/*
 * Copyright 2011 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jbpm.bpmn2.xpath;

/**
 * A helper utility that modifies XPath Expression in-place.
 */
public class XPATHExpressionModifier {

    //	/**
    //	 * Creates a new XPATHExpressionModifier object.
    //	 *
    //	 * @param contextUris
    //	 * @param namePool
    //	 */
    //	public XPATHExpressionModifier() {
    //	}
    //
    //	/**
    //	 * Insert nodes into the specified XPath expression wherever
    //	 * required 
    //	 * <p>
    //	 * To be precise, a node is added to its parent if:
    //	 * a) the node is an element...
    //	 * b) that corresponds to an step...
    //	 * c) that has a child axis...
    //	 * d) whose parent had no children with its name...
    //	 * e) and all preceding steps are element name tests.
    //	 * </p>
    //	 * @param xpathExpr
    //	 * @param namePool
    //	 *
    //	 * @throws DOMException
    //	 * @throws TransformerException
    //	 * @throws XPathExpressionException 
    //	 */
    //	public Node insertMissingData(String xpath, Node contextNode)
    //	throws DOMException, TransformerException, XPathExpressionException {
    //	    if (xpath.startsWith("/") && contextNode == null) {
    //	        xpath = xpath.substring(1);
    //	    }
    //	    Node rootNode = contextNode;
    //	    if (contextNode != null) {
    //	        contextNode = contextNode.getOwnerDocument();
    //	    }
    //	    
    //		XPathFactory xpf = new XPathFactoryImpl();
    //		XPath xpe = xpf.newXPath();    	
    //		XPathExpression xpathExpr = xpe.compile(xpath);
    //
    ////		if (contextNode == null || !(contextNode instanceof Element) ||
    ////				!(xpathExpr instanceof XPathExpressionImpl)) {
    ////			return;
    ////		}
    //
    //		Expression expression = ((XPathExpressionImpl) xpathExpr).getInternalExpression();
    //
    //		Document document = toDOMDocument(contextNode);
    //
    //		PathExpression pathExpr = null;
    //		Expression step = null;
    //
    //		if (expression instanceof PathExpression) {
    //			pathExpr = (PathExpression) expression;
    //			step = pathExpr.getFirstStep();
    //		} else if (expression instanceof AxisExpression) {
    //			pathExpr = null;
    //			step = (AxisExpression) expression;
    //		} else {
    //			return contextNode;
    //		}
    //
    //		while (step != null) {
    //			if (step instanceof AxisExpression) {
    //				AxisExpression axisExpr = (AxisExpression) step;
    //
    //				NodeTest nodeTest = axisExpr.getNodeTest();
    //
    //				if (!(nodeTest instanceof NameTest)) {
    //					break;
    //				}
    //
    //				NameTest nameTest = (NameTest) nodeTest;
    //
    //				QName childName = getQualifiedName(nameTest.getFingerprint(),
    //						((XPathFactoryImpl) xpf).getConfiguration().getNamePool()/*, contextUris*/);
    //
    //				if (Axis.CHILD == axisExpr.getAxis()) {
    //					if (NodeKindTest.ELEMENT.getNodeKindMask() != nameTest.getNodeKindMask()) {
    //						break;
    //					}
    //					if (contextNode == null) {
    //					    contextNode = document.createElementNS(childName.getNamespaceURI(), childName.getLocalPart());
    //					    document.appendChild(contextNode);
    //					    rootNode = contextNode;
    //					} else {
    //					    
    //					    NodeList children = null;
    //					    if (contextNode instanceof Element) {
    //					        children = ((Element) contextNode).getElementsByTagNameNS(childName.getNamespaceURI(),
    //					            childName.getLocalPart());
    //					    } else if (contextNode instanceof Document) {
    //					        children = ((Document) contextNode).getElementsByTagNameNS(childName.getNamespaceURI(),
    //	                                childName.getLocalPart());
    //					    } else {
    //					        throw new IllegalArgumentException(contextNode + " is of unsupported type");
    //					    }
    //					    if ((children == null) || (children.getLength() == 0)) {
    //					        Node child = document.createElementNS(childName.getNamespaceURI(),
    //					                getQualifiedName(childName));
    //					        Document currentDoc = (Document) (contextNode instanceof Document ? contextNode : contextNode.getOwnerDocument());
    //					        
    //					        contextNode.appendChild(currentDoc.importNode(child, true));
    //					        contextNode = child;
    //					    } else if (children.getLength() == 1) {
    //					        contextNode = children.item(0);
