package org.jboss.as.console.client.widgets;

/*
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

import com.google.gwt.core.client.Duration;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Style;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.DockLayoutPanel;
import com.google.gwt.user.client.ui.Widget;

/**
 * A panel that adds user-positioned splitters between each of its child
 * widgets.
 *
 * <p>
 * This panel is used in the same way as {@link com.google.gwt.user.client.ui.DockLayoutPanel}, except that
 * its children's sizes are always specified in {@link com.google.gwt.dom.client.Style.Unit#PX} units, and each
 * pair of child widgets has a splitter between them that the user can drag.
 * </p>
 *
 * <p>
 * This widget will <em>only</em> work in standards mode, which requires that
 * the HTML page in which it is run have an explicit &lt;!DOCTYPE&gt;
 * declaration.
 * </p>
 *
 * <h3>CSS Style Rules</h3>
 * <ul class='css'>
 * <li>.gwt-SplitLayoutPanel { the panel itself }</li>
 * <li>.gwt-SplitLayoutPanel .gwt-SplitLayoutPanel-HDragger { horizontal dragger
 * }</li>
 * <li>.gwt-SplitLayoutPanel .gwt-SplitLayoutPanel-VDragger { vertical dragger }
 * </li>
 * </ul>
 *
 * <p>
 * <h3>Example</h3>
 * {@example com.google.gwt.examples.SplitLayoutPanelExample}
 * </p>
 */
public class CollapsibleSplitLayoutPanel extends DockLayoutPanel {

    class HSplitter extends Splitter {
        public HSplitter(Widget target, boolean reverse) {
            super(target, reverse);
            getElement().getStyle().setPropertyPx("width", splitterSize);
            setStyleName("gwt-SplitLayoutPanel-HDragger");
        }

        @Override
        protected int getAbsolutePosition() {
            return getAbsoluteLeft();
        }

        @Override
        protected double getCenterSize() {
            return getCenterWidth();
        }

        @Override
        protected int getEventPosition(Event event) {
            return event.getClientX();
        }

        @Override
        protected int getTargetPosition() {
            return target.getAbsoluteLeft();
        }

        @Override
        protected int getTargetSize() {
            return target.getOffsetWidth();
        }
    }

    abstract class Splitter extends Widget {
        protected final Widget target;

        private int offset;
        private boolean mouseDown;
        private Scheduler.ScheduledCommand layoutCommand;

        private final boolean reverse;
        private int minSize;
        private int snapClosedSize = -1;
        private double centerSize, syncedCenterSize;

        private boolean toggleDisplayAllowed = false;
        private double lastClick = 0;
        private boolean collapsed;

        public Splitter(Widget target, boolean reverse) {
            this.target = target;
            this.reverse = reverse;

            setElement(Document.get().createDivElement());
            sinkEvents(Event.ONMOUSEDOWN | Event.ONMOUSEUP | Event.ONMOUSEMOVE
                    | Event.ONDBLCLICK);
        }

        @Override
        public void onBrowserEvent(Event event) {
            switch (event.getTypeInt()) {
                case Event.ONMOUSEDOWN:
                    mouseDown = true;

          /*
           * Resize glassElem to take up the entire scrollable window area,
           * which is the greater of the scroll size and the client size.
           */
                    int width = Math.max(Window.getClientWidth(),
                            Document.get().getScrollWidth());
                    int height = Math.max(Window.getClientHeight(),
                            Document.get().getScrollHeight());
                    glassElem.getStyle().setHeight(height, Style.Unit.PX);
                    glassElem.getStyle().setWidth(width, Style.Unit.PX);
                    Document.get().getBody().appendChild(glassElem);

                    offset = getEventPosition(event) - getAbsolutePosition();
                    Event.setCapture(getElement());
                    event.preventDefault();
                    break;

                case Event.ONMOUSEUP:
                    mouseDown = false;

                    glassElem.removeFromParent();

                    // Handle double-clicks.
                    // Fake them since the double-click event aren't fired.
                    if (this.toggleDisplayAllowed) {
                        double now = Duration.currentTimeMillis();
                        if (now - this.lastClick < DOUBLE_CLICK_TIMEOUT) {
                            now = 0;
                            toggleCollapsedState();
                        }
                        this.lastClick = now;
                    }

                    Event.releaseCapture(getElement());
                    event.preventDefault();
                    break;

                case Event.ONMOUSEMOVE:
                    if (mouseDown) {
                        int size;
                        if (reverse) {
                            size = getTargetPosition() + getTargetSize() - getSplitterSize()
                                    - getEventPosition(event) + offset;
                        } else {
                            size = getEventPosition(event) - getTargetPosition() - offset;
                        }
                        ((LayoutData) target.getLayoutData()).hidden = false;
                        setAssociatedWidgetSize(size);
                        event.preventDefault();
                    }
                    break;
            }
        }

        boolean toggleCollapsedState() {
            LayoutData layout = (LayoutData) target.getLayoutData();
            if (layout.size <= minSize) {
                // Restore the old size.
                setAssociatedWidgetSize(layout.oldSize);
                this.collapsed = false;
                return collapsed;
            } else {
                /*
                 * Collapse to size 0. We change the size instead of hiding the
                 * widget because hiding the widget can cause issues if the
                 * widget contains a flash component.
                 */
                layout.oldSize = layout.size;
                setAssociatedWidgetSize(minSize);
                this.collapsed = true;
                return collapsed;
            }
        }

        public void setMinSize(int minSize) {
            this.minSize = minSize;
            LayoutData layout = (LayoutData) target.getLayoutData();

