tapestry-core/src/main/java/org/apache/tapestry5/corelib/base/AbstractLink.java

// Copyright 2007, 2008 The Apache Software Foundation
//
// 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
//
//     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.tapestry5.corelib.base;

import org.apache.tapestry5.*;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.annotations.SetupRender;
import org.apache.tapestry5.annotations.SupportsInformalParameters;
import org.apache.tapestry5.dom.Element;
import org.apache.tapestry5.internal.services.ComponentInvocationMap;
import org.apache.tapestry5.ioc.annotations.Inject;

/**
 * Provides base utilities for classes that generate clickable links.
 */
@SupportsInformalParameters
public abstract class AbstractLink implements ClientElement
{
    @Inject
    private ComponentInvocationMap componentInvocationMap;

    /**
     * An anchor value to append to the generated URL (the hash separator will be added automatically).
     */
    @Parameter(defaultPrefix = BindingConstants.LITERAL)
    private String anchor;

    /**
     * If true, then then no link element is rendered (and no informal parameters as well). The body is, however, still
     * rendered.
     */
    @Parameter("false")
    private boolean disabled;

    @Inject
    private ComponentResources resources;

    @Inject
    private RenderSupport renderSupport;

    private Link link;

    private Element element;

    private String clientId;

    private String buildHref(Link link)
    {
        String href = link.toURI();

        if (anchor == null) return href;

        return href + "#" + anchor;
    }


    @SetupRender
    void resetElementAndClientId()
    {
        element = null;
        clientId = null;
    }

    /**
     * Writes an <a> element with the provided link as the href attribute.  A call to {@link
     * org.apache.tapestry5.MarkupWriter#end()} is <em>not</em> provided.            Automatically appends an anchor if
     * the component's anchor parameter is non-null.  Informal parameters are rendered as well.
     *
     * @param writer         to write markup to
     * @param link           the link that will form the href
     * @param namesAndValues additional attributes to write
     */
    protected final void writeLink(MarkupWriter writer, Link link, Object... namesAndValues)
    {
        element = writer.element("a", "href", buildHref(link));

        writer.attributes(namesAndValues);

        resources.renderInformalParameters(writer);

        componentInvocationMap.store(element, link);

        this.link = link;
    }

    /**
     * Returns the most recently rendered {@link org.apache.tapestry5.Link} for this component.  Subclasses calculate
     * their link value as they render, and the value is valid until the end of the request, or the next time the same
     * component renders itself (if inside a loop).
     *
     * @return the most recent link, or null
     */
    public Link getLink()
    {
        return link;
    }

    /**
     * Returns the unique client id for this element. This is valid only after the component has rendered (its start
     * tag).  A client id is generated the first time this method is invoked, after the link renders its start tag.
     */
    public final String getClientId()
    {
        if (clientId == null)
        {
            if (element == null)
                throw new IllegalStateException(
                        String.format("Client id for %s is not available as it did not render yet (or was disabled).",
                                      resources.getCompleteId()));

            clientId = renderSupport.allocateClientId(resources);

            element.forceAttributes("id", clientId);
        }

        return clientId;
    }

    /**
     * Returns true if the component is disabled (as per its disabled parameter). Disabled link components should not
     * render a tag, but should still render their body.
     */
    public boolean isDisabled()
    {
        return disabled;
    }

    /**
     * Used for testing.
     */
    final void inject(String anchor, ComponentInvocationMap map, ComponentResources resources)
    {
        this.anchor = anchor;
        componentInvocationMap = map;
        this.resources = resources;
    }
}