post_install() {

	SERVICE_NAME='twingate.service'

	# summary of how this script can be called:
	#          <new-version>
	#          <failed-install-package> <version> `removing'
	#          <conflicting-package> <version>

	if [ -d /run/systemd/system ]; then
		if [ "$1" = "configure" ] || [ "$1" = "abort-upgrade" ] || [ "$1" = "abort-deconfigure" ] || [ "$1" = "abort-remove" ]; then
			if [[ "$(cat /etc/issue)" =~ ThinPro ]]; then
				OVERRIDE_DIR="/etc/systemd/system/$SERVICE_NAME.d"
				install -m 0755 -d "$OVERRIDE_DIR"
				echo -e "[Service]\nStateDirectory=\nEnvironment=STATE_DIRECTORY=/writable/var/lib/twingate\n" > "$OVERRIDE_DIR/override.conf"
			fi

			systemctl --system daemon-reload >/dev/null || true

			if [ -x "/usr/bin/deb-systemd-helper" ]; then
				# This will only remove masks created by d-s-h on package removal.
				deb-systemd-helper unmask ${SERVICE_NAME} >/dev/null || true
			fi

			# If it is clean installation
			if [ -z "$2" ]; then
				# Reset the enable/disable status one or more unit files, as specified on the command line,
				# to the defaults configured in the preset policy files. This has the same effect as disable or enable,
				# depending how the unit is listed in the preset files.
				systemctl --no-reload preset ${SERVICE_NAME} >/dev/null || true
			fi

			# Stop and then start one or more units specified on the command line if the units are running.
			# This does nothing if units are not running.
			# It has to restart service after upgrade
			systemctl try-restart ${SERVICE_NAME} &>/dev/null

			# Update the statefile to add new symlinks (if any), which need to be
			# cleaned up on purge. Also remove old symlinks.

			if [ -x "/usr/bin/deb-systemd-helper" ]; then
				# The "update-state" action is also not present in systemctl.
				# It updates deb-systemd-helper's state file,
				# removing obsolete entries (e.g. service files that are no longer shipped by the package)
				# and adding new entries (e.g. new service files shipped by the package) without enabling them.
				deb-systemd-helper update-state ${SERVICE_NAME} >/dev/null || true
			fi
		fi
	fi
}

post_upgrade() {
	post_install
}

pre_remove() {

	SERIVCE_NAME='twingate.service'

	if [ -d /run/systemd/system ]
	then
	    if [ "$1" = "remove" ] || [ "$1" = "purge" ]; then
	        systemctl stop "${SERIVCE_NAME}" >/dev/null || true
	    fi
	fi
}

post_remove() {
	SERVICE_NAME='twingate.service'

	if [ "$1" = "purge" ]; then
	    rm -rf /var/lib/twingate
	    rm -rf /etc/twingate
	    if [ -x "/usr/bin/deb-systemd-helper" ]; then
	        deb-systemd-helper purge ${SERVICE_NAME} >/dev/null || true
	        deb-systemd-helper unmask ${SERVICE_NAME} >/dev/null || true
	    fi
	    if [[ "$(cat /etc/issue)" =~ ThinPro ]]; then
	        rm -rf /writable/var/lib/twingate
	    fi
	fi

	if [ "$1" = "remove" ]; then
	    if [ -x "/usr/bin/deb-systemd-helper" ]; then
	        deb-systemd-helper mask ${SERVICE_NAME} >/dev/null || true
	    fi
	fi
}