/*******************************************************************************
 * Copyright (c) 2005 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:
 *    Oracle Corporation - initial API and implementation
 *******************************************************************************/ 
package org.eclipse.jst.pagedesigner.dtmanager.converter.internal;

import java.net.URL;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jst.jsf.common.metadata.Trait;
import org.eclipse.jst.jsf.common.metadata.internal.IImageDescriptorProvider;
import org.eclipse.jst.jsf.common.metadata.internal.IMetaDataSourceModelProvider;
import org.eclipse.jst.jsf.common.metadata.internal.IResourceURLProvider;
import org.eclipse.jst.pagedesigner.converter.IConverterFactory;
import org.eclipse.jst.pagedesigner.converter.ITagConverter;
import org.eclipse.jst.pagedesigner.dtmanager.DTManager;
import org.eclipse.jst.pagedesigner.dtmanager.IDTInfo;
import org.eclipse.jst.pagedesigner.dtmanager.converter.ITagConverterDecorator;
import org.eclipse.jst.pagedesigner.dtmanager.dtinfo.ResolveAttributeValue;
import org.eclipse.jst.pagedesigner.dtmanager.dtinfo.TagDecorateInfo;
import org.eclipse.jst.pagedesigner.preview.PageExpressionContext;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

/**
 * ITagConverterDecorator implementation for DTTagConverter.
 * 
 * @author Ian Trimble - Oracle
 */
public class DTTagConverterDecorator implements ITagConverterDecorator {

	private static final String DECORATE_INFO_ID_DESIGN = "vpd-decorate-design"; //$NON-NLS-1$
	private static final String DECORATE_INFO_ID_PREVIEW = "vpd-decorate-preview"; //$NON-NLS-1$
	private static final String MD_PLUGIN_LOCATION = "$metadata-plugin-location$"; //$NON-NLS-1$

	/*
	 * (non-Javadoc)
	 * @see org.eclipse.jst.pagedesigner.dtmanager.converter.ITagConverterDecorator#decorate(org.eclipse.jst.pagedesigner.converter.ITagConverter)
	 */
	public void decorate(ITagConverter tagConverter) {
		if (!(tagConverter instanceof DTTagConverter)) {
			throw new IllegalArgumentException("ITagConverter argument must be an instance of DTTagConverter"); //$NON-NLS-1$
		}
		DTTagConverter dtTagConverter = (DTTagConverter)tagConverter;

		if (dtTagConverter.getMode() == IConverterFactory.MODE_DESIGNER) {
			decorateFromDTInfo(dtTagConverter, DECORATE_INFO_ID_DESIGN);
		} else if (dtTagConverter.getMode() == IConverterFactory.MODE_PREVIEW) {
			decorateFromDTInfo(dtTagConverter, DECORATE_INFO_ID_PREVIEW);
		}

		if (tagConverter.getResultElement() == null && tagConverter.isVisualByHTML()) {
			createUnknownTagRepresentation(dtTagConverter);
		}
	}

	/**
	 * Performs decoration of the specified DTTagConverter instance from
	 * IDTInfo (metadata) for the specified (by ID) TagDecorateInfo.
	 * 
	 * @param dtTagConverter DTTagConverter instance.
	 * @param tagDecorateInfoID ID of the TagDecorateInfo to be located in
	 * metadata.
	 */
	protected void decorateFromDTInfo(DTTagConverter dtTagConverter, String tagDecorateInfoID) {
		Element srcElement = dtTagConverter.getHostElement();
		DTManager dtManager = DTManager.getInstance();
		IDTInfo dtInfo = dtManager.getDTInfo(srcElement);
		if (dtInfo != null) {
			TagDecorateInfo tdInfo = dtInfo.getTagDecorateInfo(tagDecorateInfoID);
			if (tdInfo != null) {
				dtTagConverter.setMultiLevel(tdInfo.isMultiLevel());
				dtTagConverter.setNeedBorderDecorator(tdInfo.isNeedBorderDecorator());
				dtTagConverter.setNeedTableDecorator(tdInfo.isNeedTableDecorator());
				if (tdInfo.isNonVisual()) {
					setNonVisual(dtTagConverter, dtInfo, tdInfo.getNonVisualImagePath());
				}
				if (tdInfo.isResolveChildText()) {
					resolveChildText(dtTagConverter.getResultElement(), dtInfo);
				}
				if (tdInfo.isSetNonVisualChildElements()) {
					setNonVisualChildElements(dtTagConverter, srcElement);
				}
				dtTagConverter.setWidget(tdInfo.isWidget());
				dtTagConverter.setMinHeight(tdInfo.getMinHeight());
				dtTagConverter.setMinWidth(tdInfo.getMinWidth());
				ResolveAttributeValue resAttrValue = tdInfo.getResolveAttributeValue();
				if (resAttrValue != null) {
					String attributeName = resAttrValue.getAttributeName();
					if (attributeName != null && attributeName.length() > 0) {
						resolveAttributeValue(dtTagConverter.getResultElement(), attributeName, dtInfo);
					}
				}
			}
		}
	}

