size for the x axis.
     */
    protected int getYAxisFontSize(int pos) {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return DEFAULT_FONT_SIZE;
        }

        YAxisWalker walker = getYAxisWalker();

        AxisSection   as = chartSettings.getAxisSection(walker.getId(pos));
        Integer fontSize = as.getFontSize();

        return fontSize != null ? fontSize : DEFAULT_FONT_SIZE;
    }


    /**
     * This method returns the export dimension specified in ChartSettings as
     * int array [width,height].
     *
     * @return an int array with [width,height].
     */
    protected int[] getExportDimension() {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return new int[] { 600, 400 };
        }

        ExportSection export = chartSettings.getExportSection();
        Integer width  = export.getWidth();
        Integer height = export.getHeight();

        if (width != null && height != null) {
            return new int[] { width, height };
        }

        return new int[] { 600, 400 };
    }


    /**
     * Returns the Y-Axis label of a chart at position <i>pos</i>.
     *
     * @return the Y-Axis label of a chart at position <i>0</i>.
     */
    protected String getYAxisLabel(int pos) {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return getDefaultYAxisLabel(pos);
        }

        YAxisWalker walker = getYAxisWalker();
        AxisSection     as = chartSettings.getAxisSection(walker.getId(pos));
        if (as != null) {
            String label = as.getLabel();

            if (label != null) {
                return label;
            }
        }

        return getDefaultYAxisLabel(pos);
    }


    /**
     * This method searches for a specific axis in the <i>settings</i> if
     * <i>settings</i> is set. If the axis was found, this method returns the
     * specified axis range if the axis range is fixed. Otherwise, this method
     * returns null.
     *
     * @param axisId The identifier of an axis.
     *
     * @return the specified axis range from <i>settings</i> if the axis is
     * fixed, otherwise null.
     */
    public Range getRangeForAxisFromSettings(String axisId) {
        ChartSettings chartSettings = getChartSettings();
        if (chartSettings == null) {
            return null;
        }

        AxisSection as = chartSettings.getAxisSection(axisId);
        Boolean  fixed = as.isFixed();

        if (fixed != null && fixed) {
            Double upper = as.getUpperRange();
            Double lower = as.getLowerRange();

            if (upper != null && lower != null) {
                return lower < upper
                    ? new Range(lower, upper)
                    : new Range(upper, lower);
            }
        }

        return null;
    }


    /**
     * This helper mehtod is used to extract the current locale from instance
     * vairable <i>context</i>.
     *
     * @return the current locale.
     */
    protected Locale getLocale() {
        CallMeta           meta = context.getMeta();
        PreferredLocale[] prefs = meta.getLanguages();

        int len = prefs != null ? prefs.length : 0;

        Locale[] locales = new Locale[len];

        for (int i = 0; i < len; i++) {
            locales[i] = prefs[i].getLocale();
        }

        return meta.getPreferredLocale(locales);
    }


    protected String msg(String key, String def) {
        return Resources.getMsg(context.getMeta(), key, def);
    }


    protected String msg(String key, String def, Object[] args) {
        return Resources.getMsg(context.getMeta(), key, def, args);
    }


    protected String getRiverName() {
        FLYSArtifact flys = (FLYSArtifact) master;

        River river = FLYSUtils.getRiver(flys);
        return (river != null) ? river.getName() : "";
    }


    protected double[] getRange() {
        FLYSArtifact flys = (FLYSArtifact) master;

        return FLYSUtils.getKmRange(flys);
    }


    /**
     * Returns the size of a chart export as array which has been specified by
     * the incoming request document.
     *
     * @return the size of a chart as [width, height] or null if no width or
     * height are given in the request document.
     */
    protected int[] getSize() {
        int[] size = new int[2];

        Element sizeEl = (Element)XMLUtils.xpath(
            request,
            XPATH_CHART_SIZE,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

        if (sizeEl != null) {
            String uri = ArtifactNamespaceContext.NAMESPACE_URI;

            String w = sizeEl.getAttributeNS(uri, "width");
            String h = sizeEl.getAttributeNS(uri, "height");

            if (w.length() > 0 && h.length() > 0) {
                try {
                    size[0] = Integer.parseInt(w);
                    size[1] = Integer.parseInt(h);
                }
                catch (NumberFormatException nfe) {
                    logger.warn("Wrong values for chart width/height.");
                }
            }
        }

        return size[0] > 0 && size[1] > 0 ? size : null;
    }


    /**
     * This method returns the format specified in the <i>request</i> document
     * or <i>DEFAULT_CHART_FORMAT</i> if no format is specified in
     * <i>request</i>.
     *
     * @return the format used to export this chart.
     */
    protected String getFormat() {
        String format = (String) XMLUtils.xpath(
            request,
            XPATH_CHART_FORMAT,
            XPathConstants.STRING,
            ArtifactNamespaceContext.INSTANCE);

        return format == null || format.length() == 0
            ? DEFAULT_CHART_FORMAT
            : format;
    }


