SubtabRenderer.java

/*
 * RHQ Management Platform
 * Copyright (C) 2005-2008 Red Hat, Inc.
 * All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
package org.rhq.enterprise.gui.common.tabbar;

import java.io.IOException;
import java.io.StringWriter;
import java.util.LinkedHashMap;
import java.util.Map;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;
import javax.faces.render.Renderer;

import org.rhq.core.gui.util.FacesComponentUtility;
import org.rhq.core.gui.util.UrlUtility;

/**
 * A renderer that renders a {@link SubtabComponent} component as XHTML.
 *
 * @author Ian Springer
 */
public class SubtabRenderer extends Renderer {

    /**
     * Encode this component.
     *
     * @param facesContext <code>FacesContext</code> for the current request
     * @param component    <code>SubtabComponent</code> to be encoded
     */
    public void encodeBegin(FacesContext facesContext, UIComponent component) throws IOException {
        SubtabComponent subtab = (SubtabComponent) component;
        processAttributes(subtab);

        TabComponent parentTab = (TabComponent) subtab.getParent();
        if (!parentTab.isSelected()) {
            // Subtabs for tabs other than the selected tab do not need to rendered.
            return;
        }

        // Process f:param child tags...
        subtab.setParameters(FacesComponentUtility.getParameters(subtab));

        StringWriter stringWriter = new StringWriter();

        ResponseWriter writer = facesContext.getResponseWriter().cloneWithWriter(stringWriter);
        writer.startElement("td", subtab);

        // for ease of refresh, allow all subtabs to be clickable, even the current one 
        writer.startElement("a", subtab);
        writer.writeAttribute("style", "text-decoration: none;", null);
        writer.writeAttribute("href", buildURL(subtab), "url");

        writer.startElement("div", subtab);

        if (!subtab.isSelected()) {
            writer.writeAttribute("class", "subtab-inactive subtab-common", null);
            writer.writeAttribute("onmouseover", "this.className='subtab-hover subtab-common'", null);
            writer.writeAttribute("onmouseout", "this.className='subtab-inactive subtab-common'", null);
        } else {
            writer.writeAttribute("class", "subtab-active subtab-common", null);

            writer.startElement("img", subtab);
            writer.writeAttribute("src", "/images/icon_right_arrow.gif", null);
            writer.endElement("img");
            writer.write(" ");
        }

        if (subtab.getDisplayName() != null) {
            writer.write(subtab.getDisplayName().toLowerCase());
        } else {
            writer.write(subtab.getName().toLowerCase());
        }

        writer.endElement("div");
        writer.endElement("a");

        writer.endElement("td");
        subtab.setRendererOutput(stringWriter.toString());

        // NOTE: The TabBarRenderer will take care of writing our output to the response at a bit later, at the
        //       appropriate time.
        stringWriter.close();
    }

    private void processAttributes(SubtabComponent subtab) {
        if (subtab.getName() == null) {
            throw new IllegalStateException("The subtab element requires a 'name' attribute.");
        }

        if (subtab.getUrl() == null) {
            throw new IllegalStateException("The subtab element requires a 'url' attribute.");
        }
    }

    private String buildURL(SubtabComponent subtab) {
        String url = subtab.getUrl();

        // Create a master list of params from our params and the params of our enclosing tab/tabBar, in that order of
        // precedence.
        TabBarComponent tabBar = (TabBarComponent) subtab.getParent().getParent();
        Map<String, String> parameters = new LinkedHashMap<String, String>(tabBar.getParameters());
        TabComponent tab = (TabComponent) subtab.getParent();
        parameters.putAll(tab.getParameters());
        parameters.putAll(subtab.getParameters());

        url = UrlUtility.addParametersToQueryString(url, parameters);

        // Session-encode the URL in case the client doesn't have cookies enabled.
        url = FacesContext.getCurrentInstance().getExternalContext().encodeResourceURL(url);

        return url;
    }
}