package org.greenstone.gsdl3.util;

import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
import org.w3c.dom.Document;
import org.w3c.dom.Text;

import java.util.Map;
import java.util.Set;
import java.util.HashMap;
import java.util.Vector;
import java.util.Iterator;
import java.util.ArrayList;

//import java.util.Locale;

import org.apache.log4j.*;

/** various functions for extracting info out of GS XML */
public class GSXML {
  
  static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.GSXML.class.getName());
  
  // greenstone xml elements
  public static final String MESSAGE_ELEM = "message";
  public static final String REQUEST_ELEM = "request";
  public static final String RESPONSE_ELEM = "response";
  public static final String COLLECTION_ELEM = "collection";
  public static final String SERVICE_ELEM = "service";
  public static final String CLUSTER_ELEM = "serviceCluster";
  public static final String SITE_ELEM = "site";
  public static final String PARAM_ELEM = "param";
  public static final String PARAM_OPTION_ELEM = "option";
  public static final String CONTENT_ELEM = "content";
  public static final String RESOURCE_ELEM = "resource";
  public static final String DOCUMENT_ELEM = "document";
  public static final String METADATA_ELEM = "metadata";
  public static final String SERVICE_CLASS_ELEM = "serviceRack";
  public static final String CLASSIFIER_ELEM = "classifier";
  public static final String APPLET_ELEM = "applet";
  public static final String APPLET_DATA_ELEM = "appletData";
  public static final String CONFIGURE_ELEM = "configure";
  public static final String STATUS_ELEM = "status";
  public static final String ERROR_ELEM = "error";
  public static final String DEFAULT_ELEM = "default";
  public static final String STYLESHEET_ELEM = "format";//"stylesheet"; // any additional stylesheet stuff is carried in the message inside this elem
  public static final String FORMAT_ELEM = "format"; // config files use format - should we use this instead of stylesheet??
  public static final String TERM_ELEM = "term";
  public static final String SYSTEM_ELEM = "system";
  
  //config file elems
  public static final String COLLECTION_CONFIG_ELEM = "collectionConfig";
  public static final String COLLECTION_BUILD_ELEM = "buildConfig";
  public static final String COLLECTION_INIT_ELEM = "collectionInit";
  public static final String RECOGNISE_ELEM = "recognise";
  public static final String DOC_TYPE_ELEM = "docType";
  public static final String SEARCH_ELEM = "search";
  public static final String INDEX_ELEM = "index";
  public static final String INDEX_STEM_ELEM = "indexStem";
  public static final String INDEX_OPTION_ELEM = "indexOption";
  public static final String BROWSE_ELEM = "browse";
  public static final String DISPLAY_ELEM = "display";
  public static final String LEVEL_ELEM = "level";
  public static final String SHORTNAME_ATT = "shortname";
  public static final String NOTIFY_ELEM = "notify";
  public static final String NOTIFY_HOST_ATT = "host";
  
  // elems for the pages to be processed by xslt
  public final static String PAGE_ELEM = "page";
  public final static String CONFIGURATION_ELEM = "config";
  public final static String PAGE_REQUEST_ELEM = "pageRequest";
  public final static String PAGE_RESPONSE_ELEM = "pageResponse";
  public final static String PAGE_EXTRA_ELEM = "pageExtra";
  
  //public final static String DESCRIPTION_ELEM = "description";
  
  public static final String  ACTION_ELEM = "action";
  public static final String  SUBACTION_ELEM = "subaction";
  
  // add on to another elem type to get a list of that type
  public static final String LIST_MODIFIER = "List";
  
