package org.lcsim.util.xml;
   
   import java.io.IOException;
   import java.io.InputStream;
   import java.net.URL;
   
   import org.xml.sax.EntityResolver;
   import org.xml.sax.InputSource;
   import org.xml.sax.SAXException;
  
  /**
   * Resolves URIs to class resources.
   * 
   * For instance, the URI <code>http://www.lcsim.org/example/example.txt</code> would 
   * be resolved to <code>org/lcsim/example/example.txt</code>.
   *
   * @author Jeremy McCormick
   * @version $Id: ClasspathEntityResolver.java,v 1.5 2010/04/14 17:12:08 jeremy Exp $
   */
  public class ClasspathEntityResolver
  implements EntityResolver
  {    	
      public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {                        
  
          //System.out.println("ClasspathEntityResolver.resolveEntity");
          //System.out.println("  publicId: " + publicId);
          //System.out.println("  systemId: " + systemId);
  	
      	URL url = new URL(systemId);
      	String[] hostTokens = url.getHost().split("\\.");
      	String org = "";
      	for (int i = hostTokens.length - 1; i >= 0; i--) {
      		if (!hostTokens[i].equals("www"))
      			org += "/" + hostTokens[i];
      	}
      	org = org.substring(1);
      	String fullpath = org + (new URL(systemId)).getPath();     
      		
      	InputStream in = this.getClass().getClassLoader().getResourceAsStream(fullpath);
          
          InputSource src = new InputSource(in);
          src.setSystemId(systemId);
          src.setPublicId(publicId);
          
          return src;
      }
  }