/*
 * $Id: JXImagePanel.java,v 1.24 2009/05/28 02:07:01 kschaefe Exp $
 *
 * Copyright 2004 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

package org.jdesktop.swingx;

import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Insets;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import java.lang.ref.SoftReference;
import java.net.URL;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.FutureTask;
import java.util.logging.Level;
import java.util.logging.Logger;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.SwingUtilities;

/**
 * <p>
 * A panel that draws an image. The standard mode is to draw the specified image
 * centered and unscaled. The component&amp;s preferred size is based on the
 * image, unless explicitly set by the user.
 * </p>
 * <p>
 * Images to be displayed can be set based on URL, Image, etc. This is
 * accomplished by passing in an image loader.
 * 
 * <pre>
 * public class URLImageLoader extends Callable&lt;Image&gt; {
 *     private URL url;
 * 
 *     public URLImageLoader(URL url) {
 *         url.getClass(); //null check
 *         this.url = url;
 *     }
 * 
 *     public Image call() throws Exception {
 *         return ImageIO.read(url);
 *     }
 * }
 * 
 * imagePanel.setImageLoader(new URLImageLoader(url));
 * </pre>
 * 
 * </p>
 * <p>
 * This component also supports allowing the user to set the image. If the
 * <code>JXImagePanel</code> is editable, then when the user clicks on the
 * <code>JXImagePanel</code> a FileChooser is shown allowing the user to pick
 * some other image to use within the <code>JXImagePanel</code>.
 * </p>
 * <p>
 * TODO In the future, the JXImagePanel will also support tiling of images,
 * scaling, resizing, cropping, segues etc.
 * </p>
 * <p>
 * TODO other than the image loading this component can be replicated by a
 * JXPanel with the appropriate Painter. What's the point?
 * </p>
 * 
 * @author rbair
 */
public class JXImagePanel extends JXPanel {
    public static enum Style {
        CENTERED, TILED, SCALED, SCALED_KEEP_ASPECT_RATIO
    }

    private static final Logger LOG = Logger.getLogger(JXImagePanel.class.getName());

    /**
     * Text informing the user that clicking on this component will allow them
     * to set the image
     */
    private static final String TEXT = "<html><i><b>Click here<br>to set the image</b></i></html>";

    /**
     * The image to draw
     */
    private SoftReference<Image> img = new SoftReference<Image>(null);

    /**
     * If true, then the image can be changed. Perhaps a better name is
     * &quot;readOnly&quot;, but editable was chosen to be more consistent with
     * other Swing components.
     */
    private boolean editable = false;

    /**
     * The mouse handler that is used if the component is editable
     */
    private MouseHandler mhandler = new MouseHandler();

    /**
     * Specifies how to draw the image, i.e. what kind of Style to use when
     * drawing
     */
    private Style style = Style.CENTERED;

    private Image defaultImage;

    private Callable<Image> imageLoader;

    private static final ExecutorService service = Executors.newFixedThreadPool(5);

    public JXImagePanel() {
    }

    //TODO remove this constructor; no where else can a URL be used in this class
    public JXImagePanel(URL imageUrl) {
        try {
            setImage(ImageIO.read(imageUrl));
        } catch (Exception e) {
            // TODO need convert to something meaningful
            LOG.log(Level.WARNING, "", e);
        }
    }

    /**
     * Sets the image to use for the background of this panel. This image is
     * painted whether the panel is opaque or translucent.
     * 
     * @param image if null, clears the image. Otherwise, this will set the
     *        image to be painted. If the preferred size has not been explicitly
     *        set, then the image dimensions will alter the preferred size of
     *        the panel.
     */
    public void setImage(Image image) {
        if (image != img.get()) {
            Image oldImage = img.get();
            img = new SoftReference<Image>(image);
            firePropertyChange("image", oldImage, img);
            invalidate();
            repaint();
        }
    }

    /**
     * @return the image used for painting the background of this panel
     */
    public Image getImage() {
        Image image = img.get();
        
        //TODO perhaps we should have a default image loader?
        if (image == null && imageLoader != null) {
            try {
                image = imageLoader.call();
                img = new SoftReference<Image>(image);
            } catch (Exception e) {
                LOG.log(Level.WARNING, "", e);
            }
        }
        return image;
    }

    /**
     * @param editable
     */
    public void setEditable(boolean editable) {
        if (editable != this.editable) {
            // if it was editable, remove the mouse handler
            if (this.editable) {
                removeMouseListener(mhandler);
            }
            this.editable = editable;
            // if it is now editable, add the mouse handler
            if (this.editable) {
                addMouseListener(mhandler);
            }
            setToolTipText(editable ? TEXT : "");
            firePropertyChange("editable", !editable, editable);
            repaint();
        }
    }

    /**
     * @return whether the image for this panel can be changed or not via the
     *         UI. setImage may still be called, even if <code>isEditable</code>
     *         returns false.
     */
    public boolean isEditable() {
        return editable;
    }

    /**
     * Sets what style to use when painting the image
     * 
     * @param s
     */
    public void setStyle(Style s) {
        if (style != s) {
            Style oldStyle = style;
            style = s;
            firePropertyChange("style", oldStyle, s);
            repaint();
        }
    }

    /**
     * @return the Style used for drawing the image (CENTERED, TILED, etc).
     */
    public Style getStyle() {
        return style;
    }