    /**
     * Get Range of Domain ("X"-) Axis from request.
     */
    protected Range getDomainAxisRange() {
        Element xrange = (Element)XMLUtils.xpath(
            request,
            XPATH_CHART_X_RANGE,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

        if (xrange == null) {
            return null;
        }

        String uri = ArtifactNamespaceContext.NAMESPACE_URI;

        String lower = xrange.getAttributeNS(uri, "from");
        String upper = xrange.getAttributeNS(uri, "to");

        if (lower.length() > 0 && upper.length() > 0) {
            try {
                double from = Double.parseDouble(lower);
                double to   = Double.parseDouble(upper);

                if (from == 0 && to == 0) {
                    logger.debug("No range specified. Lower and upper X == 0");
                    return null;
                }

                if (from > to) {
                    double tmp = to;
                    to         = from;
                    from       = tmp;
                }

                return new Range(from, to);
            }
            catch (NumberFormatException nfe) {
                logger.warn("Wrong values for domain axis range.");
            }
        }

        return null;
    }


    protected Range getValueAxisRange() {
        Element yrange = (Element)XMLUtils.xpath(
            request,
            XPATH_CHART_Y_RANGE,
            XPathConstants.NODE,
            ArtifactNamespaceContext.INSTANCE);

        if (yrange == null) {
            return null;
        }


        String uri = ArtifactNamespaceContext.NAMESPACE_URI;


        String lower = yrange.getAttributeNS(uri, "from");
        String upper = yrange.getAttributeNS(uri, "to");

        if (lower.length() > 0 && upper.length() > 0) {
            try {
                double from = Double.parseDouble(lower);
                double to   = Double.parseDouble(upper);

                if (from == 0 && to == 0) {
                    logger.debug("No range specified. Lower and upper Y == 0");
                    return null;
                }

                return from > to
                       ? new Range(to, from)
                       : new Range(from, to);
            }
            catch (NumberFormatException nfe) {
                logger.warn("Wrong values for value axis range.");
            }
        }

        return null;
    }


    /**
     * Returns the default size of a chart export as array.
     *
     * @return the default size of a chart as [width, height].
     */
    protected int[] getDefaultSize() {
        return new int[] { DEFAULT_CHART_WIDTH, DEFAULT_CHART_HEIGHT };
    }


    /**
     * Creates a new instance of <i>IdentifiableNumberAxis</i>.
     *
     * @param idx The index of the new axis.
     * @param label The label of the new axis.
     *
     * @return an instance of IdentifiableNumberAxis.
     */
    protected NumberAxis createNumberAxis(int idx, String label) {
        YAxisWalker walker = getYAxisWalker();

        return new IdentifiableNumberAxis(walker.getId(idx), label);
    }


    /**
     * Creates a new LegendItem with <i>name</i> and font provided by
     * <i>createLegendLabelFont()</i>.
     *
     * @param theme The theme of the chart line.
     * @param The displayed name of the item.
     *
     * @return a new LegendItem instance.
     */
    public LegendItem createLegendItem(Document theme, String name) {
        // OPTIMIZE Pass font, parsed Theme items.
        ThemeAccess themeAccess = new ThemeAccess(theme);

        Color      color       = themeAccess.parseLineColorField();
        LegendItem legendItem  = new LegendItem(name, color);

        legendItem.setLabelFont(createLegendLabelFont());
        return legendItem;
    }


    /**
     * Creates Font (Family and size) to use when creating Legend Items. The
     * font size depends in the return value of <i>getLegendFontSize()</i>.
     *
     * @return a new Font instance with <i>DEFAULT_FONT_NAME</i>.
     */
    protected Font createLegendLabelFont() {
        return new Font(
            DEFAULT_FONT_NAME,
            Font.PLAIN,
            getLegendFontSize()
        );
    }


    protected void preparePDFContext(CallContext context) {
        int[] dimension = getExportDimension();

        context.putContextValue("chart.width", dimension[0]);
        context.putContextValue("chart.height", dimension[1]);
        context.putContextValue("chart.marginLeft",   5f);
        context.putContextValue("chart.marginRight",  5f);
        context.putContextValue("chart.marginTop",    5f);
        context.putContextValue("chart.marginBottom", 5f);
        context.putContextValue(
            "chart.page.format",
            ChartExportHelper.DEFAULT_PAGE_SIZE);
    }


    protected void prepareSVGContext(CallContext context) {
        int[] dimension = getExportDimension();

        context.putContextValue("chart.width", dimension[0]);
        context.putContextValue("chart.height", dimension[1]);
        context.putContextValue(
            "chart.encoding",
            ChartExportHelper.DEFAULT_ENCODING);
    }
}
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