/*
 * Copyright (c) 2006 JGoodies Karsten Lentzsch. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 * 
 *  o Redistributions of source code must retain the above copyright notice, 
 *    this list of conditions and the following disclaimer. 
 *     
 *  o Redistributions in binary form must reproduce the above copyright notice, 
 *    this list of conditions and the following disclaimer in the documentation 
 *    and/or other materials provided with the distribution. 
 *     
 *  o Neither the name of JGoodies Karsten Lentzsch nor the names of 
 *    its contributors may be used to endorse or promote products derived 
 *    from this software without specific prior written permission. 
 *     
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

package com.jgoodies.looks.common;

import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.ArrayList;
import java.util.List;

import javax.swing.*;
import javax.swing.border.Border;

/**
 * Does all the magic for getting popups with drop shadows. 
 * It adds the drop shadow border to the Popup, 
 * in <code>#show</code> it snapshots the screen background as needed, 
 * and in <code>#hide</code> it cleans up all changes made before.
 * 
 * @author Andrej Golovnin
 * @version $Revision: 1.4 $
 * 
 * @see com.jgoodies.looks.common.ShadowPopupBorder
 * @see com.jgoodies.looks.common.ShadowPopupFactory
 */
public final class ShadowPopup extends Popup {

    /**
     * Max number of items to store in the cache.
     */
    private static final int MAX_CACHE_SIZE = 5;

    /**
     * The cache to use for ShadowPopups.
     */
    private static List cache;

    /**
     * The singleton instance used to draw all borders.
     */
    private static final Border SHADOW_BORDER = ShadowPopupBorder.getInstance();

    /**
     * The size of the drop shadow.
     */
    private static final int SHADOW_SIZE = 5;

    /**
     * Indicates whether we can make snapshots from screen or not.
     */
    private static boolean canSnapshot = true;

    /**
     * The component mouse coordinates are relative to, may be null.
     */
    private Component owner;

    /**
     * The contents of the popup.
     */
    private Component contents;

    /**
     * The desired x and y location of the popup.
     */
    private int x, y;

    /**
     * The real popup. The #show() and #hide() methods will delegate
     * all calls to these popup.
     */
    private Popup popup;

    /**
     * The border of the contents' parent replaced by SHADOW_BORDER.
     */
    private Border oldBorder;

    /**
     * The old value of the opaque property of the contents' parent.
     */
    private boolean oldOpaque;

    /**
     * The heavy weight container of the popup contents, may be null.
     */
    private Container heavyWeightContainer;

    /**
     * Returns a previously used <code>ShadowPopup</code>, or a new one
     * if none of the popups have been recycled.
     */
    static Popup getInstance(Component owner, Component contents, int x,
            int y, Popup delegate) {
        ShadowPopup result;
        synchronized (ShadowPopup.class) {
            if (cache == null) {
                cache = new ArrayList(MAX_CACHE_SIZE);
            }
            if (cache.size() > 0) {
                result = (ShadowPopup) cache.remove(0);
            } else {
                result = new ShadowPopup();
            }
        }
        result.reset(owner, contents, x, y, delegate);
        return result;
    }

    /**
     * Recycles the ShadowPopup.
     */
    private static void recycle(ShadowPopup popup) {
        synchronized (ShadowPopup.class) {
            if (cache.size() < MAX_CACHE_SIZE) {
                cache.add(popup);
            }
        }
    }
    
    public static boolean canSnapshot() {
        return canSnapshot;
    }

    /**
     * Hides and disposes of the <code>Popup</code>. Once a <code>Popup</code>
     * has been disposed you should no longer invoke methods on it. A
     * <code>dispose</code>d <code>Popup</code> may be reclaimed and later used
     * based on the <code>PopupFactory</code>. As such, if you invoke methods
     * on a <code>disposed</code> <code>Popup</code>, indeterminate
     * behavior will result.<p>
     * 
     * In addition to the superclass behavior, we reset the stored
     * horizontal and vertical drop shadows - if any.
     */
    public void hide() {
        if (contents == null)
            return;

