/*
    * Copyright 2007 Joachim Grueneis
    *
    * 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.exolab.castor.xml.util.resolvers;
  
  import java.util.Map;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.exolab.castor.mapping.ClassDescriptor;
  import org.exolab.castor.xml.ResolverException;
  import org.exolab.castor.xml.util.ResolverPackageCommand;
  import org.exolab.castor.xml.util.ResolverStrategy;
  
  /**
   * The abstract resolver command provides the argument checking, writes a debug message and reads
   * the class loader from the properties... All specific code is found in the extended classes.
   * 
   * @author Joachim Grueneis, jgrueneis AT gmail DOT com
   * @version $Id$
   * @since 1.2
   */
  public abstract class AbstractResolverPackageCommand implements ResolverPackageCommand {
  
    private static final Log LOG = LogFactory.getLog(AbstractResolverPackageCommand.class);
  
    /**
     * {@inheritDoc}
     */
    public final Map<String, ClassDescriptor> resolve(final String packageName, final Map properties)
        throws ResolverException {
      String pName;
      if ((packageName == null) || ("".equals(packageName))) {
        LOG.debug("Package name is empty! Anyhow, giving it a try...");
        pName = "";
      } else {
        pName = packageName;
      }
  
      if (LOG.isDebugEnabled()) {
        LOG.debug(
            "Now in resolve method: " + this.getClass().getName() + " resolving: " + packageName);
      }
  
      ClassLoader classLoader = (ClassLoader) properties.get(ResolverStrategy.PROPERTY_CLASS_LOADER);
      if (classLoader == null) {
        LOG.debug("No domain class loader set, taking it from class.getClassLoader().");
        classLoader = this.getClass().getClassLoader();
      }
      return internalResolve(pName, classLoader, properties);
    }
  
    /**
     * Is the given package name empty?
     * 
     * @param packageName the package name to check
     * @return true if the String is empty
     */
    protected final boolean isEmptyPackageName(final String packageName) {
      return ((packageName == null) || (packageName.length() == 0) || ("".equals(packageName)));
    }
  
  
    /**
     * The required parameter checks are in the public method and here we expect that the resolve
     * logic itself is implemented.
     * 
     * @param className the name of the class to resolve
     * @param classLoader the class loader to use
     * @param props the resolve properties to use
     * @return a Map of className and XMLClassDescriptor
     * @throws ResolverException in case of unrecoverable problems at resolving
     */
    protected abstract Map<String, ClassDescriptor> internalResolve(String packageName,
        ClassLoader classLoader, Map props) throws ResolverException;
  }