/*******************************************************************************
 * Copyright (c) Emil Crumhorn - Hexapixel.com - emil.crumhorn@gmail.com
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    emil.crumhorn@gmail.com - initial API and implementation
 *******************************************************************************/ 

package com.hexapixel.widgets.generic;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;

import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

public class ImageCache {

    private static HashMap<String, Image> mImageMap;
    private static List<Image> mExternallyCreatedCache;
    
    static {
    	mImageMap = new HashMap<String, Image>();
    	mExternallyCreatedCache = new ArrayList<Image>();
    }
    
    /**
     * Returns an image that is also cached if it has to be created and does not already exist in the cache.
     * 
     * @param fileName Filename of image to fetch
     * @return Image file or null if it could not be found
     */
    public static Image getImage(String fileName) {
        Image image = mImageMap.get(fileName);
        if (image == null) {
            image = createImage(fileName);
            mImageMap.put(fileName, image);
        }
        return image;
    }

    // creates the image, and tries really hard to do so
    private static Image createImage(String fileName) {
        ClassLoader classLoader = ImageCache.class.getClassLoader();
        InputStream is = classLoader.getResourceAsStream(fileName);
        if (is == null) {
            // the old way didn't have leading slash, so if we can't find the image stream,
            // let's see if the old way works.
            is = classLoader.getResourceAsStream(fileName.substring(1));

            if (is == null) {
                is = classLoader.getResourceAsStream(fileName);
                if (is == null) {
                    is = classLoader.getResourceAsStream(fileName.substring(1));
                    if (is == null) {
                        //logger.debug("null input stream for both " + path + " and " + path);
                        return null;
                    }
                }
            }
        }

        Image img = new Image(Display.getDefault(), is);
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return img;
    }

    /**
     * Disposes ALL images that have been cached.
     *
     */
    public static void dispose() {
        Iterator<Image> e = mImageMap.values().iterator();
        while (e.hasNext()) 
        	e.next().dispose();
    }
    
    /**
     * Disposes a specific image and removes it from the image cache.
     * 
     * @param img Image to dispose
     */
    public static void dispose(Image img) {
    	if (img == null)
    		return;
    	
    	Iterator<Entry<String,Image>> set = mImageMap.entrySet().iterator();    	
        while (set.hasNext()) {
        	Entry<String,Image> entry = set.next();
        	if (entry.getValue() == img) {
        		mImageMap.remove(entry.getKey());
        		entry.getValue().dispose();
        		return;
        	}        
        }

        // not in the hash, dispose it if it's in the externally cached list
        if (mExternallyCreatedCache.contains(img))
        	mExternallyCreatedCache.remove(img);
        
        // dispose
        if (!img.isDisposed())
        	img.dispose();
    }
    
    public static void ensureImageIsCached(Image img) {
    	// check local cache first, it might have been an image created by us
    	Collection<Image> cachedImages = mImageMap.values();
    	if (cachedImages.contains(img))
    		return;
    	
    	// add it to the external cache so we can dispose it if asked
    	if (!mExternallyCreatedCache.contains(img))
    		mExternallyCreatedCache.add(img);
    }
    
    
}