/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.springframework.web.portlet.handler;

import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import javax.portlet.PortletMode;
import javax.portlet.PortletRequest;

import org.springframework.beans.BeansException;
import org.springframework.util.Assert;

/**
 * Implementation of the {@link org.springframework.web.portlet.HandlerMapping}
 * interface to map from the current PortletMode and a request parameter to
 * request handler beans. The mapping consists of two levels: first the
 * PortletMode and then the parameter value. In order to be mapped,
 * both elements must match the mapping definition.
 *
 * <p>This is a combination of the methods used in {@link PortletModeHandlerMapping PortletModeHandlerMapping}
 * and {@link ParameterHandlerMapping ParameterHandlerMapping}.  Unlike
 * those two classes, this mapping cannot be initialized with properties since it
 * requires a two-level map.
 *
 * <p>The default name of the parameter is "action", but can be changed using
 * {@link #setParameterName setParameterName()}.
 *
 * <p>By default, the same parameter value may not be used in two different portlet
 * modes.  This is so that if the portal itself changes the portlet mode, the request
 * will no longer be valid in the mapping.  This behavior can be changed with
 * {@link #setAllowDuplicateParameters setAllowDupParameters()}.
 *
 * <p>The bean configuration for this mapping will look somthing like this:
 *
 * <pre class="code">
 * &lt;bean id="portletModeParameterHandlerMapping" class="org.springframework.web.portlet.handler.PortletModeParameterHandlerMapping"&gt;
 *   &lt;property name="portletModeParameterMap"&gt;
 *     &lt;map&gt;
 *       &lt;entry key="view"&gt; &lt;!-- portlet mode: view --&gt;
 *         &lt;map&gt;
 *           &lt;entry key="add"&gt;&lt;ref bean="addItemHandler"/&gt;&lt;/entry&gt;
 *           &lt;entry key="edit"&gt;&lt;ref bean="editItemHandler"/&gt;&lt;/entry&gt;
 *           &lt;entry key="delete"&gt;&lt;ref bean="deleteItemHandler"/&gt;&lt;/entry&gt;
 *         &lt;/map&gt;
 *       &lt;/entry&gt;
 *       &lt;entry key="edit"&gt; &lt;!-- portlet mode: edit --&gt;
 *         &lt;map&gt;
 *           &lt;entry key="prefs"&gt;&lt;ref bean="preferencesHandler"/&gt;&lt;/entry&gt;
 *           &lt;entry key="resetPrefs"&gt;&lt;ref bean="resetPreferencesHandler"/&gt;&lt;/entry&gt;
 *         &lt;/map&gt;
 *       &lt;/entry&gt;
 *     &lt;/map&gt;
 *   &lt;/property&gt;
 * &lt;/bean&gt;</pre>
 *
 * <p>This mapping can be chained ahead of a {@link PortletModeHandlerMapping PortletModeHandlerMapping},
 * which can then provide defaults for each mode and an overall default as well.
 *
 * <p>Thanks to Rainer Schmitz and Yujin Kim for suggesting this mapping strategy!
 *
 * @author John A. Lewis
 * @author Juergen Hoeller
 * @since 2.0
 * @see ParameterMappingInterceptor
 */
public class PortletModeParameterHandlerMapping extends AbstractMapBasedHandlerMapping<PortletModeParameterLookupKey> {

        /**
         * Default request parameter name to use for mapping to handlers: "action".
         */
        public final static String DEFAULT_PARAMETER_NAME = "action";


        private String parameterName = DEFAULT_PARAMETER_NAME;

        private Map<String, Map<String, ?>> portletModeParameterMap;

        private boolean allowDuplicateParameters = false;

        private final Set<String> parametersUsed = new HashSet<String>();


        /**
         * Set the name of the parameter used for mapping to handlers.
         * <p>Default is "action".
         */
        public void setParameterName(String parameterName) {
                Assert.hasText(parameterName, "'parameterName' must not be empty");
                this.parameterName = parameterName;
        }

        /**
         * Set a Map with portlet mode names as keys and another Map as values.
         * The sub-map has parameter names as keys and handler bean or bean names as values.
         * <p>Convenient for population with bean references.
         * @param portletModeParameterMap two-level map of portlet modes and parameters to handler beans
         */
        public void setPortletModeParameterMap(Map<String, Map<String, ?>> portletModeParameterMap) {
                this.portletModeParameterMap = portletModeParameterMap;
        }

        /**
         * Set whether to allow duplicate parameter values across different portlet modes.
         * Default is "false".
         * <p>Doing this is dangerous because the portlet mode can be changed by the
         * portal itself and the only way to see that is a rerender of the portlet.
         * If the same parameter value is legal in multiple modes, then a change in
         * mode could result in a matched mapping that is not intended and the user
         * could end up in a strange place in the application.
         */
        public void setAllowDuplicateParameters(boolean allowDuplicateParameters) {
                this.allowDuplicateParameters = allowDuplicateParameters;
        }


        /**
         * Calls the {@code registerHandlers} method in addition
         * to the superclass's initialization.
         * @see #registerHandlers
         */
        @Override
        public void initApplicationContext() throws BeansException {
                super.initApplicationContext();
                registerHandlersByModeAndParameter(this.portletModeParameterMap);
        }

        /**
         * Register all handlers specified in the Portlet mode map for the corresponding modes.
         * @param portletModeParameterMap Map with mode names as keys and parameter Maps as values
         */
        protected void registerHandlersByModeAndParameter(Map<String, Map<String, ?>> portletModeParameterMap) {
                Assert.notNull(portletModeParameterMap, "'portletModeParameterMap' must not be null");
                for (Map.Entry<String, Map<String, ?>> entry : portletModeParameterMap.entrySet()) {
                        PortletMode mode = new PortletMode(entry.getKey());
                        registerHandler(mode, entry.getValue());
                }
        }

        /**
         * Register all handlers specified in the given parameter map.
         * @param parameterMap Map with parameter names as keys and handler beans or bean names as values
         */
        protected void registerHandler(PortletMode mode, Map<String, ?> parameterMap) {
                for (Map.Entry<String, ?> entry : parameterMap.entrySet()) {
                        registerHandler(mode, entry.getKey(), entry.getValue());
                }
        }

        /**
         * Register the given handler instance for the given PortletMode and parameter value,
         * under an appropriate lookup key.
         * @param mode the PortletMode for which this mapping is valid
         * @param parameter the parameter value to which this handler is mapped
         * @param handler the handler instance bean
         * @throws BeansException if the handler couldn't be registered
         * @throws IllegalStateException if there is a conflicting handler registered
         * @see #registerHandler(Object, Object)
         */
        protected void registerHandler(PortletMode mode, String parameter, Object handler)
                        throws BeansException, IllegalStateException {

                // Check for duplicate parameter values across all portlet modes.
                if (!this.allowDuplicateParameters && this.parametersUsed.contains(parameter)) {
                        throw new IllegalStateException(
                                        "Duplicate entries for parameter [" + parameter + "] in different Portlet modes");
                }
                this.parametersUsed.add(parameter);

                registerHandler(new PortletModeParameterLookupKey(mode, parameter), handler);
        }

        /**
         * Returns a lookup key that combines the current PortletMode and the current
         * value of the specified parameter.
         * @see javax.portlet.PortletRequest#getPortletMode()
         * @see #setParameterName
         */
        @Override
        protected PortletModeParameterLookupKey getLookupKey(PortletRequest request) throws Exception {
                PortletMode mode = request.getPortletMode();
                String parameter = request.getParameter(this.parameterName);
                return new PortletModeParameterLookupKey(mode, parameter);
        }

}