package org.apache.fulcrum.crypto;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.security.NoSuchAlgorithmException;
import java.util.HashMap;

import org.apache.avalon.framework.activity.Initializable;
import org.apache.avalon.framework.configuration.Configurable;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.logger.AbstractLogEnabled;
import org.apache.avalon.framework.thread.ThreadSafe;

/**
 * An implementation of CryptoService that uses either supplied crypto
 * Algorithms (provided in the component config xml file) or tries to get them
 * via the normal java mechanisms if this fails.
 *
 * avalon.component name="crypto" lifestyle="singleton" avalon.service
 * type="org.apache.fulcrum.crypto.CryptoService"
 *
 *
 * @author <a href="mailto:epugh@upstate.com">Eric Pugh</a>
 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 * @version $Id$
 */
public class DefaultCryptoService extends AbstractLogEnabled
		implements CryptoService, Configurable, Initializable, ThreadSafe {

	
	/** Key Prefix for our algorithms */
	private static final String ALGORITHM = "algorithm";

	/** Default Key */
	private static final String DEFAULT_KEY = "default";

	/** Default Encryption Class */
	private static final String DEFAULT_CLASS = "org.apache.fulcrum.crypto.provider.JavaCrypt";

	/** Names of the registered algorithms and the wanted classes */
	private HashMap<String, String> algos = new HashMap<>();

	/**
	 * Returns a CryptoAlgorithm Object which represents the requested crypto
	 * algorithm.
	 *
	 * @see org.apache.fulcrum.crypto.CryptoService#getCryptoAlgorithm(java.lang.String)
	 *
	 * @param algo Name of the requested algorithm
	 *
	 * @return An Object representing the algorithm
	 *
	 * @throws NoSuchAlgorithmException Requested algorithm is not available
	 *
	 */
	public CryptoAlgorithm getCryptoAlgorithm(String algo) throws NoSuchAlgorithmException 
	{
		String cryptoClass = (String) algos.get(algo);
		CryptoAlgorithm ca = null;
		if (cryptoClass == null) {
			cryptoClass = (String) algos.get(DEFAULT_KEY);
		}
		if (cryptoClass == null || cryptoClass.equalsIgnoreCase("none")) {
			throw new NoSuchAlgorithmException("TurbineCryptoService: No Algorithm for " + algo + " found");
		}
		try {
			ca = (CryptoAlgorithm) Class.forName(cryptoClass).newInstance();
		} catch (Exception e) {
			throw new NoSuchAlgorithmException(
					"TurbineCryptoService: Error instantiating " + cryptoClass + " for " + algo);
		}
		ca.setCipher(algo);
		return ca;
	}


	// ---------------- Avalon Lifecycle Methods ---------------------

	/**
	 * Avalon component lifecycle method
	 * 
	 * @param conf the configuration
	 * @throws ConfigurationException if not found
	 */
	public void configure(Configuration conf) throws ConfigurationException 
	{
		// Initialize the hash and setup default
		// Can be overriden by default key from properties
		this.algos = new HashMap<>();
		this.algos.put(DEFAULT_KEY, DEFAULT_CLASS);
		
		final Configuration algorithms = conf.getChild(ALGORITHM, false);
		if (algorithms != null) {
			Configuration[] nameVal = algorithms.getChildren();
			for ( Configuration entry : nameVal )
			{
				algos.put(entry.getName(), entry.getValue());
			}
		}
	}
	
	/**
	 * Initialize the service
	 * 
	 * @see org.apache.avalon.framework.activity.Initializable#initialize()
	 * 
	 * @throws Exception if initialization fails
	 */
	public void initialize() throws Exception 
	{
		getLogger().debug("initialize()");
	}

	/**
	 * Avalon component lifecycle method
	 */
	public void dispose() 
	{
		algos = null;
	}

}