    /**
     *  {@inheritDoc}
     *  The old property value in PCE fired by this method might not be always correct!
     */
    public Dimension getPreferredSize() {
        if (!isPreferredSizeSet() && img != null) {
            Image img = this.img.get();
            // was img GCed in the mean time?
            if (img != null) {
                // it has not been explicitly set, so return the width/height of
                // the image
                int width = img.getWidth(null);
                int height = img.getHeight(null);
                if (width == -1 || height == -1) {
                    return super.getPreferredSize();
                }
                Insets insets = getInsets();
                width += insets.left + insets.right;
                height += insets.top + insets.bottom;
                return new Dimension(width, height);
            }
        }
        return super.getPreferredSize();
    }

    /**
     * Overridden to paint the image on the panel
     * 
     * @param g
     */
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        Image img = this.img.get();
        if (img == null && imageLoader != null) {
            // schedule for loading (will repaint itself once loaded)
            // have to use new future task every time as it holds strong
            // reference to the object it retrieved and doesn't allow to reset
            // it.
            service.execute(new FutureTask<Image>(imageLoader) {

                @Override
                protected void done() {
                    super.done();
                    
                    SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                            try {
                                JXImagePanel.this.setImage(get());
                            } catch (InterruptedException e) {
                                // ignore - canceled image load
                            } catch (ExecutionException e) {
                                LOG.log(Level.WARNING, "", e);
                            }
                        }
                    });
                }

            });
            img = defaultImage;
        }
        if (img != null) {
            final int imgWidth = img.getWidth(null);
            final int imgHeight = img.getHeight(null);
            if (imgWidth == -1 || imgHeight == -1) {
                // image hasn't completed loading, return
                return;
            }

            Insets insets = getInsets();
            final int pw = getWidth() - insets.left - insets.right;
            final int ph = getHeight() - insets.top - insets.bottom;

            switch (style) {
            case CENTERED:
                Rectangle clipRect = g2.getClipBounds();
                int imageX = (pw - imgWidth) / 2 + insets.left;
                int imageY = (ph - imgHeight) / 2 + insets.top;
                Rectangle r = SwingUtilities.computeIntersection(imageX, imageY, imgWidth, imgHeight, clipRect);
                if (r.x == 0 && r.y == 0 && (r.width == 0 || r.height == 0)) {
                    return;
                }
                // I have my new clipping rectangle "r" in clipRect space.
                // It is therefore the new clipRect.
                clipRect = r;
                // since I have the intersection, all I need to do is adjust the
                // x & y values for the image
                int txClipX = clipRect.x - imageX;
                int txClipY = clipRect.y - imageY;
                int txClipW = clipRect.width;
                int txClipH = clipRect.height;

                g2.drawImage(img, clipRect.x, clipRect.y, clipRect.x + clipRect.width, clipRect.y + clipRect.height, txClipX, txClipY, txClipX + txClipW, txClipY + txClipH, null);
                break;
            case TILED:
                g2.translate(insets.left, insets.top);
                Rectangle clip = g2.getClipBounds();
                g2.setClip(0, 0, pw, ph);

                int totalH = 0;

                while (totalH < ph) {
                    int totalW = 0;

                    while (totalW < pw) {
                        g2.drawImage(img, totalW, totalH, null);
                        totalW += img.getWidth(null);
                    }

                    totalH += img.getHeight(null);
                }

                g2.setClip(clip);
                g2.translate(-insets.left, -insets.top);
                break;
            case SCALED:
                g2.drawImage(img, insets.left, insets.top, pw, ph, null);
                break;
            case SCALED_KEEP_ASPECT_RATIO:
                int w = pw;
                int h = ph;
                final float ratioW = ((float) w) / ((float) imgWidth);
                final float ratioH = ((float) h) / ((float) imgHeight);

                if (ratioW < ratioH) {
                    h = (int) (imgHeight * ratioW);
                } else {
                    w = (int) (imgWidth * ratioH);
                }

                final int x = (pw - w) / 2 + insets.left;
                final int y = (ph - h) / 2 + insets.top;
                g2.drawImage(img, x, y, w, h, null);
                break;
            default:
                LOG.fine("unimplemented");
                g2.drawImage(img, insets.left, insets.top, this);
                break;
            }
        }
    }

    /**
     * Handles click events on the component
     */
    private class MouseHandler extends MouseAdapter {
        private Cursor oldCursor;

        private JFileChooser chooser;

        public void mouseClicked(MouseEvent evt) {
            if (chooser == null) {
                chooser = new JFileChooser();
            }
            int retVal = chooser.showOpenDialog(JXImagePanel.this);
            if (retVal == JFileChooser.APPROVE_OPTION) {
                File file = chooser.getSelectedFile();
                try {
                    setImage(new ImageIcon(file.toURI().toURL()).getImage());
                } catch (Exception ex) {
                }
            }
        }

        public void mouseEntered(MouseEvent evt) {
            if (oldCursor == null) {
                oldCursor = getCursor();
                setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
            }
        }

        public void mouseExited(MouseEvent evt) {
            if (oldCursor != null) {
                setCursor(oldCursor);
                oldCursor = null;
            }
        }
    }

    public void setDefaultImage(Image def) {
        this.defaultImage = def;
    }

    public void setImageLoader(Callable<Image> loadImage) {
        this.imageLoader = loadImage;

    }
}
