/*
 * $Header: /cvsroot/eclipse-webwiz/com.muimi.webwiz/resource/struts/src/struts/org/apache/struts/taglib/html/BaseTag.java,v 1.1 2004/06/14 02:24:11 muimy Exp $
 * $Revision: 1.1 $
 * $Date: 2004/06/14 02:24:11 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2003 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Struts", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.struts.taglib.html;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;

import org.apache.struts.Globals;
import org.apache.struts.util.MessageResources;
import org.apache.struts.util.RequestUtils;

/**
 * Renders an HTML <base> element with an href 
 * attribute pointing to the absolute location of the enclosing JSP page. This 
 * tag is only valid when nested inside a head tag body. The presence 
 * of this tag allows the browser to resolve relative URL's to images,
 * CSS stylesheets  and other resources in a manner independent of the URL
 * used to call the ActionServlet.
 *
 * @author Luis Arias <luis@elysia.com>
 * @author David Graham
 * @version $Revision: 1.1 $ $Date: 2004/06/14 02:24:11 $
 */

public class BaseTag extends TagSupport {

    /**
     * The message resources for this package.
     */
    protected static MessageResources messages =
        MessageResources.getMessageResources(Constants.Package + ".LocalStrings");

    /**
     * The server name to use instead of request.getServerName().
     */
    protected String server = null;

    /**
     * The target window for this base reference.
     */
    protected String target = null;

    public String getTarget() {
        return (this.target);
    }

    public void setTarget(String target) {
        this.target = target;
    }

    /**
     * Process the start of this tag.
     *
     * @exception JspException if a JSP exception has occurred
     */
    public int doStartTag() throws JspException {
        HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();
        String serverName = (this.server == null) ? request.getServerName() : this.server;
        
        String baseTag =
            renderBaseElement(
                request.getScheme(),
                serverName,
                request.getServerPort(),
                request.getRequestURI());

        JspWriter out = pageContext.getOut();
        try {
            out.write(baseTag);
        } catch (IOException e) {
            pageContext.setAttribute(Globals.EXCEPTION_KEY, e, PageContext.REQUEST_SCOPE);
            throw new JspException(messages.getMessage("common.io", e.toString()));
        }
        
        return EVAL_BODY_INCLUDE;
    }

    /**
     * Render a fully formed HTML &lt;base&gt; element and return it as a String.
     * @param scheme The scheme used in the url (ie. http or https).
     * @param serverName
     * @param port
     * @param uri  The portion of the url from the protocol name up to the query 
     * string.
     * @return String An HTML &lt;base&gt; element.
     * @since Struts 1.1
     */
    protected String renderBaseElement(
        String scheme,
        String serverName,
        int port,
        String uri) {
            
        StringBuffer tag = new StringBuffer("<base href=\"");
        tag.append(scheme);
        tag.append("://");
        
        tag.append(serverName);
        if ("http".equals(scheme) && (port == 80)) {
            ;
        } else if ("https".equals(scheme) && (port == 443)) {
            ;
        } else {
            tag.append(":");
            tag.append(port);
        }
        
        tag.append(uri);
        tag.append("\"");
        
        if (this.target != null) {
            tag.append(" target=\"");
            tag.append(this.target);
            tag.append("\"");
        }
        
        if (RequestUtils.isXhtml(this.pageContext)) {
            tag.append(" />");
        } else {
            tag.append(">");
        }
        
        return tag.toString();
    }
    
    /**
     * Returns the server.
     * @return String
     */
    public String getServer() {
        return this.server;
    }

    /**
     * Sets the server.
     * @param server The server to set
     */
    public void setServer(String server) {
        this.server = server;
    }

}