            // Try resetting the associated widget's size, which will enforce the new
            // minSize value.
            setAssociatedWidgetSize((int) layout.size);
        }

        public void setSnapClosedSize(int snapClosedSize) {
            this.snapClosedSize = snapClosedSize;
        }

        public void setToggleDisplayAllowed(boolean allowed) {
            this.toggleDisplayAllowed = allowed;
        }

        protected abstract int getAbsolutePosition();

        protected abstract double getCenterSize();

        protected abstract int getEventPosition(Event event);

        protected abstract int getTargetPosition();

        protected abstract int getTargetSize();

        private double getMaxSize() {
            // To avoid seeing stale center size values due to deferred layout
            // updates, maintain our own copy up to date and resync when the
            // DockLayoutPanel value changes.
            double newCenterSize = getCenterSize();
            if (syncedCenterSize != newCenterSize) {
                syncedCenterSize = newCenterSize;
                centerSize = newCenterSize;
            }

            return Math.max(((LayoutData) target.getLayoutData()).size + centerSize,
                    0);
        }

        private void setAssociatedWidgetSize(double size) {
            double maxSize = getMaxSize();
            if (size > maxSize) {
                size = maxSize;
            }

            if (snapClosedSize > 0 && size < snapClosedSize) {
                size = 0;
            } else if (size < minSize) {
                size = minSize;
            }

            LayoutData layout = (LayoutData) target.getLayoutData();
            if (size == layout.size) {
                return;
            }

            // Adjust our view until the deferred layout gets scheduled.
            centerSize += layout.size - size;
            layout.size = size;

            // Defer actually updating the layout, so that if we receive many
            // mouse events before layout/paint occurs, we'll only update once.
            if (layoutCommand == null) {
                layoutCommand = new Scheduler.ScheduledCommand() {
                    @Override
                    public void execute() {
                        layoutCommand = null;
                        forceLayout();
                    }
                };
                Scheduler.get().scheduleDeferred(layoutCommand);
            }
        }

        public boolean isCollapsed() {
            return collapsed;
        }
    }

    class VSplitter extends Splitter {
        public VSplitter(Widget target, boolean reverse) {
            super(target, reverse);
            getElement().getStyle().setPropertyPx("height", splitterSize);
            setStyleName("gwt-SplitLayoutPanel-VDragger");
        }

        @Override
        protected int getAbsolutePosition() {
            return getAbsoluteTop();
        }

        @Override
        protected double getCenterSize() {
            return getCenterHeight();
        }

        @Override
        protected int getEventPosition(Event event) {
            return event.getClientY();
        }

        @Override
        protected int getTargetPosition() {
            return target.getAbsoluteTop();
        }

        @Override
        protected int getTargetSize() {
            return target.getOffsetHeight();
        }
    }

    private static final int DEFAULT_SPLITTER_SIZE = 8;
    private static final int DOUBLE_CLICK_TIMEOUT = 500;

    /**
     * The element that masks the screen so we can catch mouse events over
     * iframes.
     */
    private static Element glassElem = null;

    private final int splitterSize;

    /**
     * Construct a new {@link CollapsibleSplitLayoutPanel} with the default splitter size of
     * 8px.
     */
    public CollapsibleSplitLayoutPanel() {
        this(DEFAULT_SPLITTER_SIZE);
    }

    /**
     * Construct a new {@link CollapsibleSplitLayoutPanel} with the specified splitter size
     * in pixels.
     *
     * @param splitterSize the size of the splitter in pixels
     */
    public CollapsibleSplitLayoutPanel(int splitterSize) {
        super(Style.Unit.PX);
        this.splitterSize = splitterSize;
        setStyleName("gwt-SplitLayoutPanel");

        if (glassElem == null) {
            glassElem = Document.get().createDivElement();
            glassElem.getStyle().setPosition(Style.Position.ABSOLUTE);
            glassElem.getStyle().setTop(0, Style.Unit.PX);
            glassElem.getStyle().setLeft(0, Style.Unit.PX);
            glassElem.getStyle().setMargin(0, Style.Unit.PX);
            glassElem.getStyle().setPadding(0, Style.Unit.PX);
            glassElem.getStyle().setBorderWidth(0, Style.Unit.PX);

            // We need to set the background color or mouse events will go right
            // through the glassElem. If the SplitPanel contains an iframe, the
            // iframe will capture the event and the slider will stop moving.
            glassElem.getStyle().setProperty("background", "white");
            glassElem.getStyle().setOpacity(0.0);
        }
    }

