/* 
 *
 * Copyright 2008 Johannes Hofmann <Johannes.Hofmann@gmx.de>
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

/* This code is based on Fl_PNM_Image.cxx from fltk (http://www.fltk.org)
 */

#include <string.h>

#include "pnm.h"

int
readPnmHeader(FILE *fp, struct pnm *h) {
	char line[1024];
	char *lineptr;

	memset(h, 0, sizeof(struct pnm));

	lineptr = fgets(line, sizeof(line), fp);
	if (!lineptr) {
		fprintf(stderr, "premature end of pnm file\n");
		return 1;
	}

	lineptr ++;

	h->format = atoi(lineptr);
	while (isdigit(*lineptr)) lineptr ++;

	if (h->format == 7) lineptr = (char *)"";

	while (lineptr != NULL && h->width == 0) {
		if (*lineptr == '\0' || *lineptr == '#') {
			lineptr = fgets(line, sizeof(line), fp);
		} else if (isdigit(*lineptr)) {
			h->width = strtol(lineptr, &lineptr, 10);
		} else lineptr ++;
	}

	while (lineptr != NULL && h->height == 0) {
		if (*lineptr == '\0' || *lineptr == '#') {
			lineptr = fgets(line, sizeof(line), fp);
		} else if (isdigit(*lineptr)) {
			h->height = strtol(lineptr, &lineptr, 10);
		} else lineptr ++;
	}


	if (h->format != 1 && h->format != 4) {
		h->maxval = 0;

		while (lineptr != NULL && h->maxval == 0) {
			if (*lineptr == '\0' || *lineptr == '#') {
				lineptr = fgets(line, sizeof(line), fp);
			} else if (isdigit(*lineptr)) {
				h->maxval = strtol(lineptr, &lineptr, 10);
			} else lineptr ++;
		}
	} else {
		h->maxval = 1;
	}

	return 0;
}

int
writePnmHeader(FILE *fp, const struct pnm *h) {
	fprintf(fp, "P%d\n", h->format);
	fprintf(fp, "%d %d\n", h->width, h->height);
	fprintf(fp, "%d\n", h->maxval);

	return 0;
}