D-Net

package eu.dnetlib.dhp.wf.importer.mdrecord;

import java.util.Stack;

import org.xml.sax.Attributes;

import org.xml.sax.SAXException;

import org.xml.sax.helpers.DefaultHandler;

import eu.dnetlib.dhp.common.InfoSpaceConstants;

/**

 * MDRecord handler extracting record identifier.

 * 

 * Notice: writer is not being closed by handler. Created outside, let it be closed outside as well.

 * @author mhorst

 *

 */

public class MDRecordHandler extends DefaultHandler {

    public static final String ELEM_OBJ_IDENTIFIER = "objIdentifier";

    private static final String ELEM_HEADER = "header";

    private Stack<String> parents;

    private StringBuilder currentValue = new StringBuilder();

    private String recordId;

    // ------------------------ LOGIC --------------------------

    @Override

    public void startDocument() throws SAXException {

        parents = new Stack<String>();

        recordId = null;

    }

    @Override

    public void startElement(String uri, String localName, String qName,

            Attributes attributes) throws SAXException {

        if (this.recordId == null) {

            if (isWithinElement(localName, ELEM_OBJ_IDENTIFIER, ELEM_HEADER)) {

//              identifierType attribute is mandatory

                this.currentValue = new StringBuilder();

            }

            this.parents.push(localName);            

        }

    }

    @Override

    public void endElement(String uri, String localName, String qName)

            throws SAXException {

        if (this.recordId == null) {

            this.parents.pop();

            if (isWithinElement(localName, ELEM_OBJ_IDENTIFIER, ELEM_HEADER)) {

                this.recordId = InfoSpaceConstants.ROW_PREFIX_RESULT + this.currentValue.toString().trim();

            }

//          resetting current value;

            this.currentValue = null;

        }

    }

    @Override

    public void endDocument() throws SAXException {

        parents.clear();

        parents = null;

    }

    @Override

    public void characters(char[] ch, int start, int length)

            throws SAXException {

        if (this.currentValue!=null) {

            this.currentValue.append(ch, start, length);

        }

    }

    /**

     * @return record identifier

     */

    public String getRecordId() {

        return recordId;

    }

    // ------------------------ PRIVATE --------------------------

    private boolean isWithinElement(String localName, String expectedElement, String expectedParent) {

        return localName.equals(expectedElement) && !this.parents.isEmpty() && 

                expectedParent.equals(this.parents.peek());

    }

}