  // greenstone xml attributes
  public static final String NAME_ATT = "name";
  public static final String TO_ATT = "to";
  public static final String USER_ID_ATT = "uid";
  public static final String FROM_ATT = "from";
  public static final String LANG_ATT = "lang";
  public static final String TYPE_ATT = "type";
  public static final String VALUE_ATT = "value";
  public static final String DEFAULT_ATT = "default";
  public static final String INFO_ATT = "info";
  public static final String ACTION_ATT = "action";
  public static final String SUBACTION_ATT = "subaction";
  public static final String OUTPUT_ATT = "output";
  public static final String ADDRESS_ATT = "address";
  public static final String LOCAL_SITE_ATT = "localSite";
  public static final String LOCAL_SITE_NAME_ATT = "localSiteName";
  public static final String STATUS_ERROR_CODE_ATT = "code";
  public static final String STATUS_PROCESS_ID_ATT = "pid";
  public static final String PARAM_SHORTNAME_ATT = "shortname";
  public static final String PARAM_IGNORE_POS_ATT = "ignore";
  public static final String CLASSIFIER_CONTENT_ATT = "content";
  public static final String ERROR_TYPE_ATT = "type";
  
  // document stuff
  public static final String DOC_TYPE_ATT = "docType";
  public static final String DOC_NODE_ELEM = "documentNode";
  public static final String NODE_CONTENT_ELEM = "nodeContent";
  public static final String NODE_STRUCTURE_ELEM = "nodeStructure";
  public static final String NODE_ID_ATT = "nodeID";
  public static final String NODE_NAME_ATT = "nodeName";
  public static final String NODE_TYPE_ATT = "nodeType";
  public static final String NODE_RANK_ATT = "rank";
  public static final String NODE_TYPE_ROOT = "root";
  public static final String NODE_TYPE_INTERNAL = "internal";
  public static final String NODE_TYPE_LEAF = "leaf";
  
  public static final String DOC_TYPE_SIMPLE = "simple";
  public static final String DOC_TYPE_PAGED = "paged";
  public static final String DOC_TYPE_HIERARCHY = "hierarchy";

  public static final String SESSION_EXPIRATION = "session_expiration";
  public static final String USER_SESSION_CACHE_ATT = "user_session_cache";

  // classifier stuff
  public static final String CLASS_NODE_ELEM = "classifierNode";
  public static final String CLASS_NODE_ORIENTATION_ATT = "orientation";
  
  // parameter types
  public static final String PARAM_TYPE_INTEGER = "integer";
  public static final String PARAM_TYPE_BOOLEAN = "boolean";
  public static final String PARAM_TYPE_ENUM_START = "enum";
  public static final String PARAM_TYPE_ENUM_SINGLE = "enum_single";
  public static final String PARAM_TYPE_ENUM_MULTI = "enum_multi";
  public static final String PARAM_TYPE_STRING = "string";
  public static final String PARAM_TYPE_TEXT = "text";
  public static final String PARAM_TYPE_MULTI = "multi";
  public static final String PARAM_TYPE_FILE = "file";
  public static final String PARAM_TYPE_INVISIBLE = "invisible";
  // stuff for text strings
  public static final String DISPLAY_TEXT_ELEM = "displayItem";
  // the following are used for the name attributes
  public static final String DISPLAY_TEXT_NAME = "name";
  public static final String DISPLAY_TEXT_SUBMIT = "submit";
  public static final String DISPLAY_TEXT_DESCRIPTION = "description";
  
  // request types
  // get the module description
  public static final String REQUEST_TYPE_DESCRIBE = "describe";
  // startup a process
  public static final String REQUEST_TYPE_PROCESS = "process";
  // get the status of an ongoing process
  public static final String REQUEST_TYPE_STATUS = "status";
  // system type request - eg reload a collection
  public static final String REQUEST_TYPE_SYSTEM = "system";
  // page requests to the Receptionist/Actions
  public static final String REQUEST_TYPE_PAGE = "page"; // used to be cgi
  // get any format info for a service
  public static final String REQUEST_TYPE_FORMAT = "format";
  // modify the requests
  public static final String REQUEST_TYPE_MESSAGING = "messaging";
  
