/* Copyright (C) 2006 MySQL AB

   This program 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; version 2 of the License.

   This program 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

#include <drizzled/server_includes.h>
#include <drizzled/session.h>
#include <drizzled/function/str/strfunc.h>
#include <drizzled/util/convert.h>
#include <stdio.h>
#include <stdlib.h>
#include <libxml/tree.h>
#include <libxml/parser.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <zlib.h>

int count_xpath_expression(const char* contents, const xmlChar* xpathExpr, const xmlChar* nsList);
int register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList);

class Item_func_uncompress: public Item_str_func
{
  String buffer;
public:
  Item_func_uncompress(): Item_str_func(){}
  void fix_length_and_dec(){ maybe_null= 1; max_length= MAX_BLOB_WIDTH; }
  const char *func_name() const{return "uncompress";}
  String *val_str(String *) ;
};

String *Item_func_uncompress::val_str(String *str)
{
  assert(fixed == 1);
  String *res= args[0]->val_str(str);
  int resint = 0;
  const char* contents = (const char *) "<?xml version=\"1.0\"?><EXAMPLE prop1=\"gnome is great\" prop2=\"&amp; linux too\">  <head>   <title>Welcome to Gnome</title>  </head>  <chapter>   <title>The Linux adventure</title>   <p>bla bla bla ...</p>   <image href=\"linus.gif\"/>   <p>...</p>  </chapter>  <chapter>   <title>The Linux adventure</title>   <p>bla bla bla ...</p>   <image href=\"linus.gif\"/>   <p>...</p>  </chapter></EXAMPLE>";
  const xmlChar* expression = (const xmlChar*) "//p";
  const xmlChar* list = NULL;
  char buffer [50];
  /* Init libxml */     
  xmlInitParser();
  LIBXML_TEST_VERSION

  /* Do the main job */
  //printf("size %d\n", count_xpath_expression(contents, BAD_CAST expression, NULL));
    
  resint= sprintf(buffer, "%s", 
      (const char *) count_xpath_expression(contents, expression, list));
  //char *retchar= to_string( resint );
  res= to_string(resint);
    /* Shutdown libxml */
  xmlCleanupParser();
    
    /*
     * this is to debug memory for regression tests
     */
    // xmlMemoryDump();
    
    //free(contents);
    //free(expression);
    return res;
}

int count_xpath_expression(const char* contents, const xmlChar* xpathExpr, const xmlChar* nsList) {
    xmlDocPtr doc;
    xmlXPathContextPtr xpathCtx; 
    xmlXPathObjectPtr xpathObj; 
    int count = 0;
    
    assert(contents);
    assert(xpathExpr);
    
    /* Load XML document */
    doc = xmlParseMemory(contents, strlen(contents));
    if (doc == NULL) {
    	fprintf(stderr, "Error: unable to parse contents: \"%s\"\n", contents);
    	return(-1);
    }

    /* Create xpath evaluation context */
    xpathCtx = xmlXPathNewContext(doc);
    if(xpathCtx == NULL) {
        fprintf(stderr,"Error: unable to create new XPath context\n");
        xmlFreeDoc(doc); 
        return(-1);
    }
    
    /* Register namespaces from list (if any) */
    if((nsList != NULL) && (register_namespaces(xpathCtx, nsList) < 0)) {
        fprintf(stderr,"Error: failed to register namespaces list \"%s\"\n", nsList);
        xmlXPathFreeContext(xpathCtx); 
        xmlFreeDoc(doc); 
        return(NULL);
    }

    /* Evaluate xpath expression */
    xpathObj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
    if(xpathObj == NULL) {
        fprintf(stderr,"Error: unable to evaluate xpath expression \"%s\"\n", xpathExpr);
        xmlXPathFreeContext(xpathCtx); 
        xmlFreeDoc(doc); 
        return(-1);
    }

    /* Print results */
    count = xpathObj->nodesetval->nodeNr;
    // print_xpath_nodes(xpathObj->nodesetval, stdout);

    /* Cleanup */
    xmlXPathFreeObject(xpathObj);
    xmlXPathFreeContext(xpathCtx); 
    xmlFreeDoc(doc); 
    
    return(count);
}

int 
register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList) {
    xmlChar* nsListDup;
    xmlChar* prefix;
    xmlChar* href;
    xmlChar* next;
    
    assert(xpathCtx);
    assert(nsList);

    nsListDup = xmlStrdup(nsList);
    if(nsListDup == NULL) {
	fprintf(stderr, "Error: unable to strdup namespaces list\n");
	return(-1);	
    }
    
    next = nsListDup; 
    while(next != NULL) {
	/* skip spaces */
	while((*next) == ' ') next++;
	if((*next) == '\0') break;

	/* find prefix */
	prefix = next;
	next = (xmlChar*)xmlStrchr(next, '=');
	if(next == NULL) {
	    fprintf(stderr,"Error: invalid namespaces list format\n");
	    xmlFree(nsListDup);
	    return(-1);	
	}
	*(next++) = '\0';	
	
	/* find href */
	href = next;
	next = (xmlChar*)xmlStrchr(next, ' ');
	if(next != NULL) {
	    *(next++) = '\0';	
	}

	/* do register namespace */
	if(xmlXPathRegisterNs(xpathCtx, prefix, href) != 0) {
	    fprintf(stderr,"Error: unable to register NS with prefix=\"%s\" and href=\"%s\"\n", prefix, href);
	    xmlFree(nsListDup);
	    return(-1);	
	}
    }
    
    xmlFree(nsListDup);
    return(0);
}

Item_func* create_uncompressudf_item(MEM_ROOT* m)
{
  return  new (m) Item_func_uncompress();
}

static struct udf_func uncompressudf = {
  { C_STRING_WITH_LEN("uncompress") },
  create_uncompressudf_item
};

static int uncompressudf_plugin_init(void *p)
{
  udf_func **f = (udf_func**) p;

  *f= &uncompressudf;

  return 0;
}

static int uncompressudf_plugin_deinit(void *p)
{
  udf_func *udff = (udf_func *) p;
  (void)udff;
  return 0;
}

mysql_declare_plugin(uncompress)
{
  DRIZZLE_UDF_PLUGIN,
  "uncompress",
  "1.0",
  "Stewart Smith",
  "UDF for compress()",
  PLUGIN_LICENSE_GPL,
  uncompressudf_plugin_init, /* Plugin Init */
  uncompressudf_plugin_deinit, /* Plugin Deinit */
  NULL,   /* status variables */
  NULL,   /* system variables */
  NULL    /* config options */
}
mysql_declare_plugin_end;