#include "EventParse.h"
#include "DocParse.h"

#define R_USE_XML_ENCODING 1
#include "Utils.h"

#include <R_ext/Print.h>

#ifdef FROM_GNOME_XML_DIR
#include <gnome-xml/parserInternals.h>
#else
#include <libxml/parserInternals.h>
#endif


static USER_OBJECT_ createSAX2AttributesList(const xmlChar **attributes, int nb_attributes, int nb_defaulted, const xmlChar *encoding);



/*
  This is an event driven parsing implementation for R & S
  using the libxml (http://xmlsoft.org) rather than Jim Clark's expat.
  It works much the same way, but has some advantages
   a) only one library need be installed for both document
     and event parsing
   b) the libxml tools can read data via ftp and http.

  Both expat and libxml provide the SAX interface and allow us to share
  a great deal of code between the two event parser implementations
  within this package.
 */

void RS_XML(startElementHandler)(void *ctx, const xmlChar *name, const xmlChar **atts);
void RS_XML(commentElementHandler)(void *ctx, const xmlChar *val);
void RS_XML(charactersHandler)(void *user_data, const xmlChar *ch, int len);
void RS_XML(endElementHandler)(void *ctx, const xmlChar *name);
void RS_XML(startDocumentHandler)(void *ctx);
void RS_XML(endDocumentHandler)(void *ctx);
void RS_XML(cdataBlockHandler)(void *ctx, const xmlChar *value, int len);
void RS_XML(piHandler)(void *ctx, const xmlChar *target, const xmlChar *data);
void RS_XML(entityDeclaration)(void *ctx, const xmlChar *name, int type, const xmlChar *publicId, 
                                const xmlChar *systemId, xmlChar *content);
xmlEntityPtr RS_XML(getEntityHandler)(void *userData, const xmlChar *name);
xmlEntityPtr RS_XML(getParameterEntityHandler)(void *userData, const xmlChar *name);

int RS_XML(isStandAloneHandler)(void *ctx);
void RS_XML(warningHandler)(void *ctx, const char *msg, ...);
void RS_XML(errorHandler)(void *ctx, const char *format, ...); 
void RS_XML(fatalErrorHandler)(void *ctx, const char *msg, ...);
void RS_XML(structuredErrorHandler)(void *ctx, xmlErrorPtr err);




static void RS_XML(initXMLParserHandler)(xmlSAXHandlerPtr xmlParserHandler, int saxVersion);



USER_OBJECT_
createSAX2AttributesList(const xmlChar **attributes, int nb_attributes, int nb_defaulted, const xmlChar *encoding)
{
  int  i;
  const char **ptr;
  USER_OBJECT_ attr_names;
  USER_OBJECT_ attr_values;
  USER_OBJECT_ nsURI, nsNames;

 
  if(nb_attributes < 1)
    return(NULL_USER_OBJECT);

  PROTECT(attr_values = NEW_CHARACTER(nb_attributes));
  PROTECT(attr_names = NEW_CHARACTER(nb_attributes));

  PROTECT(nsURI = NEW_CHARACTER(nb_attributes));
  PROTECT(nsNames = NEW_CHARACTER(nb_attributes));

  ptr = (const char **) attributes; /*XXX */
  for(i=0; i < nb_attributes; i++, ptr+=5) {
      char *tmp;
      int len;

      len = (int)(ptr[4] - ptr[3] + 1);
      tmp = malloc(sizeof(char) * len);
      if(!tmp) {
         PROBLEM "Cannot allocate space for attribute of length %d", (int) (ptr[4] - ptr[3] + 2)
	 ERROR;
      }
      memcpy(tmp, ptr[3], ptr[4] - ptr[3]);
      tmp[len-1] = '\0'; /*XXX*/
      SET_STRING_ELT(attr_values, i,  ENC_COPY_TO_USER_STRING(tmp));
      free(tmp);

