/** Copyright (c) 2006 Timothy Wall  All Rights Reserved */
import java.awt.AWTEvent;
import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Window;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.awt.event.MouseEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.Area;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.swing.JComponent;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.RepaintManager;
import javax.swing.RootPaneContainer;
import javax.swing.SwingUtilities;
import javax.swing.border.LineBorder;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

/** Provide a method for consistently augmenting the appearance of a given 
 * component by painting something on it <i>after</i> the component itself
 * gets painted.  If not explicitly removed via {@link #dispose}, an instance
 * of this object will live as long as its target component.<p>
 * By default, the decorator matches the location and size of the decorated 
 * component, but the bounds can be adjusted by overriding 
 * {@link #getDecorationBounds}.
 * <p>
 * The decoration is clipped to the bounds set on the decoration, which does
 * not necessarily need to be the same as the decorated component bounds.  The
 * decoration may extend beyond the decorated component bounds, or it may be
 * reduced to a smaller region.  
 */
// TODO: should probably do some locking on Component.getTreeLock()
// TODO: synch component cursor; unfortunately we can't detect changes
// and we need to change the cursor if the decoration exceeds the component's
// bounds
public abstract class AbstractComponentDecorator {
    
    public static final int TOP = 0;
    // Disabled for now, since it doesn't work properly
    private static final int BOTTOM = -1;
    /** Account for the difference between the decorator actual origin
     * and the logical origin we want to pass to the {@link #paint} method.
     */
    private Point originOffset = new Point(0, 0);
    
    private Painter painter;
    private JComponent component;
    private Container parent;
    private Listener listener;
    private int layerOffset;
    private int position;
    private Rectangle bounds;

    /** Create a decorator for the given component. */
    public AbstractComponentDecorator(JComponent c) {
        this(c, 1);
    }

    /** Create a decorator for the given component, indicating the layer
     * offset from the target component.  Negative values mean the decoration
     * is painted <em>before</em> the target component is painted.
     */
    public AbstractComponentDecorator(JComponent c, int layerOffset) {
        this(c, layerOffset, TOP);
    }

    /** Create a decorator with the given position within its layer. 
     * Use {@link #TOP} to cover other decorations, or {@link #BOTTOM} 
     * to be covered by other decorations.<p>
     * WARNING: BOTTOM doesn't currently work, probably a JLayeredPane bug
     * in either the code or documentation.
     * @see JLayeredPane
     */
    public AbstractComponentDecorator(JComponent c, int layerOffset, int position) {
        component = c;
        this.layerOffset = layerOffset;
        this.position = position;
        this.bounds = null;
        parent = c.getParent();
        painter = new Painter();
        listener = new Listener();
        component.addHierarchyListener(listener);
        component.addComponentListener(listener);
        component.addPropertyChangeListener(listener);
        attach();
    }

    /** Set the text to be displayed when the mouse is over the decoration.
     * @see JComponent#setToolTipText(String) 
     */
    public void setToolTipText(String text) {
        painter.setToolTipText(text);
    }
    
    /** Return the currently set default tooltip text. 
     * @see JComponent#setToolTipText
     */
    public String getToolTipText() {
        return painter.getToolTipText();
    }
    
    /** Provide for different tool tips depending on the actual location
     * over the decoration.  Note that if you <em>only</em> override this
     * method, you must also invoke {@link #setToolTipText(String)} with
     * a non-<span class="javakeyword">null</span> argument.
     * @see JComponent#getToolTipText(MouseEvent)
     */
    public String getToolTipText(MouseEvent e) {
        return getToolTipText();
    }
    
    /** Use this to change the visibility of the decoration. */
    public void setVisible(boolean visible) {
        painter.setVisible(visible);
    }