	/**
	 * Creates a visual representation result Element for an unknown tag.
	 * 
	 * @param dtTagConverter DTTagConverter instance.
	 */
	protected void createUnknownTagRepresentation(DTTagConverter dtTagConverter) {
		Element element = dtTagConverter.createElement("span"); //$NON-NLS-1$
		element.setAttribute("style", "color:red;font-weight:bold;"); //$NON-NLS-1$ //$NON-NLS-2$
		Text text = dtTagConverter.createText("<" + dtTagConverter.getHostElement().getTagName() + "/>"); //$NON-NLS-1$ //$NON-NLS-2$
		element.appendChild(text);
		dtTagConverter.setResultElement(element);
		dtTagConverter.setWidget(true);
	}

	/**
	 * Adds child Elements of the specified source Element to the specified
	 * DTTagConverter instance's collection of non-visual children.
	 * 
	 * @param dtTagConverter DTTagConverter instance.
	 * @param srcElement Source Element for which child Elements are to be
	 * added.
	 */
	protected void setNonVisualChildElements(DTTagConverter dtTagConverter, Element srcElement) {
		NodeList childNodes = srcElement.getChildNodes();
		for (int i = 0; i < childNodes.getLength(); i++) {
			Node curNode = childNodes.item(i);
			if (curNode.getNodeType() == Node.ELEMENT_NODE) {
				dtTagConverter.addNonVisualChildElement((Element)curNode);
			}
		}
	}

	/**
	 * Performs simple EL resolution for the child Text Node of the specified
	 * source Element instance.
	 * 
	 * @param srcElement Source Element for which child Text Node EL resolution
	 * is to be performed.
	 * @param dtInfo IDTInfo instance.
	 */
	protected void resolveChildText(Element srcElement, IDTInfo dtInfo) {
		if (srcElement != null) {
			NodeList childNodes = srcElement.getChildNodes();
			for (int i = 0; i < childNodes.getLength(); i++) {
				Node childNode = childNodes.item(i);
				if (childNode.getNodeType() == Node.TEXT_NODE) {
					Text textNode = (Text)childNode;
					String textNodeValue = textNode.getNodeValue();
					try {
						String newTextNodeValue;
						if (textNodeValue.contains(MD_PLUGIN_LOCATION)) {
							newTextNodeValue = resolveMDPluginLocation(textNodeValue, dtInfo);
						} else {
							newTextNodeValue = (String)PageExpressionContext.getCurrent().evaluateExpression(textNodeValue, String.class, null);
						}
						if (newTextNodeValue != null && !textNodeValue.equals(newTextNodeValue)) {
							textNode.setNodeValue(newTextNodeValue);
						}
					} catch(Exception ex) {
						//ignore - could not resolve, do not change existing value
					}
				}
			}
		}
	}