      SET_STRING_ELT(attr_names, i, ENC_COPY_TO_USER_STRING(ptr[0]));

      if(ptr[2]) {
         SET_STRING_ELT(nsURI, i,  ENC_COPY_TO_USER_STRING(ptr[2]));
         if(ptr[1])
            SET_STRING_ELT(nsNames, i,  ENC_COPY_TO_USER_STRING(ptr[1]));
      }
  }
  SET_NAMES(nsURI, nsNames);
  SET_NAMES(attr_values, attr_names);
  Rf_setAttrib(attr_values, Rf_install("namespaces"), nsURI);
  UNPROTECT(4);

  return(attr_values);
}



#ifdef  NEED_CLOSE_CALLBACK
/* Is this actually needed? We can ensure that all errors
   are caught by R and so ensure that we close things.
*/
int
RS_XML_closeConnectionInput(void *context)
{
   int status;
   status = RS_XML_readConnectionInput(context, NULL, -1);

   return(1);
}
#endif


typedef struct {
    SEXP fun;
    xmlParserCtxtPtr ctx;
} RFunCtxData;

int
RS_XML_readConnectionInput(void *context, char *buffer, int len)
{
  SEXP e, tmp, arg = R_NilValue /* -Wall */;
  int n;
  int errorOccurred;
  const char *str;
  int left = len-1, count;
  int nprot = 0;

#ifdef R_XML_DEBUG
  char *orig = buffer;
#endif


  SEXP fun;
  xmlParserCtxtPtr ctx;

#ifndef LIBXML2_NEW_BUFFER
  ctx = (xmlParserCtxtPtr) context;
  fun = ctx->_private;
#else  
  RFunCtxData *user = (RFunCtxData *) context;
  ctx = user->ctx;
  fun = user->fun;
#endif

  if(len == -1)
     return(0);

  /* Setup the expression to call the user-supplied R function or call readLines(con, 1) 
     if they gave us a connection. */
  if(isFunction(fun)) {
     /* Invoke the user-provided function to get the next line. */
    PROTECT(e = allocVector(LANGSXP, 2)); nprot++;
    SETCAR(e, fun);
    PROTECT(arg = NEW_INTEGER(1)); nprot++;
    INTEGER_DATA(arg)[0] = len;
    SETCAR(CDR(e), arg);
  } else 
      e = fun;

  n = count = 0;
  while(n == 0 && left > 0) {

   str = NULL;

     /* Update the argument to the user-defined function to say how much is left. */
   if(isFunction(fun))
     INTEGER_DATA(arg)[0] = left;

   tmp = R_tryEval(e, R_GlobalEnv, &errorOccurred);

   if(errorOccurred || !IS_CHARACTER(tmp)) {
     UNPROTECT(nprot);
     if ((ctx->sax != NULL) && (ctx->sax->error != NULL))  /* throw an XML error. */
           ctx->sax->error(ctx->userData, "Failed to call read on XML connection");
     return(-1);
   }

   if(GET_LENGTH(tmp)) {

      str = CHAR_DEREF(STRING_ELT(tmp, 0));
      n = (int)strlen(str);


      if(n != 0) { /* Just add a new line and do it again. */

         if(n > left) {
            PROBLEM "string read from XML connection too long for buffer: truncating %s to %d characters", str, left
     	    WARN;
         }
         strncpy(buffer, str, left);
         left -= n;

         count += n ;
      }
   } else {
           /* Notice that we may have actually added something to the 
              buffer, specifically a sequence of empty lines \n, 
              and these will be discarded and not passed to the XML parser
              but these are extraneous anyway. Are they?
            */
      n = count = 0;
      break;
   }
  }

#ifdef R_XML_DEBUG
  fprintf(stderr, "size (len = %d, n=%d, count=%d)\nbuffer= '%s'\nRstring='%s'\n", len, n, count, buffer, str);fflush(stderr);
/*  fprintf(stderr, "size (n=%d, count=%d) %s '%s'\n", n, count, str, orig);fflush(stderr); */
#endif

  UNPROTECT(nprot);


  return(count);
/*  return(count == 0 ? -1 : count); */
}

xmlParserCtxtPtr
RS_XML_xmlCreateConnectionParserCtxt(USER_OBJECT_ con)
{
      xmlParserInputBufferPtr buf;
      xmlParserCtxtPtr ctx = NULL;

