/***********************************************************************

   Process JPEG files to display the pixel resolution.
   Optionally dump the header blocks found (-d option).

   Copyright (C) Rolf Howarth  rolf@insect.demon.co.uk

   Version History
     1.0  23 Dec 1996  Support for JPEGs
     1.1   1 Oct 1997  Better JPEG dumping; support for JPEG PICTs
     1.2  10 Oct 1997  Support for GIFs

   Bugs/To Do
     Inconsistent handling of errors and warnings (stderr? exit status?)
     No control over order of output if combining -c, -s and -t.
     GIFs should display total file size at end.

************************************************************************/

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

void process(FILE*);
void processGIF(FILE*);
void processJPEG(FILE*);
int readword(FILE*);
int readblock(FILE*);
char* type_name(int type);

#define DELIM	0xff
#define SOI 	0xd8
#define EOI 	0xd9
#define APP0	0xe0
#define SOF0	0xc0
#define SOF2	0xc2
#define COM 	0xfe
#define SOS 	0xda
#define RST0	0xd0
#define RST1	0xd1
#define RST2	0xd2
#define RST3	0xd3
#define RST4	0xd4
#define RST5	0xd5
#define RST6	0xd6
#define RST7	0xd7

int debug = 0;
int endMarker;
int H,V;
char* comment;
int showSize = 0;
int showComment = 0;
int showType = 0;
int htmlImage = 0;
char *filename;

int main(int argc, char** argv)
{
	int i;
	while (argc>1 && argv[1][0]=='-')
	{
		++argv;
		--argc;
		if (argv[0][1]=='d')
			++debug;
		else if (argv[0][1]=='c')
			showComment = 1;
		else if (argv[0][1]=='s')
			showSize = 1;
		else if (argv[0][1]=='t')
			showType = 1;
		else if (argv[0][1]=='i')
			htmlImage = 1;
		else
		{
			fprintf(stderr, "JPEGSIZE 1.2 - display characteristics of JPEG and GIF images\nUsage: %s [-csitd] [file ...]\n -c show comments\n -s image size (default if no other options specified)\n -i generate html <img src> tags\n -t show file type\n -d debug (show blocks etc.) -d -d for extra detail\n", argv[-1]);
			exit(1);
		}
	}
	if (!debug && !showComment && !showType)
		showSize = 1;
	if (debug || htmlImage)
	{
		showSize = 0;
		showComment = 0;
		showType = 0;
	}
	if (argc<=1)
	{
		filename = "???";
		process(stdin);
	}
	for (i=1; i<argc; ++i)
	{
		FILE *f;
		if (debug || (argc>2 && !htmlImage)) printf("%s: ", argv[i]);
		if (debug) printf("\n");
		filename = argv[i];
		f = fopen(filename, "rb");
		if (f==NULL)
		{
			fprintf(stderr, "Failed to open '%s'\n", filename);
			exit(1);
		}
		process(f);
		fclose(f);
	}
}

void process(FILE *file)
{
	int c1, c2;
	comment = NULL;
	H = -1;
	V = -1;

	if (file==NULL || ferror(file)) exit(2);
	c1 = fgetc(file);
	c2 = fgetc(file);
	if (c1==DELIM && c2==SOI)
	{
		if (showType) printf("JPEG\n");
		processJPEG(file);
	}
	else if (c1=='G' && c2=='I')
		processGIF(file);
	else
	{
		int pos = 1;
		int c = 0;
		while (! feof(file))
		{
			c = fgetc(file);
			++pos;
			if (c==DELIM)
			{
				if ((c=fgetc(file)) == SOI)
					break;
				else
					ungetc(c, file);
			}
		}
		if (c==SOI)
		{
			if (showType)
				printf("JPEG (offset %d)\n", pos-1);
			else
				printf("Found JPEG marker after %d bytes\n", pos-1);
			processJPEG(file);
		}
		else
		{
			printf("Not a JPEG or GIF file\n");
			return;
		}
	}
	if (showSize) printf("%d %d\n", H, V);
	if (htmlImage) printf("<img src=\"%s\" width=%d height=%d>\n", filename, H, V);
	if (showComment) printf("%s\n", comment?comment:"");
}

/**************************** JPEG **************************/

void processJPEG(FILE *file)
{
	endMarker = 0;
	while (readblock(file))
		;
	if (!endMarker) printf("Missing end marker\n");
}

int readword(FILE *file)
{
	return fgetc(file)*256 + fgetc(file);
}

int readblock(FILE *file)
{
	int i, type, start, length;
	int a,b,c,x,y;
	unsigned char buffer[256];
	int read;
	int h,v;

	if (fgetc(file) != DELIM)
	{
		printf("Expecting a block start delimeter at %ld\n", ftell(file));
		return 0;
	}
	type = fgetc(file);
	start = ftell(file);
	if (type<RST0 || type>RST7)
	{
		length = readword(file) - 2;
		if (feof(file))
			length = 0;
	}
	else
		length = 0;
	if (debug)
		printf(" Type %s (%x), length %d\n", type_name(type), type, length);
	switch (type)
	{
		case SOF0:
		case SOF2:
			a = fgetc(file);
			V = readword(file);
			H = readword(file);
			if (debug)
				printf("  %d V=%d H=%d\n", a,V,H);
			break;

