/*   Cataract - Static web photo gallery generator
 *   Copyright (C) 2008 Tomas Bzatek <tbzatek@users.sourceforge.net>
 *
 *   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; either version 2
 *   of the License, or any later version.
 *
 *   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 Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>

#include <libxml/xmlmemory.h>
#include <libxml/parser.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>

#include <glib.h>

#include "xml-parser.h"
#include "gallery-utils.h"



/*
 *   xml_parser_load: initialize and load the XML document
 */
TXMLFile *
xml_parser_load (const char *filename)
{
  TXMLFile *file;

  file = malloc (sizeof (TXMLFile));
  memset (file, 0, sizeof (TXMLFile));

  /* Load XML document */
  file->doc = xmlParseFile (filename);
  if (file->doc == NULL) {
	log_error ("Error: unable to parse file \"%s\"\n", filename);
	free (file);
	return NULL;
  }

  /* Create xpath evaluation context */
  file->xpathCtx = xmlXPathNewContext (file->doc);
  if (file->xpathCtx == NULL) {
    log_error ("Error: unable to create new XPath context\n");
    xmlFreeDoc (file->doc);
	free (file);
    return FALSE;
  }

  return file;
}


/*
 *   xml_parser_close: close the XML document parser
 */
void
xml_parser_close (TXMLFile *file)
{
  if (file)
  {
    xmlXPathFreeContext (file->xpathCtx);
	xmlFreeDoc (file->doc);
	free (file);
	file = NULL;
  }
}

/*
 *   xml_file_get_node_name: retrieve name of the XPath node
 */
char *
xml_file_get_node_name (TXMLFile *file, const char *x_path)
{
  xmlXPathObjectPtr xpathObj;
  xmlNodePtr cur;
  char *attrv;

  if ((! file) || (! x_path))
          return NULL;

  /* Evaluate xpath expression */
  xpathObj = xmlXPathEvalExpression ((const xmlChar *) x_path, file->xpathCtx);
  if (xpathObj == NULL) {
      log_error ("Error: unable to evaluate xpath expression \"%s\"\n", x_path);
      return NULL;
  }

  attrv = NULL;
  if ((xpathObj->nodesetval) && (xpathObj->nodesetval->nodeNr > 0)) {
          cur = xpathObj->nodesetval->nodeTab[0];
          if (cur->name)
            attrv = strdup ((const char *) cur->name);
  }

  xmlXPathFreeObject (xpathObj);
  return attrv;
}


/*
 *   xml_file_get_node_value: retrieve string value from XPath node
 *     - multiple matched nodes will be concatenated into one string
 *       - otherwise please use [0], [1] etc. quantificators
 */
char *
xml_file_get_node_value (TXMLFile *file, const char *x_path)
{
  xmlXPathObjectPtr xpathObj;
  xmlNodePtr cur;
  char *val, *valx;
  int i;

  if ((! file) || (! x_path))
	  return NULL;

  /* Evaluate xpath expression */
  xpathObj = xmlXPathEvalExpression ((const xmlChar *) x_path, file->xpathCtx);
  if (xpathObj == NULL) {
      log_error ("Error: unable to evaluate xpath expression \"%s\"\n", x_path);
      return NULL;
  }

  val = NULL;
  if ((xpathObj->nodesetval) && (xpathObj->nodesetval->nodeNr > 0)) {
    #ifdef __DEBUG_ALL__
      printf("Result (%d nodes):\n", xpathObj->nodesetval->nodeNr);
    #endif

    for (i = 0; i < xpathObj->nodesetval->nodeNr; i++)
      {
        cur = xpathObj->nodesetval->nodeTab[i];
        #ifdef __DEBUG_ALL__
          printf("  XPATH matched:  element node \"%s[%d]\", value = '%s'\n", cur->name, i, cur->content);
        #endif

        if (cur->content)
          {
            if (val == NULL)
              {
                val = g_strdup ((char *) cur->content);
              }
            else
              {
                valx = g_strconcat (val, (char *) cur->content, NULL);
                g_free (val);
                val = valx;
              }
          }
      }
  }

  xmlXPathFreeObject (xpathObj);
  return val;
}


/*
 *   xml_file_get_node_attribute: retrieve attribute value from XPath node
 */
char *
xml_file_get_node_attribute (TXMLFile *file, const char *x_path, const char *attr)
{
  xmlXPathObjectPtr xpathObj;
  xmlNodePtr cur;
  xmlChar *attrvx;
  char *attrv;

  if ((! file) || (! x_path))
	  return NULL;

  /* Evaluate xpath expression */
  xpathObj = xmlXPathEvalExpression ((const xmlChar *) x_path, file->xpathCtx);
  if (xpathObj == NULL) {
      log_error ("Error: unable to evaluate xpath expression \"%s\"\n", x_path);
      return NULL;
  }

  attrv = NULL;
  if ((xpathObj->nodesetval) && (xpathObj->nodesetval->nodeNr > 0)) {
	  cur = xpathObj->nodesetval->nodeTab[0];
	  attrvx = xmlGetProp (cur, (const xmlChar *) attr);
	  if (attrvx) {
	    attrv = strdup ((char*) attrvx);
	    xmlFree (attrvx);
	  }

	  #ifdef __DEBUG_ALL__
        printf("Result (%d nodes):\n", xpathObj->nodesetval->nodeNr);
	    printf("  XPATH matched:  element node \"%s\", value = '%s', property value = '%s'\n", cur->name, cur->content, attrv);
      #endif
  }

  xmlXPathFreeObject (xpathObj);
  return attrv;
}

long
xml_file_get_node_attribute_long (TXMLFile *file, const char *x_path, const char *attr, const int _default)
{
  char *s;
  long int i;

  s = xml_file_get_node_attribute (file, x_path, attr);
  if (s == NULL)
	  return _default;

  i = atol (s);
  free (s);
  return i;
}

/*
 *   xml_file_get_node_present: existency test of the XPath node
 */
gboolean
xml_file_get_node_present (TXMLFile *file, const char *x_path)
{
  return xml_file_node_get_children_count (file, x_path) > 0;
}


/*
 *   xml_file_node_get_children_count: retrieve number of children items of the specified XPath node
 */
int
xml_file_node_get_children_count (TXMLFile *file, const char *x_path)
{
  xmlXPathObjectPtr xpathObj;
  int count;

  if ((! file) || (! x_path))
	  return 0;

  /* Evaluate xpath expression */
  xpathObj = xmlXPathEvalExpression ((const xmlChar *) x_path, file->xpathCtx);
  if (xpathObj == NULL) {
      log_error ("Error: unable to evaluate xpath expression \"%s\"\n", x_path);
      return 0;
  }

  count = 0;
  if (xpathObj->nodesetval)
	  count = xpathObj->nodesetval->nodeNr;

  xmlXPathFreeObject (xpathObj);
  return count;
}