/*
    * 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.
   */
  package org.apache.commons.jci.stores;
  
  import org.apache.commons.jci.utils.ConversionUtils;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  
  /**
   * A ClassLoader backed by an array of ResourceStores
   * 
   * @author tcurdt
   */
  public final class ResourceStoreClassLoader extends ClassLoader {
  
      private final Log log = LogFactory.getLog(ResourceStoreClassLoader.class);
  
      private final ResourceStore[] stores;
  
      public ResourceStoreClassLoader( final ClassLoader pParent, final ResourceStore[] pStores ) {
          super(pParent);
          
          stores = new ResourceStore[pStores.length]; 
          System.arraycopy(pStores, 0, stores, 0, stores.length);	
      }
  
      private Class<?> fastFindClass(final String name) {
          
          if (stores != null) {
              for (ResourceStore store : stores) {
                  final byte[] clazzBytes = store.read(ConversionUtils.convertClassToResourcePath(name));
                  if (clazzBytes != null) {
                      log.debug(getId() + " found class: " + name  + " (" + clazzBytes.length + " bytes)");
                      return defineClass(name, clazzBytes, 0, clazzBytes.length);
                  }            
              }
          }
          
          return null;            
      }
      
      @Override
      protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
          // log.debug(getId() + " looking for: " + name);
          Class<?> clazz = findLoadedClass(name);
  
          if (clazz == null) {
              clazz = fastFindClass(name);
              
              if (clazz == null) {
  
                  final ClassLoader parent = getParent();
                  if (parent != null) {
                      clazz = parent.loadClass(name);
                      // log.debug(getId() + " delegating loading to parent: " + name);
                  } else {
                      throw new ClassNotFoundException(name);
                  }
                  
              } else {
                  log.debug(getId() + " loaded from store: " + name);
              }
          }
  
          if (resolve) {
              resolveClass(clazz);
          }
  
          return clazz;
      }
  
      @Override
      protected Class<?> findClass( final String name ) throws ClassNotFoundException {
          final Class<?> clazz = fastFindClass(name);
          if (clazz == null) {
              throw new ClassNotFoundException(name);
          }
          return clazz;
      }
      
      private String getId() {
          return "" + this + "[" + this.getClass().getClassLoader() + "]";
      }
  }