		case COM:
			for (i=0; i<sizeof(buffer) && i<length; ++i)
			{
				buffer[i] = fgetc(file);
				if (buffer[i] == '\0' || buffer[i]=='\n') break;
			}
			buffer[i] = '\0';
			if (debug) printf("  %s\n", buffer);
			comment = strdup((char*)buffer);
			break;
			
		case SOS:
			fseek(file, (long) start+2+length, SEEK_SET);
			// fall through to parameterless case

		case RST0:
		case RST1:
		case RST2:
		case RST3:
		case RST4:
		case RST5:
		case RST6:
		case RST7:
			read = 0;
			do
			{
				c = fgetc(file);
				++read;
				if (c==DELIM)
				{
					c = fgetc(file);
					++read;
					if (c>0)
					{
						fseek(file, -2L, SEEK_CUR);
						if (debug) printf("  (%d bytes of data read)\n", read-2);
						return 1;
					}
				}
			}
			while (c!=EOF);
			if (debug) printf("  (%d bytes of data read)\n", read-2);
			return 0;

		case EOI:
			endMarker = 1;
			if (! feof(file))
				printf("Extraneous data after end marker\n");
			break;

		case APP0:
			if (!debug) break;
			for (i=0; i<sizeof(buffer); ++i)
			{
				buffer[i] = fgetc(file);
				if (buffer[i] == '\0') break;
			}
			buffer[sizeof(buffer)-1] = '\0';
			a = fgetc(file);
			b = fgetc(file);
			c = fgetc(file);
			x = readword(file);
			y = readword(file);
			h = fgetc(file);
			v = fgetc(file);
			if (strcmp((char*)buffer, "JFIF") == 0)
				printf("  %s %d.%02d %d XD=%d YD=%d Thumbnail: %d x %d\n", buffer, a,b,c,x,y,h,v);
			else
			{
				if (a==0x10)
					printf("  %s 0x%x (JPEG Thumbnail, %d x %d)\n", buffer, a, b, c);
				else if (a==0x11)
					printf("  %s 0x%x (Indexed thumbnail, %d x %d)\n", buffer, a, b, c);
				else if (a==0x13)
					printf("  %s 0x%x (RGB thumbnail, %d x %d)\n", buffer, a, b, c);
				else
					printf("  %s 0x%x %d %d\n", buffer, a, b, c);
			}
			break;
	}
	if (feof(file)) return 0;
	fseek(file, (long) start+2+length, SEEK_SET);
	return 1;
}

char* type_name(int type)
{
	switch (type)
	{
		case 0xc0: return "SOF0";
		case 0xc1: return "SOF1";
		case 0xc2: return "SOF2";
		case 0xc3: return "SOF3";
		
		case 0xc5: return "SOF5";
		case 0xc6: return "SOF6";
		case 0xc7: return "SOF7";
		
		case 0xc8: return "JPG";
		case 0xc9: return "SOF9";
		case 0xca: return "SOF10";
		case 0xcb: return "SOF11";
		
		case 0xcd: return "SOF13";
		case 0xce: return "SOF14";
		case 0xcf: return "SOF15";
		
		case 0xc4: return "DHT";
		
		case 0xcc: return "DAC";
		
		case 0xd0: return "RST0";
		case 0xd1: return "RST1";
		case 0xd2: return "RST2";
		case 0xd3: return "RST3";
		case 0xd4: return "RST4";
		case 0xd5: return "RST5";
		case 0xd6: return "RST6";
		case 0xd7: return "RST7";
		
		case 0xd8: return "SOI";
		case 0xd9: return "EOI";
		case 0xda: return "SOS";
		case 0xdb: return "DQT";
		case 0xdc: return "DNL";
		case 0xdd: return "DRI";
		case 0xde: return "DHP";
		case 0xdf: return "EXP";
		
		case 0xe0: return "APP0";
		case 0xe1: return "APP1";
		case 0xe2: return "APP2";
		case 0xe3: return "APP3";
		case 0xe4: return "APP4";
		case 0xe5: return "APP5";
		case 0xe6: return "APP6";
		case 0xe7: return "APP7";
		case 0xe8: return "APP8";
		case 0xe9: return "APP9";
		case 0xea: return "APP10";
		case 0xeb: return "APP11";
		case 0xec: return "APP12";
		case 0xed: return "APP13";
		case 0xee: return "APP14";
		case 0xef: return "APP15";
		
		case 0xf0: return "JPG0";
		case 0xfd: return "JPG13";
		case 0xfe: return "COM";
		
		case 0x01: return "TEM";

		default: return "???";
	}
}


/**************************** GIF **************************/

int readwordl(FILE *file)
{
	return fgetc(file) + fgetc(file)*256;
}

void processGIF(FILE *file)
{
	int a,b,c,d,i,s;
	unsigned char buffer[256];
	char ver[4];
	int flags,colorTable,colorRes,sortFlag,bpp,ctabSize,transparent;
	int size, subblocks, totalsize;
	int images = 0;

	endMarker = 0;

