/*

* Copyright (c) 2007 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

package com.nokia.carbide.cpp.internal.ui.images;

import com.nokia.carbide.cpp.ui.images.*;

import org.eclipse.core.runtime.*;

import org.eclipse.swt.graphics.ImageData;

import org.eclipse.swt.graphics.Point;

import java.io.IOException;

import java.lang.ref.WeakReference;

import java.util.HashMap;

import java.util.Map;

/**

 * This is a cache for the image providers and ImageData created for given files.

 *

 */

public class CachingImageLoader implements IImageLoader {

	private Map<IPath, IImageDataProvider> pathToImageDataProviderMap = new HashMap<IPath, IImageDataProvider>();

	private ImageLoader loader = new ImageLoader();

	public CachingImageLoader() {

	}

	/* (non-Javadoc)

	 * @see com.nokia.carbide.cpp.project.ui.images.IImageLoader#createImageDataProvider(org.eclipse.core.runtime.IPath)

	 */

	public synchronized IImageDataProvider createImageDataProvider(IPath origPath)

			throws CoreException {

		if (origPath == null)

			return null;

		final IPath path = canonicalizePath(origPath);

		IImageDataProvider provider = pathToImageDataProviderMap.get(path);

		// check for changes before returning anything cached

		if (provider != null) {

			provider.notifyIfChanged();

		}

		if (provider == null) {

			final IImageDataProvider baseProvider = loader.createImageDataProvider(path);

			provider = new BaseImageDataProvider(path.toFile()) {

				/** Cache of Pair<IPath, Point> to ImageData */

				private Map<Point, WeakReference<ImageData>> imageDataCache = new HashMap<Point, WeakReference<ImageData>>();

				public ImageData getImageData(Point size) throws CoreException {

					if (notifyIfChanged() || size == null) {

						// original size always cached inside provider

						return baseProvider.getImageData(size);

					}

					ImageData data = null;

					WeakReference<ImageData> ref = imageDataCache.get(size);

					if (ref != null) {

						data = ref.get();

					}

					if (data == null) {

						data = baseProvider.getImageData(size);

						imageDataCache.put(size, new WeakReference<ImageData>(data));

					}

					return data;

				}

				/* (non-Javadoc)

				 * @see com.nokia.sdt.utils.IDisposable#dispose()

				 */

				public void dispose() {

					super.dispose();

					imageDataCache.clear();

					baseProvider.dispose();

				}

			};

			pathToImageDataProviderMap.put(path, provider);

			provider.addListener(new IImageDataProviderListener() {

				public void changed(IImageDataProvider provider) {

					unregister(path);

				}

			});

		}

		return provider;

	}

	private void disposeProvider(IImageDataProvider provider, IPath path) {

		provider.dispose();

		provider = null;  

		pathToImageDataProviderMap.remove(path);

	}

	/* (non-Javadoc)

	 * @see com.nokia.sdt.utils.IDisposable#dispose()

	 */

	public synchronized void dispose() {

		for (IImageDataProvider provider : pathToImageDataProviderMap.values()) {

			provider.dispose();

		}

		pathToImageDataProviderMap.clear();

		loader.dispose();

	}

	/**

	 * Get the canonical path so we don't load the same image under different

	 * cases or paths.

	 * @param path full path

	 * @return canonical path (full path)

	 */

	private IPath canonicalizePath(IPath path) {

		try {

			return new Path(path.toFile().getCanonicalPath());

		} catch (IOException e) {

			return path;

		}

	}

    /**

     * Unregister a cached image when its underlying resource changes

     */

    private synchronized void unregister(IPath path) {

        // remove from cache

    	IImageDataProvider provider = pathToImageDataProviderMap.get(path);

    	disposeProvider(provider, path);

    }

}