  // service types
  public static final String SERVICE_TYPE_QUERY = "query";
  public static final String SERVICE_TYPE_RETRIEVE = "retrieve";
  public static final String SERVICE_TYPE_BROWSE = "browse";
  public static final String SERVICE_TYPE_APPLET = "applet";
  public static final String SERVICE_TYPE_PROCESS = "process";
  public static final String SERVICE_TYPE_ENRICH = "enrich";
  public static final String FLAX_PAGE = "flaxPage";
  public static final String FLAX_PAGE_GENERATION = "FlaxPageGeneration";
  
  // system command types and attributes
  public static final String SYSTEM_TYPE_CONFIGURE = "configure";
  public static final String SYSTEM_TYPE_ACTIVATE = "activate";
  public static final String SYSTEM_TYPE_DEACTIVATE = "deactivate";
  
  public static final String SYSTEM_SUBSET_ATT = "subset";
  public static final String SYSTEM_MODULE_TYPE_ATT = "moduleType";
  public static final String SYSTEM_MODULE_NAME_ATT = "moduleName";
  
  // communicator types
  public static final String COMM_TYPE_SOAP_JAVA = "soap";
  
  // error types
  public static final String ERROR_TYPE_SYNTAX = "syntax";
  public static final String ERROR_TYPE_SYSTEM = "system";
  public static final String ERROR_TYPE_INVALID_ID = "invalid_id";
  public static final String ERROR_TYPE_OTHER = "other";
  
  // some system wide param names
  public static final String SUBSET_PARAM = "subset";
  
  //for plugin
  public static final String PLUGIN_ELEM = "plugin";
  public static final String IMPORT_ELEM = "import";
  
  //for authentication
   public static final String AUTHEN_NODE_ELEM="authenticationNode";
   public static final String USER_NODE_ELEM="userNode";

  /** takes a list of elements, and returns an array of strings
   * of the values of attribute att_name */
  public static String [] getAttributeValuesFromList(Element list,
    String att_name) {
    
    NodeList children = list.getChildNodes();
    
    int num_nodes = children.getLength();
    String []ids = new String[num_nodes];
    for (int i=0; i<num_nodes; i++) {
      Element e = (Element)children.item(i);
      String id = e.getAttribute(att_name);
      ids[i] = id;
    }
    
    return ids;
  }
  
  /** takes a paramList element, and gets a HashMap of name-value pairs
   * if deep=true, extracts embedded params, otherwise just top level
   * params*/
  public static HashMap extractParams(Element xml, boolean deep) {
    
    if (!xml.getNodeName().equals(PARAM_ELEM+LIST_MODIFIER)) {
      logger.error("paramList element should have been passed to extractParams, instead it was "+xml.getNodeName());
      return null;
    }
    
    NodeList params = null;
    if (deep) { // get all the nested ones
      params = xml.getElementsByTagName(PARAM_ELEM);
    } else { // just get the top  level ones
      params = xml.getChildNodes();
    }
    HashMap param_map = new HashMap();
    for (int i=0; i<params.getLength(); i++) {
      if (params.item(i).getNodeName().equals(PARAM_ELEM)) {
        Element param = (Element)params.item(i);
        String name=param.getAttribute(NAME_ATT);
        String value=getValue(param); //att or content
        int pos = name.indexOf('.');
        if (pos == -1) { // a base param
          param_map.put(name, value);
        } else { // a namespaced param
          
          String namespace = name.substring(0, pos);
          name = name.substring(pos+1);
          HashMap map = (HashMap)param_map.get(namespace);
          if (map == null) {
            map = new HashMap();
            param_map.put(namespace, map);
          }
          map.put(name, value);
        }
      }
    }
    return param_map;
  }
  
  /** gets the value att or the text content */
  public static String getValue(Element e) {
    String val = e.getAttribute(VALUE_ATT);
    if (val ==null || val.equals("")) {
      // have to get it out of the text
      val=getNodeText(e);
      