#ifdef LIBXML2
      ctx = xmlNewParserCtxt();
#ifndef LIBXML2_NEW_BUFFER  // < 2.9.1
      ctx->_private = (USER_OBJECT_) con;
                                      /* R_chk_calloc */
      buf = (xmlParserInputBufferPtr) calloc(1, sizeof(xmlParserInputBuffer));
      buf->readcallback = RS_XML_readConnectionInput;
      buf->context = (void*) ctx;
      buf->raw = NULL; /* buf->buffer; */
      xmlBufferPtr tmp = xmlBufferCreate();
      buf->buffer = tmp;
#else
    RFunCtxData *userData = (RFunCtxData *) R_alloc(sizeof(RFunCtxData), 1);
    userData->fun = con;
    userData->ctx = ctx;
    buf = xmlParserInputBufferCreateIO(RS_XML_readConnectionInput, NULL, userData, XML_CHAR_ENCODING_NONE);
#endif

      xmlParserInputPtr input = xmlNewIOInputStream(ctx, buf, XML_CHAR_ENCODING_NONE);
      if(!input) {
	  PROBLEM "can't create new IOInputStream"
	      ERROR;
      }
      inputPush(ctx, input);
#endif
      return(ctx);
}

int
RS_XML(libXMLEventParse)(const char *fileName, RS_XMLParserData *parserData, RS_XML_ContentSourceType asText,
			 int saxVersion, USER_OBJECT_ r_encoding)
{
 xmlSAXHandlerPtr xmlParserHandler;
 xmlParserCtxtPtr ctx; 
 int status;

  switch(asText) {
    case RS_XML_TEXT:
      ctx = xmlCreateDocParserCtxt(CHAR_TO_XMLCHAR(fileName));
      break;

    case RS_XML_FILENAME:
      ctx = xmlCreateFileParserCtxt(fileName);
      break;

    case RS_XML_CONNECTION:
      ctx = RS_XML_xmlCreateConnectionParserCtxt((USER_OBJECT_) fileName);

      break;
    default:
      ctx = NULL;
  }


  if(ctx == NULL) {
    PROBLEM "Can't parse %s", fileName
    ERROR;
  }


  xmlParserHandler = (xmlSAXHandlerPtr) S_alloc(sizeof(xmlSAXHandler), 1);
  /* Make certain this is initialized so that we don't have any references  to unwanted routines!  */
  memset(xmlParserHandler, '\0', sizeof(xmlSAXHandler));

  RS_XML(initXMLParserHandler)(xmlParserHandler, saxVersion);

  parserData->ctx = ctx;
  ctx->userData = parserData;
  ctx->sax = xmlParserHandler;

  if(Rf_length(r_encoding) && STRING_ELT(r_encoding, 0) != R_NaString) { 
//      Rf_PrintValue(r_encoding);
      ctx->encoding = xmlStrdup((const xmlChar *)CHAR(STRING_ELT(r_encoding, 0)));
  }

  status = xmlParseDocument(ctx);

  ctx->sax = NULL;
  xmlFreeParserCtxt(ctx);

  return(status);

/*  Free(xmlParserHandler); */
}


int
R_isBranch(const xmlChar *localname, RS_XMLParserData *rinfo)
{
    int n;
    if(rinfo->current)
        return(-2); /* we are processing a branch */

    if((n = GET_LENGTH(rinfo->branches)) > 0) {
        int i;
        USER_OBJECT_ names = GET_NAMES(rinfo->branches);
        for(i = 0 ; i < n ; i++) {
            if(strcmp(XMLCHAR_TO_CHAR(localname), CHAR_DEREF(STRING_ELT(names, i))) == 0) {
                return(i);
            }
        }

