/*******************************************************************************
 * Copyright (c) 2008 Oracle Corporation.
 * 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:
 *    Ian Trimble - initial API and implementation
 *******************************************************************************/ 
package org.eclipse.jst.pagedesigner.css2.property;

import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;

import org.eclipse.core.resources.IContainer;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IWorkspaceRoot;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.ImageRegistry;
import org.eclipse.jst.pagedesigner.IHTMLConstants;
import org.eclipse.jst.pagedesigner.PDPlugin;
import org.eclipse.jst.pagedesigner.css2.ICSSStyle;
import org.eclipse.jst.pagedesigner.utils.DOMUtil;
import org.eclipse.swt.graphics.Image;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMModel;
import org.eclipse.wst.xml.core.internal.provisional.document.IDOMNode;
import org.w3c.dom.Element;
import org.w3c.dom.css.CSSValue;

/**
 * Provides metadata for the "background-image" CSS property.
 * 
 * @author Ian Trimble - Oracle
 */
public class BackgroundImageMeta extends CSSPropertyMeta {

	private static final String[] _keywords = {ICSSPropertyID.VAL_NONE};

	/**
	 * Construct an instance.
	 */
	public BackgroundImageMeta() {
		super(false, ICSSPropertyID.VAL_NONE);
	}

	/* (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.css2.property.CSSPropertyMeta#calculateCSSValueResult(org.w3c.dom.css.CSSValue, java.lang.String, org.eclipse.jst.pagedesigner.css2.ICSSStyle)
	 */
	@Override
	public Object calculateCSSValueResult(CSSValue value, String propertyName,
			ICSSStyle style) {
		Object ret = null;
		String valueText = value.getCssText();
		if (valueText != null && valueText.length() > 0) {
			valueText = stripURLSyntax(valueText);
			ret = getImage(valueText, null);
		}
		if (ret == null) {
			ret = getInitialValue(propertyName, style);
		}
		return ret;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.css2.property.CSSPropertyMeta#calculateHTMLAttributeOverride(org.w3c.dom.Element, java.lang.String, java.lang.String, org.eclipse.jst.pagedesigner.css2.ICSSStyle)
	 */
	@Override
	public Object calculateHTMLAttributeOverride(Element element,
			String htmltag, String propertyName, ICSSStyle style) {
		Image image = null;
		if (
				element != null &&
				element.getNodeName() != null &&
				element.getNodeName().equalsIgnoreCase(IHTMLConstants.TAG_BODY)) {
			if (ICSSPropertyID.ATTR_BACKGROUND_IMAGE.equalsIgnoreCase(propertyName)) {
				String attrValue = DOMUtil.getAttributeIgnoreCase(element, IHTMLConstants.ATTR_BACKGROUND);
				if (attrValue != null && attrValue.trim().length() > 0) {
					image = getImage(attrValue.trim(), element);
				}
			}
		}
		return image;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.css2.property.CSSPropertyMeta#getKeywordValues()
	 */
	@Override
	protected String[] getKeywordValues() {
		return _keywords;
	}

	private String stripURLSyntax(String input) {
		String output = null;
		if (input != null) {
			//strip "url(...)"
			int startPos = input.indexOf("url(") + 4; //$NON-NLS-1$
			if (startPos > -1 && startPos < input.length() - 1) {
				int endPos = input.indexOf(')', startPos);
				if (endPos > startPos) {
					String insideURL = input.substring(startPos, endPos).trim();
					//strip double-quotes
					if (insideURL.startsWith("\"") && insideURL.endsWith("\"")) { //$NON-NLS-1$ //$NON-NLS-2$
						output = insideURL.substring(1, insideURL.length() - 1);
					//strip single-quotes
					} else if (insideURL.startsWith("'") && insideURL.endsWith("'")) { //$NON-NLS-1$ //$NON-NLS-2$
						output = insideURL.substring(1, insideURL.length() - 1);
					} else {
						output = insideURL;
					}
				}
			}
		}
		return output != null ? output : input;
	}

	/* Image instances returned from this method should not be disposed because
	 * they are cached in the plug-in's ImageRegistry and will be disposed of
	 * by the registry.
	 */
	private Image getImage(String imagePath, Element element) {
		Image image = null;
		if (imagePath != null && imagePath.length() > 0) {
			ImageRegistry registry = PDPlugin.getDefault().getImageRegistry();
			image = registry.get(imagePath);
			if (image == null) {
				try {
					URL imageURL = new URL(imagePath);
					ImageDescriptor imageDescriptor = ImageDescriptor.createFromURL(imageURL);
					image = imageDescriptor.createImage();
					if (image != null) {
						registry.put(imagePath, image);
					}
				} catch(MalformedURLException mue) {
					//attempt to resolve as relative to document
					if (element instanceof IDOMNode) {
						IDOMModel model = ((IDOMNode)element).getModel();
						if (model != null) {
							String baseLocation = model.getBaseLocation();
							if (baseLocation != null && baseLocation.length() > 0) {
								IWorkspaceRoot wsRoot = ResourcesPlugin.getWorkspace().getRoot();
								if (wsRoot != null) {
									IResource jspRes = wsRoot.findMember(baseLocation);
									if (jspRes != null) {
										IContainer jspFolder = jspRes.getParent();
										if (jspFolder != null) {
											IResource imageRes = jspFolder.findMember(imagePath);
											if (imageRes != null) {
												URI imageURI = imageRes.getLocationURI();
												if (imageURI != null) {
													try {
														URL imageURL = imageURI.toURL();
														ImageDescriptor imageDescriptor = ImageDescriptor.createFromURL(imageURL);
														image = imageDescriptor.createImage();
														if (image != null) {
															registry.put(imagePath, image);
														}
													} catch(MalformedURLException mue2) {
														//ignore - what else can be done?
													}
												}
											}
										}
									}
								}
							}
						}
					}
				}
			} else if (image.isDisposed()) {
				//shouldn't be able to get here from there, but...just in case
				registry.remove(imagePath);
				image = getImage(imagePath, element);
			}
		}
		return image;
	}

}