#!/bin/sh
#
# gifcompose --- a GIF compositor
#
# This script composes a GIF from a series of overlays described in an input
# text file.
#
if [ "$1" = "-v" ]
then
	echo=echo
else
	echo=:
fi

trap "rm -fr comp$$ tmp$$ btmp$$; exit 0" 0 1 2 15

mkdir comp$$;

gen="x"
while read line
do
	set -- $line
	postproc='n'
	name=$2
	case $1 in
	gif)
		$echo "Pasting GIF file $2.gif" 1>&2;
		cat $2.gif >tmp$$
		shift; shift; postproc='y' ;;
	raw)
		$echo "Pasting raw file $2" 1>&2;
		raw2gif -s $3 $4 <$2 >tmp$$
		shift; shift; shift; shift; postproc='y' ;;
	rgb)
		$echo "Pasting RGB file $2" 1>&2;
		rgb2gif -s $3 $4 <$2 >tmp$$
		shift; shift; shift; shift; postproc='y' ;;
	rle)
		$echo "Pasting RLE file $2" 1>&2;
		rle2gif $2 >tmp$$
		shift; shift; postproc='y' ;;
	text)
		$echo "Generating text \`$2'" 1>&2;
		case "$3" in
		foreground)
			text2gif -t "$2" -f $4 >tmp$$;
			shift; shift;;
		background)
			text2gif -t "$2" -c $4 $5 $6 >tmp$$;
			shift; shift; shift; shift;;
		*)
			text2gif -t "$2" >tmp$$;;
		esac
		shift; shift; postproc='y' ;;
	screen)
		case $2 in
		size) resize="$3 $4";;
		position) reposition="$3 $4";;
		*) echo "Unknown screen operation" 1>&2
		esac;;
	esac

	if [ $postproc = 'y' ]
	then
		while [ $# != 0 ]
		do
			case "$1" in
			at)
				$echo "Positioning \`$name' at $2 $3" 1>&2
				gifpos -i $2 $3 <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift; shift; shift;;
			clip)
				$echo "Clipping \`$name' to size $2 $3 $4 $5" 1>&2
				gifclip -i $2 $3 $4 $5 <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift; shift; shift; shift; shift;;
			xflip)
				$echo "Flipping \`$name' around the X axis" 1>&2;
				gifflip -x <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift;;
			yflip)
				$echo "Flipping \`$name' around the Y axis" 1>&2;
				gifflip -y <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift;;
			left)
				$echo "Rotating \`$name' left (counterclockwise)" 1>&2;
				gifflip -l <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift;;
			right)
				$echo "Rotating \`$name' right (clockwise)" 1>&2;
				gifflip -r <tmp$$ >btmp$$; mv btmp$$ tmp$$;
				shift;;
			''|\#*)
				break;;
			*)
				echo "Unknown operator \`$1'" 1>&2
				shift;;
			esac
		done

		mv tmp$$ comp$$/${gen}.gif
	fi

	gen="${gen}x";
done

gifasm comp$$/*.gif | gifovly -t 0 >tmp$$
if [ "$resize" ]
then
	gifpos -s $resize <tmp$$ >btmp$$; mv btmp$$ tmp$$;
fi
if [ "$reposition" ]
then
	gifpos -n $reposition <tmp$$ >btmp$$; mv btmp$$ tmp$$;
fi
cat tmp$$

$echo "Done."

# script ends here