/*******************************************************************************
 * Copyright (c) 2006, 2016 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.help.internal.index;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.IConfigurationElement;
import org.eclipse.core.runtime.IExtensionRegistry;
import org.eclipse.core.runtime.Platform;
import org.eclipse.help.AbstractIndexProvider;
import org.eclipse.help.IIndexContribution;
import org.eclipse.help.internal.HelpPlugin;
import org.eclipse.help.internal.util.ResourceLocator;
import org.xml.sax.SAXParseException;

/*
 * Provides index data from index XML files to the help system.
 */
public class IndexFileProvider extends AbstractIndexProvider {

	private static final String ERROR_READING_HELP_KEYWORD_INDEX_FILE = "Error reading help keyword index file /\""; //$NON-NLS-1$
	public static final String EXTENSION_POINT_ID_INDEX = HelpPlugin.PLUGIN_ID + ".index"; //$NON-NLS-1$
	public static final String ELEMENT_NAME_INDEX = "index"; //$NON-NLS-1$
	public static final String ATTRIBUTE_NAME_FILE = "file"; //$NON-NLS-1$

	@Override
	public IIndexContribution[] getIndexContributions(String locale) {
		List<IIndexContribution> contributions = new ArrayList<>();
		IndexFile[] indexFiles = getIndexFiles(locale);
		IndexFileParser parser = new IndexFileParser();
		for (int i=0;i<indexFiles.length;++i) {
			IndexFile indexFile = indexFiles[i];
			try {
				IIndexContribution toc = parser.parse(indexFile);
				contributions.add(toc);
			}  catch (SAXParseException spe) {
				StringBuffer buffer = new StringBuffer(ERROR_READING_HELP_KEYWORD_INDEX_FILE);
				buffer.append(getIndexFilePath(indexFile));
				buffer.append("\" at line "); //$NON-NLS-1$
			    buffer.append(spe.getLineNumber());
			    buffer.append(". "); //$NON-NLS-1$
	            buffer.append(spe.getMessage());

	            // Use the contained exception.
	            Exception x = spe;
	            if (spe.getException() != null)
	                x = spe.getException();
	            HelpPlugin.logError(buffer.toString(), x);

	        }
			catch (Throwable t) {
				String msg = ERROR_READING_HELP_KEYWORD_INDEX_FILE + getIndexFilePath(indexFile) + "\" (skipping file)"; //$NON-NLS-1$
				HelpPlugin.logError(msg, t);
			}
		}
		return contributions.toArray(new IIndexContribution[contributions.size()]);
	}

	private String getIndexFilePath(IndexFile indexFile) {
		String pluginId = indexFile.getPluginId();
		String file = indexFile.getFile();
		return ResourceLocator.getErrorPath(pluginId, file, indexFile.getLocale());
	}

	/*
	 * Returns all available IndexFiles for the given locale.
	 */
	private IndexFile[] getIndexFiles(String locale) {
		List<IndexFile> indexFiles = new ArrayList<>();
		IExtensionRegistry registry = Platform.getExtensionRegistry();
		IConfigurationElement[] elements = registry.getConfigurationElementsFor(EXTENSION_POINT_ID_INDEX);
		for (int i=0;i<elements.length;++i) {
			IConfigurationElement elem = elements[i];
			String pluginId = elem.getContributor().getName();
			if (elem.getName().equals(ELEMENT_NAME_INDEX)) {
				String file = elem.getAttribute(ATTRIBUTE_NAME_FILE);
				IndexFile indexFile = new IndexFile(pluginId, file, locale);
				indexFiles.add(indexFile);
			}
		}
		return indexFiles.toArray(new IndexFile[indexFiles.size()]);
	}
}