package eu.simuline.util.sgml;
   
   import java.util.List;
   import java.util.ArrayList;
   
   import org.xml.sax.ContentHandler;
   import org.xml.sax.Locator;
   import org.xml.sax.SAXException;
  import org.xml.sax.Attributes;
  
  /**
   * Saves all events in a list to be returned by {@link #getEvents}. 
   *
   * @author <a href="mailto:ernst.reissner@simuline.eu">Ernst Reissner</a>
   * @version 1.0
   */
  public final class SavingHandler 
      implements ContentHandler, ParseExceptionHandler {
  
      /* --------------------------------------------------------------------- *
       * class constants                                                       *
       * --------------------------------------------------------------------- */
  
      public static final String START_OF_DOCUMENT = "start of document";
      public static final String   END_OF_DOCUMENT =   "end of document";
  
      /* --------------------------------------------------------------------- *
       * fields                                                                *
       * --------------------------------------------------------------------- */
  
      /**
       * The sequence of events taken place so far. 
       */
      private List<String> events;
  
      /**
       * Whether to save things like processing instructions as well. 
       */
      private boolean strict;
  
      /* --------------------------------------------------------------------- *
       * constructors                                                          *
       * --------------------------------------------------------------------- */
  
      /**
       * Creates a new <code>SavingHandler</code> instance.
       *
       * @param strict 
       *    a <code>boolean</code> value signifying 
       *    whether to save things like processing instructions as well. 
       */
      public SavingHandler(boolean strict) {
  	this.events = new ArrayList<String>();
  	this.strict = strict;
      }
  
      /**
       * Creates a new <code>SavingHandler</code>. 
       */
      public SavingHandler() {
  	this(true);
      }
  
  
      /* --------------------------------------------------------------------- *
       * methods                                                               *
       * --------------------------------------------------------------------- */
  
      /**
       * Returns the sequence of events taken place so far. 
       *
       * @return 
       *    {@link #events}. 
       */
      public List<String> getEvents() {
  	return this.events;
      }
  
      /* --------------------------------------------------------------------- *
       * methods implementing ContentHandler                                   *
       * --------------------------------------------------------------------- */
  
      public void setDocumentLocator(Locator locator) {
  	// is empty. 
      }
  
      public void startDocument() throws SAXException {
  	this.events.add(START_OF_DOCUMENT);
      }
  
      public void endDocument() throws SAXException {
  	this.events.add(END_OF_DOCUMENT);
      }
  
      public void startPrefixMapping(String prefix,
  				   String uri)
  	throws SAXException {
  	// is empty. 
     }
 
     public void endPrefixMapping(String prefix)
 	throws SAXException {
 	// is empty. 
     }
 
     public void startElement(String namespaceURI,
 			     String localName,
 			     String qName,
 			     Attributes atts)
 	throws SAXException {
 	this.events.add("TS<" + qName + ">");
     }
 
     public void endElement(String namespaceURI,
 			   String localName,
 			   String qName)
 	throws SAXException {
 	this.events.add("TE</" + qName + ">");
     }
 
     public void characters(char[] chr,
 			   int start,
 			   int length)
 	throws SAXException {
 	// is empty. 
     }
 
     public void ignorableWhitespace(char[] chr,
 				    int start,
 				    int length)
 	throws SAXException {
 	// is empty. 
     }
 
     public void processingInstruction(String target,
 				      String data)
 	throws SAXException {
 	if (this.strict) {
 	    this.events.add("PI<!" + target + ", " + data + ">");
 	}
 	//System.out.println("P<" + target + ">");
     }
 
     public void skippedEntity(String name)
 	throws SAXException {
 	// is empty. 
     }
 
     /* --------------------------------------------------------------------- *
      * methods implementing ParseExceptionHandler                            *
      * --------------------------------------------------------------------- */
 
     public void foundMultipleAttribute(String attrName,
 				       Object oldAttrValue) {
 	StringBuilder buf = new StringBuilder();
 	buf.append("Found second value for attribute \"");
 	buf.append(attrName);
 	buf.append("\"; overwritten ");
 	if (oldAttrValue == AttributesImpl.NO_VALUE) {
 	    buf.append("no value. ");
 	} else {
 	    buf.append("old value \"");
 	    buf.append(oldAttrValue);
 	    buf.append('\"');
 	}
 
 	this.events.add(buf.toString());
     }
 
 
     public void foundIllegalCharInTag(char chr) {
 	this.events.add("exc: ill letter in tag: " + chr);
     }
 
     public void foundCharAfterEndOfEndTag(char chr) {
 	this.events.add("exc: etter after eo EndTag: " + chr);
     }
 
     public void foundUnexpectedEndOfDocument() {
 	// is empty. 
     }
 } // class SavingHandler