    } else {
      // unescape the xml stuff
      val = unXmlSafe(val);
    }
    return val;
  }
  
  /** extracts the text out of a node */
  public static Node getNodeTextNode(Element param) {
    param.normalize();
    Node n = param.getFirstChild();
    while (n!=null && n.getNodeType() !=Node.TEXT_NODE) {
      n=n.getNextSibling();
    }
    return n;
  }
  
  /** extracts the text out of a node */
  public static String getNodeText(Element param) {
    Node text_node = getNodeTextNode(param);
    if (text_node == null) {
      return "";
    }
    return text_node.getNodeValue();
  }
  
  public static void setNodeText(Element elem, String text) {
    Node old_text_node = getNodeTextNode(elem);
    if (old_text_node != null) {
      elem.removeChild(old_text_node);
    }
    Text t = elem.getOwnerDocument().createTextNode(text);
    elem.appendChild(t);
  }
  
  /** add text to a document/subsection  element */
  public static boolean addDocText(Document owner, Element doc, String text) {
    
    Element content = owner.createElement(NODE_CONTENT_ELEM);
    Text t = owner.createTextNode(text);
    content.appendChild(t);
    doc.appendChild(content);
    return true;
  }
  
  /** add an error message, unknown error type */
  public static boolean addError(Document owner, Element doc, String text) {
    return addError(owner, doc, text, ERROR_TYPE_OTHER);
  }
  /** add an error message */
  public static boolean addError(Document owner, Element doc, String text,
    String error_type) {
    
    Element content = owner.createElement(ERROR_ELEM);
    content.setAttribute(ERROR_TYPE_ATT, error_type);
    Text t = owner.createTextNode(text);
    content.appendChild(t);
    doc.appendChild(content);
    return true;
  }
  
  /** add an error message */
  public static boolean addError(Document owner, Element doc, Throwable error) {
    return addError(owner, doc, error, ERROR_TYPE_OTHER);
  }
  
  /** add an error message */
  public static boolean addError(Document owner, Element doc,
    Throwable error, String error_type) {
    error.printStackTrace();
    return addError(owner, doc, error.toString(), error_type);
  }
  
  public static Element createMetadataParamList(Document owner, Vector meta_values) {
    
    Element meta_param_list = owner.createElement(PARAM_ELEM+LIST_MODIFIER);
    Iterator i = meta_values.iterator();
    while(i.hasNext()) {
      String next = (String)i.next();
      Element meta_param = owner.createElement(PARAM_ELEM);
      meta_param_list.appendChild(meta_param);
      meta_param.setAttribute(NAME_ATT, "metadata");
      meta_param.setAttribute(VALUE_ATT, next);
    }
    return meta_param_list;
  }
  
  /** adds a metadata elem to a list */
  public static boolean addMetadata(Document owner, Element list,
    String meta_name, String meta_value) {
    if (meta_value==null || meta_value.equals("")) {
      return false;
    }
    Element data = owner.createElement(METADATA_ELEM);
    data.setAttribute(NAME_ATT, meta_name);
    Text t = owner.createTextNode(meta_value);
    data.appendChild(t);
    list.appendChild(data);
    return true;
    
  }
  
  /** copies the metadata out of teh metadataList of 'from' into
   * the metadataList of 'to' */
  public static boolean mergeMetadataLists(Node to, Node from) {
    Node to_meta = getChildByTagName(to, METADATA_ELEM+LIST_MODIFIER);
    Node from_meta = getChildByTagName(from, METADATA_ELEM+LIST_MODIFIER);
    
    if  (from_meta == null) { // nothing to copy
      return true;
    }
    Document to_owner = to.getOwnerDocument();
    Node new_from = to_owner.importNode(from_meta, true);
    
    if (to_meta == null) { // just copy the whole list
      to.appendChild(new_from);
      return true;
    }
    
