#!/bin/sh

export STOW_DIR=/etc/portage/stow

need_root() {
	if test "$(id -u)" -ne 0; then
		printf 'This action requires superuser access.\n'
		exit 1
	fi
}

add() {
	need_root
	stow -S "$@"
}

remove() {
	need_root
	stow -D "$@"
}

flush() {
	need_root
	list | xargs -- stow -D
}

rebuild() {
	need_root
	if test $# -gt 0; then
		stow -R "$@"
	else
		list | xargs -- stow -R
	fi
}

list() {
	subcmd="$1"
	shift
	case $subcmd in
		active) list_active;;
		all) list_all;;
		available) list_available;;
		*) list_active;;
	esac
}

list_active() {
	# Note: we de not escape any special characters in $STOW_DIR since it is
	# assumed we are in full control of its contents.
	# XXX: -r for xargs is a GNU extension
	find "$STOW_DIR/.." -type l -print0 2>/dev/null \
		| xargs -r0 readlink -f \
		| sed -n ":^$STOW_DIR: s:^$STOW_DIR/\([^/]\+\)/.*:\1:p" \
		| sort -u
}

list_all() {
	ls -1 "$STOW_DIR"
}

list_available() {
	tmp="$(mktemp)" || exit 1
	list_active > "$tmp"
	list_all | comm -13 "$tmp" - 
	rm -f "$tmp"
}

cmd="$1"
shift
case $cmd in
	add) add "$@";;
	flush) flush;;
	list) list "$@";;
	rebuild) rebuild "$@";;
	remove) remove "$@";;
	*) list_active;;
esac