package org.apache.turbine.services.velocity;
   
   /*
    * 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.
   */
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.Writer;
  
  import java.util.Iterator;
  import java.util.List;
  import java.util.Vector;
  
  import javax.servlet.ServletConfig;
  
  import org.apache.commons.collections.ExtendedProperties;
  import org.apache.commons.configuration.Configuration;
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  import org.apache.velocity.VelocityContext;
  import org.apache.velocity.app.Velocity;
  import org.apache.velocity.app.event.EventCartridge;
  import org.apache.velocity.app.event.MethodExceptionEventHandler;
  import org.apache.velocity.context.Context;
  import org.apache.velocity.runtime.log.SimpleLog4JLogSystem;
  
  import org.apache.turbine.Turbine;
  import org.apache.turbine.services.InitializationException;
  import org.apache.turbine.services.pull.PullService;
  import org.apache.turbine.services.pull.TurbinePull;
  import org.apache.turbine.services.template.BaseTemplateEngineService;
  import org.apache.turbine.util.RunData;
  import org.apache.turbine.util.TurbineException;
  
  /***
   * This is a Service that can process Velocity templates from within a
   * Turbine Screen. It is used in conjunction with the templating service
   * as a Templating Engine for templates ending in "vm". It registers
   * itself as translation engine with the template service and gets
   * accessed from there. After configuring it in your properties, it
   * should never be necessary to call methods from this service directly.
   *
   * Here's an example of how you might use it from a
   * screen:<br>
   *
   * <code>
   * Context context = TurbineVelocity.getContext(data);<br>
   * context.put("message", "Hello from Turbine!");<br>
   * String results = TurbineVelocity.handleRequest(context,"helloWorld.vm");<br>
   * data.getPage().getBody().addElement(results);<br>
   * </code>
   *
   * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
   * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
   * @author <a href="mailto:jvanzyl@periapt.com">Jason van Zyl</a>
   * @author <a href="mailto:sean@informage.ent">Sean Legassick</a>
   * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
   * @version $Id: TurbineVelocityService.java 534527 2007-05-02 16:10:59Z tv $
   */
  public class TurbineVelocityService
          extends BaseTemplateEngineService
          implements VelocityService,
                     MethodExceptionEventHandler
  {
      /*** The generic resource loader path property in velocity.*/
      private static final String RESOURCE_LOADER_PATH = ".resource.loader.path";
  
      /*** Default character set to use if not specified in the RunData object. */
      private static final String DEFAULT_CHAR_SET = "ISO-8859-1";
  
      /*** The prefix used for URIs which are of type <code>jar</code>. */
      private static final String JAR_PREFIX = "jar:";
  
      /*** The prefix used for URIs which are of type <code>absolute</code>. */
      private static final String ABSOLUTE_PREFIX = "file://";
  
      /*** Logging */
      private static Log log = LogFactory.getLog(TurbineVelocityService.class);
 
     /*** Is the pullModelActive? */
     private boolean pullModelActive = false;
 
     /*** Shall we catch Velocity Errors and report them in the log file? */
     private boolean catchErrors = true;
 
     /*** Internal Reference to the pull Service */
     private PullService pullService = null;
 
 
     /***
      * Load all configured components and initialize them. This is
      * a zero parameter variant which queries the Turbine Servlet
      * for its config.
      *
      * @throws InitializationException Something went wrong in the init
      *         stage
      */
     public void init()
             throws InitializationException
     {
         try
         {
             initVelocity();
 
             // We can only load the Pull Model ToolBox
             // if the Pull service has been listed in the TR.props
             // and the service has successfully been initialized.
             if (TurbinePull.isRegistered())
             {
                 pullModelActive = true;
 
                 pullService = TurbinePull.getService();
 
                 log.debug("Activated Pull Tools");
             }
 
             // Register with the template service.
             registerConfiguration(VelocityService.VELOCITY_EXTENSION);
 
             setInit(true);
         }
         catch (Exception e)
         {
             throw new InitializationException(
                 "Failed to initialize TurbineVelocityService", e);
         }
     }
 