    // copy individual elements
    Node child = new_from.getFirstChild();
    while ( child != null) {
      to_meta.appendChild(child);
      child = child.getNextSibling();
    }
    return true;
  }
  
  /** copies all the children from from to to */
  public static boolean mergeElements(Element to, Element from) {
    
    Document owner = to.getOwnerDocument();
    Node child = from.getFirstChild();
    while (child != null) {
      to.appendChild(owner.importNode(child, true));
      child = child.getNextSibling();
    }
    return true;
  }
  /** returns the (first) element child of the node n */
  public static Element getFirstElementChild(Node n) {
    
    Node child = n.getFirstChild();
    while (child!=null) {
      if (child.getNodeType() == Node.ELEMENT_NODE) {
        return (Element)child;
      }
      child = child.getNextSibling();
    }
    return null; //no element child found
  }
  /** returns the (first) child element with the given name */
  public static Node getChildByTagName(Node n, String name) {
    
    Node child = n.getFirstChild();
    while (child!=null) {
      if (child.getNodeName().equals(name)) {
        return child;
      }
      child = child.getNextSibling();
    }
    return null; //not found
  }
  
  /** returns the (nth) child element with the given name
   * index numbers start at 0 */
  public static Node getChildByTagNameIndexed(Node n, String name, int index) {
    if (index == -1) {
      return getChildByTagName(n, name);
    }
    int count = 0;
    Node child = n.getFirstChild();
    while (child!=null) {
      if (child.getNodeName().equals(name)) {
        if (count == index) {
          return child;
        } else {
          count++;
        }
      }
      child = child.getNextSibling();
    }
    return null; //not found
  }
  
  /** takes an xpath type expression of the form name/name/...
   * and returns the first node that matches, or null if not found */
  public static Node getNodeByPath(Node n, String path) {
    
    String link = GSPath.getFirstLink(path);
    path = GSPath.removeFirstLink(path);
    while (!link.equals("")) {
      n = getChildByTagName(n, link);
      if (n==null) {
        return null;
      }
      link = GSPath.getFirstLink(path);
      path = GSPath.removeFirstLink(path);
    }
    return n;
  }
  
  /** takes an xpath type expression of the form name/name/...
   * and returns the first node that matches, or null if not found
   * can include [i] indices. index numbers start at 0 */
  public static Node getNodeByPathIndexed(Node n, String path) {
    
    String link = GSPath.getFirstLink(path);
    int index = GSPath.getIndex(link);
    if (index != -1) {
      link = GSPath.removeIndex(link);
    }
    path = GSPath.removeFirstLink(path);
    while (!link.equals("")) {
      n = getChildByTagNameIndexed(n, link, index);
      if (n==null) {
        return null;
      }
      link = GSPath.getFirstLink(path);
      index = GSPath.getIndex(link);
      if (index != -1) {
        link = GSPath.removeIndex(link);
      }
      path = GSPath.removeFirstLink(path);
    }
    return n;
  }
  
  public static HashMap getChildrenMap(Node n) {
    
    HashMap map= new HashMap();
    Node child = n.getFirstChild();
    while (child!=null) {
      String name = child.getNodeName();
      map.put(name, child);
      child = child.getNextSibling();
    }
    return map;
  }
  
  public static NodeList getChildrenByTagName(Node n, String name) {
    MyNodeList node_list = new MyNodeList();
    Node child = n.getFirstChild();
    while (child!=null) {
      if (child.getNodeName().equals(name)) {
        node_list.addNode(child);
      }
      child = child.getNextSibling();
    }
    return node_list;
  }
  
  
  /** Duplicates an element, but gives it a new name */
  public static Element duplicateWithNewName(Document owner, Element element,
    String element_name, boolean with_attributes) {
    return duplicateWithNewNameNS(owner, element, element_name, null, with_attributes);
  }
  
