/*******************************************************************************
 * Copyright (c) 2016 École Polytechnique de Montréal
 *
 * All rights reserved. This program and the accompanying materials are
 * made available under the terms of the Eclipse Public License 2.0 which
 * accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *******************************************************************************/

package org.eclipse.tracecompass.internal.tmf.chart.ui.swtchart;

import static org.eclipse.tracecompass.common.core.NonNullUtils.checkNotNull;

import java.text.Format;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Objects;
import java.util.Set;
import java.util.function.Predicate;
import java.util.stream.Stream;

import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.jdt.annotation.Nullable;
import org.eclipse.osgi.util.NLS;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.MouseAdapter;
import org.eclipse.swt.events.MouseEvent;
import org.eclipse.swt.events.MouseMoveListener;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.graphics.GC;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.tracecompass.common.core.NonNullUtils;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.chart.ChartData;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.chart.ChartModel;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.chart.ChartSeries;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.descriptor.DataChartNumericalDescriptor;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.descriptor.DataChartStringDescriptor;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.descriptor.IDescriptorVisitor;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.resolver.INumericalResolver;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.resolver.IStringResolver;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.core.signal.ChartSelectionUpdateSignal;
import org.eclipse.tracecompass.internal.provisional.tmf.chart.ui.chart.IChartViewer;
import org.eclipse.tracecompass.internal.tmf.chart.core.aggregator.IConsumerAggregator;
import org.eclipse.tracecompass.internal.tmf.chart.core.consumer.IDataConsumer;
import org.eclipse.tracecompass.internal.tmf.chart.core.consumer.NumericalConsumer;
import org.eclipse.tracecompass.internal.tmf.chart.ui.aggregator.NumericalConsumerAggregator;
import org.eclipse.tracecompass.internal.tmf.chart.ui.consumer.ScatterStringConsumer;
import org.eclipse.tracecompass.internal.tmf.chart.ui.consumer.XYChartConsumer;
import org.eclipse.tracecompass.internal.tmf.chart.ui.consumer.XYSeriesConsumer;
import org.eclipse.tracecompass.internal.tmf.chart.ui.data.ChartRangeMap;
import org.eclipse.tracecompass.internal.tmf.chart.ui.dialog.Messages;
import org.eclipse.tracecompass.internal.tmf.chart.ui.format.LabelFormat;
import org.eclipse.tracecompass.tmf.core.signal.TmfSignalManager;
import org.swtchart.Chart;
import org.swtchart.IAxis;
import org.swtchart.IAxisSet;
import org.swtchart.IAxisTick;
import org.swtchart.ILineSeries;
import org.swtchart.ISeries;
import org.swtchart.ISeries.SeriesType;
import org.swtchart.ISeriesSet;
import org.swtchart.LineStyle;

import com.google.common.collect.BiMap;
import com.google.common.collect.HashBiMap;
import com.google.common.collect.Iterators;

/**
 * Class for building a scatter chart.
 *
 * FIXME: In this class, each method have if/then/else structure to cover string
 * or numerical axes. The specificities for each type of axes should be wrapped
 * in a small inline class that cover only the specific string or numerical
 * case. We wouldn't need the ranges and string maps all in the main class, each
 * sub-class would have only the fields it needs and it will be less
 * error-prone.
 *
 * @author Gabriel-Andrew Pollo-Guilbert
 */
public final class SwtScatterChart extends SwtXYChartViewer {

    // ------------------------------------------------------------------------
    // Constants
    // ------------------------------------------------------------------------

    private static final int SELECTION_SNAP_RANGE_MULTIPLIER = 20;

    // ------------------------------------------------------------------------
    // Members
    // ------------------------------------------------------------------------

    /**
     * Map linking X string categories to integer
     *
     * FIXME: Either the string map or a range is used for each axis, so instead
     * of having them both, we should try to group the concept in subclasses
     */
    private final BiMap<String, Integer> fXStringMap = HashBiMap.create();
    /**
     * Map linking Y string categories to integer
     */
    private final BiMap<String, Integer> fYStringMap = HashBiMap.create();
    /**
     * Range map for the X axis
     */
    private ChartRangeMap fXRanges = new ChartRangeMap();
    /**
     * Range map for the Y axis
     */
    private ChartRangeMap fYRanges = new ChartRangeMap();
    /**
     * Map used for showing X categories on the axis
     */
    private BiMap<String, Integer> fVisibleXMap = HashBiMap.create();
    /**
     * Map used for showing Y categories on the axis
     */
    private BiMap<String, Integer> fVisibleYMap = HashBiMap.create();
    /**
     * Coordinates in pixels of the currently hovered point
     */
    private Point fHoveringPoint = new Point(-1, -1);
    /**
     * The SWT reference of the currently hovered point
     */
    private @Nullable SwtChartPoint fHoveredPoint;