    protected void attach() {
        Window w = SwingUtilities.getWindowAncestor(component);
        if (w instanceof RootPaneContainer) {
            JLayeredPane lp = ((RootPaneContainer)w).getLayeredPane();
            Component layeredChild = component;
            int layer = JLayeredPane.DRAG_LAYER.intValue();
            if (this instanceof BackgroundPainter) {
                layer = ((BackgroundPainter)this).layer;
                painter.setDecoratedLayer(layer);
            }
            else if (layeredChild == lp) {
                // Is this the best layer to use?
                painter.setDecoratedLayer(layer);
            }
            else {
                while (layeredChild.getParent() != lp) {
                    layeredChild = layeredChild.getParent();
                }
                int base = lp.getLayer(layeredChild);
                // NOTE: JLayeredPane doesn't properly repaint an overlapping
                // child when an obscured child calls repaint() if the two
                // are in the same layer, so we use the next-higher layer
                // instead of simply using a different position within the 
                // layer.
                layer = base + layerOffset;
                if (layerOffset < 0) {
                    BackgroundPainter bp = (BackgroundPainter)
                    lp.getClientProperty(BackgroundPainter.key(base));
                    if (bp == null) {
                        bp = new BackgroundPainter(lp, base);
                    }
                }
                painter.setDecoratedLayer(base);
            }
            lp.add(painter, new Integer(layer), position);
        }
        else {
            // Always detach when the target component's window is null
            // or is not a suitable container,
            // otherwise we might prevent GC of the component
            Container parent = painter.getParent();
            if (parent != null) {
                parent.remove(painter);
            }
        }
        // Track size changes in any viewport parent
        if (parent != null) {
            parent.removeComponentListener(listener);
        }
        parent = component.getParent();
        if (parent != null) {
            parent.addComponentListener(listener);
        }
        synch();
    }

    /** Ensure the size of the decorator matches the current 
     * decoration bounds with appropriate clipping to viewports.
     */
    protected void synch() {
        Container painterParent = painter.getParent();
        if (painterParent != null) {
            Rectangle visible = getVisibleRect(getComponent());
            Rectangle decorated = getDecorationBounds();
            // Amount we have to translate the Graphics context
            originOffset.x = decorated.x;
            originOffset.y = decorated.y;
            // Use the painter bounds to clip to any viewport bounds;
            // since doing so changes the actual origin, adjust our
            // origin offset accordingly
            Rectangle clipped = decorated.intersection(visible);
            if (decorated.x < visible.x)
                originOffset.x += visible.x - decorated.x;
            if (decorated.y < visible.y)
                originOffset.y += visible.y - decorated.y;
            Point pt = SwingUtilities.convertPoint(component, clipped.x, clipped.y, 
                                                   painterParent);
            if (clipped.width <= 0 || clipped.height <= 0) {
                setVisible(false);
            }
            else {
                setPainterBounds(pt.x, pt.y, clipped.width, clipped.height);
                setVisible(true);
            }
        }
        painter.revalidate();
        painter.repaint();
    }
    
    private Rectangle getVisibleRect(JComponent component) {
        Rectangle visible = component.getVisibleRect();
        if (visible.x != 0 || visible.y != 0
            || visible.width != component.getWidth()
            || visible.height != component.getHeight()) {
            return visible;
        }
        Container parent = component.getParent();
        if (parent instanceof JComponent) {
            visible = ((JComponent)parent).getVisibleRect();
            visible.x -= component.getX();
            visible.y -= component.getY();
        }
        return visible;
    }

    /** Change the current decorated bounds. */ 
    public void setDecorationBounds(int x, int y, int w, int h) {
        if (this.bounds == null) {
            this.bounds = new Rectangle(x, y, w, h);
        }
        else {
            this.bounds.setBounds(x, y, w, h);
        }
        synch();
    }
    
    /** Change the current decorated bounds. */ 
    public void setDecorationBounds(Rectangle bounds) {
        if (this.bounds == null) {
            this.bounds = bounds;
        }
        else {
            this.bounds.setBounds(bounds);
        }
        synch();
    }

    /** Return the bounds, relative to the decorated component, of the
     * decoration.  The default covers the entire component.  Note that
     * this method will be called from the constructor, so be careful
     * when referencing derived class state.
     */
    protected Rectangle getDecorationBounds() {
        if (bounds == null) {
            return new Rectangle(0, 0, getComponent().getWidth(), getComponent().getHeight());
        }
        return bounds;
    }
    
    private void setPainterBounds(int x, int y, int w, int h) {
        painter.setLocation(x, y);
        painter.setSize(w, h);
        repaint();
    }
    
    protected JComponent getComponent() { return component; }
    protected JComponent getPainter() { return painter; }
    
    /** Force a refresh of the underlying component and its decoration. */
    public void repaint() {
        component.repaint();
        painter.repaint();
    }
    