    }
     
    return(-1);   
}

char *
getPropertyValue(const xmlChar **ptr)
{
  int len;
  char *tmp;

  len = (int)(ptr[4] - ptr[3] + 1);
      tmp = malloc(sizeof(char) * len);
      if(!tmp) {
         PROBLEM "Cannot allocate space for attribute of length %d", (int) (ptr[4] - ptr[3] + 2)
	 ERROR;
      }
      memcpy(tmp, ptr[3], ptr[4] - ptr[3]);
      tmp[len-1] = '\0'; /*XXX*/
      return(tmp);
}

void
R_processBranch(RS_XMLParserData * rinfo, 
                int branchIndex, 
                const xmlChar * localname, 
                const xmlChar * prefix, 
                const xmlChar * URI, 
                int nb_namespaces, 
                const xmlChar ** namespaces, 
                int nb_attributes, 
                int nb_defaulted, 
                const xmlChar ** attributes,
		Rboolean sax1)
{
    xmlNodePtr node;

    node = xmlNewNode(NULL, localname);
    if(attributes) {
        const xmlChar ** p = attributes;
        int i;
	if(sax1) {
	  for(i = 0; *p ; i += 2, p += 2) 
            xmlSetProp(node, p[0], p[1]); /*??? Do we need to xmlStrdup() this. */
	} else {
	  const xmlChar **ptr = p;
	  for(i = 0; i < nb_attributes; i++, ptr += 5) {
	    /*XXX does this get freed later on?*/
            xmlSetProp(node, xmlStrdup(ptr[0]), (const xmlChar *)getPropertyValue(ptr));
	  }
	}
    }
    if(rinfo->current) {
        /* Add to children */
        xmlAddChild(rinfo->current, node);
    } else {
        rinfo->top = node;
        rinfo->branchIndex = branchIndex;
    }
    rinfo->current = node;
}

void
R_xmlFreeNode(SEXP node)
{
  xmlNodePtr p;

  p = R_ExternalPtrAddr(node);
  if(p) {
      xmlFreeNode(p);
#ifdef R_XML_DEBUG
fprintf(stderr, "Freeing XML node from a branch\n");
#endif
  }
  R_SetExternalPtrAddr(node, NULL_USER_OBJECT);
}

int numDocsCreated = 0;

void
R_reportDocGC()
{
    REprintf("<r:docReport createdInBranch='%d' createdByXMLPackage='%d' freed='%d'/>\n", numDocsCreated, R_numXMLDocs, R_numXMLDocsFreed);
}

void
R_endBranch(RS_XMLParserData *rinfo,
            const xmlChar * localname, 
            const xmlChar * prefix, 
            const xmlChar * URI)
{
    if(rinfo->current) {
        xmlNodePtr tmp;
	xmlDocPtr doc = NULL;
        tmp = rinfo->current;
        if(tmp->parent == NULL) {
            /* Call the function with the given node.*/
	    SEXP fun, args;
	    USER_OBJECT_ rnode;
	    if(rinfo->dynamicBranchFunction)
		fun = rinfo->dynamicBranchFunction;
	    else {
		fun = VECTOR_ELT(rinfo->branches, rinfo->branchIndex);
 	    }

	    PROTECT(args = NEW_LIST(1));
	    if(tmp->doc == NULL) {
		doc = xmlNewDoc((const xmlChar*) "1.0");
		initDocRefCounter(doc);
   	        xmlDocSetRootElement(doc, tmp);
/*		fprintf(stderr, "<r:createDoc addr='%p'/>\n", doc); */
		numDocsCreated++;
	    }
	    SET_VECTOR_ELT(args, 0, rnode = R_createXMLNodeRef(tmp, rinfo->finalize));
	    RS_XML(invokeFunction)(fun, args, NULL, rinfo->ctx);
 	    UNPROTECT(1);
	    /*
            xmlFreeNode(rinfo->top);
            rinfo->top = NULL;
	    */

#if 0
            fprintf(stderr, "Finishing branch for %s %s\n", tmp->name, tmp->properties->children->content);
#endif

	    /* if(rinfo->dynamicBranchFunction)
                 R_ReleaseObject(rinfo->dynamicBranchFunction);
            */
        }

        rinfo->current = rinfo->current->parent;
	if(rinfo->current && (rinfo->current->type == XML_DOCUMENT_NODE || rinfo->current->type == XML_HTML_DOCUMENT_NODE))
            rinfo->current = NULL;
    }
}


static int 
isBranchFunction(SEXP obj)
{
    int i, n;
    SEXP classes;

    if(TYPEOF(obj) != CLOSXP) 
	return(0);

