/* gridpt2record.c */

/* ----------------------- 
 *  INPUT FILE:  geog3.nc 
 *      OUTPUT:  STDOUT 
 * ----------------------- */

/* nanr - updated 27may98 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* >>>>>> VEMAP USER's ----- Customize pathnames here ---- */

/* Meeteetse path */
#include "/contrib/netcdf-3.4/include/netcdf.h"

void grid(int gridpt, int *row, int *col, float *olat, float *olon);
void background(int row,int col,int gridpt,int *startpos);

int main(argc, argv)
int argc;
char *argv[];
{



/* Grid variables */
  int gridpt;		/* For VEMAP US Grid 1 thru 5520 */
  int startpos;		/* Gridpt record position */
  int row;		/* Row number */
  int col;		/* Column number */
  float olat;		/* cell center latitude */
  float olon;		/* cell center longitude */

/* --- Command line instructions --- */
  if(argc != 2) {
	printf("syntax is <exe> <gridpt> \n");
        printf("example: a.out 480 \n");
        return(0);
  }

  gridpt = atoi(argv[1]);
  if(gridpt > 5520 || gridpt <= 0) {
     printf("\n  Grid cell %d is out of range. \n\n",gridpt);
     printf("  Grid cells number from 1->5520. \n");
     printf("  Note that grid cell number WILL NOT equal \n");
     printf("  record number or netCDF position index.\n\n");
     printf("  e.g. RECORD NUMBER for gridcell 6 = 3\n\n");
     printf("       netCDF position index for Record 3: \n");
     printf("                     C = 2 \n");
     printf("               Fortran = 3\n\n");
     exit(1);
  }


/* --- Translate gridpoint --- */ 
/*    (1) latitude/longitude   */
/*    (2) row and column       */

  grid(gridpt,&row,&col,&olat,&olon);

/* ---------Screen for background point ------*/

  background(row,col,gridpt,&startpos);
  if(startpos == -9999) {
             printf("%5d is a background point %d \n",gridpt,startpos);
             exit(0);  
  }
  else {

/* --- Print gridpoint information --- */
	printf("      gridcell = %d\n", gridpt);
	printf("           row = %d\n", row);
	printf("        column = %d\n", col);
	printf("      latitude = %6.2f\n", olat);
	printf("     longitude = %6.2f\n", olon);
        printf(" record number = %d\n\n", startpos);
	printf(" Records number from 1->3261\n");
        printf(" Recall that record number does not\n");
        printf(" necessarily equal netCDF position index:\n\n");
        printf(" netCDF position index: \n");
        printf("             C = %d \n",startpos-1);
        printf("       Fortran = %d\n\n",startpos);


        printf("-----------------------------------------\n");

	exit(0);
   }
}


/*------------------------------------------------------------*/
void grid(int gridpt, int *row, int *col, float *olat, float *olon)
{
/* Program converts gridpoint to 2D matrix (row and col) */
/*  and returns gridcell center latitude and longitude.  */
/*  nanr 12-4-95 	           		         */

      int z;

      for (z=0; z<48; z++) {
            if ((gridpt > z*115) && (gridpt <= (z+1)*115)) {
                   *row = z+1;
                   *col = gridpt-z*115;
            }
      }

      *olat =  49.0 + (0.5 * (1 - *row)) - 0.25;
      *olon = 124.5 + (0.5 * (1 - *col)) - 0.25;

      return;
}
/*------------------------------------------------------------*/
void background(int row,int col,int gridpt,int *startpos)
{
         int backgrpt=0, datapt=0, sum=0;
	 int varid, ncid;
	 int nrows=48, ncols=115;
	 int irow=0, i=0;
	 long int count[2] = {1, 115};
	 long int start[2];
	 short var[115];
         FILE *fopen(), *fp_in;

         if(!(ncid = ncopen("geog3.nc",NC_NOWRITE))) {
		printf("ERROR:  Can't find 'geog3.nc' file. \n");
		exit(0);
	 }

	varid = ncvarid(ncid, "mask");
        while(irow < row) {
        	start[0] = irow;
        	start[1] = 0;
        	count[0] = 1;
        	count[1] = ncols;
        	ncvarget(ncid, varid, start, count, var);
		if(irow<row-1) {
			for(i=0; i<ncols; i++) {
				if(var[i]) datapt++;
                		else       backgrpt++;
			}
		}
		else if(irow==row-1) {
			for(i=0; i<col; i++) {
				if(var[i]) datapt++;
                		else       backgrpt++;
			}
		}
		irow++;
         }

         sum = backgrpt + datapt;
         if(sum != gridpt) {
                printf("bad count %d\n",sum);
                exit(1);
         }
         if(!(var[col-1])) *startpos = -9999;
         else              *startpos = datapt;
         return;
}