 
     /***
      * Inits the service using servlet parameters to obtain path to the
      * configuration file.
      *
      * @param config The ServletConfiguration from Turbine
      *
      * @throws InitializationException Something went wrong when starting up.
      * @deprecated use init() instead.
      */
     public void init(ServletConfig config)
             throws InitializationException
     {
         init();
     }
 
 
     /***
      * Create a Context object that also contains the globalContext.
      *
      * @return A Context object.
      */
     public Context getContext()
     {
         Context globalContext =
                 pullModelActive ? pullService.getGlobalContext() : null;
 
         Context ctx = new VelocityContext(globalContext);
         return ctx;
     }
 
     /***
      * This method returns a new, empty Context object.
      *
      * @return A Context Object.
      */
     public Context getNewContext()
     {
         Context ctx = new VelocityContext();
 
         // Attach an Event Cartridge to it, so we get exceptions
         // while invoking methods from the Velocity Screens
         EventCartridge ec = new EventCartridge();
         ec.addEventHandler(this);
         ec.attachToContext(ctx);
         return ctx;
     }
 
     /***
      * MethodException Event Cartridge handler
      * for Velocity.
      *
      * It logs an execption thrown by the velocity processing
      * on error level into the log file
      *
      * @param clazz The class that threw the exception
      * @param method The Method name that threw the exception
      * @param e The exception that would've been thrown
      * @return A valid value to be used as Return value
      * @throws Exception We threw the exception further up
      */
     public Object methodException(Class clazz, String method, Exception e)
             throws Exception
     {
         log.error("Class " + clazz.getName() + "." + method + " threw Exception", e);
 
         if (!catchErrors)
         {
             throw e;
         }
 
         return "[Turbine caught an Error here. Look into the turbine.log for further information]";
     }
 
     /***
      * Create a Context from the RunData object.  Adds a pointer to
      * the RunData object to the VelocityContext so that RunData
      * is available in the templates.
      *
      * @param data The Turbine RunData object.
      * @return A clone of the WebContext needed by Velocity.
      */
     public Context getContext(RunData data)
     {
         // Attempt to get it from the data first.  If it doesn't
         // exist, create it and then stuff it into the data.
         Context context = (Context)
             data.getTemplateInfo().getTemplateContext(VelocityService.CONTEXT);
 
         if (context == null)
         {
             context = getContext();
             context.put(VelocityService.RUNDATA_KEY, data);
 
             if (pullModelActive)
             {
                 // Populate the toolbox with request scope, session scope
                 // and persistent scope tools (global tools are already in
                 // the toolBoxContent which has been wrapped to construct
                 // this request-specific context).
                 pullService.populateContext(context, data);
             }
 
             data.getTemplateInfo().setTemplateContext(
                 VelocityService.CONTEXT, context);
         }
         return context;
     }
 
     /***
      * Process the request and fill in the template with the values
      * you set in the Context.
      *
      * @param context  The populated context.
      * @param filename The file name of the template.
      * @return The process template as a String.
      *
      * @throws TurbineException Any exception trown while processing will be
      *         wrapped into a TurbineException and rethrown.
      */
     public String handleRequest(Context context, String filename)
         throws TurbineException
     {
         String results = null;
         ByteArrayOutputStream bytes = null;
         OutputStreamWriter writer = null;
         String charset = getCharSet(context);
 
         try
         {
             bytes = new ByteArrayOutputStream();
 
             writer = new OutputStreamWriter(bytes, charset);
 
             executeRequest(context, filename, writer);
             writer.flush();
             results = bytes.toString(charset);
         }
         catch (Exception e)
         {
             renderingError(filename, e);
         }
         finally
         {
             try
             {
                 if (bytes != null)
                 {
                     bytes.close();
                 }
             }
             catch (IOException ignored)
             {
                 // do nothing.
             }
         }
         return results;
     }
 
     /***
      * Process the request and fill in the template with the values
      * you set in the Context.
      *
      * @param context A Context.
      * @param filename A String with the filename of the template.
      * @param output A OutputStream where we will write the process template as
      * a String.
      *
      * @throws TurbineException Any exception trown while processing will be
      *         wrapped into a TurbineException and rethrown.
      */
     public void handleRequest(Context context, String filename,
                               OutputStream output)
             throws TurbineException
     {
         String charset  = getCharSet(context);
         OutputStreamWriter writer = null;
 
         try
         {
             writer = new OutputStreamWriter(output, charset);
             executeRequest(context, filename, writer);
         }
         catch (Exception e)
         {
             renderingError(filename, e);
         }
         finally
         {
             try
             {
                 if (writer != null)
                 {
                     writer.flush();
                 }
             }
             catch (Exception ignored)
             {
                 // do nothing.
             }
         }
     }
 