    // ------------------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------------------

    /**
     * Constructor.
     *
     * @param parent
     *            parent composite
     * @param data
     *            configured data series for the chart
     * @param model
     *            chart model to use
     */
    public SwtScatterChart(Composite parent, ChartData data, ChartModel model) {
        super(parent, data, model);

        /* Add the mouse hovering listener */
        getChart().getPlotArea().addMouseMoveListener(new MouseHoveringListener());

        /* Add the mouse exit listener */
        getChart().getPlotArea().addListener(SWT.MouseExit, new MouseExitListener());

        /* Add the mouse click listener */
        getChart().getPlotArea().addMouseListener(new MouseDownListener());

        /* Add the paint listener */
        getChart().getPlotArea().addPaintListener(new ScatterPainterListener());

        populate();
    }

    // ------------------------------------------------------------------------
    // Overriden methods
    // ------------------------------------------------------------------------

    // FIXME: This is not SWTchart-specific, it should go higher up
    private class ConsumerCreatorVisitor implements IDescriptorVisitor {
        private final boolean fLogScale;
        private final BiMap<String, Integer> fMap;
        private @Nullable IDataConsumer fConsumer;

        ConsumerCreatorVisitor(boolean logScale, BiMap<String, Integer> bimap) {
            fLogScale = logScale;
            fMap = bimap;
        }

        @Override
        public void visit(@NonNull DataChartStringDescriptor<?> desc) {
            fConsumer = new ScatterStringConsumer(IStringResolver.class.cast(desc.getResolver()), fMap);
        }

        @Override
        public void visit(@NonNull DataChartNumericalDescriptor<?, ? extends @NonNull Number> desc) {
            /*
             * FIXME: Can this visitor be made generic so that we can have the
             * right parameters and not need to cast the resolver here?
             */
            INumericalResolver<Object, Number> resolver = INumericalResolver.class.cast(desc.getResolver());
            Predicate<@Nullable Number> predicate;
            if (fLogScale) {
                predicate = new LogarithmicPredicate(resolver);
            } else {
                predicate = Objects::nonNull;
            }

            /* Create a consumer for the X descriptor */
            fConsumer = new NumericalConsumer(resolver, predicate);
        }

        public IDataConsumer getConsumer() {
            IDataConsumer consumer = fConsumer;
            if (consumer == null) {
                throw new NullPointerException("The getConsumer method of the visitor should not be called before visiting a descriptor"); //$NON-NLS-1$
            }
            return consumer;
        }
    }

    @Override
    protected IDataConsumer getXConsumer(@NonNull ChartSeries series) {
        ConsumerCreatorVisitor visitor = new ConsumerCreatorVisitor(getModel().isXLogscale(), fXStringMap);
        series.getX().accept(visitor);
        return visitor.getConsumer();
    }

    @Override
    protected IDataConsumer getYConsumer(@NonNull ChartSeries series) {
        ConsumerCreatorVisitor visitor = new ConsumerCreatorVisitor(getModel().isYLogscale(), fYStringMap);
        series.getY().accept(visitor);
        return visitor.getConsumer();
    }

    @Override
    protected @Nullable IConsumerAggregator getXAggregator() {
        if (getXDescriptorsInfo().areNumerical()) {
            return new NumericalConsumerAggregator();
        }
        return null;
    }

    @Override
    protected @Nullable IConsumerAggregator getYAggregator() {
        if (getYDescriptorsInfo().areNumerical()) {
            return new NumericalConsumerAggregator();
        }
        return null;
    }

    @Override
    protected ISeries createSwtSeries(ChartSeries chartSeries, ISeriesSet swtSeriesSet, @NonNull Color color) {
        String title = chartSeries.getY().getName();

        if (getXDescriptors().stream().distinct().count() > 1) {
            title = NLS.bind(Messages.ChartSeries_MultiSeriesTitle, title, chartSeries.getX().getLabel());
        }

        ILineSeries swtSeries = (ILineSeries) swtSeriesSet.createSeries(SeriesType.LINE, title);
        swtSeries.setLineStyle(LineStyle.NONE);
        swtSeries.setSymbolColor(color);

        return swtSeries;
    }

    @Override
    protected void configureSeries(Map<@NonNull ISeries, Object[]> mapper) {
        XYChartConsumer chartConsumer = getChartConsumer();