        JComponent parent = (JComponent) contents.getParent();
        popup.hide();
        if (parent.getBorder() == SHADOW_BORDER) {
            parent.setBorder(oldBorder);
            parent.setOpaque(oldOpaque);
            oldBorder = null;
            if (heavyWeightContainer != null) {
                parent.putClientProperty(ShadowPopupFactory.PROP_HORIZONTAL_BACKGROUND, null);
                parent.putClientProperty(ShadowPopupFactory.PROP_VERTICAL_BACKGROUND, null);
                heavyWeightContainer = null;
            }
        }
        owner = null;
        contents = null;
        popup = null;
        recycle(this);
    }

    /**
     * Makes the <code>Popup</code> visible. If the popup has a 
     * heavy-weight container, we try to snapshot the background.
     * If the <code>Popup</code> is currently visible, it remains visible.
     */
    public void show() {
        if (heavyWeightContainer != null) {
            snapshot();
        }
        popup.show();
    }

    /**
     * Reinitializes this ShadowPopup using the given parameters.
     * 
     * @param owner component mouse coordinates are relative to, may be null
     * @param contents the contents of the popup
     * @param x the desired x location of the popup
     * @param y the desired y location of the popup
     * @param popup the popup to wrap
     */
    private void reset(Component owner, Component contents, int x, int y,
            Popup popup) {
        this.owner = owner;
        this.contents = contents;
        this.popup = popup;
        this.x = x;
        this.y = y;
        if (owner instanceof JComboBox) {
            return;
        }
        // Do not install the shadow border when the contents 
        // has a preferred size less than or equal to 0.
        // We can't use the size, because it is(0, 0) for new popups.
        Dimension contentsPrefSize = contents.getPreferredSize();
        if ((contentsPrefSize.width <= 0) || (contentsPrefSize.height <= 0)) {
            return;
        }
        for(Container p = contents.getParent(); p != null; p = p.getParent()) {
            if ((p instanceof JWindow) || (p instanceof Panel)) {
                // Workaround for the gray rect problem.
                p.setBackground(contents.getBackground());
                heavyWeightContainer = p;
                break;
            }
        }
        JComponent parent = (JComponent) contents.getParent();
        oldOpaque = parent.isOpaque();
        oldBorder = parent.getBorder();
        parent.setOpaque(false);
        parent.setBorder(SHADOW_BORDER);
        // Pack it because we have changed the border.
        if (heavyWeightContainer != null) {
            heavyWeightContainer.setSize(
                    heavyWeightContainer.getPreferredSize());
        } else {
            parent.setSize(parent.getPreferredSize());
        }
    }

    /**
     * The 'scratch pad' objects used to calculate dirty regions of
     * the screen snapshots.
     * 
     * @see #snapshot()
     */
    private static final Point     POINT = new Point();
    private static final Rectangle RECT  = new Rectangle();

    /**
     * Snapshots the background. The snapshots are stored as client
     * properties of the contents' parent. The next time the border is drawn,
     * this background will be used.<p>
     * 
     * Uses a robot on the default screen device to capture the screen
     * region under the drop shadow. Does <em>not</em> use the window's
     * device, because that may be an outdated device (due to popup reuse)
     * and the robot's origin seems to be adjusted with the default screen
     * device.
     * 
     * @see #show()
     * @see com.jgoodies.looks.common.ShadowPopupBorder
     * @see Robot#createScreenCapture(Rectangle)
     */
    private void snapshot() {
        try {
            Dimension size = heavyWeightContainer.getPreferredSize();
            int width = size.width;
            int height = size.height;
            
            // Avoid unnecessary and illegal screen captures 
            // for degenerated popups.
            if ((width <= 0) || (height <= SHADOW_SIZE)) {
                return;
            }

            Robot robot = new Robot(); // uses the default screen device

            RECT.setBounds(x, y + height - SHADOW_SIZE, width, SHADOW_SIZE);
            BufferedImage hShadowBg = robot.createScreenCapture(RECT);

            RECT.setBounds(x + width - SHADOW_SIZE, y, SHADOW_SIZE,
                    height - SHADOW_SIZE);
            BufferedImage vShadowBg = robot.createScreenCapture(RECT);

