/*
 * Copyright (C) 2003-2011 eXo Platform SAS.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package org.etk.kernel.container.configuration;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Created by The eXo Platform SAS Author : eXoPlatform exo@exoplatform.com Jun
 * 20, 2011
 */
public class EntityResolverImpl implements EntityResolver {

	/** . */
	private final Map<String, String> systemIdToResourcePath;

	/** . */
	private final ConcurrentMap<String, byte[]> systemIdToSource;

	/** . */
	private final ClassLoader loader;

	public EntityResolverImpl(ClassLoader loader,
			Map<String, String> systemIdToResourcePath) {
		// Defensive copy
		this.systemIdToResourcePath = new HashMap<String, String>(
				systemIdToResourcePath);
		this.systemIdToSource = new ConcurrentHashMap<String, byte[]>();
		this.loader = loader;
	}

	public InputSource resolveEntity(String publicId, String systemId)
			throws SAXException, IOException {
		if (systemId != null) {
			byte[] data = systemIdToSource.get(systemId);

			//
			if (data == null) {
				String path = systemIdToResourcePath.get(systemId);
				if (path != null) {
					InputStream in = loader.getResourceAsStream(path);
					if (in != null) {
						//data = IOUtil.getStreamContentAsBytes(in);
					}
				}

				// Black list it, we won't find it
				if (data == null) {
					data = new byte[0];
				}

				// Put in cache
				systemIdToSource.put(systemId, data);

				// Some basic prevention against stupid use of this class that
				// could cause OOME
				if (systemIdToSource.size() > 1000) {
					systemIdToSource.clear();
				}
			}

			//
			if (data != null && data.length > 0) {
				return new InputSource(new ByteArrayInputStream(data));
			}
		}

		//
		return null;
	}

}