        /* Obtain the X ranges if possible */
        NumericalConsumerAggregator xAggregator = (NumericalConsumerAggregator) chartConsumer.getXAggregator();
        if (xAggregator != null) {
            if (getModel().isXLogscale()) {
                fXRanges = clampInputDataRange(xAggregator.getChartRanges());
            } else {
                fXRanges = xAggregator.getChartRanges();
            }
        }

        /* Obtain the Y ranges if possible */
        NumericalConsumerAggregator yAggregator = (NumericalConsumerAggregator) chartConsumer.getYAggregator();
        if (yAggregator != null) {
            if (getModel().isYLogscale()) {
                fYRanges = clampInputDataRange(yAggregator.getChartRanges());
            } else {
                fYRanges = yAggregator.getChartRanges();
            }
        }

        /* Generate data for each SWT series */
        for (XYSeriesConsumer seriesConsumer : chartConsumer.getSeries()) {
            double[] xData;
            double[] yData;
            Object[] object = seriesConsumer.getConsumedElements().toArray();

            /* Generate data for the X axis */
            if (getXDescriptorsInfo().areNumerical()) {
                NumericalConsumer consumer = (NumericalConsumer) seriesConsumer.getXConsumer();
                List<Number> data = consumer.getData();
                int size = data.size();

                xData = new double[size];
                for (int i = 0; i < size; i++) {
                    Number number = checkNotNull(data.get(i));
                    xData[i] = fXRanges.getInternalValue(number).doubleValue();
                }
            } else {
                ScatterStringConsumer consumer = (ScatterStringConsumer) seriesConsumer.getXConsumer();
                List<String> list = consumer.getList();

                xData = new double[list.size()];
                for (int i = 0; i < xData.length; i++) {
                    String str = list.get(i);
                    xData[i] = checkNotNull(fXStringMap.get(str));
                }
            }

            /* Generate data for the Y axis */
            if (getYDescriptorsInfo().areNumerical()) {
                NumericalConsumer consumer = (NumericalConsumer) seriesConsumer.getYConsumer();
                List<Number> data = consumer.getData();

                yData = new double[data.size()];
                for (int i = 0; i < yData.length; i++) {
                    Number number = checkNotNull(data.get(i));
                    yData[i] = fYRanges.getInternalValue(number).doubleValue();
                }
            } else {
                ScatterStringConsumer consumer = (ScatterStringConsumer) seriesConsumer.getYConsumer();
                List<String> list = consumer.getList();

                yData = new double[list.size()];
                for (int i = 0; i < yData.length; i++) {
                    String str = list.get(i);
                    yData[i] = checkNotNull(fYStringMap.get(str));
                }
            }

            /* Set the data for the SWT series */
            ISeries series = checkNotNull(getSeriesMap().get(seriesConsumer.getSeries()));
            series.setXSeries(xData);
            series.setYSeries(yData);

            /* Create a series mapper */
            mapper.put(series, checkNotNull(object));
        }
    }

    @Override
    protected void configureAxes() {
        /* Format X axes */
        Stream.of(getChart().getAxisSet().getXAxes()).forEach(a -> {
            IAxisTick tick = checkNotNull(a.getTick());
            Format format;

            /* Give a continuous formatter if the descriptors are numericals */
            if (getXDescriptorsInfo().areNumerical()) {
                format = getContinuousAxisFormatter(fXRanges, getXDescriptorsInfo());
            } else {
                fVisibleXMap = HashBiMap.create(fXStringMap);
                format = new LabelFormat(fVisibleXMap);
                updateTickMark(fVisibleXMap, tick, getChart().getPlotArea().getSize().x);
            }

            tick.setFormat(format);
        });

        /* Format Y axes */
        Stream.of(getChart().getAxisSet().getYAxes()).forEach(a -> {
            IAxisTick tick = checkNotNull(a.getTick());
            Format format;

            /* Give a continuous formatter if the descriptors are numericals. */
            if (getYDescriptorsInfo().areNumerical()) {
                format = getContinuousAxisFormatter(fYRanges, getYDescriptorsInfo());
            } else {
                fVisibleYMap = HashBiMap.create(fYStringMap);
                format = new LabelFormat(fVisibleYMap);
                updateTickMark(fVisibleYMap, tick, getChart().getPlotArea().getSize().y);
            }

            tick.setFormat(format);
        });
    }

    @Override
    protected void refreshDisplayLabels() {

        /**
         * TODO: support for the Y axis too
         */

        /* Only refresh if labels are visible */
        Chart chart = getChart();
        IAxisSet axisSet = chart.getAxisSet();
        IAxis xAxis = axisSet.getXAxis(0);
        if (!xAxis.getTick().isVisible()) {
            return;
        }

