/*****************************************************************************
 * Copyright (c) 2004 IBM Corporation and others. 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: IBM Corporation - initial API and implementation
 ****************************************************************************/
package org.eclipse.wst.css.ui.internal.image;


import java.util.HashMap;
import java.util.Map;

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.ImageRegistry;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.swt.graphics.Image;
import org.eclipse.ui.plugin.AbstractUIPlugin;
import org.eclipse.wst.css.ui.internal.CSSUIPlugin;
import org.eclipse.wst.css.ui.internal.editor.CSSEditorPluginImages;


public class CSSImageHelper {
	private static CSSImageHelper fInstance = null;

	/**
	 * singleton
	 */
	public synchronized static CSSImageHelper getInstance() {
		if (fInstance == null) {
			fInstance = new CSSImageHelper();
		}
		return fInstance;
	}

	private HashMap fImageDescRegistry = null;	// save a descriptor for each image
	private Map fTypeMap = null;

	/**
	 * 
	 */
	private CSSImageHelper() {
		super();
	}

	/**
	 * 
	 */
	private Image createImage(String resource) {
		ImageDescriptor desc = AbstractUIPlugin.imageDescriptorFromPlugin(CSSUIPlugin.ID, resource);
		Image image = null;

		if (desc == null) {
			desc = ImageDescriptor.getMissingImageDescriptor();
			image = desc.createImage();
		} else {
			image = desc.createImage();
			getImageRegistry().put(resource, image);
		}

		return image;
	}

	/**
	 * Creates an image descriptor from the given imageFilePath and adds the
	 * image descriptor to the image descriptor registry. If an image
	 * descriptor could not be created, the default "missing" image descriptor
	 * is returned but not added to the image descriptor registry.
	 * 
	 * @param imageFilePath
	 * @return ImageDescriptor image descriptor for imageFilePath or default
	 *         "missing" image descriptor if resource could not be found
	 */
	private ImageDescriptor createImageDescriptor(String imageFilePath) {
		ImageDescriptor imageDescriptor = AbstractUIPlugin.imageDescriptorFromPlugin(CSSUIPlugin.ID, imageFilePath);
		if (imageDescriptor != null) {
			getImageDescriptorRegistry().put(imageFilePath, imageDescriptor);
		} else {
			imageDescriptor = ImageDescriptor.getMissingImageDescriptor();
		}

		return imageDescriptor;
	}

	/**
	 * by type
	 */
	public Image getImage(CSSImageType type) {
		if (fTypeMap == null) {
			fTypeMap = new HashMap();
			fTypeMap.put(CSSImageType.STYLESHEET, CSSEditorPluginImages.IMG_OBJ_STYLESHEET);

			fTypeMap.put(CSSImageType.RULE_CHARSET, CSSEditorPluginImages.IMG_OBJ_RULE_CHARSET);
			fTypeMap.put(CSSImageType.RULE_FONTFACE, CSSEditorPluginImages.IMG_OBJ_RULE_FONTFACE);
			fTypeMap.put(CSSImageType.RULE_IMPORT, CSSEditorPluginImages.IMG_OBJ_RULE_IMPORT);
			fTypeMap.put(CSSImageType.RULE_MEDIA, CSSEditorPluginImages.IMG_OBJ_RULE_MEDIA);
			fTypeMap.put(CSSImageType.RULE_PAGE, CSSEditorPluginImages.IMG_OBJ_RULE_PAGE);
			fTypeMap.put(CSSImageType.RULE_STYLE, CSSEditorPluginImages.IMG_OBJ_RULE_STYLE);
			fTypeMap.put(CSSImageType.RULE_UNKNOWN, CSSEditorPluginImages.IMG_OBJ_RULE_UNKNOWN);

			fTypeMap.put(CSSImageType.SELECTOR_CLASS, CSSEditorPluginImages.IMG_OBJ_SELECTOR_CLASS);
			fTypeMap.put(CSSImageType.SELECTOR_ID, CSSEditorPluginImages.IMG_OBJ_SELECTOR_ID);
			fTypeMap.put(CSSImageType.SELECTOR_PSEUDO, CSSEditorPluginImages.IMG_OBJ_SELECTOR_PSEUDO);
			fTypeMap.put(CSSImageType.SELECTOR_TAG, CSSEditorPluginImages.IMG_OBJ_SELECTOR_TAG);
			fTypeMap.put(CSSImageType.SELECTOR_LINK, CSSEditorPluginImages.IMG_OBJ_SELECTOR_LINK);
			fTypeMap.put(CSSImageType.SELECTOR_DEFAULT, CSSEditorPluginImages.IMG_OBJ_SELECTOR_DEFAULT);

