/*********************************************************************
   Copyright 2018, UCAR/Unidata See netcdf/COPYRIGHT file for
   copying and redistribution conditions.
 *********************************************************************/

#include "config.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "nc.h"

#define ID_SHIFT (16)
#define NCFILELISTLENGTH 0x10000

/* Version one just allocates the max space (sizeof(NC*)*2^16)*/
static NC** nc_filelist = NULL;

static int numfiles = 0;

/* Common */
int
count_NCList(void)
{
    return numfiles;
}


void
free_NCList(void)
{
    if(numfiles > 0) return; /* not empty */
    if(nc_filelist != NULL) free(nc_filelist);
    nc_filelist = NULL;
}

int
add_to_NCList(NC* ncp)
{
    int i;
    int new_id;
    if(nc_filelist == NULL) {
	if (!(nc_filelist = calloc(1, sizeof(NC*)*NCFILELISTLENGTH)))
	    return NC_ENOMEM;
	numfiles = 0;
    }
#ifdef USE_REFCOUNT
    /* Check the refcount */
    if(ncp->refcount > 0)
	return NC_NOERR;
#endif

    new_id = 0; /* id's begin at 1 */
    for(i=1; i < NCFILELISTLENGTH; i++) {
	if(nc_filelist[i] == NULL) {new_id = i; break;}
    }
    if(new_id == 0) return NC_ENOMEM; /* no more slots */
    nc_filelist[new_id] = ncp;
    numfiles++;
    new_id = (new_id << ID_SHIFT);
    ncp->ext_ncid = new_id;
    return NC_NOERR;
}

void
del_from_NCList(NC* ncp)
{
   unsigned int ncid = ((unsigned int)ncp->ext_ncid) >> ID_SHIFT;
   if(numfiles == 0 || ncid == 0 || nc_filelist == NULL) return;
   if(nc_filelist[ncid] != ncp) return;
#ifdef USE_REFCOUNT
   /* Check the refcount */
   if(ncp->refcount > 0)
	return; /* assume caller has decrecmented */
#endif

   nc_filelist[ncid] = NULL;
   numfiles--;

   /* If all files have been closed, release the filelist memory. */
   if (numfiles == 0)
      free_NCList();
}

NC *
find_in_NCList(int ext_ncid)
{
   NC* f = NULL;
   unsigned int ncid = ((unsigned int)ext_ncid) >> ID_SHIFT;
   if(numfiles > 0 && nc_filelist != NULL && ncid < NCFILELISTLENGTH)
	f = nc_filelist[ncid];

   /* for classic files, ext_ncid must be a multiple of (1<<ID_SHIFT) */
   if (f != NULL && f->model == NC_FORMATX_NC3 && (ext_ncid % (1<<ID_SHIFT)))
       return NULL;

   return f;
}

/*
Added to support open by name
*/
NC*
find_in_NCList_by_name(const char* path)
{
   int i;
   NC* f = NULL;
   if(nc_filelist == NULL)
	return NULL;
   for(i=1; i < NCFILELISTLENGTH; i++) {
	if(nc_filelist[i] != NULL) {
	    if(strcmp(nc_filelist[i]->path,path)==0) {
		f = nc_filelist[i];
		break;
	    }
	}
   }
   return f;
}

int
iterate_NCList(int index, NC** ncp)
{
    /* Walk from 0 ...; 0 return => stop */
    if(index < 0 || index >= NCFILELISTLENGTH)
	return NC_ERANGE;
    if(ncp) *ncp = nc_filelist[index];
    return NC_NOERR;
}