#!/bin/sh

# This script set a specific grub entry (winLOOSE…) for the next boot.
# Then reboot the host

# Vars {{{
readonly PROGNAME=$(basename "${0}")
readonly PROGDIR=$(readlink -m $(dirname "${0}"))
readonly ARGS="${*}"
readonly NBARGS="${#}"

readonly GRUB_DEFAULT_PATH='/etc/default/grub'
readonly GRUB_DEFAULT_DIR='/etc/default/grub.d'
readonly WIN_GRUB="2"

## By default, the host should reboot at the end of the script
REBOOT=0

# }}}

main() {                                                        # {{{

	# First check in Grub default dir if saved mode is set
	if grep -q -E -R -- "^GRUB_DEFAULT=saved" "${GRUB_DEFAULT_DIR}"
	then
		printf '%b' "Reboot to windaube partition\\n"
		sudo grub-reboot "${WIN_GRUB}"
		[ "${REBOOT}" -eq "0" ] && sudo systemctl reboot
	fi

	# Otherwise check the default grub file
	if grep -q -E -- "^GRUB_DEFAULT=saved" "${GRUB_DEFAULT_PATH}"
	then
		printf '%b' "Reboot to windaube partition\\n"
		sudo grub-reboot "${WIN_GRUB}"
		[ "${REBOOT}" -eq "0" ] && sudo systemctl reboot
	else

		printf '%b' "GRUB_DEFAULT is not set in 'saved' mode\\n"
		sudo sed -i 's/\(^GRUB_DEFAULT.*\)/#\1\nGRUB_DEFAULT=saved/' "${GRUB_DEFAULT_PATH}"
		GRUB_DEFAULT_ENTRY=$(grep -E -- "#GRUB_DEFAULT=" "${GRUB_DEFAULT_PATH}" | cut -d"=" -f2)
		sudo grub-set-default "${GRUB_DEFAULT_ENTRY}"
		sudo update-grub
		printf '%b' "Please launch this script (${PROGDIR}/${PROGNAME} ${ARGS}) once again.\\n"
	fi
}
# }}}

# Manage arguments                                                # {{{
# This code can't be in a function due to arguments

if [ ! "${NBARGS}" -eq "0" ]; then

	manage_arg="0"

	# Parse all options (start with a "-") one by one
	while printf -- '%s' "${1}" | grep -q -E -- "^-+"; do

	case "${1}" in
		--reboot )        ## A reboot was requested (default behaviour)
			REBOOT=0
			;;
		-- )              ## End of options list
			## End the while loop
			break
			;;
		* )                    ## unknow option
			printf '%b\n' "${RED}Invalid option: ${1}${RESET}"
			printf '%b\n' "---"
			usage
			exit 1
			;;
	esac

	## Move to the next argument
	shift
	manage_arg=$((manage_arg+1))

	done

fi

# }}}

main

exit 0