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package org.openoffice.xmerge.merger.merge;

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

import org.openoffice.xmerge.ConverterCapabilities;
import org.openoffice.xmerge.converter.xml.OfficeConstants;


/** 
 *  Utility methods to handle sheet XML tree.
 */
public class SheetUtil {

    /** 
     *  <p>Empty the content of a cell value.   This includes the following:
     *  </p>
     *
     *  <p><ul><li>
     *    Remove all of the supported attributes.
     *  </li><li>
     *    Remove the first <i>text:p</i> <code>Node</code> for most of the cells.
     *  </li></ul>
     *
     *  @param  cc    The <code>ConverterCapabilities</code>.
     *  @param  node  The <code>Node</code>.
     */
    public static void emptyCell(ConverterCapabilities cc, Node node) {

        NamedNodeMap attrNodes = node.getAttributes();

        if (attrNodes != null) {
            
            // empty the first text:p node. 
            // Note: it's not necessary only string type cell contain text:p
            // basically, all different type of cell will contain one
            Element cell = (Element)node;

            // get the paragraph node list
            NodeList paraNodes = 
                cell.getElementsByTagName(OfficeConstants.TAG_PARAGRAPH);

            Node firstParaNode = paraNodes.item(0);

            // remove the first paragraph element node
            if (firstParaNode != null) {
                Node parent = firstParaNode.getParentNode();
                parent.removeChild(firstParaNode);
            }

            // check all the attributes and remove those we supported in 
            // converter 
            // NOTE: for attribute list, refer to section 4.7.2 in specification
            int len = attrNodes.getLength();

            for (int i = 0; i < len; ) {
                Node attr = attrNodes.item(i);

                // when we hit the end of the attribute nodes, return
                // it may happen sooner as we keep on removing nodes
                if (attr == null) {
                    break;
                }
                // remove the supported attr except columns repeated attribute
                if (cc.canConvertAttribute(OfficeConstants.TAG_TABLE_CELL,
                                           attr.getNodeName()) &&
                    !attr.getNodeName().equals(
                        OfficeConstants.ATTRIBUTE_TABLE_NUM_COLUMNS_REPEATED)) {

                    attrNodes.removeNamedItem(attr.getNodeName());
                } else {
                    i++;
                }
            }
        }
    }
}