    //					    } else {
    //					        break;
    //					    }
    //					}
    //				} else if (Axis.ATTRIBUTE == axisExpr.getAxis()) {
    //					if (NodeKindTest.ATTRIBUTE.getNodeKindMask() != nameTest.getNodeKindMask()) {
    //						break;
    //					}
    //
    //					Attr attribute = ((Element) contextNode).getAttributeNodeNS(childName.getNamespaceURI(), childName.getLocalPart());
    //					if (attribute == null) {
    //						attribute = document.createAttributeNS(childName.getNamespaceURI(), childName.getLocalPart());
    //						((Element) contextNode).setAttributeNode(attribute);
    //						contextNode = attribute;
    //					} else {
    //						break;
    //					}
    //
    //				} else {
    //					break;
    //				}
    //
    //
    //			} else if (step instanceof ItemChecker) {
    //				ItemChecker itemChecker = (ItemChecker) step;
    //				Expression baseExpr = itemChecker.getBaseExpression();
    //
    //				if (!(baseExpr instanceof VariableReference)) {
    //					break;
    //				}
    //			} else {
    //				break;
    //			}
    //
    //			if (pathExpr != null) {
    //				Expression remainingSteps = pathExpr.getRemainingSteps();
    //
    //				if (remainingSteps instanceof PathExpression) {
    //					pathExpr = (PathExpression) remainingSteps;
    //					step = pathExpr.getFirstStep();
    //				} else if (remainingSteps instanceof AxisExpression) {
    //					pathExpr = null;
    //					step = (AxisExpression) remainingSteps;
    //				} else {
    //					throw new RuntimeException("Not supported step " + remainingSteps + " in expression " + expression);
    //				}
    //			} else {
    //				break;
    //			}
    //		}
    //		return rootNode;
    //	}
    //
    //	/**
    //	 * Create the QName by running the given finger print against the
    //	 * given context
    //	 *
    //	 * @param fingerprint
    //	 * @param namePool
    //	 * @param nsContext
    //	 *
    //	 * @return The QName corresponding to the finger print
    //	 */
    //	private QName getQualifiedName(int fingerprint, NamePool namePool) {
    //		String localName = namePool.getLocalName(fingerprint);
    //		String prefix = namePool.getPrefix(fingerprint);
    //		String uri = namePool.getURI(fingerprint);
    //
    //		// Unfortunately, NSContext.getPrefix(String URI) doesn't always work
    //		// So, we need to find the prefix for the URI the hard way
    //		//        if ((prefix == null) || "".equals(prefix)) {
    //		//            for (String nsPrefix : nsContext.getPrefixes()) {
    //		//                String nsUri = nsContext.getNamespaceURI(nsPrefix);
    //		//
    //		//                if (nsUri.equals(uri)) {
    //		//                    prefix = nsPrefix;
    //		//                }
    //		//            }
    //		//        }
    //
    //		return new QName(uri, localName, prefix);
    //	}
    //
    //	public static Document toDOMDocument(Node node) throws TransformerException {
    //		// If the node is the document, just cast it
    //		if (node instanceof Document) {
    //		    return newDocument();
    //			// If the node is an element
    //		} else if (node instanceof Element) {
    //			Element elem = (Element) node;
    //			// If this is the root element, return its owner document
    //			//            if (elem.getOwnerDocument().getDocumentElement() == elem) {
    //			return elem.getOwnerDocument();
    //			// else, create a new doc and copy the element inside it
    //			//            } else {
    //			//                Document doc = newDocument();
    //			//                doc.appendChild(doc.importNode(node, true));
    //			//                return doc;
    //			//            }
    //			// other element types are not handled
    //		} else if (node == null) {
    //		    return newDocument();
    //		} else {
    //			throw new TransformerException("Unable to convert DOM node to a Document");
    //		}
    //	}
    //
    //	public static Document newDocument() {
    //		try {
    //			DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
    //			return db.newDocument();
    //		} catch (ParserConfigurationException e) {
    //			//            __log.error(e);
    //			throw new RuntimeException(e);
    //		}
    //	}
    //
    //	public static String getQualifiedName(QName qName) {
    //		String prefix = qName.getPrefix(), localPart = qName.getLocalPart();
    //		return (prefix == null || "".equals(prefix)) ? localPart : (prefix + ":" + localPart);
    //	}

}