    /** Stop decorating. */
    public void dispose() {
        component.removeHierarchyListener(listener);
        component.removeComponentListener(listener);
        component.removePropertyChangeListener(listener);
        if (parent != null) {
            parent.removeComponentListener(listener);
        }
        Container painterParent = painter.getParent();
        if (painterParent != null) {
            Rectangle bounds = painter.getBounds();
            painterParent.remove(painter);
            painterParent.repaint(bounds.x, bounds.y, bounds.width, bounds.height);
        }
        component.repaint();
        component = null;
    }

    /** Define the decoration's appearance.  The point (0,0) represents
     * the upper left corner of the decorated component.
     * The default clip mask will be the extents of the decoration bounds, as 
     * indicated by {@link #getDecorationBounds()}, which defaults to the 
     * decorated component bounds.
     */
    public abstract void paint(Graphics g);
    
    public String toString() {
        return super.toString() + " on " + getComponent();
    }
    
    private static Field nComponents;
    static {
        try {
            nComponents = Container.class.getDeclaredField("ncomponents");
            nComponents.setAccessible(true);
        }
        catch(Exception e) {
            nComponents = null;
        }
    }
    
    private static boolean useSimpleBackground() {
        return nComponents == null;
    }

    /** Used to hook into the Swing painting architecture. */
    private class Painter extends JComponent {
        private int base;
        public JComponent getComponent() {
            return AbstractComponentDecorator.this.getComponent();
        }
        public void setDecoratedLayer(int base) {
            this.base = base;
        }
        public int getDecoratedLayer() {
            return base;
        }
        public boolean isBackgroundDecoration() { 
            return layerOffset < 0; 
        }
        public void paint(Graphics g) {
            if (!component.isShowing())
                return;
            Graphics2D g2d = (Graphics2D)g;
            AffineTransform xform = g2d.getTransform();
            try {
                g2d.translate(-originOffset.x, -originOffset.y);
                AbstractComponentDecorator.this.paint(g);
            }
            finally {
                g2d.setTransform(xform);
            }
        }
        public String getToolTipText(MouseEvent e) {
            return AbstractComponentDecorator.this.getToolTipText(e);
        }
        public String toString() {
            return "Painter for " + AbstractComponentDecorator.this;
        }
    }
    
    /** Provides a shared background painting mechanism for multiple 
     * decorations.  This ensures that the background is only painted once
     * if more than one background decorator is applied.
     */
    private static class BackgroundPainter extends AbstractComponentDecorator {
        private static String key(int layer) {
            return "backgroundPainter" + layer;
        }
        private String key;
        private int layer;
        public BackgroundPainter(JLayeredPane p, int layer) {
            super(p, 0, TOP);
            this.layer = layer;
            key = key(layer);
            p.putClientProperty(key, this);
        }
        private int hideChildren(Container c) {
            if (c == null)
                return 0;
            int value = c.getComponentCount();
            try {
                nComponents.set(c, new Integer(0));
            }
            catch(Exception e) {
                return c.getComponentCount();
            }
            return value;
        }
        
        private void restoreChildren(Container c, int count) {
            if (c != null) {
                try {
                    nComponents.set(c, new Integer(count));
                }
                catch(Exception e) {
                }        
            }
        }
        
        private void paintBackground(Graphics g, Component parent, JComponent jc) {
            int x = jc.getX();
            int y = jc.getY();
            int w = jc.getWidth();
            int h = jc.getHeight();
            paintBackground(g.create(x, y, w, h), jc);
        }
        