  /** Duplicates an element, but gives it a new name */
  public static Element duplicateWithNewNameNS(Document owner,
    Element element,
    String element_name,
    String namespace_uri,
    boolean with_attributes) {
    Element duplicate;
    if (namespace_uri == null) {
      duplicate = owner.createElement(element_name);
    } else {
      duplicate = owner.createElementNS(namespace_uri, element_name);
    }
    // Copy element attributes
    if (with_attributes) {
      NamedNodeMap attributes = element.getAttributes();
      for (int i = 0; i < attributes.getLength(); i++) {
        Node attribute = attributes.item(i);
        duplicate.setAttribute(attribute.getNodeName(), attribute.getNodeValue());
      }
    }
    
    // Copy element children
    NodeList children = element.getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
      Node child = children.item(i);
      duplicate.appendChild(owner.importNode(child, true));
    }
    
    return duplicate;
  }
  
  public static void copyAllChildren(Element to, Element from) {
    
    Document to_doc = to.getOwnerDocument();
    Node child = from.getFirstChild();
    while (child != null) {
      to.appendChild(to_doc.importNode(child, true));
      child = child.getNextSibling();
    }
  }
  /** returns a basic request message */
  public static  Element createBasicRequest(Document owner,
    String request_type, String to,
    String lang,
    String uid) {
    Element request = owner.createElement(REQUEST_ELEM);
    request.setAttribute(TYPE_ATT, request_type);
    request.setAttribute(LANG_ATT, lang);
    request.setAttribute(TO_ATT, to);
    request.setAttribute(USER_ID_ATT, uid);
    return request;
  }
  
  public static Element createTextElement(Document owner, String elem_name,
    String text) {
    Element e = owner.createElement(elem_name);
    Text t = owner.createTextNode(text);
    e.appendChild(t);
    return e;
    
  }
  
  public static Element createDisplayTextElement(Document owner,
    String text_name,
    String text) {
    Element e = owner.createElement(DISPLAY_TEXT_ELEM);
    e.setAttribute(NAME_ATT, text_name);
    Text t = owner.createTextNode(text);
    e.appendChild(t);
    return e;
    
  }
  
  
  public static Element createParameter(Document owner, String name,
    String value) {
    Element param = owner.createElement(PARAM_ELEM);
    param.setAttribute(NAME_ATT, name);
    param.setAttribute(VALUE_ATT, value);
    return param;
  }
  
  public static void addParametersToList(Document owner, Element param_list,
    HashMap params) {
    Set items = params.entrySet();
    Iterator i = items.iterator();
    while(i.hasNext()) {
      Map.Entry m = (Map.Entry)i.next();
      param_list.appendChild(createParameter(owner, (String)m.getKey(), (String)m.getValue()));
    }
    
  }
  
  public static Element createParameterDescription(Document owner,
    String id,
    String display_name,
    String type,
    String default_value,
    String []option_ids,
    String []option_names) {
    
    
    Element p = owner.createElement(PARAM_ELEM);
    p.setAttribute(NAME_ATT, id);
    p.setAttribute(TYPE_ATT, type);
    p.appendChild(createDisplayTextElement(owner, GSXML.DISPLAY_TEXT_NAME, display_name));
    
    if (default_value != null) {
      p.setAttribute(DEFAULT_ATT, default_value);
    }
    if (option_ids!=null && option_names!=null) {
      for (int i=0; i<option_ids.length; i++) {
        Element e = owner.createElement(PARAM_OPTION_ELEM);
        e.setAttribute(NAME_ATT, option_ids[i]);
        e.appendChild(createDisplayTextElement(owner, GSXML.DISPLAY_TEXT_NAME, option_names[i]));
        p.appendChild(e);
      }
    }
    return p;
  }
  public static Element createParameterDescription2(Document owner,
    String id,
    String display_name,
    String type,
    String default_value,
    ArrayList option_ids,
    ArrayList option_names) {
    
