package org.naftulin.configmgr.parsers;
   
   import java.beans.IntrospectionException;
   import java.io.IOException;
   import java.net.URL;
   
   import org.apache.commons.betwixt.io.BeanReader;
   import org.apache.log4j.Logger;
   import org.naftulin.configmgr.ConfigurationManagementEntryImpl;
  import org.naftulin.configmgr.ConfigurationManagerException;
  import org.naftulin.configmgr.ConfigurationManagementEntry;
  import org.naftulin.configmgr.ConfigurationType;
  import org.xml.sax.SAXException;
  
  /***
   * Configuration entry parser converts xml configuration record into supplied class instance configuration management entry.
   * It parses the property file that the record describes, and stores the configuration
   * as a properties in content of an {@link org.naftulin.configmgr.ConfigurationManagementEntry entry}.
   * 
   * @author Henry Naftulin
   * @since 1.0
   */
  public class XmlFileParserImpl implements ConfigEntryParser {
  	private static final long serialVersionUID = 1L;
  	private static final Logger log = Logger.getLogger(XmlFileParserImpl.class);
  	private final String className;
  	
  	public XmlFileParserImpl(final String className) {
  		this.className = className;
  	}
  	
  	/***
  	 * Returns configuration management entry by parsing the record passed in.
  	 * Note xml file has to match the class passed in, per betwix specfications. 
  	 * @param key the key configuration entry will be assigned
  	 * @param fileUrl the file URL to be parsed.
  	 * @return a configuration managment entry by parsing the record passed in.
  	 * @throws ConfigurationManagerException if an error occurs while parsing an entry.
  	 */
  	public ConfigurationManagementEntry getConfigurationManagementEntry(final String key, 
  			final URL fileUrl) throws ConfigurationManagerException {
  		validateParameters(key, fileUrl);
  		Class<Object> beanClass;
  		
  		try {
  			beanClass = (Class<Object>) Class.forName(className);
  		} catch (ClassNotFoundException e) {
  			throw new ConfigurationManagerException("className " + className + " could not be found in the classpath.", e);
  		}
  		
  		final String fileName = fileUrl.getFile();
  		Object content = null;
  		try {
  			// Now convert this to a bean using betwixt
  	        // Create BeanReader
  	        final BeanReader beanReader  = new BeanReader();	        
  	        //beanReader.getXMLIntrospector().getConfiguration().setAttributesForPrimitives(false);
  	        //beanReader.getBindingConfiguration().setMapIDs(false);
  	        
  	        // Register beans so that betwixt knows what the xml is to be converted to
  	        // Since the element mapped to a PersonBean isn't called the same 
  	        // as Betwixt would have guessed, need to register the path as well
  	        log.debug("class name " + getSimpleName(beanClass));
  	        beanReader.registerBeanClass(getSimpleName(beanClass), beanClass);
  	        
  	        // Now we parse the xml
  	        content =  beanReader.parse(fileUrl);
  	        
  	        // send bean to system out
  	        log.debug("xml object parsed by XML Parser is: " + content);
  		} catch (IOException e) {
  			log.warn("Error while reading property file", e);
  			throw new ConfigurationManagerException("Error while reading property file",e);
  		} catch (IntrospectionException e) {
  			log.warn("Error while parsing xml.", e);
  			throw new ConfigurationManagerException("Error while parsing xml.",e);
  		} catch (SAXException e) {
  			log.warn("Error while parsing xml.", e);
  			throw new ConfigurationManagerException("Error while parsing xml.",e);
  		}
  		ConfigurationManagementEntry entry = new ConfigurationManagementEntryImpl(key, fileName, content, this, ConfigurationType.XML);
  		
  		return entry;
  	}
  
  	private void validateParameters(final String key, final URL fileUrl)
  			throws ConfigurationManagerException {
  		if (fileUrl == null) {
  			throw new ConfigurationManagerException("file URL is null");
  		}
  		if (fileUrl.getFile() == null) {
  			throw new ConfigurationManagerException("file name passed in the URL " + fileUrl + " is null");
  		}
  		if (key == null) { 
  			throw new ConfigurationManagerException("key is null for file " + fileUrl );
  		}
  		if (className == null) { 
  			throw new ConfigurationManagerException("className is null for file " + fileUrl + " and key " + key );
  		}
 	}
 	
 	/***
 	 * Immitates the JDK 1.5 API to get the simple class name. Class is not null.
 	 * @param cl class
 	 * @return simple class name as defined in JDK 1.5
 	 */
 	private String getSimpleName(final Class<Object> cl) {
 		final int lastDot = cl.getName().lastIndexOf(".");
 		return cl.getName().substring(lastDot +1);
 	}
 	/***
 	 * Returns a string representation of this parser.
 	 * @return a string representation of this parser.
 	 */
 	public String toString() {
 		return "Xml file parser";
 	}
 }