/**
 * This file Copyright (c) 2003-2012 Magnolia International
 * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
 *
 *
 * This file is dual-licensed under both the Magnolia
 * Network Agreement and the GNU General Public License.
 * You may elect to use one or the other of these licenses.
 *
 * This file is distributed in the hope that it will be
 * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
 * Redistribution, except as permitted by whichever of the GPL
 * or MNA you select, is prohibited.
 *
 * 1. For the GPL license (GPL), you can redistribute and/or
 * modify this file under the terms of the GNU General
 * Public License, Version 3, as published by the Free Software
 * Foundation.  You should have received a copy of the GNU
 * General Public License, Version 3 along with this program;
 * if not, write to the Free Software Foundation, Inc., 51
 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * 2. For the Magnolia Network Agreement (MNA), this file
 * and the accompanying materials are made available under the
 * terms of the MNA which accompanies this distribution, and
 * is available at http://www.magnolia-cms.com/mna.html
 *
 * Any modifications to this file must keep this entire header
 * intact.
 *
 */
package info.magnolia.cms.filters;

import info.magnolia.cms.beans.config.VirtualURIManager;
import info.magnolia.cms.core.AggregationState;
import info.magnolia.cms.util.RequestDispatchUtil;
import info.magnolia.context.MgnlContext;

import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Handle redirects configured using VirtualURIMappings.
 *
 * @author Fabrizio Giustina
 * @version $Id$
 * @see info.magnolia.cms.beans.config.VirtualURIMapping
 */
public class VirtualUriFilter extends AbstractMgnlFilter {

    private static final Logger log = LoggerFactory.getLogger(VirtualUriFilter.class);

    @Override
    public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain)
            throws IOException, ServletException {

        final AggregationState aggregationState = MgnlContext.getAggregationState();
        String targetUri = getURIMapping(aggregationState.getCurrentURI(), aggregationState.getQueryString());

        if (StringUtils.isEmpty(targetUri)) {
            chain.doFilter(request, response);
            return;
        }

        if (response.isCommitted()) {
            log.warn(
                    "Response is already committed, cannot apply virtual URI {} (original URI was {})",
                    targetUri,
                    request.getRequestURI());
            chain.doFilter(request, response);
            return;
        }

        if (RequestDispatchUtil.dispatch(targetUri, request, response)) {
            return;
        }

        aggregationState.setCurrentURI(targetUri);
        chain.doFilter(request, response);
    }

    /**
     * @return URI mapping as in ServerInfo
     */
    protected String getURIMapping(String currentURI) {
        return VirtualURIManager.getInstance().getURIMapping(currentURI);
    }

    /**
     * @return URI mapping as in ServerInfo
     */
    protected String getURIMapping(String currentURI, String queryString) {
        return VirtualURIManager.getInstance().getURIMapping(currentURI, queryString);
    }
}