/*
 * 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.cocoon.acting;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import org.apache.avalon.framework.parameters.Parameters;
import org.apache.avalon.framework.thread.ThreadSafe;

import org.apache.cocoon.environment.ObjectModelHelper;
import org.apache.cocoon.environment.Redirector;
import org.apache.cocoon.environment.Request;
import org.apache.cocoon.environment.SourceResolver;

/**
 * This action makes some request details available to the sitemap via parameter
 * substitution.
 *
 * {context}      - is the context path of the servlet (usually "/cocoon")
 * {requestURI}   - is the requested URI without parameters
 * {requestQuery} - is the query string like "?param1=test" if there is one
 *
 * Additionlly all request parameters can be made available for use in the sitemap.
 * if the parameter "parameters" is set to true.
 * (A variable is created for each request parameter (only if it doesn't exist)
 * with the same name as the parameter itself)
 *
 * Default values can be set for request parameters, by including sitemap parameters
 * named "default.<parameter-name>".
 *
 * Sitemap definition:
 *
 * <pre>
 * <map:action name="request" src="org.apache.cocoon.acting.RequestParamAction"/>
 * </pre>
 *
 * <p>
 *
 * Example use:
 *
 * <pre>
 * <map:match pattern="some-resource">
 *  <map:act type="request">
 *     <map:parameter name="parameters" value="true"/>
 *     <map:parameter name="default.dest" value="invalid-destination.html"/>
 *     <map:redirect-to uri="{context}/somewhereelse/{dest}"/>
 *  </map:act>
 * </map:match>
 * </pre>
 *
 * Redirection is only one example, another use:
 *
 * <pre>
 * <map:match pattern="some-resource">
 *  <map:act type="request">
 *     <map:parameter name="parameters" value="true"/>
 *     <map:generate src="users/menu-{id}.xml"/>
 *  </map:act>
 *  <map:transform src="menus/personalisation.xsl"/>
 *  <map:serialize/>
 * </map:match>
 * </pre>
 *
 * etc, etc.
 *
 * @author <a href="mailto:Marcus.Crafter@osa.de">Marcus Crafter</a>
 * @author <a href="mailto:tcurdt@dff.st">Torsten Curdt</a>
 * @version CVS $Id$
 */
public class RequestParamAction extends ServiceableAction implements ThreadSafe {

    public final static String MAP_URI         = "requestURI";
    public final static String MAP_QUERY       = "requestQuery";
    public final static String MAP_CONTEXTPATH = "context";

    public final static String PARAM_PARAMETERS     = "parameters";
    public final static String PARAM_DEFAULT_PREFIX = "default.";

    public Map act(Redirector redirector, SourceResolver resolver, Map objectModel,
                   String source, Parameters param) throws Exception {

        Request request = ObjectModelHelper.getRequest(objectModel);

        Map map = new HashMap();

        map.put(MAP_URI, request.getRequestURI());

        String query = request.getQueryString();
        if (query != null && query.length() > 0) {
            map.put(MAP_QUERY, "?" + query);
        } else {
            map.put(MAP_QUERY, "");
        }

        map.put(MAP_CONTEXTPATH, request.getContextPath());

        if ("true".equalsIgnoreCase(param.getParameter(PARAM_PARAMETERS, null))) {
            Enumeration e = request.getParameterNames();
            while (e.hasMoreElements()) {
                String name = (String)e.nextElement();
                String value = request.getParameter(name);

                if (value != null && !map.containsKey(name)) {
                    map.put(name, value);
                }
            }

            String[] paramNames = param.getNames();
            for (int i = 0; i < paramNames.length; i++) {
                if (paramNames[i].startsWith(PARAM_DEFAULT_PREFIX)
                        && (request.getParameter(paramNames[i].substring(PARAM_DEFAULT_PREFIX.length())) == null)) {
                    map.put(paramNames[i].substring(PARAM_DEFAULT_PREFIX.length()),
                            param.getParameter(paramNames[i]));
                }
            }
        }
        return (map);
    }

}