 
     /***
      * Process the request and fill in the template with the values
      * you set in the Context.
      *
      * @param context A Context.
      * @param filename A String with the filename of the template.
      * @param writer A Writer where we will write the process template as
      * a String.
      *
      * @throws TurbineException Any exception trown while processing will be
      *         wrapped into a TurbineException and rethrown.
      */
     public void handleRequest(Context context, String filename, Writer writer)
             throws TurbineException
     {
         try
         {
             executeRequest(context, filename, writer);
         }
         catch (Exception e)
         {
             renderingError(filename, e);
         }
         finally
         {
             try
             {
                 if (writer != null)
                 {
                     writer.flush();
                 }
             }
             catch (Exception ignored)
             {
                 // do nothing.
             }
         }
     }
 
 
     /***
      * Process the request and fill in the template with the values
      * you set in the Context. Apply the character and template
      * encodings from RunData to the result.
      *
      * @param context A Context.
      * @param filename A String with the filename of the template.
      * @param writer A OutputStream where we will write the process template as
      * a String.
      *
      * @throws Exception A problem occured.
      */
     private void executeRequest(Context context, String filename,
                                 Writer writer)
             throws Exception
     {
         String encoding = getEncoding(context);
 
         if (encoding != null)
         {
             Velocity.mergeTemplate(filename, encoding, context, writer);
         }
         else
         {
             Velocity.mergeTemplate(filename, context, writer);
         }
     }
 
     /***
      * Retrieve the required charset from the Turbine RunData in the context
      *
      * @param context A Context.
      * @return The character set applied to the resulting String.
      */
     private String getCharSet(Context context)
     {
         String charset = null;
 
         Object data = context.get(VelocityService.RUNDATA_KEY);
         if ((data != null) && (data instanceof RunData))
         {
             charset = ((RunData) data).getCharSet();
         }
 
         return (StringUtils.isEmpty(charset)) ? DEFAULT_CHAR_SET : charset;
     }
 
     /***
      * Retrieve the required encoding from the Turbine RunData in the context
      *
      * @param context A Context.
      * @return The encoding applied to the resulting String.
      */
     private String getEncoding(Context context)
     {
         String encoding = null;
 
         Object data = context.get(VelocityService.RUNDATA_KEY);
         if ((data != null) && (data instanceof RunData))
         {
             encoding = ((RunData) data).getTemplateEncoding();
         }
 
         return encoding;
     }
 
     /***
      * Macro to handle rendering errors.
      *
      * @param filename The file name of the unrenderable template.
      * @param e        The error.
      *
      * @exception TurbineException Thrown every time.  Adds additional
      *                             information to <code>e</code>.
      */
     private static void renderingError(String filename, Exception e)
             throws TurbineException
     {
         String err = "Error rendering Velocity template: " + filename;
         log.error(err, e);
         throw new TurbineException(err, e);
     }
 
     /***
      * Setup the velocity runtime by using a subset of the
      * Turbine configuration which relates to velocity.
      *
      * @exception Exception An Error occured.
      */
     private synchronized void initVelocity()
         throws Exception
     {
         // Get the configuration for this service.
         Configuration conf = getConfiguration();
 
         catchErrors = conf.getBoolean(CATCH_ERRORS_KEY, CATCH_ERRORS_DEFAULT);
 
         conf.setProperty(Velocity.RUNTIME_LOG_LOGSYSTEM_CLASS,
                 SimpleLog4JLogSystem.class.getName());
         conf.setProperty(Velocity.RUNTIME_LOG_LOGSYSTEM
                 + ".log4j.category", "velocity");
 
         Velocity.setExtendedProperties(createVelocityProperties(conf));
         Velocity.init();
     }
 
 
     /***
      * This method generates the Extended Properties object necessary
      * for the initialization of Velocity. It also converts the various
      * resource loader pathes into webapp relative pathes. It also
      *
      * @param conf The Velocity Service configuration
      *
      * @return An ExtendedProperties Object for Velocity
      *
      * @throws Exception If a problem occured while converting the properties.
      */
 
     public ExtendedProperties createVelocityProperties(Configuration conf)
             throws Exception
     {
         // This bugger is public, because we want to run some Unit tests
         // on it.
 