    
    Element p = owner.createElement(PARAM_ELEM);
    p.setAttribute(NAME_ATT, id);
    p.setAttribute(TYPE_ATT, type);
    p.appendChild(createDisplayTextElement(owner, GSXML.DISPLAY_TEXT_NAME, display_name));
    if (default_value != null) {
      p.setAttribute(DEFAULT_ATT, default_value);
    }
    if (option_ids!=null && option_names!=null) {
      for (int i=0; i<option_ids.size(); i++) {
        Element e = owner.createElement(PARAM_OPTION_ELEM);
        e.setAttribute(NAME_ATT, (String)option_ids.get(i));
        e.appendChild(createDisplayTextElement(owner, GSXML.DISPLAY_TEXT_NAME, (String)option_names.get(i)));
        p.appendChild(e);
      }
    }
    return p;
  }
  
  
  /** returns the element parent/node_name[@attribute_name='attribute_value']
   */
  public static Element getNamedElement(Element parent, String node_name,
    String attribute_name,
    String attribute_value) {
    
    NodeList children = parent.getChildNodes();
    for (int i=0; i<children.getLength(); i++) {
      Node child = children.item(i);
      if (child.getNodeName().equals(node_name)) {
        if (((Element)child).getAttribute(attribute_name).equals(attribute_value))
          return (Element)child;
      }
    }
    // not found
    return null;
  }
  
  public static int SORT_TYPE_STRING = 0;
  public static int SORT_TYPE_INT = 1;
  public static int SORT_TYPE_FLOAT = 2;
  
  // sort type:
  public static Element insertIntoOrderedList(Element parent_node,
    String node_name,
    Element start_from_elem,
    Element new_elem, String sort_att,
    boolean descending) {
    if (new_elem == null) return null;
    Element cloned_elem = (Element)parent_node.getOwnerDocument().importNode(new_elem, true);
    if (start_from_elem == null) {
      parent_node.appendChild(cloned_elem);
      return cloned_elem;
    }
    
    Node current_node = start_from_elem;
    String insert_att = cloned_elem.getAttribute(sort_att);
    String list_att = start_from_elem.getAttribute(sort_att);
    while ((!descending && list_att.compareTo(insert_att)<0) || (descending && list_att.compareTo(insert_att)>0)) {
      current_node = current_node.getNextSibling();
      if (current_node == null) break; // end of the list
      if (!current_node.getNodeName().equals(node_name)) {
        continue; // not a valid node
      }
      list_att = ((Element)current_node).getAttribute(sort_att);
    }
    
    parent_node.insertBefore(cloned_elem, current_node);
    return cloned_elem;
  }
  
  
  /** Returns the appropriate language element from a display elem,
   * display is the containing element, name is the name of the element to
   * look for, lang is the preferred language, lang_default is the fall back
   * lang if neither lang is found, will return the first one it finds*/
  public static String getDisplayText(Element display, String name,
    String lang, String lang_default) {
    
    String def = null;
    String first = null;
    NodeList elems = display.getElementsByTagName(DISPLAY_TEXT_ELEM);
    if (elems.getLength() == 0) return "";
    for (int i=0; i<elems.getLength(); i++) {
      Element e = (Element)elems.item(i);
      String n = e.getAttribute(NAME_ATT);
      if (name.equals(n)) {
        String l = e.getAttribute(LANG_ATT);
        if (lang.equals(l)) {
          return getNodeText(e);
        } else if (lang_default.equals(l)) {
          def = getNodeText(e);
        } else if (first == null) {
          first = getNodeText(e);
        }
      } else {
        continue;
      }
    }
    
    if (def != null) {
      return def;
    }
    if (first != null) {
      return first;
    }
    return "";
  }
  
  // replaces < > " ' & in the original with their entities
  public static String xmlSafe(String original) {
    
