MgnlGroovyRescueServlet

/**
 * This file Copyright (c) 2010-2010 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.info/mna.html
 *
 * Any modifications to this file must keep this entire header
 * intact.
 *
 */
package info.magnolia.module.groovy.servlets;

import java.io.IOException;

import info.magnolia.context.MgnlContext;
import info.magnolia.module.groovy.console.MgnlGroovyInteractiveConsole;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * A special servlet which makes at your disposal the Magnolia's Groovy interactive console bypassing the
 * normal Magnolia's filters chain. This can be useful, for instance, to perform rescue operations on a corrupted Magnolia instance.
 * <strong>Warning:</strong> All operations are executed in system context, meaning that no security restrictions are enforced which
 * might expose your data to risk of irreversible damages if you are not aware of what you are doing. In other words, <strong>use it at your own risk</strong>.
 * <br>
 * To use it, in your <code>web.xml</code> you must explicitely comment out the Magnolia filter chain part and add or uncomment the Groovy rescue servlet.
 * <strong>Important</strong>: You also need to explicitely add a <code>servlet</code> and a <code>servlet-mapping</code> for
 * <code>info.magnolia.cms.servlets.ClasspathSpool</code> as this is needed to serve correctly the javascript and css needed by the console. <br>
 * For a sample configuration, see the <code>web.xml</code> fragment below:
 *
 * <pre>
 * [...]
 * &lt;!--
 * &lt;filter&gt;
 *   &lt;display-name&gt;Magnolia global filters&lt;/display-name&gt;
 *   &lt;filter-name&gt;magnoliaFilterChain&lt;/filter-name&gt;
 *   &lt;filter-class&gt;info.magnolia.cms.filters.MgnlMainFilter&lt;/filter-class&gt;
 * &lt;/filter&gt;
 * &lt;filter-mapping&gt;
 *   &lt;filter-name&gt;magnoliaFilterChain&lt;/filter-name&gt;
 *   &lt;url-pattern&gt;/*&lt;/url-pattern&gt;
 *   &lt;dispatcher&gt;REQUEST&lt;/dispatcher&gt;
 *   &lt;dispatcher&gt;FORWARD&lt;/dispatcher&gt;
 *   &lt;dispatcher&gt;ERROR&lt;/dispatcher&gt;
 * &lt;/filter-mapping&gt;
 * --&gt;
 * &lt;servlet&gt;
 *   &lt;servlet-name&gt;mgnlGroovyServlet&lt;/servlet-name&gt;
 *   &lt;servlet-class&gt;info.magnolia.module.groovy.servlets.MgnlGroovyRescueServlet&lt;/servlet-class&gt;
 * &lt;/servlet&gt;
 * &lt;servlet-mapping&gt;
 *   &lt;servlet-name&gt;mgnlGroovyServlet&lt;/servlet-name&gt;
 *   &lt;url-pattern&gt;/.magnolia/pages/groovyInteractiveConsole.html&lt;/url-pattern&gt;
 * &lt;/servlet-mapping&gt;
 * &lt;servlet&gt;
 *   &lt;servlet-name&gt;resourcesServlet&lt;/servlet-name&gt;
 *   &lt;servlet-class&gt;info.magnolia.cms.servlets.ClasspathSpool&lt;/servlet-class&gt;
 * &lt;/servlet&gt;
 * &lt;servlet-mapping&gt;
 *   &lt;servlet-name&gt;resourcesServlet&lt;/servlet-name&gt;
 *   &lt;url-pattern&gt;/.resources/*&lt;/url-pattern&gt;
 * &lt;/servlet-mapping&gt;
 * [...]
 * </pre>
 * Once configured and having restarted the web container, you can access the console like this
 * <pre>
 * http://yourserver[:port]/contextname/.magnolia/pages/groovyInteractiveConsole.html
 * </pre>
 * @author fgrilli
 * @version $Id$
 *
 */
public final class MgnlGroovyRescueServlet extends HttpServlet {

    private static final long serialVersionUID = 222L;

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

    @Override
    public void init() throws ServletException {
        log.info("Starting MgnlGroovyRescueServlet...");
        super.init();
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
        try {
            MgnlContext.doInSystemContext(new MgnlContext.Op<Void, Throwable>() {
                public Void exec() throws Throwable {
                    executeCommand(request, response);
                    return null;
                }
            }, true );
        }
        catch (Throwable e) {
            log.error("An error occurred: ", e);
        }
    }

    private void executeCommand(final HttpServletRequest request, final HttpServletResponse response) throws IOException {
          final MgnlGroovyInteractiveConsole handler = new MgnlGroovyInteractiveConsole(null, request, response);
          //if no command was found, defaults to clean (removes old groovy binding from http session and creates a new empty one)
          final String command = request.getParameter("command") == null || request.getParameter("command").length() == 0 ? "clean" : request.getParameter("command");
          final String code = request.getParameter("code");
          log.info("Executing  {}",  code != null ? code : command);
          final String view = handler.execute(command);
          response.setCharacterEncoding("UTF-8");
          handler.renderHtml(view);
    }
}