package yarfraw.utils;

 import java.io.ByteArrayOutputStream;

 import java.io.IOException;

 import java.io.InputStream;

 import java.io.StringReader;

 import java.util.ArrayList;

 import java.util.List;

 import javax.xml.namespace.QName;

 import javax.xml.parsers.DocumentBuilderFactory;

 import javax.xml.parsers.ParserConfigurationException;

 import javax.xml.transform.Result;

 import javax.xml.transform.Source;

 import javax.xml.transform.Transformer;

 import javax.xml.transform.TransformerConfigurationException;

 import javax.xml.transform.TransformerException;

 import javax.xml.transform.TransformerFactory;

 import javax.xml.transform.stream.StreamResult;

 import javax.xml.transform.stream.StreamSource;

 import org.apache.commons.collections.CollectionUtils;

 import org.apache.commons.lang.ObjectUtils;

 import org.apache.commons.lang.StringUtils;

 import org.w3c.dom.Document;

 import org.w3c.dom.Element;

 import org.w3c.dom.NamedNodeMap;

 import org.w3c.dom.Node;

 import org.w3c.dom.NodeList;

 import org.xml.sax.InputSource;

 import org.xml.sax.SAXException;

 import yarfraw.core.datamodel.YarfrawException;

 public class XMLUtils{

   private XMLUtils(){}

   /**

    * Parses an xml string to a Document object.

    * 

    * @param xml - xml to be parsed

    * @param validating - see {@link DocumentBuilderFactory}

    * @param ignoringComments - see {@link DocumentBuilderFactory}

    * @return a W3 DOM object representation of the input string

    * @throws SAXException

    * @throws IOException

    * @throws ParserConfigurationException

    */

   public static Document parseXml(String xml, boolean validating, boolean ignoringComments) 

   throws SAXException, IOException, ParserConfigurationException{

    return parseXml(new InputSource(new StringReader(xml)), validating, ignoringComments); 

   }

   /**

    * Parses an xml stream to a Document object.

    * 

    * @param stream - xml to be parsed

    * @param validating - see {@link DocumentBuilderFactory}

    * @param ignoringComments - see {@link DocumentBuilderFactory}

    * @return a W3 DOM object representation of the input string

    * @throws SAXException

    * @throws IOException

    * @throws ParserConfigurationException

    */

   public static Document parseXml(InputStream stream, boolean validating, boolean ignoringComments) 

   throws SAXException, IOException, ParserConfigurationException{

    return parseXml(new InputSource(stream), validating, ignoringComments);

   }

   /**

    * Parses xml to a Document object.

    * 

    * @param source - xml source to be parsed

    * @param validating - see {@link DocumentBuilderFactory}

    * @param ignoringComments - see {@link DocumentBuilderFactory}

    * @return a W3 DOM object representation of the input string

    * @throws SAXException

    * @throws IOException

    * @throws ParserConfigurationException

    */

   public static Document parseXml(InputSource source, boolean validating, boolean ignoringComments)

   throws SAXException, IOException, ParserConfigurationException{

     DocumentBuilderFactory factory = 

       DocumentBuilderFactory.newInstance();

    factory.setValidating(validating);

    factory.setIgnoringComments(ignoringComments);

    factory.setNamespaceAware(true);

    return factory.newDocumentBuilder().parse(source);

   }

   /**

    * Search through the input element list and return the first element that matches

    * both input the namespaceURI and the localName.

    * 

    * @param namespaceURI - namespaceURI of the element to be search for

    * @param localName - localName of the element

    * @return - null if no matching element is found,

    * the matching element otherwise.

    */

   public static Element getElementByNS(List<Element> elements, String namespaceURI, String localName){

     if(CollectionUtils.isEmpty(elements)){

       return null;

     }

     for(Element e : elements){

       if(ObjectUtils.equals(localName, e.getLocalName()) && 

               ObjectUtils.equals(namespaceURI, emptyIfNull(e.getNamespaceURI()))){

         return e;

       }

     }    

     return null;

   }

   /**

    * Search through the input element list and return the FIRST element that matches

    * the localName.

    * 

    * @param localName - localName of the element

    * @return - null if no matching element is found,

    * the matching element otherwise.

