/**
    * $Id: AbstractConfigurationReader.java 17 2006-10-19 15:11:35Z maldito_orco $
    * $Revision: 17 $
    * $Date: 2006-10-19 12:11:35 -0300 (Thu, 19 Oct 2006) $
    *
    * =========================================================================
    *
    * Copyright 2005 Tubo
    *
   *  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.tubo.configuration.reader;
  
  //log
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  //tubo-configuration
  import org.tubo.configuration.def.Configuration;
  import org.tubo.configuration.def.IncludeDef;
  //tubo-configuration-default
  import org.tubo.configuration.def.baseimpl.BaseConfigurationImpl;
  //tubo-exception
  import org.tubo.exception.TuboConfigurationException;
  //net
  import java.net.URL;
  //io
  import java.io.Reader;
  import java.io.InputStreamReader;
  import java.io.IOException;
  //util
  import java.util.List;
  import java.util.Iterator;
  
  /**
   * Created: Jun 23, 2005 6:36:17 AM
   * Last Modification Date: $Date: 2006-10-19 12:11:35 -0300 (Thu, 19 Oct 2006) $
   *
   * @author jvlio (jvlio@users.sourceforge.net)
   * @version $Revision: 17 $
   */
  public abstract class AbstractConfigurationReader implements ConfigurationReader {
      public static final String RCS_ID = "$Id: AbstractConfigurationReader.java 17 2006-10-19 15:11:35Z maldito_orco $";
      private static Log log = LogFactory.getLog(AbstractConfigurationReader.class);
  
      private ClassLoader classLoader = null;
  
      /**
       *
       * @return
       */
      public ClassLoader getReaderClassLoader() {
          if (classLoader==null)
              classLoader = this.getClass().getClassLoader();
          return classLoader;
      }
  
      /**
       *
       * @param classLoader
       */
      public void setReaderClassLoader(ClassLoader classLoader) {
          this.classLoader = classLoader;
      }
  
  
      /**
       * Create a new Configuration Object based on resource configuration. This method use createEmptyConfigurationObject
       * to create a new Configuration implementation.
       *
       * @param resource Configuration Resource
       * @return A new configuration
       * @throws TuboConfigurationException If something occurs.
       */
      public Configuration load(String resource) throws TuboConfigurationException {
          Configuration config = createEmptyConfigurationObject();
          config = append(resource,config);
          return config;
      }
  
      /**
       * This method append configuration data stored on resource object to config object, replacing duplicated items.
       * @param resource A class loader resource. see ClassLoader.getResource()
       * @return config object with resource data append.
       * @throws TuboConfigurationException
       */
      public Configuration append(String resource, Configuration config) throws TuboConfigurationException {
          //
          // obtains resource url
          URL url = getReaderClassLoader().getResource(resource);
         //
         // check resource loading
         if (url == null) {
             log.fatal(".read() - Resource "+resource+" can't be found. Check your classpath.");
             throw new TuboConfigurationException("Resource "+resource+" can't be found.");
         }
         //
         // append url resource to configuration
         config = append(url, config);
         //
         // return configuration with appends
         return config;
     }
 
     /**
      * This method append configuration data linked by URL to config object, replacing duplicated items.
      * @param url Link to configuration data
      * @return config object with resource data append.
      * @throws TuboConfigurationException
      */
     public Configuration append(URL url, Configuration config) throws TuboConfigurationException {
         log.debug(".append() - Reading configuration from: "+url);
         Reader reader = null;
         try {
             //
             // create a reader for url
             reader = new InputStreamReader(url.openStream());
         } catch (IOException ex) {
             log.fatal(".read() - Error trying to open configuration from "+url,ex);
             throw new TuboConfigurationException("Error trying to open configuration from "+url);
         }
         //
         // reading master configuration
         config = append(reader,config);
         //
         // return configuration with appends
         return config;
     }
 
 
     /**
      * This method append configuration data stored in reader object to config object, replacing duplicated items.
      * @param reader
      * @param config
      * @return
      * @throws TuboConfigurationException
      */
     public Configuration append(Reader reader, Configuration config) throws TuboConfigurationException {
         //validate(reader);
         //
         // parse this resource and use config like new parsed config repository
         config = parse(reader, config);
         //
         // append configuration referenced by includeds
         config = recursiveIncludeAppend(config);
         //
         // return configuration
         return config;
     }
 
 
     /**
      *
      * @return
      */
     protected Configuration createEmptyConfigurationObject() {
         Configuration config = new BaseConfigurationImpl();
         return config;
     }
 
     /**
      *
      * @param config
      * @return
      * @throws TuboConfigurationException
      */
     protected Configuration recursiveIncludeAppend(Configuration config) throws TuboConfigurationException {
         //
         // get all includes in configuration
         List includeDefs = config.getIncludeDefs();
         //
         // iterate all elements
         for(Iterator it=includeDefs.iterator(); it.hasNext();) {
             //
             // obtains current element
             IncludeDef includeDef = (IncludeDef)it.next();
             //
             // if this include as bean proceced on previus step (remember is recursive), then leave this.
             if (!includeDef.isLoaded())  {
                 //
                 // obtain resource
                 String resource = includeDef.getResource();
                 //
                 // mark this include like loaded (because if not enter in infinite loop)
                 includeDef.setLoaded(true);
                 //
                 // append this resource to configuration
                 config = append(resource, config);
             }
         }
         //
         // return configuration with all includes included
         return config;
     }
 
     /**
      * Parse resource and fill configuration object.
      * @param reader Resource reader
      * @param config Configuration Repository
      * @return Return the same config object with configuration append.
      */
     protected abstract Configuration parse(Reader reader, Configuration config) throws TuboConfigurationException;
 
 }