/*

 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.swing;

import java.awt.GraphicsConfiguration;

import java.awt.Image;

import java.lang.ref.SoftReference;

import java.util.Iterator;

import java.util.LinkedList;

/**

 * Cache is used to cache an image based on a set of arguments.

 */

public class ImageCache {

    // Maximum number of entries to cache

    private int maxCount;

    // The entries.

    final private LinkedList<SoftReference<Entry>> entries;

    public ImageCache(int maxCount) {

        this.maxCount = maxCount;

        entries = new LinkedList<SoftReference<Entry>>();

    }

    void setMaxCount(int maxCount) {

        this.maxCount = maxCount;

    }

    public void flush() {

        entries.clear();

    }

    private Entry getEntry(Object key, GraphicsConfiguration config,

                           int w, int h, Object[] args) {

        Entry entry;

        Iterator<SoftReference<Entry>> iter = entries.listIterator();

        while (iter.hasNext()) {

            SoftReference<Entry> ref = iter.next();

            entry = ref.get();

            if (entry == null) {

                // SoftReference was invalidated, remove the entry

                iter.remove();

            }

            else if (entry.equals(config, w, h, args)) {

                // Put most recently used entries at the head

                iter.remove();

                entries.addFirst(ref);

                return entry;

            }

        }

        // Entry doesn't exist

        entry = new Entry(config, w, h, args);

        if (entries.size() >= maxCount) {

            entries.removeLast();

        }

        entries.addFirst(new SoftReference<Entry>(entry));

        return entry;

    }

    /**

     * Returns the cached Image, or null, for the specified arguments.

     */

    public Image getImage(Object key, GraphicsConfiguration config,

            int w, int h, Object[] args) {

        Entry entry = getEntry(key, config, w, h, args);

        return entry.getImage();

    }

    /**

     * Sets the cached image for the specified constraints.

     */

    public void setImage(Object key, GraphicsConfiguration config,

            int w, int h, Object[] args, Image image) {

        Entry entry = getEntry(key, config, w, h, args);

        entry.setImage(image);

    }

    /**

     * Caches set of arguments and Image.

     */

    private static class Entry {

        final private GraphicsConfiguration config;

        final private int w;

        final private int h;

        final private Object[] args;

        private Image image;

        Entry(GraphicsConfiguration config, int w, int h, Object[] args) {

            this.config = config;

            this.args = args;

            this.w = w;

            this.h = h;

        }

        public void setImage(Image image) {

            this.image = image;

        }

        public Image getImage() {

            return image;

        }

        public String toString() {

            String value = super.toString() +

                    "[ graphicsConfig=" + config +

                    ", image=" + image +

                    ", w=" + w + ", h=" + h;

            if (args != null) {

                for (int counter = 0; counter < args.length; counter++) {

                    value += ", " + args[counter];

                }

            }

            value += "]";

            return value;

        }

        public boolean equals(GraphicsConfiguration config,

                 int w, int h, Object[] args) {

            if (this.w == w && this.h == h &&

                    ((this.config != null && this.config.equals(config)) ||

                    (this.config == null && config == null))) {

                if (this.args == null && args == null) {

                    return true;

                }

                if (this.args != null && args != null &&

                        this.args.length == args.length) {

                    for (int counter = args.length - 1; counter >= 0;

                    counter--) {

                        Object a1 = this.args[counter];

                        Object a2 = args[counter];

                        if ((a1 == null && a2 != null) ||

                                (a1 != null && !a1.equals(a2))) {

                            return false;

                        }

                    }

                    return true;

                }

            }

            return false;

        }

    }

}