/*

  * Licensed to the Apache Software Foundation (ASF) under one or more

  * contributor license agreements.  See the NOTICE file distributed with

  * this work for additional information regarding copyright ownership.

  * The ASF licenses this file to You 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.apache.commons.pipeline.stage;

 import java.lang.reflect.InvocationTargetException;

 import java.lang.reflect.Method;

 import org.apache.commons.pipeline.StageException;

 /**

  * Runs a static method with the object (or array) being processed. The returned object 

  * will be exqueued on the main pipeline if it is not null. If the returned

  * object is null, this stage will attempt to place the original object on the 

  * branch specified by {@link #setNullResultBranchTag(String)}.

  */

 public class InvokeStaticMethodStage extends BaseStage {

     // Branch upon which the original objects will be enqueued if the defined

     // Method returned a null result.

     private String nullResultBranchKey;

     // Method used to process objects in the queue

     private Method method;

     /**

      * Creates a new instance of InvokeStaticMethodStage

      */

     public InvokeStaticMethodStage(Method method) {

         super();

         this.method = method;

     }

     /** 

      * Convenience method to create the new stage with String description of className, methodName and argumentType

      *

      * @param className The fully qualified class name, such as "java.lang.String" of the class in which the method resides

      * @param methodName The name of the method

      * @param argumentType The argument type of the method (Sorry, this doesn't support multiple argument methods)

      */

     public InvokeStaticMethodStage(String className, String methodName, String... argumentTypeNames) throws ClassNotFoundException, NoSuchMethodException {

         Class clazz = InvokeStaticMethodStage.class.getClassLoader().loadClass(className);

         Class[] argTypes = new Class[argumentTypeNames.length];

         for (int i = 0; i < argumentTypeNames.length; i++) {

             argTypes[i] = Class.forName(argumentTypeNames[i]);

         }

         this.method = clazz.getMethod(methodName, argTypes);

     }

     /** 

      * Returns the Method object for the method that will be used to process

      * objects in the queue.

      */

     public Method getMethod(){

         return this.method;

     }

     /** 

      * <p>Calls the defined static method and exqueues the returned object if it is 

      * not null, otherwise placing the original object on the branch specified

      * by the nullResultBranchKey property if nullResultBranchKey is not null.</p>

      *

      * @param obj The object to be processed.

      */

     public void process(Object obj) throws StageException {

         try {

             Object result = this.method.invoke(null, obj);

             if (result != null){

                 this.emit(result);

             } else if (nullResultBranchKey != null) {

                 this.context.getBranchFeeder(nullResultBranchKey).feed(obj);

             }

         } catch (IllegalAccessException e){

             throw new StageException(this, e);

         } catch (InvocationTargetException e){

             throw new StageException(this, e);

         }       

     }

     /**

      * Getter for property nullResultBranchKey.

      *

      * @return Value of property nullResultBranchKey.

      */

     public String getNullResultBranchKey() {

         return this.nullResultBranchKey;

     }

     /**

      * Setter for property nullResultBranchKey. If set to null (default) 

      * then objects generating null results are simply dropped from the stream.

      *

      * @param nullResultBranchKey New value of property nullResultBranchKey.

      */

     public void setNullResultBranchKey(String nullResultBranchKey) {

         this.nullResultBranchKey = nullResultBranchKey;

     }

 }