    */

   public static Element getElementByLocalName(List<Element> elements, String localName){

     if(CollectionUtils.isEmpty(elements)){

       return null;

     }

     for(Element e : elements){

       if(ObjectUtils.equals(localName, e.getLocalName())){

         return e;

       }

     }    

     return null;

   }

   public static boolean same(QName qn1, QName qn2){

     return ObjectUtils.equals(qn1, qn2);

   }

   /**

    * Return empty string if input is null.

    * @param str

    * @return

    */

   public static String emptyIfNull(String str){

     return str == null?StringUtils.EMPTY:str;

   }

   /**

    * Get the attribute value of the attribute that matches the specified {@link QName}.

    * @param element - the element to be searched on.

    * @param name - 

    * @return - the value of the specified attribute, null if the attribute is not found.

    */

   public static String getAttributeValue(Node element, QName name){

     return getAttributeValue(element, name.getLocalPart(), name.getNamespaceURI());

   }

   /**

    * Get the attribute value of the attribute that matches the specified localName.

    * @param element - the element to be searched on.

    * @param name - 

    * @return - the value of the specified attribute, null if the attribute is not found.

    */

   public static String getAttributeValue(Node element, String attributeLocalName){

     return getAttributeValue(element, attributeLocalName, null);

   }

   /**

    * Get the attribute value of the attribute that matches the specified localName and NamespaceUri

    * @param element - the element to be searched on.

    * @param name - 

    * @return - the value of the specified attribute, null if the attribute is not found.

    */

   public static String getAttributeValue(Node element, String attributeLocalName, String namespaceUri){

     NamedNodeMap attr = element.getAttributes();

     if(attr == null){

       return null;

     }

     for(int i=0; i<attr.getLength(); i++){

       Node a = attr.item(i);

       boolean sameUri = namespaceUri == null? true: namespaceUri.equals(a.getNamespaceURI());

       if(sameUri && attributeLocalName.equals(a.getLocalName())){

         return a.getNodeValue();

       }

     }

     return null;

   }

   /**

    * Construct a {@link QName} object using a node's localName and NamespaceUri

    * @param n - a DOM node

    * @return - a new {@link QName} object that has input localName as it's localName and

    * input NamespaceUri as its NamespaceUri.

    */

   public static QName getQName(Node n){

     return new QName(emptyIfNull(n.getNamespaceURI()), n.getLocalName());

   }

   /**

    * Get a list of Children nodes of the input parent using a localName

    * @param parent - the parent node

    * @param localName - local name of the children to be searched for

    * @return - all children nodes that matches the input localName. 

    */

   public static List<Node> getChildrenNodesByName(Node parent, String localName){

     return getChildrenByName(parent, localName, false);

   }

   /**

    * Get a single Children node of the input parent using a localName

    * @param parent - the parent node

    * @param localName - local name of the children to be searched for

    * @return - the FIRST children node that matches the input localName. 

    */

   public static Node getChildrenNodeByName(Node parent, String localName){

     List<Node> result = getChildrenByName(parent, localName, true);

     return result.size() > 0? result.get(0) : null;

   }

   public static String transformWithXsl(String xslt, String xml) throws YarfrawException{

     Source source = new StreamSource(xml);

     ByteArrayOutputStream out = new ByteArrayOutputStream();

     Result res = new StreamResult(out);  

     TransformerFactory transFact = TransformerFactory.newInstance();

     Transformer trans;

     try {

       trans = transFact.newTransformer(new StreamSource(xslt));

       trans.transform(source, res);

     } catch (TransformerConfigurationException e) {

       throw new YarfrawException("Transformer config exception", e);

     } catch (TransformerException e) {

       throw new YarfrawException("Transform exception", e);

     }

     return out.toString();

   }

   private static List<Node> getChildrenByName(Node parent, String localName, boolean single){

     List<Node> nodes = new ArrayList<Node>();

     NodeList list = parent.getChildNodes();

     for(int i =0; i< list.getLength(); i++){

       if(localName.equals(list.item(i).getLocalName())){

         nodes.add(list.item(i));

         if(single){

           return nodes;

         }

       }

     }

     return nodes;

   }

 }