    classes = GET_CLASS(obj);
    n = GET_LENGTH(classes);
    for(i = 0; i < n; i++)
	if(strcmp(CHAR(STRING_ELT(classes, i)), "SAXBranchFunction") == 0)
	    return(1);
    
    return(0);
}


static void	
RS_XML(xmlSAX2StartElementNs)(void * userData, 
			      const xmlChar * localname, 
			      const xmlChar * prefix, 
			      const xmlChar * URI, 
			      int nb_namespaces, 
			      const xmlChar ** namespaces, 
			      int nb_attributes, 
			      int nb_defaulted, 
			      const xmlChar ** attributes)
{
  int i, n;
  USER_OBJECT_ tmp, names;
  USER_OBJECT_ opArgs, ans;
  RS_XMLParserData *rinfo = (RS_XMLParserData*) userData;
  DECL_ENCODING_FROM_EVENT_PARSER(rinfo)

  if(!localname)
      return;

  /* if there is a branch function in the branches argument of xmlEventParse() with this name, call that and return.*/
  if((i = R_isBranch(localname, rinfo)) != -1) {
      R_processBranch(rinfo, i, localname, prefix, URI, nb_namespaces, namespaces, nb_attributes, nb_defaulted, attributes, FALSE);
      return;
  }

  PROTECT(opArgs = NEW_LIST(4));
  SET_VECTOR_ELT(opArgs, 0, NEW_CHARACTER(1));
  SET_STRING_ELT(VECTOR_ELT(opArgs, 0), 0, ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR(localname))); 

      /* Now convert the attributes list. */
  SET_VECTOR_ELT(opArgs, 1, createSAX2AttributesList(attributes, nb_attributes, nb_defaulted, encoding));


  PROTECT(tmp = NEW_CHARACTER(1));
  if(URI) {
     SET_STRING_ELT(tmp, 0, ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR(URI))); 
     SET_NAMES(tmp, ScalarString(CreateCharSexpWithEncoding(encoding,  ( (void*)prefix ? prefix : (const xmlChar *)"")))); 
  }
  SET_VECTOR_ELT(opArgs, 2, tmp);
  UNPROTECT(1);

  n = nb_namespaces;
  PROTECT(tmp = NEW_CHARACTER(n));
  PROTECT(names = NEW_CHARACTER(n));
  for(i = 0, n = 0; n < nb_namespaces; n++, i+=2) {
      SET_STRING_ELT(tmp, n, ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR(namespaces[i+1])));
      if(namespaces[i])
         SET_STRING_ELT(names, n, ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR(namespaces[i])));
  }
  SET_NAMES(tmp, names);
  SET_VECTOR_ELT(opArgs, 3, tmp);
  UNPROTECT(2);


  ans = RS_XML(callUserFunction)(HANDLER_FUN_NAME(rinfo, "startElement"), XMLCHAR_TO_CHAR(localname), rinfo, opArgs);

  /* If the handler function returned us a SAXBranchFunction function, then we need to build the node's sub-tree and 
     then invoke the function with that node as the main argument. (It may also get the context/parser.) */
  if(isBranchFunction(ans)) {
         /* Hold on to the function to avoid it being garbage collected. */
      R_PreserveObject(rinfo->dynamicBranchFunction = ans);
         /* Start the creation of the node's sub-tree. */
      R_processBranch(rinfo, -1, localname, prefix, URI, nb_namespaces, namespaces, nb_attributes, nb_defaulted, attributes, FALSE);
  }

  UNPROTECT(1);
}


static void
RS_XML(xmlSAX2EndElementNs)(void * ctx, 
			    const xmlChar * localname, 
			    const xmlChar * prefix, 
			    const xmlChar * URI)
{
  USER_OBJECT_ args, tmp, fun;
  RS_XMLParserData *rinfo = (RS_XMLParserData *) ctx;
  DECL_ENCODING_FROM_EVENT_PARSER(rinfo)

  if(rinfo->current) {
      R_endBranch(rinfo, localname, prefix, URI);
      return;
  }

  PROTECT(args = NEW_LIST(2));
  SET_VECTOR_ELT(args, 0, ScalarString(ENC_COPY_TO_USER_STRING(localname)));

