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 * Copyright (c) 2010, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package com.sun.javafx.scene.control.behavior;

import com.sun.javafx.util.Utils;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.event.EventType;
import javafx.geometry.NodeOrientation;
import javafx.geometry.Orientation;
import javafx.scene.control.Control;
import javafx.scene.control.ScrollBar;
import javafx.scene.control.Skin;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.util.Duration;

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

import static javafx.scene.input.KeyCode.*;
import static javafx.scene.input.KeyEvent.KEY_RELEASED;

/**
 * A Behavior implementation for ScrollBars.
 *
 */

public class ScrollBarBehavior extends BehaviorBase<ScrollBar> {

    /***************************************************************************
     *                                                                         *
     * Constructors                                                            *
     *                                                                         *
     **************************************************************************/

    public ScrollBarBehavior(ScrollBar scrollBar) {
        super(scrollBar, SCROLL_BAR_BINDINGS);
    }

    /***************************************************************************
     *                                                                         *
     * Functions                                                               *
     *                                                                         *
     **************************************************************************/

    void home() {
        getControl().setValue(getControl().getMin());
    }

    void decrementValue() {
        getControl().adjustValue(0);
    }

    void end() {
        getControl().setValue(getControl().getMax());
    }

    void incrementValue() {
        getControl().adjustValue(1);
    }

    /***************************************************************************
     *                                                                         *
     * Key event handling                                                      *
     *                                                                         *
     **************************************************************************/

    /* We manually specify the focus traversal keys because Slider has
     * different usage for up/down arrow keys.
     */
    protected static final List<KeyBinding> SCROLL_BAR_BINDINGS = new ArrayList<>();
    static {
        SCROLL_BAR_BINDINGS.add(new KeyBinding(F4, "TraverseDebug").alt().ctrl().shift());

        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(LEFT, "DecrementValue"));
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(KP_LEFT, "DecrementValue"));
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(UP, "DecrementValue").vertical());
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(KP_UP, "DecrementValue").vertical());
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(RIGHT, "IncrementValue"));
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(KP_RIGHT, "IncrementValue"));
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(DOWN, "IncrementValue").vertical());
        SCROLL_BAR_BINDINGS.add(new ScrollBarKeyBinding(KP_DOWN, "IncrementValue").vertical());

        SCROLL_BAR_BINDINGS.add(new KeyBinding(HOME, KEY_RELEASED, "Home"));
        SCROLL_BAR_BINDINGS.add(new KeyBinding(END, KEY_RELEASED, "End"));
    }

    protected /*final*/ String matchActionForEvent(KeyEvent e) {
        String action = super.matchActionForEvent(e);
        if (action != null) {
            if (e.getCode() == LEFT || e.getCode() == KP_LEFT) {
                if (getControl().getEffectiveNodeOrientation() == NodeOrientation.RIGHT_TO_LEFT) {
                    action = getControl().getOrientation() == Orientation.HORIZONTAL ? "IncrementValue" : "DecrementValue";
                }
            } else if (e.getCode() == RIGHT || e.getCode() == KP_RIGHT) {
                if (getControl().getEffectiveNodeOrientation() == NodeOrientation.RIGHT_TO_LEFT) {
                    action = getControl().getOrientation() == Orientation.HORIZONTAL ? "DecrementValue" : "IncrementValue";
                }
            }
        }
        return action;
    }

    @Override protected void callAction(String name) {
        if ("Home".equals(name)) home();
        else if ("End".equals(name)) end();
        else if ("IncrementValue".equals(name)) incrementValue();
        else if ("DecrementValue".equals(name)) decrementValue();
        else super.callAction(name);
        super.callAction(name);
    }

    /***************************************************************************
     *                                                                         *
     * Mouse event handling                                                    *
     *                                                                         *
     **************************************************************************/

    /**
     * This timeline is used to adjust the value of the bar when the
     * track has been pressed but not released.
     */
    Timeline timeline;

    /**
     * Invoked by the ScrollBar {@link Skin} implementation whenever a mouse
     * press occurs on the "track" of the bar. This will cause the thumb to
     * be moved by some amount.
     *
     * @param position The mouse position on track with 0.0 being beginning of track and 1.0 being the end
     */
    public void trackPress(double position) {

        /* We can get a press if someone presses an end button.  In that
         * case, we don't want to start a timeline because the end button
         * will have already done so.  We can detect that because the timeline
         * will not be null.
         */
        if (timeline != null) return;

