/*
 * QName.java
 * Copyright (C) 2004 The Free Software Foundation
 * 
 * This file is part of GNU JAXP, a library.
 *
 * GNU JAXP is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU JAXP is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Linking this library statically or dynamically with other modules is
 * making a combined work based on this library.  Thus, the terms and
 * conditions of the GNU General Public License cover the whole
 * combination.
 *
 * As a special exception, the copyright holders of this library give you
 * permission to link this library with independent modules to produce an
 * executable, regardless of the license terms of these independent
 * modules, and to copy and distribute the resulting executable under
 * terms of your choice, provided that you also meet, for each linked
 * independent module, the terms and conditions of the license of that
 * module.  An independent module is a module which is not derived from
 * or based on this library.  If you modify this library, you may extend
 * this exception to your version of the library, but you are not
 * obliged to do so.  If you do not wish to do so, delete this
 * exception statement from your version. 
 */

package javax.xml.namespace;

import javax.xml.XMLConstants;

/**
 * An XML
 * <a href='http://www.w3.org/TR/REC-xml-names/#ns-qualnames'>qualified name</a>.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 * @since 1.3
 */
public class QName
{

  private final String namespaceURI;
  private final String localPart;
  private final String prefix;
  private final String qName;
  int hashCode = -1;

  public QName(String namespaceURI, String localPart)
  {
    this(namespaceURI, localPart, null);
  }

  public QName(String namespaceURI, String localPart, String prefix)
  {
    if (namespaceURI == null)
      {
        namespaceURI = XMLConstants.NULL_NS_URI;
      }
    if (localPart == null)
      {
        throw new IllegalArgumentException();
      }
    if (prefix == null)
      {
        prefix = XMLConstants.DEFAULT_NS_PREFIX;
      }
    this.namespaceURI = namespaceURI;
    this.localPart = localPart;
    this.prefix = prefix;
    
    StringBuffer buf = new StringBuffer();
    if (namespaceURI != null && namespaceURI.length() > 0)
      {
        buf.append('{');
        buf.append(namespaceURI);
        buf.append('}');
      }
    if (prefix != null && prefix.length() > 0)
      {
        buf.append(prefix);
        buf.append(':');
      }
    buf.append(localPart);
    qName = buf.toString();
  }

  public QName(String localPart)
  {
    this(null, localPart, null);
  }

  public String getNamespaceURI()
  {
    return namespaceURI;
  }

  public String getLocalPart()
  {
    return localPart;
  }

  public String getPrefix()
  {
    return prefix;
  }

  public boolean equals(Object obj)
  {
    if (obj instanceof QName)
      {
        QName qname = (QName) obj;
        return qname.getLocalPart().equals(localPart) &&
          qname.getNamespaceURI().equals(namespaceURI);
      }
    return false;
  }

  public final int hashCode()
  {
    if (hashCode == -1)
      {
        StringBuffer buf = new StringBuffer();
        buf.append('{');
        buf.append(namespaceURI);
        buf.append('}');
        buf.append(localPart);
        hashCode = buf.toString().hashCode();
      }
    return hashCode;
  }

  public String toString()
  {
    return qName;
  }

  public static QName valueOf(String qNameAsString)
  {
    String namespaceUri = "", prefix = null;
    int start = qNameAsString.indexOf('{');
    int end = qNameAsString.indexOf('}');
    if (start != -1)
      {
        if (end < start)
          {
            throw new IllegalArgumentException(qNameAsString);
          }
        namespaceUri = qNameAsString.substring(start + 1, end);
        qNameAsString = qNameAsString.substring(end + 1);
      }
    start = qNameAsString.indexOf(':');
    if (start != -1)
      {
        prefix = qNameAsString.substring(0, start);
        qNameAsString = qNameAsString.substring(start + 1);
      }
    return new QName(namespaceUri, qNameAsString, prefix);
  }
  
}