import java.util.*;

class URIParser {
  
  private static Vector Tokenize(String s, String delim) {
    
    StringTokenizer st = new StringTokenizer(s, delim);
    Vector v = new Vector();
    
    while (st.hasMoreTokens()) 
      v.add(st.nextToken());
    return v;
  }

  public URI parseResource(String s) 
    throws URLParseException {
    
    if (s.indexOf("?") > 0) {

      Vector v = Tokenize(s, "?");
      if (v.size() != 2)
	throw new URLParseException("parseResource detected a syntax error: "+s);

      return new URI((String) v.elementAt(0), parseArguments((String) v.elementAt(1)));
    }
    else
      return new URI(s);
  }

  public Hashtable parseArguments(String s) 
    throws URLParseException {
    
    Vector args = Tokenize(s, "&");
    Hashtable h = new Hashtable();

    for (Enumeration e = args.elements(); e.hasMoreElements();) {
      String arg = (String) e.nextElement();
      if (arg.indexOf("=") > 0) {
	Vector v = Tokenize(arg, "=");
	if (v.size() != 2)
	  throw new URLParseException("parseArguments detected a syntax error: "+arg);
	h.put(v.elementAt(0), decodeArgument((String)v.elementAt(1)));
      }
      else
	h.put(arg, "");
    }

    return h;
  }

  private String decodeArgument(String s)
    throws URLParseException {

    String t = new String();
    int i,j=0;

    for (i = s.indexOf("%"); (i < s.length()) && (i > 0);) {
      if (i+3 > s.length())
	throw new URLParseException("decodeArgument detected a syntax error: "+s);
      else {
	try {
	  String code = s.substring(i,i+3).trim();
	  Integer intcode = new Integer(0);
	  code = code.replace('%','#');
	  intcode = intcode.decode(code);
	  t = t+s.substring(j,i)+(char)intcode.intValue();
	}
	catch (NumberFormatException nf) {
	  throw new URLParseException("decodeArgument detected a syntax error (number format): "
				      +nf.getMessage());
	}
      }
      j=i+3;
      i = s.indexOf("%", i+1);
    }
    t = t+s.substring(j,s.length());
    t = t.replace('+',' ');
    return t;
  }
}