        // determine the percentage of the way between min and max
        // represented by this mouse event
        final ScrollBar bar = getControl();
        if (!bar.isFocused() && bar.isFocusTraversable()) bar.requestFocus();
        final double pos = position;
        final boolean incrementing = (pos > ((bar.getValue() - bar.getMin())/(bar.getMax() - bar.getMin())));
        timeline = new Timeline();
        timeline.setCycleCount(Timeline.INDEFINITE);

        final EventHandler<ActionEvent> step =
                event -> {
                    boolean i = (pos > ((bar.getValue() - bar.getMin())/(bar.getMax() - bar.getMin())));
                    if (incrementing == i) {
                        // we started incrementing and still are, or we
                        // started decrementing and still are
                        bar.adjustValue(pos);
                    }
                    else {
                        stopTimeline();
                    }
                };

        final KeyFrame kf = new KeyFrame(Duration.millis(200), step);
        timeline.getKeyFrames().add(kf);
        // do the first step immediately
        timeline.play();
        step.handle(null);
    }

    /**
     */
    public void trackRelease() {
        stopTimeline();
    }

    /**
     * Invoked by the ScrollBar {@link Skin} implementation whenever a mouse
     * press occurs on the decrement button of the bar.
     */
    public void decButtonPressed() {
        final ScrollBar bar = getControl();
        if (!bar.isFocused() && bar.isFocusTraversable()) bar.requestFocus();
        stopTimeline();
        timeline = new Timeline();
        timeline.setCycleCount(Timeline.INDEFINITE);

        final EventHandler<ActionEvent> dec =
                event -> {
                    if (bar.getValue() > bar.getMin()) {
                        bar.decrement();
                    }
                    else {
                        stopTimeline();
                    }
                };

        final KeyFrame kf = new KeyFrame(Duration.millis(200), dec);
        timeline.getKeyFrames().add(kf);
        // do the first step immediately
        timeline.play();
        dec.handle(null);
    }

    /**
     */
    public void decButtonReleased() {
        stopTimeline();
    }

    /**
     * Invoked by the ScrollBar {@link Skin} implementation whenever a mouse
     * press occurs on the increment button of the bar.
     */
    public void incButtonPressed() {
        final ScrollBar bar = getControl();
        if (!bar.isFocused() && bar.isFocusTraversable()) bar.requestFocus();
        stopTimeline();
        timeline = new Timeline();
        timeline.setCycleCount(Timeline.INDEFINITE);

        final EventHandler<ActionEvent> inc =
                event -> {
                    if (bar.getValue() < bar.getMax()) {
                        bar.increment();
                    }
                    else {
                        stopTimeline();
                    }
                };

        final KeyFrame kf = new KeyFrame(Duration.millis(200), inc);
        timeline.getKeyFrames().add(kf);
        // do the first step immediately
        timeline.play();
        inc.handle(null);
    }

    /**
     */
    public void incButtonReleased() {
        stopTimeline();
    }

    /**
     * @param position The mouse position on track with 0.0 being begining of track and 1.0 being the end
     */
    //public function thumbPressed(e:MouseEvent, position:Number):Void {
    //}

    /**
     * @param position The mouse position on track with 0.0 being begining of track and 1.0 being the end
     */
    public void thumbDragged(double position) {
        final ScrollBar scrollbar = getControl();

        // Stop the timeline for continuous increments as drags take precedence
        stopTimeline();

        if (!scrollbar.isFocused() && scrollbar.isFocusTraversable()) scrollbar.requestFocus();
        double newValue = (position * (scrollbar.getMax() - scrollbar.getMin())) + scrollbar.getMin();
        if (!Double.isNaN(newValue)) {
            scrollbar.setValue(Utils.clamp(scrollbar.getMin(), newValue, scrollbar.getMax()));
        }
    }

    private void stopTimeline() {
        if (timeline != null) {
            timeline.stop();
            timeline = null;
        }
    }

    /**
     * Class to handle key bindings based upon the orientation of the control.
     */
    public static class ScrollBarKeyBinding extends OrientedKeyBinding {
        public ScrollBarKeyBinding(KeyCode code, String action) {
            super(code, action);
        }

        public ScrollBarKeyBinding(KeyCode code, EventType<KeyEvent> type, String action) {
            super(code, type, action);
        }

        public @Override boolean getVertical(Control control) {
            return ((ScrollBar)control).getOrientation() == Orientation.VERTICAL;
        }
    }
}