/*
    * Copyright 2011 FatWire Corporation. All Rights Reserved.
    *
    * 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 com.fatwire.gst.foundation.groovy;
  
  import groovy.util.GroovyScriptEngine;
  import groovy.util.ResourceException;
  import groovy.util.ScriptException;
  
  import java.io.File;
  import java.io.FileFilter;
  import java.net.MalformedURLException;
  import java.net.URI;
  import java.net.URL;
  
  import javax.servlet.ServletContext;
  
  import org.apache.commons.lang.StringUtils;
  import org.apache.commons.logging.Log;
  import org.codehaus.groovy.control.CompilationFailedException;
  
  import com.fatwire.gst.foundation.facade.logging.LogUtil;
  
  /**
   * Loader for groovy script classes, configured via the ServletContext
   * 
   * @author Dolf Dijkstra
   * @since Mar 28, 2011
   */
  /*
   * alternative method:
   * http://groovy.codehaus.org/Alternate+Spring-Groovy-Integration
   */
  public class DiskGroovyLoader implements GroovyLoader {
  
      private Log logger = LogUtil.getLog(getClass());
      private GroovyScriptEngine groovyScriptEngine;
  
      private File scriptPath;
      private String configPath = "/WEB-INF/gsf-groovy";
      private int minimumRecompilationInterval = 0;
  
      public DiskGroovyLoader() {
          super();
  
      }
  
      public DiskGroovyLoader(ServletContext servletContext) {
          bootEngine(servletContext.getRealPath(configPath));
  
      }
  
      public void bootEngine(String path) {
          scriptPath = new File(path).getAbsoluteFile();
          scriptPath.mkdirs();
          if (!scriptPath.exists() || !scriptPath.isDirectory())
              throw new IllegalStateException("The realPath " + scriptPath + " is not a directory.");
          URI u = scriptPath.toURI();
          URL[] paths;
          try {
              paths = new URL[] { u.toURL() };
              groovyScriptEngine = new GroovyScriptEngine(paths, Thread.currentThread().getContextClassLoader());
              groovyScriptEngine.getConfig().setRecompileGroovySource(true);
              groovyScriptEngine.getConfig().setMinimumRecompilationInterval(minimumRecompilationInterval);
          } catch (MalformedURLException e) {
              throw new IllegalStateException("The realPath " + scriptPath + " can't be made into a URL. "
                      + e.getMessage(), e);
          }
  
      }
  
      @Override
      public Object load(final String name) throws Exception {
  
          Class<?> c;
          try {
              c = groovyScriptEngine.loadScriptByName(toScriptName(name));
          } catch (ResourceException e) {
  
              if (logger.isDebugEnabled())
                  logger.debug("GroovyScriptEngine was not able to load " + name + " as a script: " + e.getMessage()
                          + ". Now trying as a class.");
              String className = name.replace('/', '.');
              try {
                  c = groovyScriptEngine.getGroovyClassLoader().loadClass(className);
              } catch (ClassNotFoundException cnfe) {
                 if (logger.isDebugEnabled())
                     logger.debug("GroovyClassLoader was not able to load " + className + ": " + cnfe.getMessage()
                             + ". Aborting.");
                 return null;
 
             }
         }
 
         return c.newInstance();
     }
 
     protected String toScriptName(String name) {
         if (name.endsWith(".groovy")) {
             return StringUtils.removeEnd(name, ".groovy").replace('.', '/') + ".groovy";
         } else
             return name.replace('.', '/') + ".groovy";
     }
 
     protected String toClassName(String name) {
 
         return name.replace('/', '.').replace('\\', '.').substring(0, name.length() - 7);
     }
 
     public void precompile() {
         doDir(scriptPath);
 
     }
 
     protected void doDir(File dir) {
         File[] listFiles = dir.listFiles(new FileFilter() {
 
             @Override
             public boolean accept(File pathname) {
                 return pathname.isDirectory() || pathname.getName().endsWith(".groovy");
             }
 
         });
         for (File file : listFiles) {
             if (file.isDirectory()) {
                 doDir(file);
             } else {
                 String name = file.getAbsolutePath().substring(scriptPath.getAbsolutePath().length() + 1);
                 try {
 
                     groovyScriptEngine.loadScriptByName(name);
                 } catch (CompilationFailedException e) {
                     logger.warn(e.getMessage() + " on " + name + " during precompilation.");
                 } catch (ResourceException e) {
                     logger.warn(e.getMessage() + " on " + name + " during precompilation.");
                 } catch (ScriptException e) {
                     logger.warn(e.getMessage() + " on " + name + " during precompilation.");
                 }
             }
         }
     }
 
     /**
      * @return the configPath
      */
     public String getConfigPath() {
         return configPath;
     }
 
     /**
      * @param configPath the configPath to set
      */
     public void setConfigPath(String configPath) {
         this.configPath = configPath;
     }
 
     /**
      * @return the minimumRecompilationInterval
      */
     public int getMinimumRecompilationInterval() {
         return minimumRecompilationInterval;
     }
 
     /**
      * Sets the minimumRecompilationInterval of the GroovyScriptEngine
      * configuration.
      * 
      * @param minimumRecompilationInterval the minimumRecompilationInterval to
      *            set
      */
     public void setMinimumRecompilationInterval(int minimumRecompilationInterval) {
         this.minimumRecompilationInterval = minimumRecompilationInterval;
         GroovyScriptEngine g = getGroovyScriptEngine();
         if (g != null) {
             g.getConfig().setMinimumRecompilationInterval(minimumRecompilationInterval);
         }
     }
 
     public GroovyScriptEngine getGroovyScriptEngine() {
         return groovyScriptEngine;
     }
 
     public void setGroovyScriptEngine(GroovyScriptEngine groovyScrptEngine) {
         this.groovyScriptEngine = groovyScrptEngine;
     }
 
 }