#!/bin/bash
VERBOSITY="${VERBOSITY:-0}"
SUDO_PROGRAM="${SUDO_PROGRAM:-sudo}"
USER_WARNING="${USER_WARNING:-1}"
[ "$VERBOSITY" = "1" ] && set -x
set -uo pipefail

function log {
	LEVEL=$1
	shift
	echo "[${LEVEL}]" $@ >&2
}

if [ "$EUID" = 0 ] ; then
  log WARNING "Do not run this command as root, as it won't delete proper files in your system"
  exit
fi

if [ "$USER_WARNING" = 1 ] ; then
	cat <<EOF
This is a destructive operation, it will delete the following:

Services:

- nix-daemon.service
- nix-daemon.socket
- nix.mount
- mkdir-rootfs@.service

Files & Directories:

- $HOME/{.nix-channels,.nix-defexpr,.nix-profile,.config/nixpkgs}
- /etc/profile.d/nix-app-icons.sh
- /etc/profile.d/nix.sh
- /etc/nix
- /etc/tmpfiles.d/nix-daemon.conf 
- ~root/.nix-channels 
- ~root/.nix-defexpr 
- ~root/.nix-profile

Users & Groups:

- nixbld[0-32]

If you are unsure about everything that will be done, make sure to read the source code of this script by running "cat $(realpath $0)" on your terminal.

EOF

	read -r -p "Are you sure you want to proceed? [y/N] " response
	case "$response" in
		[yY][eE][sS]|[yY]) 
	        ;;
		*)
			exit
		;;
	esac
fi

log TASK 'Removing nix configuration from "\$HOME"'
log TASK 'To finish removing everything, make sure to remove the '. "$HOME/.nix-profile/etc/profile.d/nix.sh"' line in your ~/.profile or ~/.bash_profile'

rm -rf $HOME/{.nix-channels,.nix-defexpr,.nix-profile,.config/nixpkgs,.local/state/nix,.cache/nix}

log TASK 'Deleting nix system users'
for i in $(seq 1 32); do
	"$SUDO_PROGRAM" userdel "nixbld$i"
done
"$SUDO_PROGRAM" groupdel 'nixbld'

log TASK 'Removing nix systemd services'
"$SUDO_PROGRAM" systemctl disable --now nix-daemon.service nix-daemon.socket nix.mount mkdir-rootfs@.service
"$SUDO_PROGRAM" systemctl daemon-reload
"$SUDO_PROGRAM" rm -rf '/etc/systemd/system/mkdir-rootfs@.service' '/etc/systemd/system/nix.mount' /etc/systemd/system/nix-daemon.{service,socket} '/etc/systemd/system/nix-daemon.service.d/'

log TASK 'Removing remaining nix system configuration'
"$SUDO_PROGRAM" rm -rf '/etc/profile.d/nix-app-icons.sh' '/etc/nix' '/etc/profile.d/nix.sh' '/etc/tmpfiles.d/nix-daemon.conf' ~root/.nix-channels ~root/.nix-defexpr ~root/.nix-profile
"$SUDO_PROGRAM" cp -f '/etc/bashrc.backup-before-nix' '/etc/bashrc'

log TASK 'Removing /var/lib/nix'
"$SUDO_PROGRAM" restorecon -RF '/var/lib/nix'
"$SUDO_PROGRAM" restorecon -RF '/nix'
"$SUDO_PROGRAM" rm -rf '/var/lib/nix'

log INFO 'Make sure to remove residual configurations from the following files:' "/etc/bash.bashrc /etc/bashrc /etc/profile /etc/zsh/zshrc /etc/zshrc $HOME/.bashr $HOME/.bash_profile $HOME/.zshrc $HOME/.profile"

log INFO 'You may now reboot your system to confirm these changes with "systemctl reboot"'