  PROTECT(tmp = ScalarString(ENC_COPY_TO_USER_STRING(URI ? URI : (const xmlChar *)""))); 
  if(prefix)
      SET_NAMES(tmp, ScalarString(ENC_COPY_TO_USER_STRING(prefix)));
  SET_VECTOR_ELT(args, 1, tmp);

  fun = findEndElementFun((const char *)localname, rinfo);
  if(fun)  {
      USER_OBJECT_ val = PROTECT(RS_XML(invokeFunction)(fun, args, rinfo->stateObject, rinfo->ctx));
      updateState(val, rinfo);
      UNPROTECT(1);
  } else
      RS_XML(callUserFunction)(HANDLER_FUN_NAME(ctx, "endElement"), NULL, (RS_XMLParserData *)ctx, args);

  UNPROTECT(2);
}



#if 0
static void
RS_XML(xmlSAX2StartDocument)(void *userData)
{
}
#endif

void
RS_XML(initXMLParserHandler)(xmlSAXHandlerPtr xmlParserHandler, int saxVersion)
{

  if(saxVersion == 2) {
     xmlParserHandler->initialized = 0;
     xmlSAX2InitDefaultSAXHandler(xmlParserHandler, 0);
     xmlParserHandler->initialized = XML_SAX2_MAGIC;

     xmlParserHandler->startElementNs = RS_XML(xmlSAX2StartElementNs);
     xmlParserHandler->endElementNs = RS_XML(xmlSAX2EndElementNs);
     xmlParserHandler->startElement = NULL;
     xmlParserHandler->endElement = NULL;

     xmlParserHandler->serror = RS_XML(structuredErrorHandler);

  } else {
     xmlParserHandler->startElement = RS_XML(startElementHandler);
     xmlParserHandler->endElement = RS_XML(endElementHandler);
  }

  xmlParserHandler->entityDecl = RS_XML(entityDeclaration);
  xmlParserHandler->getEntity = RS_XML(getEntityHandler);


  xmlParserHandler->comment = RS_XML(commentElementHandler);

  xmlParserHandler->characters = RS_XML(charactersHandler);
  xmlParserHandler->processingInstruction = RS_XML(piHandler);
  xmlParserHandler->cdataBlock = RS_XML(cdataBlockHandler);

  xmlParserHandler->startDocument = RS_XML(startDocumentHandler);
  xmlParserHandler->endDocument = RS_XML(endDocumentHandler);

  xmlParserHandler->isStandalone = RS_XML(isStandAloneHandler);
  xmlParserHandler->fatalError = RS_XML(fatalErrorHandler);
  xmlParserHandler->warning = RS_XML(warningHandler);
  xmlParserHandler->error = RS_XML(errorHandler);

  /* external entity  */

  xmlParserHandler->internalSubset = NULL;
  xmlParserHandler->externalSubset = NULL;
  xmlParserHandler->hasInternalSubset = NULL;
  xmlParserHandler->hasExternalSubset = NULL;
  xmlParserHandler->resolveEntity = NULL;

  xmlParserHandler->getParameterEntity = RS_XML(getParameterEntityHandler);
  xmlParserHandler->attributeDecl = NULL;
  xmlParserHandler->elementDecl = NULL;
  xmlParserHandler->notationDecl = NULL;
  xmlParserHandler->unparsedEntityDecl = NULL;
	       
  xmlParserHandler->setDocumentLocator = NULL;
  xmlParserHandler->reference = NULL;
  xmlParserHandler->ignorableWhitespace = NULL;


}


void
RS_XML(startElementHandler)(void *userData, const xmlChar *name, const xmlChar **atts)
{
  RS_XML(startElement)(userData, (const char *)name, (const char **)atts);
}

void
RS_XML(endElementHandler)(void *ctx, const xmlChar *name)
{
  RS_XML(endElement)(ctx, (const char *)name);
}

void
RS_XML(commentElementHandler)(void *ctx, const xmlChar *val)
{
  RS_XML(commentHandler)(ctx, (const XML_Char*)val);
}

void 
RS_XML(charactersHandler)(void *user_data, const xmlChar *ch, int len)
{
  RS_XML(textHandler)(user_data, (const XML_Char*)ch, len);
}

