001// Copyright 2010 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.services.linktransform;
016
017import org.apache.tapestry5.Link;
018import org.apache.tapestry5.internal.services.ComponentEventDispatcher;
019import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
020import org.apache.tapestry5.services.ComponentEventRequestParameters;
021import org.apache.tapestry5.services.LocalizationSetter;
022import org.apache.tapestry5.services.Request;
023
024/**
025 * Allows for selective replacement of the default {@link Link} used to represent a component event request.
026 * This is a service, but also the contribution to the service, as a chain of command.
027 * <p>
028 * This transformer follows the same pattern as {@link PageRenderLinkTransformer}.
029 * 
030 * @since 5.2.0
031 */
032@UsesOrderedConfiguration(ComponentEventLinkTransformer.class)
033public interface ComponentEventLinkTransformer
034{
035    /**
036     * Allows the default Link created for the component event request to be replaced.
037     * 
038     * @param defaultLink
039     *            the default Link generated for a component event request
040     * @param parameters
041     *            used to create the default Link
042     * @return a replacement Link, or null
043     */
044    Link transformComponentEventLink(Link defaultLink, ComponentEventRequestParameters parameters);
045
046    /**
047     * Attempts to decode the page render request, to perform the opposite action for
048     * {@link #transformComponentEventLink(Link, ComponentEventRequestParameters)}. The transformer
049     * is also responsible for identifying the locale in the request (as part of the path, or as a
050     * query parameter or cookie) and setting the locale for the request.
051     * <p>
052     * This method will be invoked from the {@link ComponentEventDispatcher} and a non-null value returned from this
053     * method will prevent the default
054     * {@link org.apache.tapestry5.services.ComponentEventLinkEncoder#decodeComponentEventRequest(Request)} method
055     * from being invoked.
056     * 
057     * @return decoded parameters, or null to proceed normally
058     * @see LocalizationSetter#setLocaleFromLocaleName(String)
059     */
060    ComponentEventRequestParameters decodeComponentEventRequest(Request request);
061}