/*
 * DomElement.java
 * Copyright (C) 1999,2000,2001,2004 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 gnu.xml.dom;

import java.util.HashSet;
import java.util.Set;
import javax.xml.XMLConstants;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.TypeInfo;

/**
 * <p> "Element" implementation.
 *
 * @author David Brownell 
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 */
public class DomElement
  extends DomNsNode
  implements Element
{

  /**
   * User-defined ID attributes.
   * Used by DomAttr.isId and DomDocument.getElementById
   */
  Set userIdAttrs;

  // Attributes are VERY expensive in DOM, and not just for
  // this implementation.  Avoid creating them.
  private DomNamedNodeMap attributes;

  // xml:space cache
  String xmlSpace = "";

  /**
   * Constructs an Element node associated with the specified document.
   *
   * <p>This constructor should only be invoked by a Document as part
   * of its createElement functionality, or through a subclass which is
   * similarly used in a "Sub-DOM" style layer.
   *
   * @param owner The document with which this node is associated
   * @param namespaceURI Combined with the local part of the name,
   *	this is used to uniquely identify a type of element
   * @param name Name of this element, which may include a prefix
   */
  protected DomElement(DomDocument owner, String namespaceURI, String name)
  {
    super(ELEMENT_NODE, owner, namespaceURI, name);
  }

  /**
   * <b>DOM L1</b>
   * Returns the element's attributes
   */
  public NamedNodeMap getAttributes()
  {
    if (attributes == null)
      {
        attributes = new DomNamedNodeMap(this, Node.ATTRIBUTE_NODE);
      }
    return attributes;
  }

  /**
   * <b>DOM L2></b>
   * Returns true iff this is an element node with attributes.
   */
  public boolean hasAttributes()
  {
    return attributes != null && attributes.length != 0;
  }

  /**
   * Shallow clone of the element, except that associated
   * attributes are (deep) cloned.
   */
  public Object clone()
  {
    DomElement node = (DomElement) super.clone();

    if (attributes != null)
      {
        node.attributes = new DomNamedNodeMap(node, Node.ATTRIBUTE_NODE);
        for (DomNode ctx = attributes.first; ctx != null; ctx = ctx.next)
          {
            node.attributes.setNamedItemNS(ctx.cloneNode(true));
          }
      }
    return node;
  }

  void setOwner(DomDocument doc)
  {
    if (attributes != null)
      {
        for (DomNode ctx = attributes.first; ctx != null; ctx = ctx.next)
          {
            ctx.setOwner(doc);
          }
      }
    super.setOwner(doc);
  }

  /**
   * Marks this element, its children, and its associated attributes as
   * readonly.
   */
  public void makeReadonly()
  {
    super.makeReadonly();
    if (attributes != null)
      {
        attributes.makeReadonly();
      }
  }

  /**
   * <b>DOM L1</b>
   * Returns the element name (same as getNodeName).
   */
  final public String getTagName()
  {
    return getNodeName();
  }

  /**
   * <b>DOM L1</b>
   * Returns the value of the specified attribute, or an
   * empty string.
   */
  public String getAttribute(String name)
  {
    if ("xml:space" == name) // NB only works on interned string
      {
        // Use cached value
        return xmlSpace;
      }
    Attr attr = getAttributeNode(name);
    return (attr == null) ? "" : attr.getValue();
  }

  /**
   * <b>DOM L2</b>
   * Returns true if the element has an attribute with the
   * specified name (specified or DTD defaulted).
   */
  public boolean hasAttribute(String name)
  {
    return getAttributeNode(name) != null;
  }

  /**
   * <b>DOM L2</b>
   * Returns true if the element has an attribute with the
   * specified name (specified or DTD defaulted).
   */
  public boolean hasAttributeNS(String namespaceURI, String local)
  {
    return getAttributeNodeNS(namespaceURI, local) != null;
  }

  /**
   * <b>DOM L2</b>
   * Returns the value of the specified attribute, or an
   * empty string.
   */
  public String getAttributeNS(String namespaceURI, String local)
  {
    Attr attr = getAttributeNodeNS(namespaceURI, local);
    return (attr == null) ? "" : attr.getValue();
  }

