# This should be readable by /bin/sh

# Sets up XDG environmental variables, so programs using them don't have to
# worry about checking if they are set.
# http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html

[ -n "$XDG_DATA_HOME"   ] || export XDG_DATA_HOME="$HOME/.local/share"
[ -n "$XDG_CONFIG_HOME" ] || export XDG_CONFIG_HOME="$HOME/.config"
[ -n "$XDG_DATA_DIRS"   ] || export XDG_DATA_DIRS="/usr/local/share/:/usr/share/"
[ -n "$XDG_CONFIG_DIRS" ] || export XDG_CONFIG_DIRS="/etc/xdg"
[ -n "$XDG_CACHE_HOME"  ] || export XDG_CACHE_HOME="$HOME/.cache"
[ -n "$XDG_VTNR"        ] || export XDG_VTNR="$(tty 2>/dev/null | sed -n 's,^/dev/tty,,p')"

# Check if XDG_VTNR got set to empty
[ -n "$XDG_VTNR"        ] || unset XDG_VTNR

# Check if XDG_RUNTIME_DIR is set, but has a bogus setting
if [ -n "$XDG_RUNTIME_DIR" ] && [ ! -d "$XDG_RUNTIME_DIR" ]; then
	unset XDG_RUNTIME_DIR
fi

# Set XDG_RUNTIME_DIR if we can
if [ -z "$XDG_RUNTIME_DIR" ] && type flock &>/dev/null; then
	_diy_xdg_runtime_login() {
		export XDG_RUNTIME_DIR="$XDG_CACHE_HOME/xdg-runtime-dir/$HOSTNAME"
		# There's a race condition here, between the `ln -s` and `flock`.
		# But it's not like I'll be hammering a box with logins.
		if [ ! -d "$XDG_RUNTIME_DIR" ]; then
			local tmp="$(mktemp -d --tmpdir -- "${USER}@${HOSTNAME}-runtime.XXXXXXXXXX")"
			mkdir -p -- "$XDG_CACHE_HOME/xdg-runtime-dir"
			ln -sfT -- "$tmp" "$XDG_RUNTIME_DIR"
		fi
		if ! [ /dev/fd/7 -ef "$XDG_CACHE_HOME/xdg-runtime-dir/.lock" ]; then
			exec 7>"$XDG_CACHE_HOME/xdg-runtime-dir/.lock"
			if flock -sn 7; then
				# Unfortunately this doesn't survive across exec(1).
				trap _diy_xdg_runtime_logout EXIT
			fi
		fi
	}
	_diy_xdg_runtime_logout() {
		if flock -xn 7; then
			rm -rf -- "$(readlink "$XDG_RUNTIME_DIR")"
		fi
	}
	_diy_xdg_runtime_login
fi