#include <stdlib.h>
#include <unistd.h>
#include <grass/gis.h>
#include "method.h"

#define STATS "r.stats"
#define RECLASS "r.reclass"

#define MDEBUG(a) fprintf(stderr,"%s\n",a);


int 
o_average (char *basemap, char *covermap, char *outputmap, int usecats, struct Categories *cats)
{
    char *me="o_average";
    char command[1024];
    
    long catb, basecat, covercat;
    double x, area, sum1, sum2;
    int stat;
    char *tempfile1, *tempfile2;
    FILE *fd1, *fd2;



    tempfile1 = G_tempfile();
    tempfile2 = G_tempfile();

    sprintf (command, "%s -an input='%s,%s' fs=space > %s",
	STATS, basemap, covermap, tempfile1);
    if (stat = system(command))
    {
	unlink(tempfile1);
	fprintf (stderr, "%s: ERROR running %s command\n", me, STATS);
	exit(stat);
    }

    fd1 = fopen (tempfile1, "r");
    fd2 = fopen (tempfile2, "w");
    if (fd1 == NULL || fd2 == NULL)
    {
	unlink(tempfile1);
	unlink(tempfile2);
	fprintf (stderr, "%s: ERROR can't open tempfile\n", me);
	exit(1);
    }
    out(fd2, 0L, 0.0, 1.0);	/* force at least one reclass rule */

    catb = 0;
    sum1 = 0.0;
    sum2 = 0.0;
    while (fscanf (fd1, "%ld %ld %lf", &basecat, &covercat, &area) == 3)
    {
	if (catb != basecat)
	{
	    out(fd2, catb, sum1, sum2);
	    sum1 = 0.0;
	    sum2 = 0.0;
	    catb = basecat;
	}
	if (usecats)
	    sscanf (G_get_cat((CELL)covercat, cats), "%lf", &x);
	else
	    x = covercat;
	sum1 += x * area;
	sum2 += area;
    }
    out(fd2, basecat, sum1, sum2);
    fclose (fd1);
    fclose (fd2);
    sprintf (command, "%s input='%s' output='%s' < %s",
	RECLASS, basemap, outputmap, tempfile2);
    stat = system(command);
    unlink (tempfile1);
    unlink (tempfile2);
    return(stat);
}

int 
out (FILE *fd, long cat, double sum1, double sum2)
{
    char buf[80];

    if (sum2 == 0) return -1;
    if (cat == 0)
	*buf = 0;
    else
    {
	sprintf (buf, "%.10f", sum1/sum2);
	G_trim_decimal (buf);
    }
    fprintf (fd, "%ld = %ld %s\n", cat, cat, buf);

    return 0;
}