	// Header

	if (fgetc(file)!='F')
		return;
	fgets(ver, 4, file);

	// Logical screen descriptor

	H = readwordl(file);
	V = readwordl(file);
	flags = fgetc(file);
	colorTable = flags & 0x80;
	colorRes = flags & 0x70;
	sortFlag = flags & 0x08;
	bpp = (flags & 0x07) + 1;
	ctabSize = 1<<bpp;
	transparent = 0;
	a = fgetc(file);
	b = fgetc(file);
	if (debug)
		printf(" GIF%s w=%d h=%d bits/pixel=%d color_res=%d flags=0x%02x bgcol=%d aspect=%d\n", ver, H, V, bpp, ((flags>>4)&7)+1, flags, a, b);

	// Global color table

	if (colorTable)
	{
		if (debug>1) printf(" Global color table (%d entries)%s\n", ctabSize,
			(flags&0x08) ? " [Sorted]" : "");
		for (i=0; i<3*ctabSize; ++i)
			fgetc(file);
	}

	c = fgetc(file);
	while (!feof(file) && !endMarker)
	{
		switch(c)
		{
			case 0x2c:
				// Image descriptor
				a = readwordl(file);
				b = readwordl(file);
				c = readwordl(file);
				d = readwordl(file);
				flags = fgetc(file);
				if (debug) printf(" IMAGE w=%d h=%d ", c, d);
				if (debug && a!=0 || b!=0) printf("offset=(%d,%d) ");
				if (debug) printf("flags=0x%02x %s", flags,
					flags&0x40 ? "[Interlaced] " : "");
				++images;
				colorTable = flags & 0x80;
				bpp = (flags & 0x07) + 1;
				ctabSize = 1<<bpp;

				// Local color table
				if (colorTable)
				{
					if (debug>1) printf(" Local color table (%d entries)%s\n",
						ctabSize, (flags&0x20) ? " [Sorted]" : "");

					for (i=0; i<3*ctabSize; ++i)
						fgetc(file);
				}

				// Table based image data
				c = fgetc(file);
				subblocks = 0;
				totalsize = 0;
				while ((s=fgetc(file)) > 0)
				{
					++subblocks;
					totalsize += s;
					for (i=0; i<s; ++i)
						fgetc(file);
				}
				if (debug) printf(": %d bytes in %d blocks\n", totalsize, subblocks);
				if (debug>1) printf("  (LZW mcs = %d)\n", c);
				break;

			case 0x21:	// Extension
			{
				c = fgetc(file);
				size = fgetc(file);
				subblocks = 1;
				for (i=0; i<size && i<sizeof(buffer)-1; ++i)
					buffer[i] = fgetc(file);
				buffer[i] = 0;
				totalsize = i;
				while ((s=fgetc(file)) > 0)
				{
					++subblocks;
					for (i=0; i<s; ++i)
					{
						if (totalsize+i < sizeof(buffer)-1)
							buffer[totalsize+i] = fgetc(file);
						else
							fgetc(file);
					}
					totalsize += s;
				}
				if (debug>1) printf("  (Extension type 0x%02x, %d block(s), %d bytes)\n", c, subblocks, totalsize);
				switch(c)
				{
					case 0xfe:	// Comment
						comment = strdup((char*)buffer);
						if (debug) printf("  Comment '%s'\n", comment);
						break;

					case 0xff:	// Application extension
						if (debug)
						{
							printf("  Application extension '%.8s' [%02x %02x %02x] ", buffer, buffer[8], buffer[9], buffer[10]);
							for (i=11; i<totalsize && i<32; ++i)
								printf(" %02x");
							printf((i<totalsize) ? "...\n" : "\n");
						}
						break;

					case 0xf9:	// Graphic control
						if (debug)
						{
							printf("  Control: delay=%.01f disposal=%d",
								(buffer[1]+buffer[2]*256)/100.0,
								(buffer[0]>>2)&7 );
							if (buffer[0]&2) printf(" UserInput");
							if (buffer[0]&1) printf(" Transparent (index=%d)", buffer[3]);
							printf("\n");
						}
						transparent |= (buffer[0]&1);
						break;

					case 0x01:	// Plain text extension
						if (debug) printf("  Plain text '%s'\n", buffer+12);
						break;

					default:
						if (debug==1) printf("  Extension type 0x%02x, %d block(s), %d bytes\n", c, subblocks, totalsize);
				}
				break;
			}

			case 0x3b:	// Trailer
				c = fgetc(file);
				if (debug>1) printf(" Trailer\n");
				endMarker = 1;
				if (! feof(file))
					printf("Extraneous data (0x%02x) after end marker\n", c);
				break;

			default:
				printf("Unknown block 0x%02x\n", c);
				break;
		}
		c = fgetc(file);
	}
			
	if (!endMarker) printf("Missing end marker\n");
	if (debug) printf(" %d image(s) in total\n", images);
	if (showType)
	{
		printf("GIF%s", ver);
		if (transparent) printf(" Transparent");
		if (images != 1) printf(" (%d images)", images);
		printf("\n");
	}
}