/*
 * $Header: /home/cvspublic/jakarta-slide/proposals/taglib/src/jstl/org/apache/slide/taglib/tag/jstl/RevisionTag.java,v 1.3 2004/07/30 06:51:49 ozeigermann Exp $
 * $Revision: 1.3 $
 * $Date: 2004/07/30 06:51:49 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 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", "Slide", 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/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */ 

package org.apache.slide.taglib.tag.jstl;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;

import org.apache.slide.content.NodeRevisionNumber;
import org.apache.slide.taglib.bean.NodeBean;
import org.apache.slide.taglib.tag.RevisionTagSupport;


/**
 * Tag class for tags that represent a revision of a node.
 * 
 * @author <a href="mailto:cmlenz@apache.org">Christopher Lenz</a>
 * @version $Revision: 1.3 $
 */
public class RevisionTag
    extends RevisionTagSupport {
    
    
    // ----------------------------------------------------- Instance Variables
    
    
    /**
     * Value of the 'node' attribute, which should be a JSP-EL expression 
     * referencing the NodeBean to use.
     */
    protected String node;
    
    
    // ----------------------------------------------------------- Construction
    
    
    /**
     * Initialize inherited and local state.
     */
    public RevisionTag() {
        super();
        
        init();
    }
    
    
    // ------------------------------------------------------------ Tag Methods
    
    
    /**
     * Called by the JSP Engine when opening this tag.
     *
     * @throws JspException if the 'number' attribute does not contain a 
     *         version number in a valid format
     */
    public int doStartTag()
        throws JspException {
        
        // evaluate the 'number' attribute
        String evalNumber = (String)
            JstlTagUtils.evaluateOptionalAttribute("revision", "number",
                                                   number, String.class, this,
                                                   pageContext);
        
        // evaluate the 'branch' attribute
        String evalBranch = (String)
            JstlTagUtils.evaluateOptionalAttribute("revision", "branch",
                                                   branch, String.class, this,
                                                   pageContext);
        
        // if neither revision number nor branch name have been specified,
        // first check whether we're inside an iteration over revisions
        NodeRevisionNumber nrn = null;
        if (evalNumber != null) {
            try {
                nrn = new NodeRevisionNumber(evalNumber);
            }
            catch (NumberFormatException e) {
                throw new JspException("The attribute 'number' of " +
                    "the 'revision' tag contains an invalid version " +
                    "number.");
            }
        }
        
        NodeBean nodeBean = null;
        try {
            nodeBean = (NodeBean)
                JstlTagUtils.evaluateOptionalAttribute("revision", "node",
                                                       node, NodeBean.class,
                                                       this, pageContext);
        } catch (JspException e) {
            // ignore
        }
        if (nodeBean == null) {
            nodeBean = JstlTagUtils.findNode(this, pageContext);
            if (nodeBean == null) {
                throw new JspTagException("The 'revision' tag must be " +
                    "nested inside a 'node' tag or an iteration over nodes, " +
                    "or the 'node' attribute must be set.");
            }
        }
        
        revision = getRevision(nodeBean, nrn, evalBranch);
        
        return super.doStartTag();
    }
    
    
    /**
     * Called by the JSP Engine when closing of this tag.
     *
     * @throws JspException never thrown
     */
    public int doEndTag()
        throws JspException {
        
        init();
        
        return super.doEndTag();
    }
    
    
    /**
     * Releases any resources we may have (or inherit).
     */
    public void release() {
        super.release();
        
        init();
    }
    
    
    // --------------------------------------------------------- Public Methods
    
    
    /**
     * Sets the 'node' attribute.
     *
     * @param node the attribute value
     */
    public void setNode(String node) {
        
        this.node = node;
    }
    
    
    /**
     * Set the 'var' attribute.
     *
     * @param var the attribute value
     */
    public void setVar(String var) {
        
        attrName = var;
    }
    
    
    // -------------------------------------------------------- Private Methods
    
    
    /**
     * Reset internal state.
     */
    private void init() {
        
        node = null;
    }
    
    
}

