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;
016
017import java.io.Serializable;
018
019import org.apache.tapestry5.annotations.ImmutableSessionPersistedObject;
020import org.apache.tapestry5.internal.InternalConstants;
021import org.apache.tapestry5.ioc.internal.util.InternalUtils;
022import org.apache.tapestry5.services.PageRenderLinkSource;
023
024/**
025 * A way of capturing the name of a page and the page activation context so that, at a future date,
026 * the page can be invoked with that data. This kind of callback is very useful when creating more
027 * complicated workflows, where access to a page is "interrupted" with some operation before
028 * returning (via a callback) to the original flow.
029 * <p>
030 * Since the callback is serializable, it can be stored in the session.
031 * 
032 * @since 5.2.0
033 */
034@ImmutableSessionPersistedObject
035public class PageCallback implements Serializable
036{
037    private static final long serialVersionUID = -8067619978636824702L;
038
039    private String pageName;
040
041    private String[] activationContext;
042
043    public PageCallback(String pageName, String[] activationContext)
044    {
045        assert InternalUtils.isNonBlank(pageName);
046        this.pageName = pageName;
047        assert activationContext != null;
048        this.activationContext = activationContext;
049    }
050
051    public PageCallback(String pageName, EventContext activationContext)
052    {
053        this(pageName, activationContext.toStrings());
054    }
055
056    public PageCallback(String pageName)
057    {
058        this(pageName, InternalConstants.EMPTY_STRING_ARRAY);
059    }
060
061    public String getPageName()
062    {
063        return pageName;
064    }
065
066    @Override
067    public String toString()
068    {
069        if (hasActivationContext())
070            return String.format("PageCallback[%s %s]", pageName, activationContextDescription());
071
072        return String.format("PageCallback[%s]", pageName);
073    }
074
075    /** Does the activation context have any values? Used, typically, inside an override of {@link #toString()}. */
076    protected final boolean hasActivationContext()
077    {
078        return activationContext.length > 0;
079    }
080
081    /**
082     * Returns the activation context as a string of value separated by slashes. Typically used inside
083     * an override of {@link #toString()}.
084     */
085    protected final String activationContextDescription()
086    {
087        StringBuilder builder = new StringBuilder();
088
089        String sep = "";
090
091        for (String c : activationContext)
092        {
093            builder.append(sep);
094            builder.append(c);
095
096            sep = "/";
097        }
098
099        return builder.toString();
100    }
101
102    /**
103     * Converts the callback (the page name and activation context) to a link; such a link may be
104     * returned from a event handler method to cause Tapestry to redirect to the page. Most of the
105     * details
106     * are encapsulated inside the {@link PageRenderLinkSource} service.
107     * 
108     * @param linkSource
109     *            used to generate the link
110     * @return link corresponding to this callback
111     */
112    public Link toLink(PageRenderLinkSource linkSource)
113    {
114        return linkSource.createPageRenderLinkWithContext(pageName, (Object[]) activationContext);
115    }
116}