void
RS_XML(startDocumentHandler)(void *ctx)
{
    RS_XML(callUserFunction)(HANDLER_FUN_NAME(ctx, "startDocument"), NULL, ((RS_XMLParserData*) ctx), NULL_USER_OBJECT);
}

void
RS_XML(endDocumentHandler)(void *ctx)
{
    RS_XML(callUserFunction)(HANDLER_FUN_NAME(ctx, "endDocument"), NULL, ((RS_XMLParserData*) ctx), NULL_USER_OBJECT);
}

void
RS_XML(cdataBlockHandler)(void *ctx, const xmlChar *value, int len)
{
 USER_OBJECT_ opArgs;
 RS_XMLParserData *parserData = (RS_XMLParserData*) ctx;
 DECL_ENCODING_FROM_EVENT_PARSER(parserData)

  if(parserData->current) {
      xmlAddChild(parserData->current, xmlNewCDataBlock(NULL, value, len));
      return;
  }

 PROTECT(opArgs = NEW_LIST(1));
 SET_VECTOR_ELT(opArgs, 0, NEW_CHARACTER(1));
   SET_STRING_ELT(VECTOR_ELT(opArgs, 0), 0, ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR(value)));
   RS_XML(callUserFunction)(HANDLER_FUN_NAME(parserData, "cdata"), (const char *)NULL, (RS_XMLParserData*)ctx, opArgs);
  UNPROTECT(1);
}

void
RS_XML(piHandler)(void *ctx, const xmlChar *target, const xmlChar *data)
{
  RS_XML(processingInstructionHandler)(ctx, (const XML_Char*)target, (const XML_Char*)data);
}



//#define RString(x) (x ? mkString(XMLCHAR_TO_CHAR((x))) : NEW_CHARACTER(1))
#define RString(x) (x ? ScalarString(ENC_COPY_TO_USER_STRING(XMLCHAR_TO_CHAR((x)))) : NEW_CHARACTER(1))

/* Relies on the order and numbering of xmlEntityType from entities.h */
static const char * const EntityTypeNames[]  = {

    "Internal_General",
    "External_General_Parsed",
    "External_General_Unparsed",
    "Internal_Parameter",
    "External_Parameter",
    "Internal_Predefined"
};

void
RS_XML(entityDeclaration)(void *ctx,
                            const xmlChar *name, int type, const xmlChar *publicId,
			    const xmlChar *systemId, xmlChar *content)
{
    USER_OBJECT_ fun, opArgs, tmp;
    RS_XMLParserData *parserData = (RS_XMLParserData*) ctx;
    DECL_ENCODING_FROM_EVENT_PARSER(parserData)

    /* check if there is a function to call before making the list of 5 elements. */
    fun = RS_XML(findFunction)(HANDLER_FUN_NAME(parserData, "entityDeclaration"), parserData->methods); 
    if(fun == NULL || fun == NULL_USER_OBJECT) 
	return;

    PROTECT(fun);
    PROTECT(opArgs = NEW_LIST(5));
    SET_VECTOR_ELT(opArgs, 0, RString(name));
    PROTECT(tmp = ScalarInteger(type));
    SET_NAMES(tmp, mkString(EntityTypeNames[type-1]));
    SET_VECTOR_ELT(opArgs, 1, tmp);
    UNPROTECT(1);
    SET_VECTOR_ELT(opArgs, 2, RString(content));
    SET_VECTOR_ELT(opArgs, 3, RString(systemId));
    SET_VECTOR_ELT(opArgs, 4, RString(publicId));

    (void) RS_XML(invokeFunction)(fun, opArgs, parserData->stateObject, parserData->ctx);    
    UNPROTECT(2);
}


static xmlEntityPtr
do_getEntityHandler(void *userData, const xmlChar *name, const char * r_funName)
{
    SEXP opArgs, r_ans;
    xmlEntityPtr ans = NULL;
    RS_XMLParserData *parserData = (RS_XMLParserData*) userData;
    DECL_ENCODING_FROM_EVENT_PARSER(parserData)

