/*
 * ppmutil.c: Open PPM file and get size of width and height.
 *                                    (Only support P6/P5 format file)
 *
 *    Oct.6.'94. Oshiro.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#include "ppmutils.h"

int GetCharIgnoreSpaceAndComment(FILE *fp)
{
	static begin_line=1;
	int c;
	
	while (1) {
		c=getc(fp);
		if (begin_line==1) {
			while (1) {
				if (!isspace(c) || c=='\n')
					break;
				c=getc(fp);
			}
			begin_line=0;
		}
		if (c=='#') {
			while ((c=getc(fp))!='\n')
				;
			begin_line=1;
			continue;
		}
		if (c=='\n') begin_line=1;
		break;
	}
	return c;
}

int GetOneLine(FILE *fp, char *str)
{
	int c;
	int i;
	
	for (i=0; (c=GetCharIgnoreSpaceAndComment(fp))!='\n'; i++) {
		if (i>=PPMUTILS_CHECK_STR_MAX) {
			return -1;
		}
		str[i]=c;
	}
	str[i]='\0';

	return 0;
}	

int CheckPPMFile(FILE *fp, int *type,
		 int *width, int *height, int *depth)
{
	char str[PPMUTILS_CHECK_STR_MAX];
	int w, h, d;
	int i, c;
	
	if (GetOneLine(fp, str)!=0)          return -1;
	fprintf(stderr, "type:%s", str);
	if (strcmp(str, "P6")!=0 && strcmp(str, "P5")!=0)
		                             return -1;
	*type=str[1];
	if (GetOneLine(fp, str)!=0)          return -1;
	if (sscanf(str, "%d %d", &w, &h)!=2) return -1;
	if (GetOneLine(fp, str)!=0)          return -1;
	d=atoi(str);
	if (d<=0 || d>255)                   return -1;
	/* if (strcmp(str, "255")!=0)           return -1; */

	*width=w;
	*height=h;
	*depth=d;

	return 0;
}

FILE *OpenAndCheckPPMFile(char *fname, int *type,
			  int *width, int *height, int *depth)
{
	FILE *fp;

	if (fname==NULL) {
		fp=stdin;
	} else {
		fp=fopen(fname, "rb");
		if (fp==NULL) return NULL;
	}

	if (CheckPPMFile(fp, type, width, height, depth)!=0) {
		fclose(fp);
		return NULL;
	}
	
	return fp;
}

#ifdef PPMUTILS_TEST
int main(int argc, char **argv)
{
	FILE *fp;
	int w, h, d;
	
	if (argc==2) {
		fp=OpenAndCheckPPMFile(argv[1], &w, &h, &d);
		if (fp==NULL) {
			fprintf(stderr, "Incorrect PPM file `%s'.\n",
				argv[1]);
			exit(-1);
		}
	} else {
		fp=stdin;
		if (CheckPPMFile(stdin, &w, &h, &d)!=0) {
			fprintf(stderr, "Incorrect PPM file `%s'.\n",
				argv[1]);
			exit(-1);
		}
	}
	
	printf("ImageSize: %dx%d(%d)\n", w, h, d);

	return 0;
}
#endif /* PPMUTILS_TEST */