         ExtendedProperties veloConfig = new ExtendedProperties();
 
         // Fix up all the template resource loader pathes to be
         // webapp relative. Copy all other keys verbatim into the
         // veloConfiguration.
 
         for (Iterator i = conf.getKeys(); i.hasNext();)
         {
             String key = (String) i.next();
             if (!key.endsWith(RESOURCE_LOADER_PATH))
             {
                 Object value = conf.getProperty(key);
 
                 // Since 1.0-pre-something, Commons Collections suddently
                 // no longer returns a vector for multiple value-keys but a
                 // List object. Velocity will choke if we add this object because
                 // org.apache.commons.collections.ExtendedProperties expect a
                 // Vector object. Ah, the joys of incompatible class changes,
                 // unwritten assumptions and general Java JAR Hell... =8-O
                 if (value instanceof List)
                 {
                     List srcValue = (List) value;
                     Vector targetValue = new Vector(srcValue.size());
 
                     for (Iterator it = srcValue.iterator(); it.hasNext(); )
                     {
                         targetValue.add(it.next());
                     }
 
                     veloConfig.addProperty(key, targetValue);
                 }
                 else
                 {
                     veloConfig.addProperty(key, value);
                 }
 
                 continue; // for()
             }
 
             List paths = conf.getList(key, null);
             if (paths == null)
             {
                 // We don't copy this into VeloProperties, because
                 // null value is unhealthy for the ExtendedProperties object...
                 continue; // for()
             }
 
             Velocity.clearProperty(key);
 
             // Translate the supplied pathes given here.
             // the following three different kinds of
             // pathes must be translated to be webapp-relative
             //
             // jar:file://path-component!/entry-component
             // file://path-component
             // path/component
 
             for (Iterator j = paths.iterator(); j.hasNext();)
             {
                 String path = (String) j.next();
 
                 log.debug("Translating " + path);
 
                 if (path.startsWith(JAR_PREFIX))
                 {
                     // skip jar: -> 4 chars
                     if (path.substring(4).startsWith(ABSOLUTE_PREFIX))
                     {
                         // We must convert up to the jar path separator
                         int jarSepIndex = path.indexOf("!/");
 
                         // jar:file:// -> skip 11 chars
                         path = (jarSepIndex < 0)
                             ? Turbine.getRealPath(path.substring(11))
                         // Add the path after the jar path separator again to the new url.
                             : (Turbine.getRealPath(path.substring(11, jarSepIndex)) + path.substring(jarSepIndex));
 
                         log.debug("Result (absolute jar path): " + path);
                     }
                 }
                 else if (path.startsWith(ABSOLUTE_PREFIX))
                 {
                     // skip file:// -> 7 chars
                     path = Turbine.getRealPath(path.substring(7));
 
                     log.debug("Result (absolute URL Path): " + path);
                 }
                 // Test if this might be some sort of URL that we haven't encountered yet.
                 else if (path.indexOf("://") < 0)
                 {
                     path = Turbine.getRealPath(path);
 
                     log.debug("Result (normal fs reference): " + path);
                 }
 
                 log.debug("Adding " + key + " -> " + path);
                 // Re-Add this property to the configuration object
                 veloConfig.addProperty(key, path);
             }
         }
         return veloConfig;
     }
 
     /***
      * Find out if a given template exists. Velocity
      * will do its own searching to determine whether
      * a template exists or not.
      *
      * @param template String template to search for
      * @return True if the template can be loaded by Velocity
      */
     public boolean templateExists(String template)
     {
         return Velocity.templateExists(template);
     }
 
     /***
      * Performs post-request actions (releases context
      * tools back to the object pool).
      *
      * @param context a Velocity Context
      */
     public void requestFinished(Context context)
     {
         if (pullModelActive)
         {
             pullService.releaseTools(context);
         }
     }
 }