        /*
         * Shorten all the labels to 5 characters plus "…" when the longest
         * label length is more than 50% of the chart height.
         */
        Rectangle rect = chart.getClientArea();
        int lengthLimit = (int) (rect.height * 0.40);

        GC gc = new GC(getParent());
        gc.setFont(xAxis.getTick().getFont());

        // FIXME: the refresh of labels should be done differently for numerical
        // or string axes. Here this only refreshes the X axis labels for string
        // labels.
        if (!fXStringMap.isEmpty()) {

            /* Find the longest category string */
            String longestString = Collections.max(fXStringMap.keySet(), Comparator.comparingInt(String::length));

            /* Get the length and height of the longest label in pixels */
            Point pixels = gc.stringExtent(longestString);

            /* Completely arbitrary */
            int cutLen = 5;

            if (pixels.x > lengthLimit) {
                /* We have to cut down some strings */
                for (Entry<String, Integer> entry : fXStringMap.entrySet()) {
                    String reference = checkNotNull(entry.getKey());

                    if (reference.length() > cutLen) {
                        String key = reference.substring(0, cutLen) + ELLIPSIS;
                        fVisibleXMap.remove(reference);
                        fVisibleXMap.put(key, entry.getValue());
                    } else {
                        fVisibleXMap.inverse().remove(entry.getValue());
                        fVisibleXMap.put(reference, entry.getValue());
                    }
                }
            } else {
                /* All strings should fit */
                resetBiMap(fXStringMap, fVisibleXMap);
            }

            for (IAxis axis : axisSet.getXAxes()) {
                IAxisTick tick = axis.getTick();
                tick.setFormat(new LabelFormat(fVisibleXMap));
            }
        }

        /* Cleanup */
        gc.dispose();
    }

    @Override
    protected void setSelection(@NonNull Set<@NonNull Object> set) {
        super.setSelection(set);

        /* Set color of selected symbol */
        Iterator<Color> colorsIt = Iterators.cycle(COLORS);
        Iterator<Color> lightColorsIt = Iterators.cycle(COLORS_LIGHT);

        for (ISeries series : getChart().getSeriesSet().getSeries()) {
            /* Series color */
            Color lightColor = NonNullUtils.checkNotNull(lightColorsIt.next());
            Color color = NonNullUtils.checkNotNull(colorsIt.next());

            if (set.isEmpty()) {
                /* Put all symbols to the normal colors */
                ((ILineSeries) series).setSymbolColor(color);
            } else {
                /*
                 * Fill with light colors to represent the deselected state. The
                 * paint listener is then responsible for drawing the cross and
                 * the dark colors for the selection.
                 */
                ((ILineSeries) series).setSymbolColor(lightColor);
            }
        }
    }

    // ------------------------------------------------------------------------
    // Util methods
    // ------------------------------------------------------------------------

    /**
     * Util method used to reset a bimap from a reference.
     *
     * @param reference
     *            Reference map
     * @param map
     *            Map to modify
     */
    public static <K, V> void resetBiMap(BiMap<K, V> reference, BiMap<K, V> map) {
        map.clear();
        map.putAll(reference);
    }

    // ------------------------------------------------------------------------
    // Listeners
    // ------------------------------------------------------------------------

    private final class MouseHoveringListener implements MouseMoveListener {
        @Override
        public void mouseMove(@Nullable MouseEvent event) {
            if (event == null) {
                return;
            }

            double closestDistance = -1.0;

            boolean found = false;
            for (ISeries swtSeries : getChart().getSeriesSet().getSeries()) {
                ILineSeries series = (ILineSeries) swtSeries;
                double[] xSeries = series.getXSeries();

                for (int i = 0; i < xSeries.length; i++) {
                    Point dataPoint = series.getPixelCoordinates(i);

                    /*
                     * Find the distance between the data point and the mouse
                     * location and compare it to the symbol size * the range
                     * multiplier, so when a user hovers the mouse near the dot
                     * the cursor cross snaps to it.
                     */
                    int snapRangeRadius = series.getSymbolSize() * SELECTION_SNAP_RANGE_MULTIPLIER;

