source: main/trunk/greenstone3/src/java/org/greenstone/gsdl3/util/GSXSLT.java@ 25397

/*
 *    GSXSLT.java
 *    Copyright (C) 2008 New Zealand Digital Library, http://www.nzdl.org
 *
 *    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; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    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.greenstone.gsdl3.util;

import org.w3c.dom.Node;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.w3c.dom.Document;

import java.util.Vector;
import java.util.ArrayList;

/** various functions for manipulating Greenstone xslt */
public class GSXSLT
{
    /**
     * takes a stylesheet Document, and adds in any child nodes from extra_xsl
     * named templates overwrite any existing one, while match templates are
     * just added to the end of teh stylesheet
     */
    public static void mergeStylesheets(Document main_xsl, Element extra_xsl)
    {
        Element main = main_xsl.getDocumentElement();

        NodeList children = extra_xsl.getElementsByTagNameNS("http://www.w3.org/1999/XSL/Transform", "import");
        for (int i = 0; i < children.getLength(); i++) {
                Node node = children.item(i);
            // If the new xsl:import element is identical (in terms of href attr value) 
            // to any in the merged document, don't copy it over
            if(!isDuplicateElement(main, node, "xsl:import", "href")) {
                // Import statements should be the first children of an xsl:stylesheet element
                // If firstchild is null, then this xsl:import element will be inserted at the "end"
                // Although Node.insertBefore() will first remove identical nodes before inserting, we check
                // only the href attribute to see if they're "identical" to any pre-existing <xsl:import>
                main.insertBefore(main_xsl.importNode(node, true), main.getFirstChild());
            }
        }
        
        children = extra_xsl.getElementsByTagNameNS("http://www.w3.org/1999/XSL/Transform", "include");
        for (int i = 0; i < children.getLength(); i++) {
                Node node = children.item(i);
            // If the new xsl:include element is identical (in terms of href attr value)
            // to any in the merged document, don't copy it over
            // Although Node.appendChild() will first remove identical nodes before appending, we check
            // only the href attribute to see if they're "identical" to any pre-existing <xsl:include>
            if(!isDuplicateElement(main, node, "xsl:include", "href")) {
                main.appendChild(main_xsl.importNode(node, true));
            }
        }

        children = extra_xsl.getElementsByTagNameNS("http://www.w3.org/1999/XSL/Transform", "output");
        for (int i = 0; i < children.getLength(); i++) {
                Node node = children.item(i);
            // If the new xsl:output element is identical (in terms of the value for the method attr) 
            // to any in the merged document, don't copy it over
            if(!isDuplicateElement(main, node, "xsl:output", "method")) {
                main.appendChild(main_xsl.importNode(node, true));
            }
        }

        children = extra_xsl.getElementsByTagNameNS("http://www.w3.org/1999/XSL/Transform", "template");
        for (int i = 0; i < children.getLength(); i++)
        {
            Node node = children.item(i);
            // remove any previous occurrences of xsl:template with the same value for name
            // or even the same value for match (should we use priorities for match?)
            removeDuplicateElementsFrom(main, node, "xsl:template", "name");
            removeDuplicateElementsFrom(main, node, "xsl:template", "match");
            main.appendChild(main_xsl.importNode(node, true));
        }
    }

    // In element main, tries to find any previous occurrence of elements with xsl-template-name=templateName, 
    // and whose named attribute (attributeName) has the same value as the same attribute in node.
    // If this is the case, such a previous occurrence is removed from element main, since
    // the new node will contain a more specific redefinition of this element.
    public static void removeDuplicateElementsFrom(Element main, Node node, String templateName, String attrName) {
    String attr = ((Element) node).getAttribute(attrName);
    if (!attr.equals(""))
        {
        Element old_template = GSXML.getNamedElement(main, templateName, attrName, attr);
        if (old_template != null)
            {
            main.removeChild(old_template);
            }
        }
    }

    // Call this method on elements like xsl:include, xsl:import and xsl:output
    // In element main, tries to find any previous occurrence of elements with xsl-element-name=xslName, 
    // and whose named attribute (attributeName) has the same value as the same attribute in node.
    // If this is the case, it returns true, since the element would a complete duplicate for our intents.
    public static boolean isDuplicateElement(Element main, Node node, String xslName, String attrName) {
    String attr = ((Element) node).getAttribute(attrName);
    if (!attr.equals(""))
        {
        Element old_element = GSXML.getNamedElement(main, xslName, attrName, attr);
        if (old_element != null)
            {
            return true;
            }
        }
    return false;
    }

    /**
     * takes any import or include nodes, and creates absolute path names for
     * the files
     */
    public static void absoluteIncludePaths(Document stylesheet, String gsdl3_home, String site_name, String collection, String interface_name, ArrayList base_interfaces)
    {

        Element base_node = stylesheet.getDocumentElement();
        if (base_node == null)
        {
            return;
        }
        Node child = base_node.getFirstChild();
        while (child != null)
        {
            String name = child.getNodeName();
            if (name.equals("xsl:import") || name.equals("xsl:include"))
            {
                ((Element) child).setAttribute("href", GSFile.stylesheetFile(gsdl3_home, site_name, collection, interface_name, base_interfaces, ((Element) child).getAttribute("href")));
            }
            child = child.getNextSibling();
        }

    }

    /**
     * looks through a stylesheet for <xxx:template match='template_name'>
     * inside this template it looks for any <xxx:value-of
     * select='metadataList/metadata[@name=yyy]> elements, and extracts the
     * metadata names into a Vector
     */
    public static Vector extractWantedMetadata(Document stylesheet, String template_name)
    {

        Vector metadata = new Vector();
        Element base_node = stylesheet.getDocumentElement();
        NodeList templates = base_node.getElementsByTagNameNS("*", "template");
        for (int i = 0; i < templates.getLength(); i++)
        {
            Element template = (Element) templates.item(i);
            String match_name = template.getAttribute("match");
            if (!match_name.equals(template_name))
            {
                continue; // we're only looking for specific templates
            }
            String mode = template.getAttribute("mode");
            if (!mode.equals(""))
            {
                continue; // we only want ones without modes - these are processing ones, not display ones
            }
            // we have one that we want to look through
            NodeList values = template.getElementsByTagNameNS("*", "value-of");
            for (int v = 0; v < values.getLength(); v++)
            {
                String select = ((Element) values.item(v)).getAttribute("select");
                if (select.startsWith("metadataList/metadata[@name="))
                {
                    String[] bits = select.split("'|\"");
                    // there should be two quotes in teh string, therefore 3 items, and the second one is teh one we want
                    String name = bits[1];
                    metadata.add(name);
                }
            }
        }
        return metadata;
    }

}