/*
 * This is a program to test the concept of an XML Streamer.
 * Ref: http://blogs.msdn.com/mfussell/archive/2005/02/12/371546.aspx
 */

#include <stdlib.h>
#include <string.h>
#include <glib.h>
#include <libxml/xmlreader.h>
#include <libxml/xmlwriter.h>

#undef DEBUG

static const xmlChar *build_qname(const char *prefix,const char *name)
{
    static xmlChar *buf=0;
    static int buflen=0;
    int len;
    if (!prefix)
    {
	if (!name && buf)
	{
	    g_free((char *)buf);
	    buf=NULL;
	    buflen=0;
	}
	return BAD_CAST name;
    }
    else
    {
	len=strlen(prefix)+strlen(name)+2;
	if (buflen<len)
	{
	    g_free((char *)buf);
	    buflen=len*2;
	    buf=BAD_CAST g_malloc(buflen);
	}
	sprintf(buf,"%s:%s",prefix,name);
	return buf;
    }
}

GSList *stream_element(xmlTextWriter *dst,xmlTextReader *src,
  GTree *namespaces,GSList *elements)
{
    int i,r,type,count;
    GPtrArray *array=NULL;
    const char *uri,*prefix;
    uri=xmlTextReaderConstNamespaceUri(src);
    if (uri && *uri)
	prefix=g_tree_lookup(namespaces,uri);
    else
	prefix=NULL;
    if (prefix)
	xmlTextWriterStartElement(dst,build_qname(prefix,
	  xmlTextReaderConstLocalName(src)));
    else if (uri && *uri)
    {
	prefix=xmlTextReaderConstPrefix(src);
	array=g_ptr_array_new();
	g_ptr_array_add(array,(gpointer)uri);
	g_tree_insert(namespaces,(gpointer)uri,(gpointer)prefix);
	xmlTextWriterStartElementNS(dst,prefix,xmlTextReaderConstLocalName(src),
	  uri);
    }
    else
	xmlTextWriterStartElement(dst,xmlTextReaderConstLocalName(src));
    count=xmlTextReaderAttributeCount(src);
    for(i=0;i<count;i++)
    {
	xmlTextReaderMoveToAttributeNo(src,i);
	uri=xmlTextReaderConstNamespaceUri(src);
	if (uri && *uri)
	    prefix=g_tree_lookup(namespaces,uri);
	else
	    prefix=NULL;
	if (prefix)
	{
	    if (!strcmp(prefix,"xmlns"))
	    {
		uri=xmlTextReaderConstValue(src);
		if (uri && *uri)
		{
		    prefix=g_tree_lookup(namespaces,uri);
		    if (!prefix)
		    {
			prefix=xmlTextReaderConstLocalName(src);
			if (!array)
			    array=g_ptr_array_new();
			g_ptr_array_add(array,(gpointer)uri);
			g_tree_insert(namespaces,(gpointer)uri,
			  (gpointer)prefix);
			xmlTextWriterStartAttribute(dst,
			  build_qname("xmlns",prefix));
		    }
		    else
			continue;
		}
		else
		    /* xmlns:prefix="" is illegal XML; drop it */
		    continue;
	    }
	    else
		xmlTextWriterStartAttribute(dst,
		  build_qname(prefix,
		  xmlTextReaderConstLocalName(src)));
	}
	else if (uri && *uri)
	{
	    prefix=xmlTextReaderConstPrefix(src);
	    if (!array)
		array=g_ptr_array_new();
	    g_ptr_array_add(array,(gpointer)uri);
	    g_tree_insert(namespaces,(gpointer)uri,
	      (gpointer)prefix);
	    xmlTextWriterStartAttributeNS(dst,prefix,
	      xmlTextReaderConstLocalName(src),uri);
	}
	else
	    xmlTextWriterStartAttribute(dst,
	      xmlTextReaderConstLocalName(src));
	while ((r=xmlTextReaderReadAttributeValue(src))==1)
	{
	    type=xmlTextReaderNodeType(src);
#ifdef DEBUG
	    fprintf(stderr,"=== Node type %d\n",type);
#endif
	    switch(type)
	    {
		case XML_READER_TYPE_TEXT:
		case XML_READER_TYPE_WHITESPACE:
		case XML_READER_TYPE_SIGNIFICANT_WHITESPACE:
		    xmlTextWriterWriteString(dst,
		      xmlTextReaderConstValue(src));
		    break;
		case XML_READER_TYPE_ENTITY_REFERENCE:
		    xmlTextWriterWriteFormatRaw(dst,"&%s;",
		      xmlTextReaderConstName(src));
		    break;
	    }
	}
	xmlTextWriterEndAttribute(dst);
    }
    if (count)
	xmlTextReaderMoveToElement(src);
    if (xmlTextReaderIsEmptyElement(src))
    {
	if (array)
	{
	    for(i=0;i<array->len;i++)
		g_tree_remove(namespaces,
		  g_ptr_array_index(array,i));
	    g_ptr_array_free(array,TRUE);
	}
	xmlTextWriterEndElement(dst);
    }
    else
	elements=g_slist_prepend(elements,array);
    return elements;
}

