/*
 * $Id$
 *
 * 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.
 */
package org.apache.struts2.dispatcher;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.struts2.ServletActionContext;
import org.apache.struts2.dispatcher.mapper.ActionMapper;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.inject.Inject;


/**
 * <!-- START SNIPPET: description -->
 *
 * Calls the {@link HttpServletResponse#sendRedirect(String) sendRedirect}
 * method to the location specified. The response is told to redirect the
 * browser to the specified location (a new request from the client). The
 * consequence of doing this means that the action (action instance, action
 * errors, field errors, etc) that was just executed is lost and no longer
 * available. This is because actions are built on a single-thread model. The
 * only way to pass data is through the session or with web parameters
 * (url?name=value) which can be OGNL expressions.
 *
 * <!-- END SNIPPET: description -->
 * <p/>
 * <b>This result type takes the following parameters:</b>
 *
 * <!-- START SNIPPET: params -->
 *
 * <ul>
 *
 * <li><b>location (default)</b> - the location to go to after execution.</li>
 *
 * <li><b>parse</b> - true by default. If set to false, the location param will
 * not be parsed for Ognl expressions.</li>
 *
 * </ul>
 *
 * <p>
 * This result follows the same rules from {@link StrutsResultSupport}.
 * </p>
 *
 * <!-- END SNIPPET: params -->
 *
 * <b>Example:</b>
 *
 * <pre><!-- START SNIPPET: example -->
 * &lt;result name="success" type="redirect"&gt;
 *   &lt;param name="location"&gt;foo.jsp&lt;/param&gt;
 *   &lt;param name="parse"&gt;false&lt;/param&gt;
 * &lt;/result&gt;
 * <!-- END SNIPPET: example --></pre>
 *
 */
public class ServletRedirectResult extends StrutsResultSupport {

    private static final long serialVersionUID = 6316947346435301270L;

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

    protected boolean prependServletContext = true;

    private ActionMapper actionMapper;

    public ServletRedirectResult() {
        super();
    }

    public ServletRedirectResult(String location) {
        super(location);
    }
    
    @Inject
    public void setActionMapper(ActionMapper mapper) {
        this.actionMapper = mapper;
    }

    /**
     * Sets whether or not to prepend the servlet context path to the redirected URL.
     *
     * @param prependServletContext <tt>true</tt> to prepend the location with the servlet context path,
     *                              <tt>false</tt> otherwise.
     */
    public void setPrependServletContext(boolean prependServletContext) {
        this.prependServletContext = prependServletContext;
    }

    /**
     * Redirects to the location specified by calling {@link HttpServletResponse#sendRedirect(String)}.
     *
     * @param finalLocation the location to redirect to.
     * @param invocation    an encapsulation of the action execution state.
     * @throws Exception if an error occurs when redirecting.
     */
    protected void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
        ActionContext ctx = invocation.getInvocationContext();
        HttpServletRequest request = (HttpServletRequest) ctx.get(ServletActionContext.HTTP_REQUEST);
        HttpServletResponse response = (HttpServletResponse) ctx.get(ServletActionContext.HTTP_RESPONSE);

        if (isPathUrl(finalLocation)) {
            if (!finalLocation.startsWith("/")) {
                String namespace = actionMapper.getMapping(
                        request, Dispatcher.getInstance().getConfigurationManager()).getNamespace();

                if ((namespace != null) && (namespace.length() > 0) && (!"/".equals(namespace))) {
                    finalLocation = namespace + "/" + finalLocation;
                } else {
                    finalLocation = "/" + finalLocation;
                }
            }

            // if the URL's are relative to the servlet context, append the servlet context path
            if (prependServletContext && (request.getContextPath() != null) && (request.getContextPath().length() > 0)) {
                finalLocation = request.getContextPath() + finalLocation;
            }

            finalLocation = response.encodeRedirectURL(finalLocation);
        }

        if (log.isDebugEnabled()) {
            log.debug("Redirecting to finalLocation " + finalLocation);
        }

        response.sendRedirect(finalLocation);
    }

    private static boolean isPathUrl(String url) {
        // filter out "http:", "https:", "mailto:", "file:", "ftp:"
        // since the only valid places for : in URL's is before the path specification
        // either before the port, or after the protocol
        return (url.indexOf(':') == -1);
    }
}
