/*

  * Copyright 1999-2001,2004 The Apache Software Foundation.

  * 

  * 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.apache.commons.workflow.base;

 import java.util.ArrayList;

 import org.apache.commons.workflow.Activity;

 import org.apache.commons.workflow.Step;

 /**

  * <p><strong>BaseActivity</strong> is a convenient base class for more

  * sophisticated <code>Activity</code> implementations.  It includes

  * management of the static relationships of Steps to each other as part

  * of an owning Activity.</p>

  *

  * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $

  * @author Craig R. McClanahan

  */

 public class BaseActivity implements Activity {

     // ----------------------------------------------------- Instance Variables

     /**

      * The first Step associated with this Activity.

      */

     protected Step firstStep = null;

     /**

      * The unique identifier of this Activity.

      */

     protected String id = null;

     /**

      * The last Step associated with this Activity.

      */

     protected Step lastStep = null;

     // ------------------------------------------------------------- Properties

     /**

      * Return the first Step associated with this Activity.

      */

     public Step getFirstStep() {

         return (this.firstStep);

     }

     /**

      * Return the unique identifier of this Activity.

      */

     public String getId() {

         return (this.id);

     }

     /**

      * Set the unique identifier of this Activity.

      *

      * @param id The new unique identifier

      */

     public void setId(String id) {

         this.id = id;

     }

     /**

      * Return the last Step associated with this Activity.

      */

     public Step getLastStep() {

         return (this.lastStep);

     }

     // ---------------------------------------------------------- Owner Methods

     /**

      * Add a new Step to the end of the sequence of Steps associated with

      * this Activity.

      *

      * @param step The new step to be added

      */

     public void addStep(Step step) {

         step.setOwner(this);

         if (firstStep == null) {

             step.setPreviousStep(null);

             step.setNextStep(null);

             firstStep = step;

             lastStep = step;

         } else {

             step.setPreviousStep(lastStep);

             step.setNextStep(null);

             lastStep.setNextStep(step);

             lastStep = step;

         }

     }

     /**

      * Clear any existing Steps associated with this Activity.

      */

     public void clearSteps() {

         Step current = firstStep;

         while (current != null) {

             Step next = current.getNextStep();

             current.setOwner(null);

             current.setPreviousStep(null);

             current.setNextStep(null);

             current = next;

         }

         firstStep = null;

         lastStep = null;

     }

     /**

      * Return the identified Step from this Activity, if it exists.

      * Otherwise, return <code>null</code>.

      *

      * @param id Identifier of the desired Step

      */

     public Step findStep(String id) {

         Step current = getFirstStep();

         while (current != null) {

             if (id.equals(current.getId()))

                 return (current);

             current = current.getNextStep();

         }

         return (null);

     }

     /**

      * Return the set of Steps associated with this Activity.

      */

     public Step[] getSteps() {

         ArrayList list = new ArrayList();

         Step currentStep = firstStep;

         while (currentStep != null) {

             list.add(currentStep);

             currentStep = currentStep.getNextStep();

         }

         Step steps[] = new Step[list.size()];

         return ((Step[]) list.toArray(steps));

     }

     /**

      * Set the set of Steps associated with this Activity, replacing any

      * existing ones.

      *

      * @param steps The new set of steps.

      */

     public void setSteps(Step steps[]) {

         clearSteps();

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

             addStep(steps[i]);

     }

 }