#include <stdio.h>
#include <stdint.h>
#include <string.h>

#define THRESHOLD 1200

/* portions derived from IJG code */

#define readbyte(a,b) do if(((a)=getc((b))) == EOF) return 0; while (0)
#define readword(a,b) do { int cc_=0,dd_=0; \
                          if((cc_=getc((b))) == EOF \
        		  || (dd_=getc((b))) == EOF) return 0; \
                          (a) = (cc_<<8) + (dd_); \
                          } while(0)


int scanhead (FILE * infile, int * image_width, int * image_height) {
  int marker=0;
  int dummy=0;
  if ( getc(infile) != 0xFF || getc(infile) != 0xD8 )
    return 0;

  for (;
      ;) {


    int discarded_bytes=0;
    readbyte(marker,infile);
    while (marker != 0xFF) {
      discarded_bytes++;
      readbyte(marker,infile);
    }
    do readbyte(marker,infile); while (marker == 0xFF);

    if (discarded_bytes != 0) return 0;

    switch (marker) {
    case 0xC0:
    case 0xC1:
    case 0xC2:
    case 0xC3:
    case 0xC5:
    case 0xC6:
    case 0xC7:
    case 0xC9:
    case 0xCA:
    case 0xCB:
    case 0xCD:
    case 0xCE:
    case 0xCF: {
      readword(dummy,infile);	/* usual parameter length count */
      readbyte(dummy,infile);
      readword((*image_height),infile);
      readword((*image_width),infile);
      readbyte(dummy,infile);

      return 1;
      break;
      }
    case 0xDA:
    case 0xD9:
      return 0;
    default: {
	int length;

	readword(length,infile);

	if (length < 2)
	  return 0;
	length -= 2;
	while (length > 0) {
	  readbyte(dummy, infile);
	  length--;
	}
      }
      break;
    }
  }
}

int scanPNG(FILE *fp, int *width, int *height)
{
	uint8_t img_buf[4];
	uint32_t w;
	uint32_t h;

	// NO SEEKING IN PIPE
	// fseek(fp, 16, SEEK_SET);
	fread(img_buf, 1, 4, fp);
	fread(img_buf, 1, 4, fp);
	fread(img_buf, 1, 4, fp);
	fread(img_buf, 1, 4, fp);

	// Read Width
	fread(img_buf, 1, 4, fp);
	w = img_buf[0];
	w <<= 8;
	w += img_buf[1];
	w <<= 8;
	w += img_buf[2];
	w <<= 8;
	w += img_buf[3];

	// Read Height
	fread(img_buf, 1, 4, fp);
	h = img_buf[0];
	h <<= 8;
	h += img_buf[1];
	h <<= 8;
	h += img_buf[2];
	h <<= 8;
	h += img_buf[3];

	*width = w;
	*height = h;
	return 0;
}

int fpeek(FILE *stream)
{
    int c;

	if (feof(stream))
	{
		return EOF;
	}
    c = fgetc(stream);
    ungetc(c, stream);

    return c;
}

int main(int argc, char **argv)
{
	int width;
	int height;
	int peek;
	FILE *pp;
	char cmd[2048];

	if (argc < 2)
	{
		printf("Need filename\n");
		return -1;
	}

	strcpy(cmd, "metaflac --export-picture-to=- \"");
	strcat(cmd, argv[1]);
	strcat(cmd, "\" 2>&1");

	pp = popen(cmd, "r");
	if (NULL == pp)
	{
		printf("Bad PP: '%s'\n", argv[1]);
		return -1;
	}

	peek = fpeek(pp);
	switch (peek)
	{
	case 0xFF:
		//JPG
		scanhead(pp, &width, &height);
		if ((width > THRESHOLD) || (height > THRESHOLD))
		{
			printf("'%s' W:%04d H:%04d\n", argv[1], width, height);
		}
		break;

	case 0x89:
		//PNG
		scanPNG(pp, &width, &height);
		if ((width > THRESHOLD) || (height > THRESHOLD))
		{
			printf("'%s' W:%04d H:%04d\n", argv[1], width, height);
		}
		break;

	case 0x2F:
		break;

	default:
		//NaN
		printf("'%s' WeirdChamp: 0x%02X\n", argv[1], peek);
	}
	pclose(pp);

	return 0;
}