/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/

package org.apache.tomcat.vault.security;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.res.StringManager;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

/**
 * External command password cache.
 * Singleton password cache.
 *
 * @author Peter Skopek (pskopek_at_redhat_dot_com)
 * @version $Revision:$
 */
public class ExternalPasswordCache implements PasswordCache {

    private static final StringManager sm = StringManager.getManager("org.apache.tomcat.vault.security.ExternalPasswordCache");
    private static final Log log = LogFactory.getLog(ExternalPasswordCache.class);

    private static final ExternalPasswordCache PASSWORD_CACHE = new ExternalPasswordCache();

    private Map<String, PasswordRecord> cache;
    private MessageDigest md5Digest = null;

    private ExternalPasswordCache() {
        cache = Collections.synchronizedMap(new HashMap<String, PasswordRecord>());
        try {
            md5Digest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            // Cannot get MD5 algorithm instance for hashing password commands. Using NULL.
            log.error(sm.getString("externalPasswordCache.cannotGetMD5AlgorithmInstance"));
        }
    }

    public static ExternalPasswordCache getExternalPasswordCacheInstance() {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new RuntimePermission(ExternalPasswordCache.class.getName() + ".getExternalPasswordCacheInstance"));
        }
        return PASSWORD_CACHE;
    }

    /* (non-Javadoc)
     * @see org.jboss.security.PasswordCache#contains(java.lang.String)
     */
    @Override
    public boolean contains(String key, long timeOut) {
        String transformedKey = transformKey(key);
        PasswordRecord pr = cache.get(transformedKey);
        if (pr != null && (timeOut == 0 || System.currentTimeMillis() - pr.timeOut < timeOut)) {
            return true;
        }
        return false;
    }

    /* (non-Javadoc)
     * @see org.jboss.security.PasswordCache#getPassword(java.lang.String)
     */
    @Override
    public char[] getPassword(String key) {
        String newKey = transformKey(key);
        log.trace(sm.getString("externalPasswordCache.retrievingPasswordFromCache", newKey));
        PasswordRecord pr = cache.get(newKey);
        return pr.password;
    }

    /* (non-Javadoc)
     * @see org.jboss.security.PasswordCache#storePassword(java.lang.String, char[])
     */
    @Override
    public void storePassword(String key, char[] password) {
        String newKey = transformKey(key);
        log.trace(sm.getString("externalPasswordCache.storingPasswordToCache", newKey));
        PasswordRecord pr = new PasswordRecord();
        pr.timeOut = System.currentTimeMillis();
        pr.password = password;
        cache.put(newKey, pr);
    }

    private String transformKey(String key) {
        String newKey = key;
        if (md5Digest != null) {
            md5Digest.reset();
            byte[] bt = key.getBytes();
            byte[] md5 = md5Digest.digest(bt);
            newKey = new String(Base64Utils.tob64(md5));
        }
        return newKey;
    }

    /**
     * Get number of cached passwords.
     * Mainly for testing purpose.
     */
    public int getCachedPasswordsCount() {
        return cache.size();
    }

    /* (non-Javadoc)
     * @see org.jboss.security.PasswordCache#reset()
     */
    @Override
    public void reset() {
        log.trace(sm.getString("externalPasswordCache.resettingCache"));
        cache.clear();
    }


}

class PasswordRecord {

    long timeOut;
    char[] password;

}