        private void paintBackground(Graphics g, JComponent jc) {
            if (jc.isOpaque()) {
                if (useSimpleBackground()) {
                    g.setColor(jc.getBackground());
                    g.fillRect(0, 0, jc.getWidth(), jc.getHeight());
                }
                else {
                    int count = hideChildren(jc);
                    boolean db = jc.isDoubleBuffered();
                    if (db)
                        jc.setDoubleBuffered(false);
                    jc.paint(g);
                    if (db)
                        jc.setDoubleBuffered(true);
                    restoreChildren(jc, count);
                }
            }
            Component[] kids = jc.getComponents();
            for (int i=0;i < kids.length;i++) {
                if (kids[i] instanceof JComponent) {
                    paintBackground(g, jc, (JComponent)kids[i]);
                }
            }
        }
        private List findOpaque(Component root) {
            List list = new ArrayList();
            if (root.isOpaque() && root instanceof JComponent) {
                list.add(root);
                ((JComponent)root).setOpaque(false);
            }
            if (root instanceof Container) {
                Component[] kids = ((Container)root).getComponents();
                for (int i=0;i < kids.length;i++) {
                    list.addAll(findOpaque(kids[i]));
                }
            }
            return list;
        }
        private List findDoubleBuffered(Component root) {
            List list = new ArrayList();
            if (root.isDoubleBuffered() && root instanceof JComponent) {
                list.add(root);
                ((JComponent)root).setDoubleBuffered(false);
            }
            if (root instanceof Container) {
                Component[] kids = ((Container)root).getComponents();
                for (int i=0;i < kids.length;i++) {
                    list.addAll(findDoubleBuffered(kids[i]));
                }
            }
            return list;
        }
        private void paintForeground(Graphics g, JComponent jc) {
            List opaque = findOpaque(jc);
            List db = findDoubleBuffered(jc);
            jc.paint(g);
            for (Iterator i=opaque.iterator();i.hasNext();) {
                ((JComponent)i.next()).setOpaque(true);
            }
            for (Iterator i=db.iterator();i.hasNext();) {
                ((JComponent)i.next()).setDoubleBuffered(true);
            }
        }
        
        /** Walk the list of "background" decorators and paint them. */
        public void paint(Graphics g) {

            JLayeredPane lp = (JLayeredPane)getComponent();
            Component[] kids = lp.getComponents();
            // Construct an area of the intersection of all decorators
            Area area = new Area();
            List painters = new ArrayList();
            List components = new ArrayList();
            for (int i=kids.length-1;i >=0; i--) {
                if (kids[i] instanceof Painter) {
                    Painter p = (Painter)kids[i];
                    if (p.isBackgroundDecoration() 
                        && p.getDecoratedLayer() == layer
                        && p.isShowing()) {
                        painters.add(p);
                        area.add(new Area(p.getBounds()));
                    }
                }
                else if (lp.getLayer(kids[i]) == layer
                         && kids[i] instanceof JComponent) {
                    components.add(kids[i]);
                }
            }
            if (painters.size() == 0) {
                dispose();
                return;
            }
            g.setClip(area);

            // Paint background for that area
            for (Iterator i=components.iterator();i.hasNext();) {
                JComponent c = (JComponent)i.next();
                paintBackground(g, lp, c);
            }
            
            // Paint the bg decorators
            for (Iterator i=painters.iterator();i.hasNext();) {
                Painter p = (Painter)i.next();
                p.paint(g.create(p.getX(), p.getY(), p.getWidth(), p.getHeight()));
            }
            // Paint foreground for the area
            for (Iterator i=components.iterator();i.hasNext();) {
                JComponent c = (JComponent)i.next();
                paintForeground(g.create(c.getX(), c.getY(), c.getWidth(), c.getHeight()), c);
            }
        }
        public void dispose() {
            getComponent().putClientProperty(key, null);
            super.dispose();
        }
        public String toString() {
            return key + " on " + getComponent();
        }
    }
    /** Tracks changes to component configuration. */
    private final class Listener extends ComponentAdapter 
        implements HierarchyListener, PropertyChangeListener {
        public void hierarchyChanged(HierarchyEvent e) {
            if ((e.getChangeFlags() & HierarchyEvent.PARENT_CHANGED) != 0) {
                attach();
            }
        }
        public void propertyChange(PropertyChangeEvent e) {
            if (JLayeredPane.LAYER_PROPERTY.equals(e.getPropertyName())) {
                attach();
            }
        }
        public void componentMoved(ComponentEvent e) {
            // FIXME figure out why attach works and synch doesn't
            // when painting a selection marquee over a decorated background
            attach();
        }
        public void componentResized(ComponentEvent e) {
            // FIXME figure out why attach works and synch doesn't
            // when painting a selection marquee over a decorated background
            attach();
        }
        public void componentHidden(ComponentEvent e) {
            setVisible(false);
        }
        public void componentShown(ComponentEvent e) {
            setVisible(true);
        }
    }
}