/*
 * $Header: /cvsroot/mvnforum/myvietnam/src/net/myvietnam/mvncore/filter/UserAgentFilter.java,v 1.4 2004/04/30 03:19:54 drjavanomous Exp $
 * $Author: drjavanomous $
 * $Revision: 1.4 $
 * $Date: 2004/04/30 03:19:54 $
 *
 * ====================================================================
 *
 * Copyright (C) 2002-2004 by MyVietnam.net
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or any later version.
 *
 * All copyright notices regarding MyVietnam and MyVietnam CoreLib
 * MUST remain intact in the scripts and source code.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Correspondence and Marketing Questions can be sent to:
 * info@MyVietnam.net
 *
 * @author: Minh Nguyen  minhnn@MyVietnam.net
 * @author: Mai  Nguyen  mai.nh@MyVietnam.net
 */
package net.myvietnam.mvncore.filter;

import javax.servlet.http.HttpServletRequest;
import net.myvietnam.mvncore.util.StringUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public final class UserAgentFilter {

    private static Log log = LogFactory.getLog(UserAgentFilter.class);

    private static String[] blockedUserAgent = null;

    private UserAgentFilter() { //prevent instantiation
    }

    static {
        UserAgentOptions UserAgentOptions = new UserAgentOptions();
        blockedUserAgent = StringUtil.getStringArray(UserAgentOptions.blockedUserAgent, ";");
    }

    /**
     * Filter the UserAgent
     * @param request
     * @return true  if the UserAgent in this request is ok
     *         false if the UserAgent in this request is blocked
     */
    public static boolean filter(HttpServletRequest request) {
        if (request == null) {
            throw new NullPointerException("Cannot accept a null request in UserAgentFilter");
        }
        String checkUserAgent = request.getHeader("User-Agent");

        //@todo: in this case, should we return true or false ?
        if (checkUserAgent == null) return true;

        for (int i = 0; i < blockedUserAgent.length; i++) {
            String currentBlockedUserAgent = blockedUserAgent[i];
            if (checkUserAgent.indexOf(currentBlockedUserAgent) != -1) {
                return false;
            }
        }
        return true;
    }
}