    PROTECT(opArgs = NEW_LIST(1)) ;
    SET_VECTOR_ELT(opArgs, 0, ScalarString(ENC_COPY_TO_USER_STRING(name))); /*XXX should we encode this? Done now! */
    r_ans = RS_XML(callUserFunction)(r_funName, NULL, (RS_XMLParserData *) userData, opArgs);
    
    PROTECT(r_ans) ;
    if(r_ans != NULL_USER_OBJECT && GET_LENGTH(r_ans) > 0) {
	if(TYPEOF(r_ans) == STRSXP) {
	    const char *value;
	    value = CHAR_DEREF(STRING_ELT(r_ans, 0));
	    ans = (xmlEntityPtr) malloc(sizeof(xmlEntity));
	    memset(ans, 0, sizeof(xmlEntity));
	    ans->type = XML_ENTITY_DECL;
	    ans->etype = XML_INTERNAL_GENERAL_ENTITY;
	    ans->name = xmlStrdup(name);
	    ans->orig = NULL; // xmlStrdup(CHAR_TO_XMLCHAR(value));
	    ans->content = xmlStrdup(CHAR_TO_XMLCHAR(value));	    
	    ans->length = (int)strlen(value);
#ifndef NO_CHECKED_ENTITY_FIELD
	    ans->checked = 1;
#endif
	}
    }
    UNPROTECT(2);

    return(ans);
}

xmlEntityPtr
RS_XML(getEntityHandler)(void *userData, const xmlChar *name)
{
    return(do_getEntityHandler(userData, name, HANDLER_FUN_NAME(userData, "getEntity")));
}


xmlEntityPtr
RS_XML(getParameterEntityHandler)(void *userData, const xmlChar *name)
{
    return(do_getEntityHandler(userData, name, HANDLER_FUN_NAME(userData, "getParameterEntity")));
}




int
RS_XML(isStandAloneHandler)(void *ctx)
{
  return(1);
}

void
RS_XML(fatalErrorHandler)(void *ctx, const char *format, ...)
{

  const char *msg = "error message unavailable";
  va_list args;
  va_start(args, format);

  if(strcmp(format, "%s") == 0)
    msg = va_arg(args, char *);

  va_end(args);


  PROBLEM "Fatal error in the XML event driven parser for %s: %s",
	  ((RS_XMLParserData*) ctx)->fileName, msg
  ERROR;

}

void
RS_XML(errorHandler)(void *ctx, const char *format, ...)
{
  const char *msg = "error message unavailable";
  va_list args;
  va_start(args, format);

  if(strcmp(format, "%s") == 0)
    msg = va_arg(args, char *);

  va_end(args);

  PROBLEM "Error in the XML event driven parser for %s: %s",
    ((RS_XMLParserData*) ctx)->fileName, msg
  ERROR;

}

void 
RS_XML(structuredErrorHandler)(void *ctx, xmlErrorPtr err)
{
   if(err->level == XML_ERR_FATAL) {
      PROBLEM "Error in the XML event driven parser (line = %d, column = %d): %s",
         err->line, err->int2 , err->message
      ERROR;
   } else {
      PROBLEM "Error in the XML event driven parser (line = %d, column = %d): %s",
         err->line, err->int2 , err->message
      WARN;
   }
}

void
RS_XML(warningHandler)(void *ctx, const char *msg, ...)
{

 PROBLEM "XML event driven parser warning from %s.",
   ((RS_XMLParserData*) ctx)->fileName
 WARN;

}



SEXP 
RS_XML_xmlStopParser(SEXP r_context)
{
    xmlParserCtxtPtr context;

    if(TYPEOF(r_context) != EXTPTRSXP || R_ExternalPtrTag(r_context) != Rf_install(XML_PARSER_CONTEXT_TYPE_NAME)) {
	PROBLEM "xmlStopParser requires an " XML_PARSER_CONTEXT_TYPE_NAME " object"
	    ERROR;
    }
    context = (xmlParserCtxtPtr) R_ExternalPtrAddr(r_context);

    if(!context) {
	PROBLEM "NULL value passed to RS_XML_xmlStopParser. Is it a value from a previous session?"
	    ERROR;
    }
    
    xmlStopParser(context);
    return(ScalarLogical(1));
}