			fTypeMap.put(CSSImageType.VALUE_FUNCTION, CSSEditorPluginImages.IMG_OBJ_VALUE_FUNCTION);
			fTypeMap.put(CSSImageType.VALUE_NUMBER, CSSEditorPluginImages.IMG_OBJ_VALUE_NUMBER);
			fTypeMap.put(CSSImageType.VALUE_STRING, CSSEditorPluginImages.IMG_OBJ_VALUE_STRING);

			fTypeMap.put(CSSImageType.CATEGORY_AURAL, CSSEditorPluginImages.IMG_OBJ_CATEGORY_AURAL);
			fTypeMap.put(CSSImageType.CATEGORY_BOX, CSSEditorPluginImages.IMG_OBJ_CATEGORY_BOX);
			fTypeMap.put(CSSImageType.CATEGORY_COLORANDBACKGROUND, CSSEditorPluginImages.IMG_OBJ_CATEGORY_COLORANDBACKGROUND);
			fTypeMap.put(CSSImageType.CATEGORY_CONTENT, CSSEditorPluginImages.IMG_OBJ_CATEGORY_CONTENT);
			fTypeMap.put(CSSImageType.CATEGORY_FONT, CSSEditorPluginImages.IMG_OBJ_CATEGORY_FONT);
			fTypeMap.put(CSSImageType.CATEGORY_PAGE, CSSEditorPluginImages.IMG_OBJ_CATEGORY_PAGE);
			fTypeMap.put(CSSImageType.CATEGORY_TABLES, CSSEditorPluginImages.IMG_OBJ_CATEGORY_TABLES);
			fTypeMap.put(CSSImageType.CATEGORY_TEXT, CSSEditorPluginImages.IMG_OBJ_CATEGORY_TEXT);
			fTypeMap.put(CSSImageType.CATEGORY_UI, CSSEditorPluginImages.IMG_OBJ_CATEGORY_UI);
			fTypeMap.put(CSSImageType.CATEGORY_VISUAL, CSSEditorPluginImages.IMG_OBJ_CATEGORY_VISUAL);
			fTypeMap.put(CSSImageType.CATEGORY_DEFAULT, CSSEditorPluginImages.IMG_OBJ_CATEGORY_DEFAULT);
		}
		return getImage((String) fTypeMap.get(type));
	}

	/**
	 * by relative path(from here)
	 */
	public Image getImage(String resource) {
		if (resource == null) {
			return null;
		}
		Image image = getImageRegistry().get(resource);
		if (image == null) {
			image = createImage(resource);
		}
		return image;
	}

	/**
	 * Retrieves the image descriptor associated with resource from the image
	 * descriptor registry. If the image descriptor cannot be retrieved,
	 * attempt to find and load the image descriptor at the location specified
	 * in resource.
	 * 
	 * @param resource
	 *            the image descriptor to retrieve
	 * @return ImageDescriptor the image descriptor assocated with resource or
	 *         the default "missing" image descriptor if one could not be
	 *         found
	 */
	public ImageDescriptor getImageDescriptor(String resource) {
		ImageDescriptor imageDescriptor = null;
		Object o = getImageDescriptorRegistry().get(resource);
		if (o == null) {
			// create a descriptor
			imageDescriptor = createImageDescriptor(resource);
		} else {
			imageDescriptor = (ImageDescriptor) o;
		}
		return imageDescriptor;
	}

	/**
	 * Returns the image descriptor registry for this plugin.
	 * 
	 * @return HashMap - image descriptor registry for this plugin
	 */
	private HashMap getImageDescriptorRegistry() {
		if (fImageDescRegistry == null)
			fImageDescRegistry = new HashMap();
		return fImageDescRegistry;
	}

	private ImageRegistry getImageRegistry() {
		return JFaceResources.getImageRegistry();
	}
}