#!/bin/sh

: ${DISORDER=0}

set -uex

verb=$1
front=$2
back=$front-back

[ "tmp/build/${front#tmp/build/}" = "$front" ]
[ "tmp/build/${back#tmp/build/}" = "$back" ]

remove_hard() {
	if [ -e "$1" ]; then
		sudo umount "$1" 2>/dev/null || true
		if ! rm -rf "$1" 2>/dev/null; then
			chmod -R +w "$1"
			rm -rf "$1"
		fi
	fi
}

if [ "$verb" = create ]; then
	echo "### helpers/builddir: creating $front..."
	remove_hard "$front"; remove_hard "$back"
	mkdir -p "$front"
	if [ "$DISORDER" = 1 ]; then
		sudo umount "$back" || true
		rm -rf "$back"
		mkdir -p "$front" "$back"
		sudo mount -o size=16G -t tmpfs tmpfs "$back"
		sudo mount --bind "$back" "$front"
		[ $(findmnt -no FSTYPE "$front") = tmpfs ]
	fi
elif [ "$verb" = pre-build ]; then
	[ -e "$front" ]
	if [ "$DISORDER" = 1 ]; then
		echo "### helpers/builddir: disordering $front..."
		[ -e "$back" ]
		[ $(findmnt -no FSTYPE "$back") = tmpfs ]
		sudo umount "$front"
		sudo disorderfs --shuffle-dirents=yes \
				-o allow_other --multi-user=yes \
				"$back" "$front"
		[ $(findmnt -no FSTYPE "$front") = fuse.disorderfs ]
	fi
elif [ "$verb" = post-build ]; then
	if [ "$DISORDER" = 1 ]; then
		echo "### helpers/builddir: ordering $front..."
		[ ! -e "$front" ] && [ ! -e "$back" ]
		[ $(findmnt -no FSTYPE "$front") = fuse.disorderfs ]
		[ $(findmnt -no FSTYPE "$back") = tmpfs ]
		sudo umount "$front"
		sudo mount --bind "$back" "$front"
	fi
elif [ "$verb" = remove ]; then
	echo "### helpers/builddir: removing $front..."
	if [ "$DISORDER" = 1 ]; then
		[ $(findmnt -no FSTYPE "$back") = tmpfs ]
		sudo umount "$front"
		sudo umount "$back"
		rm -d "$front" "$back"
	else
		remove_hard "$front"; remove_hard "$back"
	fi
	[ ! -e "$front" ] && [ ! -e "$back" ]
else
	exit 9
fi