/* img_grab_constraints <topo.img> -B<mask.bit> > output
 *
 * WHFS 23 Feb 2009
 *
 * Read an imgfile of topography/bathymetry
 * that has even/odd constraint encoding, and
 * grab the odd numbered points.
 *
 * This is done to make an input for testing
 * the Nettleton routines.  Eventually the
 * correct way to do the Nettleton input will
 * be by starting from the edited cruise and xyz
 * data, and computing correct error bars from
 * that.
 * Here, we fake the error bars by assigning
 * EPCT of the depth as the error.
 *
 */
 
#include "img_predict.h"

#define EPCT 0.01	/* Error, relative to depth  */


static unsigned char maskset[8] = {128, 64, 32, 16, 8, 4, 2, 1};

int	main (int argc, char **argv) {

	struct BLOCK_CONSTRAINT	output;
	unsigned char	*b;
	short int h;
	int	verbose = 0, error = 0, k, nx, ny, nt, nc = 0, h_abs;
	size_t	nbytes;
	char	*bfile, *tfile;
	FILE	*fp;
	
	bfile = tfile = (char *)NULL;

	/* Parse arg list:  */
	
	for (k = 1; k < argc; k++) {
		if (argv[k][0] == '-') {
			switch (argv[k][1]) {
				case 'B':
					bfile = &argv[k][2];
					break;
				case 'V':
					verbose = 1;
					break;
				default:
					fprintf (stderr, "img_grab_constraints:  Unsupported option:  %s\n", argv[k]);
					error ++;
					break;
			}
		}
		else {
			tfile = argv[k];
		}
	}
	if (bfile == (char *)NULL) {
		fprintf (stderr, "img_grab_constraints:  You must supply -B<bitfile> name for constraint bitmask.\n");
		error ++;
	}
	if (tfile == (char *)NULL) {
		fprintf (stderr, "img_grab_constraints:  You must supply <tfile.img> of topography with constraints marked.\n");
		error ++;
	}
	
	if (error) {
		fprintf (stderr, "usage:  img_grab_constraints <tfile.img> -B<bfile> [-V] > output\n\n");
		fprintf (stderr, "\tInput tfile.img is an img file of bathy/topo with constraints marked odd.\n");
		fprintf (stderr, "\tOutput -B<bfile> is a bit mask indicating which pixels were constrained.\n");
		fprintf (stderr, "\tOutput to stderr is binary constraint structures.\n");
		fprintf (stderr, "\tOption -V reports verbose operations to stderr.\n");
		exit (EXIT_FAILURE);
	}
	
	if (check_imgfile_size (tfile, &nx, &ny) ) {
		fprintf (stderr, "img_grab_constraints:  FATAL ERROR cannot get file size of %s\n", tfile);
		exit (EXIT_FAILURE);
	}
	if ( (fp = fopen (tfile, "r") ) == NULL) {
		fprintf (stderr, "img_grab_constraints:  FATAL ERROR cannot open %s\n", tfile);
		exit (EXIT_FAILURE);
	}
	
	nt = nx * ny;
	nbytes = nt / 8;
	
	if ( (b = (unsigned char *) calloc (nbytes, (size_t)1) ) == NULL) {
		fprintf (stderr, "img_grab_constraints:  FATAL ERROR cannot calloc %d bytes for bitmask.\n", (int)nbytes);
		fclose (fp);
		exit (EXIT_FAILURE);
	}
	
	for (k = 0; k < nt; k++) {
		if ( (fread ((void *)&h, (size_t)2, (size_t)1, fp) ) != 1) {
			fprintf (stderr, "img_grab_constraints:  FATAL ERROR reading input at k = %d\n", k);
			fclose (fp);
			free ((void *)b);
			exit (EXIT_FAILURE);
		}
		
		h_abs = abs ( (int)h);
		
		if (h_abs%2) {
			/* h is an odd number  */
			output.index = k;
			output.source_id = (h > 0) ? 1 : 2;		/* This is faked, of course.  */
			output.z = h;
			output.s = (short int) ceil (EPCT * h_abs);
			b[k/8] |= maskset[k%8];
			fwrite ((void *)&output, (size_t)12, (size_t)1, stdout);
			nc++;
		}
	}

	fclose (fp);
	
	if ( (fp = fopen (bfile, "w") ) == NULL) {
		fprintf (stderr, "img_grab_constraints:  FATAL ERROR cannot open %s\n", bfile);
		exit (EXIT_FAILURE);
	}

	if ( (fwrite ((void *)b, (size_t)1, nbytes, fp) ) != nbytes) {
		fprintf (stderr, "img_grab_constraints:  FATAL ERROR cannot write %s\n", bfile);
		fclose (fp);
		free ((void *)b);
		exit (EXIT_FAILURE);
	}
	
	fclose (fp);
	free ((void *)b);
	
	if (verbose) fprintf (stderr, "img_grab_constraints:  Found %d constraints in %d pixels.\n", nc, nt);
	exit (EXIT_SUCCESS);
}