// Script to insert a TIFF tag in the correct position (numerical order)
// 
// Copyright (C) 2007 by Scott Winder
// May be freely copied and used for any purpose, but the author disclaims all 
// responsibility for any damage caused by this script.
// 
// Description:
//    This script is fairly simplistic but will do in most cases: it increments the 
// "offset" attribute for any tags with data that fall after the insertion point of 
// the new tag, and it updates the IFD numentries attribute appropriately (if this 
// doesn't make sense to you, use extra caution when using this script). It then 
// inserts the tag with the requested number in the proper position, and sets a 
// default type of eSHORT and a default count of 1, and zeros out the default data.
// 
// If you know enough about the TIFF spec to be mucking around here, you should be 
// able to take it from there.
// 
// Note: This script requires that the TIFF template included with 010 Editor (or 
// available on the website) be run on the file in question. MAKE A BACKUP BEFORE 
// RUNNING because some edits seem to be done in place.

void addToOffsetsAfter( quad startingOffset, int32 summand )
{
	int i;
	while( exists( ifd.dir[i] ) )
	{
		if ( exists( ifd.dir[i].offset ) ) {
			Printf( "Offset[%d]: %Xh", ifd.dir[i].tag, ifd.dir[i].offset );
			
			if ( ifd.dir[i].offset >= startingOffset ) {
				ifd.dir[i].offset += summand;
				Printf( " => %Xh\n", ifd.dir[i].offset );
			} else {
				Printf( " (no change)\n" );
			}
		}
		
		i++;
	}
}


uint16 getTagNumber()
{
	int n;

	while ( n = InputNumber( "New Tag", "Enter a new TIFF tag number", "" ) )
	{
		if ( n == BAD_VALUE ) {
			Exit(0);
		} 
		
		if ( n < 0 || n > 65535 ) {
			MessageBox( idOk, "Bad Tag",
	                            "%d is an invalid tag number", n );
		} else {
			return n;
		}
	}
}


uint16 tagnum = getTagNumber();
int i;
int addToEnd = 1;
while( exists( ifd.dir[i] ) )
{
	if ( ifd.dir[i].tag > tagnum ) {
		addToEnd = 0;
		break;
	}
	
	i++;
}

// i now holds the index before which we would like to insert
quad tagoffset;

if ( addToEnd == 1 ) {
	tagoffset = startof( ifd.dir[i-1] ) + 12;
} else {
	tagoffset = startof( ifd.dir[i] );
}

// tagoffset is now where we will eventually insert our tag bytes, but
// first we'll increment the offset variable in all of the relevant entries
addToOffsetsAfter( tagoffset, 12 );

// Now we insert the tag
ifd.numentries += 1;
InsertBytes( tagoffset, 12 );

quad pos = tagoffset;
WriteUShort( pos, tagnum );
pos += 2;
WriteUShort( pos, 3 ); // eSHORT
pos += 2;
WriteUInt( pos, 1 );   // count = 1
pos += 4;
WriteUInt( pos, 0 );   // zero out the data portion
pos += 4;              // unnecessary but provides clarity

SetCursorPos( tagoffset );

MessageBox( idOk, "Tag Added",
            "Tag number %d has been added--press Ok, then F10 to re-run the template.", tagnum );