    /**
     * Return the size of the splitter in pixels.
     *
     * @return the splitter size
     */
    public int getSplitterSize() {
        return splitterSize;
    }

    @Override
    public void insert(Widget child, Direction direction, double size, Widget before) {
        super.insert(child, direction, size, before);
        if (direction != Direction.CENTER) {
            insertSplitter(child, before);
        }
    }

    @Override
    public boolean remove(Widget child) {
        assert !(child instanceof Splitter) : "Splitters may not be directly removed";

        int idx = getWidgetIndex(child);
        if (super.remove(child)) {
            // Remove the associated splitter, if any.
            // Now that the widget is removed, idx is the index of the splitter.
            if (idx < getWidgetCount()) {
                // Call super.remove(), or we'll end up recursing.
                super.remove(getWidget(idx));
            }
            return true;
        }
        return false;
    }

    @Override
    public void setWidgetHidden(Widget widget, boolean hidden) {
        super.setWidgetHidden(widget, hidden);
        Splitter splitter = getAssociatedSplitter(widget);
        if (splitter != null) {
            // The splitter is null for the center element.
            super.setWidgetHidden(splitter, hidden);
        }
    }

    /**
     * Sets the minimum allowable size for the given widget.
     *
     * <p>
     * Its associated splitter cannot be dragged to a position that would make it
     * smaller than this size. This method has no effect for the
     * {@link DockLayoutPanel.Direction#CENTER} widget.
     * </p>
     *
     * @param child the child whose minimum size will be set
     * @param minSize the minimum size for this widget
     */
    public void setWidgetMinSize(Widget child, int minSize) {
        assertIsChild(child);
        Splitter splitter = getAssociatedSplitter(child);
        // The splitter is null for the center element.
        if (splitter != null) {
            splitter.setMinSize(minSize);
        }
    }

    /**
     * Sets a size below which the slider will close completely. This can be used
     * in conjunction with {@link #setWidgetMinSize} to provide a speed-bump
     * effect where the slider will stick to a preferred minimum size before
     * closing completely.
     *
     * <p>
     * This method has no effect for the {@link DockLayoutPanel.Direction#CENTER}
     * widget.
     * </p>
     *
     * @param child the child whose slider should snap closed
     * @param snapClosedSize the width below which the widget will close or
     *        -1 to disable.
     */
    public void setWidgetSnapClosedSize(Widget child, int snapClosedSize) {
        assertIsChild(child);
        Splitter splitter = getAssociatedSplitter(child);
        // The splitter is null for the center element.
        if (splitter != null) {
            splitter.setSnapClosedSize(snapClosedSize);
        }
    }

    /**
     * Sets whether or not double-clicking on the splitter should toggle the
     * display of the widget.
     *
     * @param child the child whose display toggling will be allowed or not.
     * @param allowed whether or not display toggling is allowed for this widget
     */
    public void setWidgetToggleDisplayAllowed(Widget child, boolean allowed) {
        assertIsChild(child);
        Splitter splitter = getAssociatedSplitter(child);
        // The splitter is null for the center element.
        if (splitter != null) {
            splitter.setToggleDisplayAllowed(allowed);
        }
    }

    void assertIsChild(Widget widget) {
        assert (widget == null) || (widget.getParent() == this) : "The specified widget is not a child of this panel";
    }

    private Splitter getAssociatedSplitter(Widget child) {
        // If a widget has a next sibling, it must be a splitter, because the only
        // widget that *isn't* followed by a splitter must be the CENTER, which has
        // no associated splitter.
        int idx = getWidgetIndex(child);
        if (idx > -1 && idx < getWidgetCount() - 1) {
            Widget splitter = getWidget(idx + 1);
            assert splitter instanceof Splitter : "Expected child widget to be splitter";
            return (Splitter) splitter;
        }
        return null;
    }

    private void insertSplitter(Widget widget, Widget before) {
        assert getChildren().size() > 0 : "Can't add a splitter before any children";

        LayoutData layout = (LayoutData) widget.getLayoutData();
        Splitter splitter = null;
        switch (getResolvedDirection(layout.direction)) {
            case WEST:
                splitter = new HSplitter(widget, false);
                break;
            case EAST:
                splitter = new HSplitter(widget, true);
                break;
            case NORTH:
                splitter = new VSplitter(widget, false);
                break;
            case SOUTH:
                splitter = new VSplitter(widget, true);
                break;
            default:
                assert false : "Unexpected direction";
        }

        super.insert(splitter, layout.direction, splitterSize, before);
    }

    public boolean toggleCollapsedState(Widget widget) {
        Splitter splitter = getAssociatedSplitter(widget);
        assert (splitter != null) : "The specified widget is not a child of this panel";
        return splitter.toggleCollapsedState();
    }

    public boolean isCollapsed(Widget widget) {
        Splitter splitter = getAssociatedSplitter(widget);
        assert (splitter != null) : "The specified widget is not a child of this panel";
        return splitter.isCollapsed();
    }

    @Override
    public void addWest(Widget widget, double size) {
        super.addWest(widget, size);
        widget.addStyleName("split-west");
    }
}

