/*******************************************************************************
 * 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:
 *    Ian Trimble - initial API and implementation
 *******************************************************************************/ 
package org.eclipse.jst.jsf.core.jsfappconfig;

import java.io.IOException;
import java.util.Collections;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.emf.common.util.EList;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.jst.jsf.core.internal.JSFCorePlugin;
import org.eclipse.jst.jsf.core.internal.Messages;
import org.eclipse.jst.jsf.facesconfig.emf.FacesConfigType;
import org.eclipse.jst.jsf.facesconfig.util.FacesConfigResourceFactory;
import org.eclipse.osgi.util.NLS;

/**
 * JARFileJSFAppConfigProvider provides the root element of an application
 * configuration model by loading the model from a /META-INF/faces-config.xml
 * entry in a JAR file.
 * 
 * <p><b>Provisional API - subject to change</b></p>
 * 
 * @author Ian Trimble - Oracle
 */
public class JARFileJSFAppConfigProvider extends AbstractJSFAppConfigProvider {

	/**
	 * Prefix required to turn filename into a JAR URI.
	 */
	public static final String JARFILE_URI_PREFIX = "jar:file:///";

	/**
	 * Suffix required to turn filename into a JAR URI.
	 */
	public static final String FACES_CONFIG_IN_JAR_SUFFIX = "!/META-INF/faces-config.xml";

	/**
	 * Name of a JAR file that contains a /META-INF/faces-config.xml entry.
	 */
	protected String filename = null;

	/**
	 * Cached {@link FacesConfigType} instance.
	 */
	protected FacesConfigType facesConfig = null;

	/**
	 * Flag to track if load error has been logged at least once.
	 */
	protected boolean loadErrorLogged = false;

	/**
	 * Creates an instance, storing the passed IProject instance and file name
	 * String to be used for subsequent processing.
	 * 
	 * @param filename Name of a JAR file that contains a
	 * /META-INF/faces-config.xml entry.
	 */
	public JARFileJSFAppConfigProvider(String filename) {
		this.filename = filename;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.jst.jsf.core.jsfappconfig.IJSFAppConfigProvider#getFacesConfigModel()
	 */
	public FacesConfigType getFacesConfigModel() {
	    // TODO: should this job be pushed into the model?
		if (facesConfig == null) {
			if (filename != null) {
				StringBuffer sb = new StringBuffer();
				sb.append(JARFILE_URI_PREFIX);
				sb.append(filename);
				sb.append(FACES_CONFIG_IN_JAR_SUFFIX);
				URI jarFileURI = URI.createURI(sb.toString());
				FacesConfigResourceFactory resourceFactory = FacesConfigResourceFactory.createResourceFactoryForJar();
				Resource resource = resourceFactory.createResource(jarFileURI);
				try {
					resource.load(Collections.EMPTY_MAP);
					if (resource != null) {
						EList resourceContents = resource.getContents();
						if (resourceContents != null && resourceContents.size() > 0) {
							facesConfig = (FacesConfigType)resourceContents.get(0);
							if (facesConfig != null) {
								jsfAppConfigLocater.getJSFAppConfigManager().addFacesConfigChangeAdapter(facesConfig);
							}
						}
					}
				} catch(IllegalStateException ise) {
					//log error
					logLoadError(ise);
				} catch(IOException ioe) {
					//log error
					logLoadError(ioe);
				}
			}
		}
		return facesConfig;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.jst.jsf.core.jsfappconfig.IJSFAppConfigProvider#releaseFacesConfigModel()
	 */
	public void releaseFacesConfigModel() {
		jsfAppConfigLocater.getJSFAppConfigManager().removeFacesConfigChangeAdapter(facesConfig);
	}

	/**
	 * Called to log a load error; load error will be logged once only per
	 * instance, per VM session.
	 * 
	 * @param ex Throwable instance to be logged.
	 */
	protected void logLoadError(Throwable ex) {
		if (!loadErrorLogged) {
			JSFCorePlugin.log(
					IStatus.ERROR,
					NLS.bind(Messages.JARFileJSFAppConfigProvider_ErrorLoadingModel, JARFILE_URI_PREFIX + filename + FACES_CONFIG_IN_JAR_SUFFIX),
					ex);
			loadErrorLogged = true;
		}
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	public boolean equals(Object otherObject) {
		boolean equals = false;
		if (otherObject instanceof JARFileJSFAppConfigProvider) {
			String otherFilename = ((JARFileJSFAppConfigProvider)otherObject).filename;
			if (filename != null) {
				equals = filename.equals(otherFilename);
			} else {
				equals = otherFilename == null;
			}
		}
		return equals;
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		return filename != null ? filename.hashCode() : 0;
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		StringBuffer sb = new StringBuffer("JARFileJSFAppConfigProvider["); //$NON-NLS-1$
		if (filename != null) {
			sb.append(filename);
		} else {
			sb.append("null"); //$NON-NLS-1$
		}
		sb.append("]"); //$NON-NLS-1$
		return sb.toString();
	}

}