    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.services.linktransform;
    014
    015import org.apache.tapestry5.Link;
    016import org.apache.tapestry5.internal.services.PageRenderDispatcher;
    017import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
    018import org.apache.tapestry5.services.ComponentEventLinkEncoder;
    019import org.apache.tapestry5.services.LocalizationSetter;
    020import org.apache.tapestry5.services.PageRenderRequestParameters;
    021import org.apache.tapestry5.services.Request;
    022
    023/**
    024 * Allows the default {@link Link} for a page render request to be replaced.
    025 * This is a service, but also the contribution to the service, as a chain of command.
    026 *
    027 * A contributed implementation of this interface is expected to identify which requests it wants to transform. The
    028 * {@link #transformPageRenderLink(Link, PageRenderRequestParameters)} method can return a {@link Link} that is allowed
    029 * to differ from Tapestry normal default. Later, when that request is triggered,
    030 * {@link #decodePageRenderRequest(Request)} is required to reverse the operation, identifying the original parameters
    031 * so that request handling can continue.
    032 *
    033 * @since 5.2.0
    034 */
    035@UsesOrderedConfiguration(PageRenderLinkTransformer.class)
    036public interface PageRenderLinkTransformer
    037{
    038    /**
    039     * Transforms a page render link.
    040     *
    041     * @param defaultLink
    042     *            default Link for this request
    043     * @param parameters
    044     *            that define the request
    045     * @return replacement Link, or null
    046     */
    047    Link transformPageRenderLink(Link defaultLink, PageRenderRequestParameters parameters);
    048
    049    /**
    050     * Attempts to decode the page render request, to perform the opposite action for
    051     * {@link #transformPageRenderLink(Link, PageRenderRequestParameters)}. The transformer
    052     * is also responsible for identifying the locale in the request (as part of the path, or as a
    053     * query parameter or cookie) and setting the locale for the request.
    054     *
    055     * This method will be invoked from the {@link PageRenderDispatcher} and a non-null value returned from this method
    056     * will prevent the default {@link ComponentEventLinkEncoder#decodePageRenderRequest(Request)} method from being
    057     * invoked.
    058     *
    059     * @return decoded parameters, or null to proceed normally
    060     * @see LocalizationSetter#setLocaleFromLocaleName(String)
    061     */
    062    PageRenderRequestParameters decodePageRenderRequest(Request request);
    063}