  /**
   * <b>DOM L1</b>
   * Returns the appropriate attribute node; the name is the
   * nodeName property of the attribute.
   */
  public Attr getAttributeNode(String name)
  {
    return (attributes == null) ? null :
      (Attr) attributes.getNamedItem(name);
  }

  /**
   * <b>DOM L2</b>
   * Returns the appropriate attribute node; the name combines
   * the namespace name and the local part.
   */
  public Attr getAttributeNodeNS(String namespace, String localPart)
  {
    return (attributes == null) ? null :
      (Attr) attributes.getNamedItemNS(namespace, localPart);
  }

  /**
   * <b>DOM L1</b>
   * Modifies an existing attribute to have the specified value,
   * or creates a new one with that value.  The name used is the
   * nodeName value. 
   */
  public void setAttribute(String name, String value)
  {
    Attr attr = getAttributeNode(name);
    if (attr != null)
      {
        attr.setNodeValue(value);
        ((DomAttr) attr).setSpecified(true);
        return;
      }
    attr = owner.createAttribute(name);
    attr.setNodeValue(value);
    setAttributeNode(attr);
  }

  /**
   * <b>DOM L2</b>
   * Modifies an existing attribute to have the specified value,
   * or creates a new one with that value.
   */
  public void setAttributeNS(String uri, String aname, String value)
  {
    if (("xmlns".equals (aname) || aname.startsWith ("xmlns:"))
        && !XMLConstants.XMLNS_ATTRIBUTE_NS_URI.equals (uri))
      {
        throw new DomEx(DomEx.NAMESPACE_ERR,
                        "setting xmlns attribute to illegal value", this, 0);
      }

    Attr attr = getAttributeNodeNS(uri, aname);
    if (attr != null)
      {
        attr.setNodeValue(value);
        return;
      }
    attr = owner.createAttributeNS(uri, aname);
    attr.setNodeValue(value);
    setAttributeNodeNS(attr);
  }

  /**
   * <b>DOM L1</b>
   * Stores the specified attribute, optionally overwriting any
   * existing one with that name.
   */
  public Attr setAttributeNode(Attr attr)
  {
    return (Attr) getAttributes().setNamedItem(attr);
  }

  /**
   * <b>DOM L2</b>
   * Stores the specified attribute, optionally overwriting any
   * existing one with that name.
   */
  public Attr setAttributeNodeNS(Attr attr)
  {
    return (Attr) getAttributes().setNamedItemNS(attr);
  }

  /**
   * <b>DOM L1</b>
   * Removes the appropriate attribute node.
   * If there is no such node, this is (bizarrely enough) a NOP so you
   * won't see exceptions if your code deletes non-existent attributes.
   *
   * <p>Note that since there is no portable way for DOM to record
   * DTD information, default values for attributes will never be
   * provided automatically.
   */
  public void removeAttribute(String name)
  {
    if (attributes == null)
      {
        return;
      }

    try
      {
        attributes.removeNamedItem(name);
      }
    catch (DomEx e)
      {
        if (e.code != DomEx.NOT_FOUND_ERR)
          {
            throw e;
          }
      }
  }

  /**
   * <b>DOM L1</b>
   * Removes the appropriate attribute node; the name is the
   * nodeName property of the attribute.
   *
   * <p>Note that since there is no portable way for DOM to record
   * DTD information, default values for attributes will never be
   * provided automatically.
   */
  public Attr removeAttributeNode(Attr node)
  {
    if (attributes == null)
      {
        throw new DomEx(DomEx.NOT_FOUND_ERR, null, node, 0);
      }
    return (Attr) attributes.removeNamedItem(node.getNodeName());
  }

  /**
   * <b>DOM L2</b>
   * Removes the appropriate attribute node; the name combines
   * the namespace name and the local part.
   *
   * <p>Note that since there is no portable way for DOM to record
   * DTD information, default values for attributes will never be
   * provided automatically.
   */
  public void removeAttributeNS(String namespace, String localPart)
  {
    if (attributes == null)
      {
        throw new DomEx(DomEx.NOT_FOUND_ERR, localPart, null, 0);
      }
    attributes.removeNamedItemNS (namespace, localPart);
  }

