/*

  * 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.web;

 import java.io.IOException;

 import java.util.EmptyStackException;

 import javax.servlet.RequestDispatcher;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

 import org.apache.commons.workflow.Context;

 import org.apache.commons.workflow.Step;

 import org.apache.commons.workflow.StepException;

 import org.apache.commons.workflow.base.BaseStep;

 /**

  * <p>Unconditionally transfer control to the step that is identified by

  * a request parameter with the specified name.</p>

  *

  * <p>Supported Attributes:</p>

  * <ul>

  * <li><strong>step</strong> - Name of a request parameter, included on the

  *     current request, that contains the identifier of the Step (within the

  *     current Activity) to which control should be transferred.  If not

  *     specified, a request parameter named <code>step</code> is used.</li>

  * </ul>

  *

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

  * @author Craig R. McClanahan

  */

 public class GotoStep extends BaseStep {

     // ----------------------------------------------------------= Constructors

     /**

      * Construct a default instance of this Step.

      */

     public GotoStep() {

         super();

     }

     /**

      * Construct an instance of this Step with the specified identifier.

      *

      * @param id Step identifier

      */

     public GotoStep(String id) {

         super();

         setId(id);

     }

     /**

      * Construct a fully configured instance of this Step.

      *

      * @param id Step identifier

      * @param step Request parameter name containing our step identifier

      */

     public GotoStep(String id, String step) {

         super();

         setId(id);

         setStep(step);

     }

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

     /**

      * The request parameter containing the identifier of the Step to which

      * control should be transferred.

      */

     protected String step = "step";

     public String getStep() {

         return (this.step);

     }

     public void setStep(String step) {

         this.step = step;

     }

     // --------------------------------------------------------- Public Methods

     /**

      * Perform the executable actions related to this Step, in the context of

      * the specified Context.

      *

      * @param context The Context that is tracking our execution state

      *

      * @exception StepException if a processing error has occurred

      */

     public void execute(Context context) throws StepException {

         // Make sure our executing Context is a WebContext

         if (!(context instanceof WebContext))

             throw new StepException("Execution context is not a WebContext",

                                     this);

         WebContext webContext = (WebContext) context;

         // Locate the step identifier to which we will transfer control

         ServletRequest request = webContext.getServletRequest();

         String id = request.getParameter(step);

         if (id == null)

             throw new StepException("No request parameter '" + step + "'",

                                     this);

         // Locate the step to which we will transfer control

         Step next = getOwner().findStep(id);

         if (next == null)

             throw new StepException("Cannot find step '" + id + "'", this);

         // Tell our Context to transfer control

         context.setNextStep(next);

     }

     /**

      * Render a string representation of this Step.

      */

     public String toString() {

         StringBuffer sb = new StringBuffer("<web:goto");

         if (getId() != null) {

             sb.append(" id=\"");

             sb.append(getId());

             sb.append("\"");

         }

         sb.append(" step=\"");

         sb.append(getStep());

         sb.append("\"/>");

         return (sb.toString());

     }

 }