	/**
	 * Performs simple EL resolution for the value of the specified attribute
	 * of the specified Element.
	 * 
	 * @param srcElement Source Element instance.
	 * @param attributeName Name of attribute for which the value should be
	 * resolved.
	 * @param dtInfo IDTInfo instance.
	 */
	protected void resolveAttributeValue(Element srcElement, String attributeName, IDTInfo dtInfo) {
		if (srcElement != null) {
			Element targetElement = srcElement;
			String targetAttributeName = attributeName;
			//determine if attributeName is XPath and re-target as appropriate
			if (attributeName.contains("/")) { //$NON-NLS-1$
				int lastSlashPos = attributeName.lastIndexOf("/"); //$NON-NLS-1$
				String xPathExpression = attributeName.substring(0, lastSlashPos);
				XPath xPath = XPathFactory.newInstance().newXPath();
				try {
					Object resultObject = xPath.evaluate(xPathExpression, srcElement, XPathConstants.NODE);
					if (resultObject instanceof Element) {
						targetElement = (Element)resultObject;
						targetAttributeName = attributeName.substring(lastSlashPos + 1);
					}
				} catch(XPathExpressionException xee) {
					//could not evaluate - leave targetElement and targetAttributeName unchanged
				}
			}
			String oldAttributeValue = targetElement.getAttribute(targetAttributeName);
			if (oldAttributeValue != null && oldAttributeValue.length() > 0) {
				try {
					String newAttributeValue;
					if (oldAttributeValue.contains(MD_PLUGIN_LOCATION)) {
						newAttributeValue = resolveMDPluginLocation(oldAttributeValue, dtInfo);
					} else {
						newAttributeValue = (String)PageExpressionContext.getCurrent().evaluateExpression(oldAttributeValue, String.class, null);
					}
					if (newAttributeValue != null && !oldAttributeValue.equals(newAttributeValue)) {
						targetElement.setAttribute(targetAttributeName, newAttributeValue);
					}
				} catch(Exception ex) {
					//ignore - could not resolve, do not change existing value
				}
			}
		}
	}

	/**
	 * Resolves any instance of MD_PLUGIN_LOCATION in input String.
	 * 
	 * @param input Input String.
	 * @param dtInfo IDTInfo instance.
	 * @return Input String with any instance of MD_PLUGIN_LOCATION resolved.
	 */
	protected String resolveMDPluginLocation(String input, IDTInfo dtInfo) {
		String output = input;
		if (input != null && input.contains(MD_PLUGIN_LOCATION)) {
			int tokenStart = input.indexOf(MD_PLUGIN_LOCATION);
			int tokenEnd = tokenStart + MD_PLUGIN_LOCATION.length();
			String prefix = input.substring(0, tokenStart);
			String suffix = input.substring(tokenEnd);
			Trait trait = dtInfo.getTrait();
			IMetaDataSourceModelProvider mdSourceModelProvider = trait.getSourceModelProvider();
			IResourceURLProvider resourceURLProvider = (IResourceURLProvider)mdSourceModelProvider.getAdapter(IResourceURLProvider.class);
			URL url = resourceURLProvider.getResourceURL("/META-INF/"); //$NON-NLS-1$
			String resolvedToken = url.toExternalForm();
			resolvedToken = resolvedToken.substring(0, resolvedToken.length() - 10);
			output = prefix + resolvedToken + suffix;
		}
		return output;
	}

	/**
	 * Sets DTTagConverter instance as non-visual as HTML and sets the
	 * ImageDescriptor instance that DTTagConverter will use to return an Image
	 * for rendering.
	 * 
	 * @param dtTagConverter DTTagConverter instance.
	 * @param dtInfo IDTInfo instance.
	 * @param imagePath Image path, relative to declaring plug-in.
	 */
	protected void setNonVisual(DTTagConverter dtTagConverter, IDTInfo dtInfo, String imagePath) {
		dtTagConverter.setVisualByHTML(false);
		if (imagePath != null && imagePath.length() > 0) {
			Trait trait = dtInfo.getTrait();
			IImageDescriptorProvider imgDescProvider = (IImageDescriptorProvider)trait.getSourceModelProvider().getAdapter(IImageDescriptorProvider.class);
			if (imgDescProvider != null) {
				ImageDescriptor imageDescriptor = imgDescProvider.getImageDescriptor(imagePath);
				dtTagConverter.setVisualImageDescriptor(imageDescriptor);
			}
		}
	}

}