    StringBuffer filtered = new StringBuffer(original.length());
    char c;
    for (int i=0; i<original.length(); i++) {
      c = original.charAt(i);
      if (c == '>') {
        filtered.append("&gt;");
      } else if (c == '<') {
        filtered.append("&lt;");
      } else if (c == '"') {
        filtered.append("&quot;");
      } else if (c == '&') {
        filtered.append("&amp;");
      } else if (c == '\'') {
        filtered.append("&apos;");
      } else {
        filtered.append(c);
      }
    }
    return filtered.toString();
  }
  
  
  // replaces < > " ' & entities with their originals
  public static String unXmlSafe(String original) {
    
    StringBuffer filtered = new StringBuffer(original.length());
    char c;
    for (int i=0; i<original.length(); i++) {
      c = original.charAt(i);
      if (c == '&') {
        int pos = original.indexOf(";", i);
        String entity = original.substring(i+1, pos);
        if (entity.equals("gt")) {
          filtered.append(">");
        } else if (entity.equals("lt")) {
          filtered.append("<");
        } else if (entity.equals("apos")) {
          filtered.append("'");
        } else if (entity.equals("amp")) {
          filtered.append("&");
        } else if (entity.equals("quot")) {
          filtered.append("\"");
        } else {
          filtered.append("&"+entity+";");
        }
        i = pos;
      } else {
        filtered.append(c);
      }
    }
    return filtered.toString();
  }
  
  public static void printXMLNode(Node e) {
    printXMLNode(e, 0) ;
  }
  
  public static String xmlNodeToString(Node e){
    StringBuffer sb = new StringBuffer("");
    xmlNodeToString(sb,e,0);
    return sb.toString();
  }
  
  private static void xmlNodeToString(StringBuffer sb, Node e, int depth){
    
    for (int i=0 ; i<depth ; i++)
      sb.append(' ') ;
    
    if (e.getNodeType() == Node.TEXT_NODE){
      sb.append("text") ;
      return ;
    }
    
    sb.append('<');
    sb.append(e.getNodeName());
    NamedNodeMap attrs = e.getAttributes();
    for (int i = 0; i < attrs.getLength(); i++) {
      Node attr = attrs.item(i);
      sb.append(' ');
      sb.append(attr.getNodeName());
      sb.append("=\"");
      sb.append(attr.getNodeValue());
      sb.append('"');
    }
    
    NodeList children = e.getChildNodes();
    
    if (children == null || children.getLength() == 0)
      sb.append("/>\n") ;
    else {
      
      sb.append(">\n") ;
      
      int len = children.getLength();
      for (int i = 0; i < len; i++) {
        xmlNodeToString(sb,children.item(i), depth + 1);
      }
      
      for (int i=0 ; i<depth ; i++)
        sb.append(' ') ;
      
      sb.append("</" + e.getNodeName() + ">\n");
    }
    
    
  }
  
  public static void printXMLNode(Node e, int depth) { //recursive method call using DOM API...
    
    for (int i=0 ; i<depth ; i++)
      System.out.print(' ') ;
    
    if (e.getNodeType() == Node.TEXT_NODE){
      // shouldn't we actually print the text here????
      System.out.println("text") ;
      return ;
    }
    
    System.out.print('<');
    System.out.print(e.getNodeName());
    NamedNodeMap attrs = e.getAttributes();
    for (int i = 0; i < attrs.getLength(); i++) {
      Node attr = attrs.item(i);
      System.out.print(' ');
      System.out.print(attr.getNodeName());
      System.out.print("=\"");
      System.out.print(attr.getNodeValue());
      System.out.print('"');
    }
    
    NodeList children = e.getChildNodes();
    
    if (children == null || children.getLength() == 0)
      System.out.println("/>") ;
    else {
      
      System.out.println('>') ;
      
      int len = children.getLength();
      for (int i = 0; i < len; i++) {
        printXMLNode(children.item(i), depth + 1);
      }
      
      for (int i=0 ; i<depth ; i++)
        System.out.print(' ') ;
      
      System.out.println("</" + e.getNodeName() + ">");
    }
    
  }
}