/*
    * Copyright 2007 the original author or authors.
    *
    * 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.springframework.ws.server.endpoint.adapter;
  
  import java.lang.annotation.Annotation;
  import java.lang.reflect.Method;
  import java.util.Properties;
  import javax.xml.namespace.QName;
  import javax.xml.transform.Source;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.dom.DOMResult;
  import javax.xml.xpath.XPath;
  import javax.xml.xpath.XPathConstants;
  import javax.xml.xpath.XPathExpressionException;
  import javax.xml.xpath.XPathFactory;
  
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.ws.WebServiceMessage;
  import org.springframework.ws.context.MessageContext;
  import org.springframework.ws.server.endpoint.MethodEndpoint;
  import org.springframework.ws.server.endpoint.annotation.XPathParam;
  import org.springframework.xml.namespace.SimpleNamespaceContext;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  /**
   * Adapter that supports endpoint methods that use marshalling. Supports methods with the following signature:
   * <pre>
   * void handleMyMessage(@XPathParam("/root/child/text")String param);
   * </pre>
   * or
   * <pre>
   * Source handleMyMessage(@XPathParam("/root/child/text")String param1, @XPathParam("/root/child/number")double
   * param2);
   * </pre>
   * I.e. methods that return either <code>void</code> or a {@link Source}, and have parameters annotated with {@link
   * XPathParam} that specify the XPath expression that should be bound to that parameter. The parameter can be of the
   * following types: <ul> <li><code>boolean</code>, or {@link Boolean}</li> <li><code>double</code>, or {@link
   * Double}</li> <li>{@link String}</li> <li>{@link Node}</li> <li>{@link NodeList}</li> </ul>
   *
   * @author Arjen Poutsma
   * @since 1.0.0
   */
  public class XPathParamAnnotationMethodEndpointAdapter extends AbstractMethodEndpointAdapter
          implements InitializingBean {
  
      private XPathFactory xpathFactory;
  
      private Properties namespaces;
  
      /** Sets namespaces used in the XPath expression. Maps prefixes to namespaces. */
      public void setNamespaces(Properties namespaces) {
          this.namespaces = namespaces;
      }
  
      public void afterPropertiesSet() throws Exception {
          xpathFactory = XPathFactory.newInstance();
      }
  
      /** Supports methods with @XPathParam parameters, and return either <code>Source</code> or nothing. */
      protected boolean supportsInternal(MethodEndpoint methodEndpoint) {
          Method method = methodEndpoint.getMethod();
          if (!(Source.class.isAssignableFrom(method.getReturnType()) || Void.TYPE.equals(method.getReturnType()))) {
              return false;
          }
          Class<?>[] parameterTypes = method.getParameterTypes();
          for (int i = 0; i < parameterTypes.length; i++) {
              if (getXPathParamAnnotation(method, i) == null || !isSuportedType(parameterTypes[i])) {
                  return false;
              }
          }
          return true;
      }
  
      private XPathParam getXPathParamAnnotation(Method method, int paramIdx) {
          Annotation[][] paramAnnotations = method.getParameterAnnotations();
          for (int annIdx = 0; annIdx < paramAnnotations[paramIdx].length; annIdx++) {
              if (paramAnnotations[paramIdx][annIdx].annotationType().equals(XPathParam.class)) {
                  return (XPathParam) paramAnnotations[paramIdx][annIdx];
              }
          }
          return null;
      }
 
     private boolean isSuportedType(Class<?> clazz) {
         return Boolean.class.isAssignableFrom(clazz) || Boolean.TYPE.isAssignableFrom(clazz) ||
                 Double.class.isAssignableFrom(clazz) || Double.TYPE.isAssignableFrom(clazz) ||
                 Node.class.isAssignableFrom(clazz) || NodeList.class.isAssignableFrom(clazz) ||
                 String.class.isAssignableFrom(clazz);
     }
 
     protected void invokeInternal(MessageContext messageContext, MethodEndpoint methodEndpoint) throws Exception {
         Element payloadElement = getRootElement(messageContext.getRequest().getPayloadSource());
         Object[] args = getMethodArguments(payloadElement, methodEndpoint.getMethod());
         Object result = methodEndpoint.invoke(args);
         if (result != null && result instanceof Source) {
             Source responseSource = (Source) result;
             WebServiceMessage response = messageContext.getResponse();
             transform(responseSource, response.getPayloadResult());
         }
     }
 
     private Object[] getMethodArguments(Element payloadElement, Method method) throws XPathExpressionException {
         Class<?>[] parameterTypes = method.getParameterTypes();
         XPath xpath = createXPath();
         Object[] args = new Object[parameterTypes.length];
         for (int i = 0; i < parameterTypes.length; i++) {
             String expression = getXPathParamAnnotation(method, i).value();
             QName conversionType;
             if (Boolean.class.isAssignableFrom(parameterTypes[i]) || Boolean.TYPE.isAssignableFrom(parameterTypes[i])) {
                 conversionType = XPathConstants.BOOLEAN;
             }
             else
             if (Double.class.isAssignableFrom(parameterTypes[i]) || Double.TYPE.isAssignableFrom(parameterTypes[i])) {
                 conversionType = XPathConstants.NUMBER;
             }
             else if (Node.class.isAssignableFrom(parameterTypes[i])) {
                 conversionType = XPathConstants.NODE;
             }
             else if (NodeList.class.isAssignableFrom(parameterTypes[i])) {
                 conversionType = XPathConstants.NODESET;
             }
             else if (String.class.isAssignableFrom(parameterTypes[i])) {
                 conversionType = XPathConstants.STRING;
             }
             else {
                 throw new IllegalArgumentException("Invalid parameter type [" + parameterTypes[i] + "]. " +
                         "Supported are: Boolean, Double, Node, NodeList, and String.");
             }
             args[i] = xpath.evaluate(expression, payloadElement, conversionType);
         }
         return args;
     }
 
     private XPath createXPath() {
         XPath xpath = xpathFactory.newXPath();
         if (namespaces != null) {
             SimpleNamespaceContext namespaceContext = new SimpleNamespaceContext();
             namespaceContext.setBindings(namespaces);
             xpath.setNamespaceContext(namespaceContext);
         }
         return xpath;
     }
 
     /**
      * Returns the root element of the given source.
      *
      * @param source the source to get the root element from
      * @return the root element
      */
     private Element getRootElement(Source source) throws TransformerException {
         DOMResult domResult = new DOMResult();
         transform(source, domResult);
         Document document = (Document) domResult.getNode();
         return document.getDocumentElement();
     }
 
 
 }