int stream(xmlTextWriter *dst,xmlTextReader *src)
{
    int i,r,type;
    GTree *namespaces;		/* key: URI, value: prefix */
    GSList *elements=NULL;	/* Tail is root, Head is current element */
    GPtrArray *array;		/* Array of keys */
    const char *uri,*prefix;
    gboolean doc_started=FALSE;
    xmlNode *node;
    xmlDtd *dtd;
    xmlBuffer *buf;
    namespaces=g_tree_new((GCompareFunc)strcmp);
    g_tree_insert(namespaces,"http://www.w3.org/XML/1998/namespace","xml");
    g_tree_insert(namespaces,"http://www.w3.org/2000/xmlns/","xmlns");
    xmlTextReaderSetParserProp(src,XML_PARSER_LOADDTD,0);
    xmlTextReaderSetParserProp(src,XML_PARSER_DEFAULTATTRS,0);
    xmlTextReaderSetParserProp(src,XML_PARSER_VALIDATE,0);
    xmlTextReaderSetParserProp(src,XML_PARSER_SUBST_ENTITIES,0);
    while ((r=xmlTextReaderRead(src))==1)
    {
	type=xmlTextReaderNodeType(src);
	if (!doc_started && type==XML_READER_TYPE_ELEMENT ||
	  type==XML_READER_TYPE_DOCUMENT || type==XML_READER_TYPE_DOCUMENT_TYPE)
	{
	    i=xmlTextReaderStandalone(src);
	    xmlTextWriterStartDocument(dst,
	      xmlTextReaderConstXmlVersion(src),
	      xmlTextReaderConstEncoding(src),
	      i>0?"yes":i==0?"no":NULL);
	    doc_started=TRUE;
	}
#ifdef DEBUG
	fprintf(stderr,"*** Node type %d\n",type);
#endif
	switch(type)
	{
	    case XML_READER_TYPE_ELEMENT:
		elements=stream_element(dst,src,namespaces,elements);
		break;
	    case XML_READER_TYPE_TEXT:
	    case XML_READER_TYPE_WHITESPACE:
	    case XML_READER_TYPE_SIGNIFICANT_WHITESPACE:
		xmlTextWriterWriteString(dst,xmlTextReaderConstValue(src));
		break;
	    case XML_READER_TYPE_CDATA:
		xmlTextWriterWriteCDATA(dst,xmlTextReaderConstValue(src));
		break;
	    case XML_READER_TYPE_ENTITY_REFERENCE:
		xmlTextWriterWriteFormatRaw(dst,"&%s;",
		  xmlTextReaderConstName(src));
		break;
	    case XML_READER_TYPE_XML_DECLARATION:
		/* Not generated by libxml version 2.6.27 */
		break;
	    case XML_READER_TYPE_PROCESSING_INSTRUCTION:
		xmlTextWriterWritePI(dst,xmlTextReaderConstName(src),
		  xmlTextReaderConstValue(src));
		break;
	    case XML_READER_TYPE_DOCUMENT_TYPE:
		node=xmlTextReaderCurrentNode(src);
		if (node->type!=XML_DTD_NODE)
		    xmlTextWriterWriteDTD(dst,xmlTextReaderConstName(src),
		      NULL,NULL,NULL);
		else
		{
		    dtd=(xmlDtd *)node;
		    buf=xmlBufferCreate();
		    if (dtd->entities)
			xmlDumpEntitiesTable(buf,
			  (xmlEntitiesTable *)dtd->entities);
		    if (dtd->pentities)
			xmlDumpEntitiesTable(buf,
			  (xmlEntitiesTable *)dtd->pentities);
		    /* This is not quite right in that it expands entities,
		     * but I don't know how to do better.
		     */
		    if (dtd->elements)
			xmlDumpElementTable(buf,
			  (xmlElementTable *)dtd->elements);
		    if (dtd->attributes)
			xmlDumpAttributeTable(buf,
			  (xmlAttributeTable *)dtd->attributes);
		    if (dtd->notations)
			xmlDumpNotationTable(buf,
			  (xmlNotationTable *)dtd->notations);
		    xmlTextWriterWriteDTD(dst,dtd->name,dtd->ExternalID,
		      dtd->SystemID,*buf->content?buf->content:NULL);
		    xmlBufferFree(buf);
		}
		break;
	    case XML_READER_TYPE_COMMENT:
		xmlTextWriterWriteComment(dst,xmlTextReaderConstValue(src));
		break;
	    case XML_READER_TYPE_END_ELEMENT:
		array=elements->data;
		elements=g_slist_remove_link(elements,elements);
		if (array)
		{
		    for(i=0;i<array->len;i++)
			g_tree_remove(namespaces,g_ptr_array_index(array,i));
		    g_ptr_array_free(array,TRUE);
		}
		xmlTextWriterEndElement(dst);
		break;
	    case XML_READER_TYPE_NONE:
	    case XML_READER_TYPE_ATTRIBUTE:
	    case XML_READER_TYPE_ENTITY:
	    case XML_READER_TYPE_DOCUMENT:
	    case XML_READER_TYPE_DOCUMENT_FRAGMENT:
	    case XML_READER_TYPE_NOTATION:
	    case XML_READER_TYPE_END_ENTITY:
		break;
	}
    }
    if (doc_started)
	xmlTextWriterEndDocument(dst);
    return r;
}

main()
{
    int r;
    xmlTextWriter *dst;
    xmlTextReader *src;
    src=xmlReaderForFd(0,NULL,NULL,XML_PARSE_NONET);
    dst=xmlNewTextWriterFilename("/dev/stdout",0);
    r=stream(dst,src);
    xmlFreeTextReader(src);
    xmlFreeTextWriter(dst);
    exit(r);
}