user_username = u
user_home_path := $(shell getent passwd "$(user_username)" | (IFS=: read _ _ _ _ _ homedir _; echo $$homedir))
user_home_btrfs = $(user_home_path).btrfs
user_home_bytes = 10GiB
user_home_force_replace =

user_exists = getent passwd "$(user_username)" >/dev/null

is_btrfs = df ~$(user_username) -t btrfs >/dev/null

user-account:
	[ "$(user_username)" ]
	$(user_exists) || sudo useradd "$(user_username)" -G sudo -m -p '' -s /bin/bash
	$(is_btrfs) || $(MAKE) mount-user-btrfs-home >/dev/null 2>&1 || $(MAKE) user-btrfs-home

remove_user_home_btrfs = sudo mv -b "$(user_home_btrfs)" "$(user_home_btrfs)"~"$$(date -Is)"

user-btrfs-home:
	[ "$(user_home_path)" ]
	[ ! -e "$(user_home_btrfs)" ] || $(if $(user_home_force_replace),$(remove_user_home_btrfs),false)
	[ ! -e "$(user_home_btrfs)" ]
	! mountpoint -q "$(user_home_path)" || sudo umount "$(user_home_path)"
	[ ! -e "$(user_home_path)" ] || sudo rmdir "$(user_home_path)" || sudo mv -b "$(user_home_path)" "$(user_home_path)"~"$$(date -Is)"
	[ -e "$(user_home_btrfs)" ] || sudo fallocate -l "$(user_home_bytes)" "$(user_home_btrfs)"
	sudo mkdir "$(user_home_path)"
	sudo mkfs.btrfs "$(user_home_btrfs)"
	sudo mount -t btrfs "$(user_home_btrfs)" "$(user_home_path)"
	sudo rsync -a /etc/skel/ "$(user_home_path)"/
	sudo chown -R "$(user_username):" "$(user_home_path)"

mount-user-btrfs-home:
	mountpoint -q "$(user_home_path)" || sudo mount -t btrfs "$(user_home_btrfs)" "$(user_home_path)"