package xml;

import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

public class parser {

	public static List<register> run (String xml_file) { 

		/*parse the XML file and get the document object*/
		Document doc = parse_xml_file (xml_file);

		/*get each image element and create a Icdar object*/
		List<register> list = parse_document (doc);

		return list;
	}

	private static Document parse_xml_file (String xml_file) {

		Document doc = null;

		/*get the factory*/
		DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();

		try {
			/*using factory get an instance of document builder*/
			DocumentBuilder db = dbf.newDocumentBuilder();

			/*parse using builder to get the document representation of the XML file*/
			doc = db.parse(xml_file);
		}		
		catch(ParserConfigurationException pce) {
			pce.printStackTrace();
		}		
		catch(SAXException se) {
			se.printStackTrace();
		}		
		catch(IOException ioe) {
			ioe.printStackTrace();
		}
		return doc;
	}

	private static List<register> parse_document (Document doc){

		List<register> list = new ArrayList<register>();

		/*get the root elememt*/
		Element docEle = doc.getDocumentElement();

		/*get a nodelist of <image> elements*/
		NodeList nl = docEle.getElementsByTagName("image");

		if(nl != null && nl.getLength() > 0) {

			/*getting each image tag do*/
			for(int i = 0 ; i < nl.getLength();i++) {

				/*get the element*/
				Element elem = (Element)nl.item(i);

				/*get the image information element*/
				register r = extract (elem);

				/*add it to list*/
				list.add(r);
			}
		}
		return list;
	}

	/*get each image register in the ICDAR 2003 format*/
	private static register extract (Element node) {

		LinkedList<fields> list = new LinkedList<fields>();

		/*getting image name*/
		String image_name = getTextValue(node, "imageName");

		/*getting image dimensions*/
		NodeList dimension = node.getElementsByTagName("resolution");		
		Element d = (Element)dimension.item(0);
		int image_width = Integer.parseInt(d.getAttribute("x")); /*image width*/		
		int image_height = Integer.parseInt(d.getAttribute("y")); /*image height*/

		/*getting image regions*/				
		NodeList regions = node.getElementsByTagName("taggedRectangle");

		/*getting the text region parameters*/
		for(int i = 0 ; i < regions.getLength(); i++)
		{
			fields f = new fields ();

			Element reg = (Element)regions.item(i);

			f.set_x (Double.parseDouble(reg.getAttribute("x")));

			f.set_y (Double.parseDouble(reg.getAttribute("y")));

			f.set_w (Double.parseDouble(reg.getAttribute("width")));

			f.set_h (Double.parseDouble(reg.getAttribute("height")));

			list.add(f);
		}

		register r = new register (image_name, image_width, image_height, list, regions.getLength());

		return r;
	}

	private static String getTextValue (Element ele, String tagName) {		
		String textVal = null;		
		NodeList nl = ele.getElementsByTagName(tagName);		
		if(nl != null && nl.getLength() > 0) {
			Element el = (Element)nl.item(0);
			textVal = el.getFirstChild().getNodeValue();
		}
		return textVal;
	}
}