#include "executor/spi.h"
#include "postgres.h"
#include <string.h>



text *sts_strcatex (char **str_pointer, char *str, text *txt,
		    long *saved_chars, long *allocated_free, long page_size)
{
  long l = strlen (str);
  if (l > page_size)
    elog (ERROR, "Retezec je vetsi nez velikost stranky");
  if (*allocated_free < l)
    {
      text *txtn;
      long ma = ((*saved_chars + l) / page_size + 1) * page_size;
      elog (NOTICE, "before alloc %d", ma);
      txtn = (text *) palloc (ma);
      elog (NOTICE, "after alloc");
      elog (NOTICE, "Alokovan %d", txtn);
      memcpy ((void *) VARDATA(txtn), (void *) VARDATA(txt), *saved_chars);
      elog (NOTICE, "after memcpy");
      *allocated_free = ma - *saved_chars; *str_pointer = VARDATA(txtn) + *saved_chars;
      elog (NOTICE, "befor pfree");
      pfree (txt); txt = txtn;
      elog (NOTICE, "after pfree");
    }
  strcpy (*str_pointer, str);
  *str_pointer += l; *saved_chars += l; *allocated_free -= l;
  VARATT_SIZEP (txt) = *saved_chars + VARHDRSZ;
  return txt;
}

PG_FUNCTION_INFO_V1 (html_list);

Datum
html_list (PG_FUNCTION_ARGS)
{
  long ret, sloupec, radek, saved_chars, allocated_free, page_size, max;
  char *str_pointer, *query, *column_name; text *txt; 
  
  if (PG_ARGISNULL (0) | PG_ARGISNULL (1))
    elog (ERROR, "Parametrs have'nt to be NULL");

  if ((ret = SPI_connect()) < 0)
    elog (ERROR, "SPI_connect returned %d", ret);

  query = PG_GETARG_CSTRING (0); column_name = PG_GETARG_CSTRING (1);
  max = PG_GETARG_INT32 (2); page_size = PG_GETARG_INT32 (3);

  if ((ret = SPI_exec (query, max)) < 0)
    elog (ERROR, "SPI_exec returned %d", ret);
  
  sloupec = SPI_fnumber(SPI_tuptable->tupdesc, column_name);

  if (sloupec <= 0)
    elog (ERROR, "SPI_ERROR_NOATTRIBUTE");
  
  saved_chars = 0; allocated_free = page_size;
  txt = (text*) palloc (VARHDRSZ + allocated_free);
  str_pointer = VARDATA(txt);

  txt = sts_strcatex (&str_pointer, "<ul>\n", txt, &saved_chars, &allocated_free, page_size);

  for (radek = 0; radek < SPI_processed; radek++)
    {
      txt = sts_strcatex (&str_pointer, "<li>", txt, &saved_chars, &allocated_free, page_size);
      txt = sts_strcatex (&str_pointer,
      			  SPI_getvalue (SPI_tuptable->vals[radek], 
      					SPI_tuptable->tupdesc, sloupec),
    			  txt, &saved_chars, &allocated_free, page_size);
      txt = sts_strcatex (&str_pointer, "</li>\n", txt, &saved_chars, &allocated_free, page_size);
    }
  txt = sts_strcatex (&str_pointer, "</ul>", txt, &saved_chars, &allocated_free, page_size);
  elog (NOTICE,"BEFORE finish");
  SPI_finish ();
  elog (NOTICE, "AFTER FINISH");
  PG_RETURN_TEXT_P(txt);
}