  // DOM Level 3 methods

  public String lookupPrefix(String namespaceURI)
  {
    if (namespaceURI == null)
      {
        return null;
      }
    String namespace = getNamespaceURI();
    if (namespace != null && namespace.equals(namespaceURI))
      {
        return getPrefix();
      }
    if (attributes != null)
      {
        for (DomNode ctx = attributes.first; ctx != null; ctx = ctx.next)
          {
            if (XMLConstants.XMLNS_ATTRIBUTE_NS_URI
                .equals(ctx.getNamespaceURI()))
              {
                String value = ctx.getNodeValue();
                if (value.equals(namespaceURI))
                  {
                    return ctx.getLocalName();
                  }
              }
          }
      }
    return super.lookupPrefix(namespaceURI);
  }

  public boolean isDefaultNamespace(String namespaceURI)
  {
    String namespace = getNamespaceURI();
    if (namespace != null && namespace.equals(namespaceURI))
      {
        return getPrefix() == null;
      }
    if (attributes != null)
      {
        for (DomNode ctx = attributes.first; ctx != null; ctx = ctx.next)
          {
            if (XMLConstants.XMLNS_ATTRIBUTE_NS_URI
                .equals(ctx.getNamespaceURI()))
              {
                String qName = ctx.getNodeName();
                return (XMLConstants.XMLNS_ATTRIBUTE.equals(qName));
              }
          }
      }
    return super.isDefaultNamespace(namespaceURI);
  }

  public String lookupNamespaceURI(String prefix)
  {
    String namespace = getNamespaceURI();
    if (namespace != null && equal(prefix, getPrefix()))
      {
        return namespace;
      }
    if (attributes != null)
      {
        for (DomNode ctx = attributes.first; ctx != null; ctx = ctx.next)
          {
            if (XMLConstants.XMLNS_ATTRIBUTE_NS_URI
                .equals(ctx.getNamespaceURI()))
              {
                if (prefix == null)
                  {
                    if (XMLConstants.XMLNS_ATTRIBUTE.equals(ctx.getNodeName()))
                      {
                        return ctx.getNodeValue();
                      }
                  }
                else
                  {
                    if (prefix.equals(ctx.getLocalName()))
                      {
                        return ctx.getNodeValue();
                      }
                  }
              }
          }
      }
    return super.lookupNamespaceURI(prefix);
  }
  
  public String getBaseURI()
  {
    if (attributes != null)
      {
        Node xmlBase =
          attributes.getNamedItemNS(XMLConstants.XML_NS_URI, "base");
        if (xmlBase != null)
          {
            return xmlBase.getNodeValue();
          }
      }
    return super.getBaseURI();
  }
  
  public TypeInfo getSchemaTypeInfo()
  {
    // DTD implementation
    DomDoctype doctype = (DomDoctype) owner.getDoctype();
    if (doctype != null)
      {
        return doctype.getElementTypeInfo(getNodeName());
      }
    // TODO XML Schema implementation
    return null;
  }

  public void setIdAttribute(String name, boolean isId)
  {
    NamedNodeMap attrs = getAttributes();
    Attr attr = (Attr) attrs.getNamedItem(name);
    setIdAttributeNode(attr, isId);
  }
  
  public void setIdAttributeNode(Attr attr, boolean isId)
  {
    if (readonly)
      {
        throw new DomEx(DomEx.NO_MODIFICATION_ALLOWED_ERR);
      }
    if (attr == null || attr.getOwnerElement() != this)
      {
        throw new DomEx(DomEx.NOT_FOUND_ERR);
      }
    if (isId)
      {
        if (userIdAttrs == null)
          {
            userIdAttrs = new HashSet();
          }
        userIdAttrs.add(attr);
      }
    else if (userIdAttrs != null)
      {
        userIdAttrs.remove(attr);
        if (userIdAttrs.isEmpty())
          {
            userIdAttrs = null;
          }
      }
  }

  public void setIdAttributeNS(String namespaceURI, String localName,
                               boolean isId)
  {
    NamedNodeMap attrs = getAttributes();
    Attr attr = (Attr) attrs.getNamedItemNS(namespaceURI, localName);
    setIdAttributeNode(attr, isId);
  }
  
}
