/*

  * 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.io;

 import java.io.BufferedInputStream;

 import java.io.InputStream;

 import java.io.InputStreamReader;

 import java.io.IOException;

 import java.net.MalformedURLException;

 import java.net.URL;

 import java.net.URLConnection;

 import java.util.EmptyStackException;

 import org.apache.commons.workflow.Context;

 import org.apache.commons.workflow.StepException;

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

 import org.apache.commons.workflow.util.WorkflowUtils;

 /**

  * <p>Retrieve the contents of a specified URL resource, and push the

  * contents as a String object onto the evaluation stack.</p>

  *

  * <p>Supported Attributes:</p>

  * <ul>

  * <li><strong>url</strong> - URL of the resource to be retrieved, or

  *     omitted to pop a computed String value from the top of the

  *     evaluation stack.</li>

  * </ul>

  *

  * <strong>DESIGN QUESTION - What about binary content?</strong>

  *

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

  * @author Craig R. McClanahan

  */

 public class GetStep extends BaseStep {

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

     /**

      * Construct a default instance of this Step.

      */

     public GetStep() {

         super();

     }

     /**

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

      *

      * @param id Step identifier

      */

     public GetStep(String id) {

         super();

         setId(id);

     }

     /**

      * Construct a fully configured instance of this Step.

      *

      * @param id Step identifier

      * @param url Resource url

      */

     public GetStep(String id, String url) {

         super();

         setId(id);

         setUrl(url);

     }

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

     /**

      * The URL of the resource to be retrieved.

      */

     protected String url = null;

     public String getUrl() {

         return (this.url);

     }

     public void setUrl(String url) {

         this.url = url;

     }

     // --------------------------------------------------------- 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 {

         // Get the remote URL we will be contacting

         Object remote = this.url;

         URL remoteURL = null;

         if (remote == null) {

             try {

                 remote = (String) context.pop();

             } catch (EmptyStackException e) {

                 throw new StepException("Evaluation stack is empty", this);

             }

         }

         if (remote instanceof URL) {

             remoteURL = (URL) remote;

         } else if (remote instanceof String) {

             try {

                 remoteURL = new URL((String) remote);

             } catch (MalformedURLException e) {

                 throw new StepException("Invalid URL '" + remote + "'",

                                         e, this);

             }

         } else {

             try {

                 remoteURL = new URL(remote.toString());

             } catch (MalformedURLException e) {

                 throw new StepException("Invalid URL '" + remote + "'",

                                         e, this);

             }

         }

         // Define variables we will need later

         URLConnection conn = null;

         InputStream is = null;

         BufferedInputStream bis = null;

         InputStreamReader isr = null;

         StringBuffer sb = null;

         StepException se = null;

         try {

             // Open a connection to the specified URL

             conn = remoteURL.openConnection();

             conn.setDoInput(true);

             conn.setDoOutput(false);

             conn.connect();

             int contentLength = conn.getContentLength();

             if (contentLength < 2048)

                 contentLength = 2048;

             sb = new StringBuffer(contentLength);

             // Parse the character encoding to be used

             String contentType = conn.getContentType();

             String encoding =

                 WorkflowUtils.parseCharacterEncoding(contentType);

             // Construct a suitable InputStreamReader

             is = conn.getInputStream();

             bis = new BufferedInputStream(is, 2048);

             if (encoding == null)

                 isr = new InputStreamReader(bis);

             else

                 isr = new InputStreamReader(bis, encoding);

             // Copy all characters from this resource

             while (true) {

                 int ch = isr.read();

                 if (ch < 0)

                     break;

                 sb.append((char) ch);

             }

             // Close the input file

             isr.close();

             isr = null;

             bis = null;

             is = null;

         } catch (IOException e) {

             se = new StepException("IOException processing '" + remoteURL +

                                    "'", e, this);

         } finally {

             if (isr != null) {

                 try {

                     isr.close();

                 } catch (Throwable t) {

                     ;

                 }

             } else if (bis != null) {

                 try {

                     bis.close();

                 } catch (Throwable t) {

                     ;

                 }

             } else if (is != null) {

                 try {

                     is.close();

                 } catch (Throwable t) {

                     ;

                 }

             }

         }

         // Push results or throw exception as appropriate

         if (se != null)

             throw se;

         context.push(sb.toString());

     }

 }