                    /*
                     * FIXME: if and only if performance of this code is an
                     * issue for large sets, this can be accelerated by getting
                     * the distance squared, and if it is smaller than
                     * snapRangeRadius squared, then check hypot.
                     */
                    double distance = Math.hypot(dataPoint.x - event.x, dataPoint.y - event.y);

                    if (distance < snapRangeRadius && (closestDistance == -1 || distance < closestDistance)) {
                        fHoveringPoint.x = dataPoint.x;
                        fHoveringPoint.y = dataPoint.y;

                        fHoveredPoint = new SwtChartPoint(series, i);

                        closestDistance = distance;
                        found = true;
                    }
                }
            }

            /* Check if a point was found */
            if (!found) {
                fHoveredPoint = null;
            }

            refresh();
        }
    }

    private final class MouseExitListener implements Listener {
        @Override
        public void handleEvent(@Nullable Event event) {
            if (event != null) {
                fHoveringPoint.x = -1;
                fHoveringPoint.y = -1;

                fHoveredPoint = null;

                refresh();
            }
        }
    }

    private final class MouseDownListener extends MouseAdapter {
        @Override
        public void mouseDown(@Nullable MouseEvent event) {
            if (event == null || event.button != 1) {
                return;
            }

            /* Check if a point is hovered */
            SwtChartPoint selection = fHoveredPoint;
            if (selection == null) {
                getSelection().clear();
            } else {
                boolean ctrl = (event.stateMask & SWT.CTRL) != 0;
                getSelection().touch(selection, ctrl);
            }

            /* Redraw the selected points */
            refresh();

            /* Find these points map to which objects */
            Set<Object> set = new HashSet<>();
            for (SwtChartPoint point : getSelection().getPoints()) {
                Object[] objects = checkNotNull(getObjectMap().get(point.getSeries()));

                /* Add objects to the set */
                Object obj = objects[point.getIndex()];
                if (obj != null) {
                    set.add(obj);
                }
            }

            /* Send the update signal */
            setSelection(set);
            ChartSelectionUpdateSignal signal = new ChartSelectionUpdateSignal(SwtScatterChart.this, getData().getDataProvider(), set);
            TmfSignalManager.dispatchSignal(signal);
        }
    }

    private final class ScatterPainterListener implements PaintListener {
        @Override
        public void paintControl(@Nullable PaintEvent event) {
            if (event == null) {
                return;
            }

            GC gc = event.gc;
            if (gc == null) {
                return;
            }

            /* Draw the hovering cross */
            drawHoveringCross(gc);

            /* Don't draw if there's no selection */
            if (!getSelection().getPoints().isEmpty()) {
                /* Draw the selected points */
                drawSelectedDot(gc);
            }

        }

        private void drawHoveringCross(GC gc) {
            if (fHoveredPoint == null) {
                return;
            }

            gc.setLineWidth(1);
            gc.setLineStyle(SWT.LINE_SOLID);
            gc.setForeground(Display.getCurrent().getSystemColor(SWT.COLOR_BLACK));
            gc.setBackground(Display.getCurrent().getSystemColor(SWT.COLOR_WHITE));

            /* Vertical line */
            gc.drawLine(fHoveringPoint.x, 0, fHoveringPoint.x, getChart().getPlotArea().getSize().y);

            /* Horizontal line */
            gc.drawLine(0, fHoveringPoint.y, getChart().getPlotArea().getSize().x, fHoveringPoint.y);
        }

        private void drawSelectedDot(GC gc) {
            for (SwtChartPoint point : getSelection().getPoints()) {
                ISeries series = point.getSeries();
                Point coor = series.getPixelCoordinates(point.getIndex());
                int symbolSize = ((ILineSeries) series).getSymbolSize();

                Color symbolColor = ((ILineSeries) series).getSymbolColor();
                if (symbolColor == null) {
                    continue;
                }
                Color darkColor = IChartViewer.getCorrespondingColor(symbolColor);
                /* Create a colored dot for selection */
                gc.setBackground(darkColor);
                gc.fillOval(coor.x - symbolSize, coor.y - symbolSize, symbolSize * 2, symbolSize * 2);

                /* Configure cross settings */
                gc.setLineWidth(2);
                gc.setLineStyle(SWT.LINE_SOLID);
                int drawingDelta = 2 * symbolSize;

                /* Vertical line */
                gc.drawLine(coor.x, coor.y - drawingDelta, coor.x, coor.y + drawingDelta);

                /* Horizontal line */
                gc.drawLine(coor.x - drawingDelta, coor.y, coor.x + drawingDelta, coor.y);
            }
        }
    }

}