            JComponent parent = (JComponent) contents.getParent();
            parent.putClientProperty(ShadowPopupFactory.PROP_HORIZONTAL_BACKGROUND, hShadowBg);
            parent.putClientProperty(ShadowPopupFactory.PROP_VERTICAL_BACKGROUND, vShadowBg);

            Container layeredPane = getLayeredPane();
            if (layeredPane == null) {
                // This could happen if owner is null.
                return;
            }

            int layeredPaneWidth = layeredPane.getWidth();
            int layeredPaneHeight = layeredPane.getHeight();

            POINT.x = x;
            POINT.y = y;
            SwingUtilities.convertPointFromScreen(POINT, layeredPane);

            // If needed paint dirty region of the horizontal snapshot.
            RECT.x = POINT.x;
            RECT.y = POINT.y + height - SHADOW_SIZE;
            RECT.width = width;
            RECT.height = SHADOW_SIZE;

            if ((RECT.x + RECT.width) > layeredPaneWidth) {
                RECT.width = layeredPaneWidth - RECT.x;
            }
            if ((RECT.y + RECT.height) > layeredPaneHeight) {
                RECT.height = layeredPaneHeight - RECT.y;
            }
            if (!RECT.isEmpty()) {
                Graphics g = hShadowBg.createGraphics();
                g.translate(-RECT.x, -RECT.y);
                g.setClip(RECT);
                if (layeredPane instanceof JComponent) {
                    JComponent c = (JComponent) layeredPane;
                    boolean doubleBuffered = c.isDoubleBuffered();
                    c.setDoubleBuffered(false);
                    c.paintAll(g);
                    c.setDoubleBuffered(doubleBuffered);
                } else {
                    layeredPane.paintAll(g);
                }
                g.dispose();
            }

            // If needed paint dirty region of the vertical snapshot.
            RECT.x = POINT.x + width - SHADOW_SIZE;
            RECT.y = POINT.y;
            RECT.width = SHADOW_SIZE;
            RECT.height = height - SHADOW_SIZE;

            if ((RECT.x + RECT.width) > layeredPaneWidth) {
                RECT.width = layeredPaneWidth - RECT.x;
            }
            if ((RECT.y + RECT.height) > layeredPaneHeight) {
                RECT.height = layeredPaneHeight - RECT.y;
            }
            if (!RECT.isEmpty()) {
                Graphics g = vShadowBg.createGraphics();
                g.translate(-RECT.x, -RECT.y);
                g.setClip(RECT);
                if (layeredPane instanceof JComponent) {
                    JComponent c = (JComponent) layeredPane;
                    boolean doubleBuffered = c.isDoubleBuffered();
                    c.setDoubleBuffered(false);
                    c.paintAll(g);
                    c.setDoubleBuffered(doubleBuffered);
                } else {
                    layeredPane.paintAll(g);
                }
                g.dispose();
            }
        } catch (AWTException e) {
            canSnapshot = false;
        } catch (SecurityException e) {
            canSnapshot = false;
        }
    }

    /**
     * @return the top level layered pane which contains the owner.
     */
    private Container getLayeredPane() {
        // The code below is copied from PopupFactory#LightWeightPopup#show()
        Container parent = null;
        if (owner != null) {
            parent = owner instanceof Container
                    ? (Container) owner 
                    : owner.getParent();
        }
        // Try to find a JLayeredPane and Window to add 
        for (Container p = parent; p != null; p = p.getParent()) {
            if (p instanceof JRootPane) {
                if (p.getParent() instanceof JInternalFrame) {
                    continue;
                }
                parent = ((JRootPane) p).getLayeredPane();
                // Continue, so that if there is a higher JRootPane, we'll
                // pick it up.
            } else if (p instanceof Window) {
                if (parent == null) {
                    parent = p;
                }
                break;
            } else if (p instanceof JApplet) {
                // Painting code stops at Applets, we don't want
                // to add to a Component above an Applet otherwise
                // you'll never see it painted.
                break;
            }
        }
        return parent;
    }

}