#! /bin/sh

usage()
{
	echo "$0 [-s <size>] [-j <jobs>] [-h] -d <root> <path>"
}

SIZE=96

while getopts d:s:h arg
do
	case $arg in
	d) ROOT="$OPTARG"
	;;
	s) SIZE="$OPTARG"
	;;
	h) usage
		exit 0
	;;
	?) usage >&2
		exit 1
	;;
	esac
done

if [ -z "$ROOT" ]; then
	usage >&2
	exit 1
fi

shift $(($OPTIND - 1))

if [ $# != 1 ]; then
	usage >&2
	exit 1
fi

TDIR="$(echo "$1" | sed "s,$ROOT/user,$ROOT/thumbnails,")"
eval find \"$1\"/* -prune >/dev/null || return 0
mkdir -p "$TDIR"
MK="$(echo "$TDIR/Makefile")"
cat <<-"EOF" > "$MK"
	.POSIX:
EOF
echo "DIRS=\\" >> "$MK"
eval find \"$TDIR\"/* -prune -type d > "$TDIR/.dirs"

while read dir
do
	D="$(echo "$dir" | sed "s, ,\\\\ ,g")"
	echo "$D \\" >> "$MK"
done < "$TDIR/.dirs"

echo >> "$MK"
echo "DEPS=\\" >> "$MK"
eval find \"$1\"/* -prune -type f \
		-a -iname '*.jpeg' \
		-o -iname '*.jpg' \
		-o -iname '*.png' \
		-o -iname '*.jpeg' > "$TDIR/.files"

while read f
do
	THUMBNAIL="$(echo "$f" | sed "s,$ROOT/user/,$ROOT/thumbnails/," \
		| sed "s, ,\\\\ ,g")"
	echo "$THUMBNAIL \\" >> "$MK"
done < "$TDIR/.files"

echo >> "$MK"
echo 'all: $(DEPS) $(DIRS)' >> "$MK"
echo 'FORCE:' >> "$MK"

while read dir
do
	D="$(echo "$dir" | sed "s, ,\\\\ ,g")"
	echo "$D: FORCE" >> "$MK"
	printf '\t+cd $@ && $(MAKE)\n' >> "$MK"
done < "$TDIR/.dirs"

while read f
do
	THUMBNAIL="$(echo "$f" | sed "s,$ROOT/user/,$ROOT/thumbnails/," \
		| sed "s, ,\\\\ ,g")"
	EF=$(echo "$f" | sed "s, ,\\\\ ,g")
	echo $THUMBNAIL: $EF >> "$MK"
	printf '\tconvert -thumbnail x%d "$<" "$@" || :\n' $SIZE >> "$MK"
done < "$TDIR/.files"

echo "Successfully generated $MK"