package fr.ifremer.tutti.persistence;
   
   /*
    * #%L
    * Tutti :: Persistence
    * %%
    * Copyright (C) 2012 - 2014 Ifremer
    * %%
    * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as
   * published by the Free Software Foundation, either version 3 of the 
   * License, or (at your option) any later version.
   * 
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   * 
   * You should have received a copy of the GNU General Public 
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/gpl-3.0.html>.
   * #L%
   */
  
  import com.google.common.base.Preconditions;
  import com.google.common.base.Predicate;
  import com.google.common.base.Predicates;
  import com.google.common.collect.Lists;
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.nuiton.jaxx.application.ApplicationIOUtil;
  import org.nuiton.jaxx.application.ApplicationTechnicalException;
  
  import java.io.File;
  import java.io.IOException;
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.Enumeration;
  import java.util.List;
  
  import static org.nuiton.i18n.I18n.t;
  
  /**
   * A class loader that search first in a given directory before in parent
   * class loader.
   *
   * @author Tony Chemit - chemit@codelutin.com
   * @since 0.3
   */
  public class RessourceClassLoader extends ClassLoader {
  
      /** Logger. */
      private static final Log log =
              LogFactory.getLog(RessourceClassLoader.class);
  
      public static final URL[] EMPTY_URL_ARRAY = new URL[0];
  
      protected URLClassLoader loader;
  
      protected Predicate<String> searchInDirectoriesPredicate;
  
      protected final List<File> directories;
  
      public RessourceClassLoader(ClassLoader parent) {
          super(parent);
  
          // by default try in directories if there is some
          this.searchInDirectoriesPredicate = new Predicate<String>() {
              @Override
              public boolean apply(String input) {
                  return !directories.isEmpty();
              }
          };
          directories = Lists.newArrayList();
          loader = URLClassLoader.newInstance(EMPTY_URL_ARRAY);
      }
  
      public void addDirectory(File... directories) {
          for (File directory : directories) {
              if (!this.directories.contains(directory)) {
                  this.directories.add(directory);
  
                  // force to create directory
                  ApplicationIOUtil.forceMkdir(directory, t("tutti.io.mkDir.error", directory));
              }
          }
          loader = null;
      }
  
      public void removeDirectory(File... directories) {
          for (File directory : directories) {
              this.directories.remove(directory);
          }
          loader = null;
      }
  
      public Predicate<String> getSearchInDirectoriesPredicate() {
          return searchInDirectoriesPredicate;
     }
 
     public void addSearchInDirectoriesPredicate(Predicate<String> predicate) {
         Preconditions.checkNotNull(predicate,
                                    "search predicate can not be null");
         this.searchInDirectoriesPredicate =
                 Predicates.and(searchInDirectoriesPredicate, predicate);
     }
 
     public void setSearchInDirectoriesPredicate(Predicate<String> searchInDirectoriesPredicate) {
         Preconditions.checkNotNull(searchInDirectoriesPredicate,
                                    "search predicate can not be null");
         this.searchInDirectoriesPredicate = searchInDirectoriesPredicate;
     }
 
     @Override
     public URL findResource(String name) {
         URL result = null;
         if (searchInDirectoriesPredicate.apply(name)) {
             if (log.isDebugEnabled()) {
                 log.debug("findResource [" + name + "] in " + directories);
             }
             result = getLoader().findResource(name);
         }
         if (result == null) {
             result = super.findResource(name);
         }
         return result;
     }
 
     @Override
     public Enumeration<URL> findResources(String name) throws IOException {
         Enumeration<URL> result = null;
         if (searchInDirectoriesPredicate.apply(name)) {
             if (log.isDebugEnabled()) {
                 log.debug("findResources [" + name + "] in " + directories);
             }
             result = getLoader().findResources(name);
         }
         if (result == null || !result.hasMoreElements()) {
             result = super.findResources(name);
         }
         return result;
     }
 
     @Override
     public URL getResource(String name) {
         URL result = null;
         if (searchInDirectoriesPredicate.apply(name)) {
             if (log.isDebugEnabled()) {
                 log.debug("getResource [" + name + "] in " +
                           directories);
             }
             result = getLoader().getResource(name);
         }
         if (result == null) {
             result = super.getResource(name);
         }
         return result;
     }
 
     @Override
     public Enumeration<URL> getResources(String name) throws IOException {
         Enumeration<URL> result = null;
         if (searchInDirectoriesPredicate.apply(name)) {
             if (log.isDebugEnabled()) {
                 log.debug("getResources [" + name + "] in " + directories);
             }
             result = getLoader().getResources(name);
         }
         if (result == null || !result.hasMoreElements()) {
             result = super.getResources(name);
         }
         return result;
     }
 
     protected URLClassLoader getLoader() {
         if (loader == null) {
             try {
                 URL[] urls = FileUtils.toURLs(
                         directories.toArray(new File[directories.size()]));
                 loader = URLClassLoader.newInstance(urls, null);
             } catch (IOException e) {
                 throw new ApplicationTechnicalException(t("tutti.persistence.loader.error", directories), e);
             }
         }
         return loader;
     }
 }