#!/bin/bash
#
# This script is indended to decrypt, mount and chroot in a LUKS+EFI+LVM USB

if [[ $UID != 0 ]]; then
	printf "You need root permissions to use this script!\n"
	exit 1
fi

usage()
{
	echo -e "\nUsage: $(basename "$0") [options] [luks_device]\n\n" \
		"Options:\n" \
		"\t-m, --mount          Mount the LUKS device (Default)\n" \
		"\t-u, --umount         Unmount the LUKS device\n" \
		"\t-n, --nochroot       Don't run arch-chroot\n" \
		"\t-c, --chroot         Run arch-chroot (Default)\n" \
		"\t-h, --help           Display this message\n"
}

# Mute lvm utilities
export LVM_SUPPRESS_FD_WARNINGS=true

# Some sane defaults
ACTION=mount
RUN_CHROOT=true
USB_LUKS_PART=

# Call getopt to validate the provided input. 
if ! options=$(getopt -o chmnu -l chroot,nochroot,mount,umount,help -- "$@"); then
	usage
	exit 1
fi
eval set -- "$options"
while true; do
	case "$1" in
	(-m|--mount)	ACTION=mount ;;
	(-u|--umount)	ACTION=umount ;;
	(-n|--nochroot)	RUN_CHROOT=false ;;
	(-c|--chroot)	RUN_CHROOT=true ;;
	(-h|--help)	usage; exit 1;;
	(--)		shift; break;;
	(*)		usage; break;;
	esac
	shift
done
if [ "$#" -gt 1 ]; then
	echo "error: Only 1 device argument possible! Got $#: $*"
	usage
	exit 1
fi

if [ "$1" ]; then
	USB_LUKS_PART="$1"
fi

get_archy_usb_dev_path()
{
	declare -A dev_map='([by-id]="usb-ADATA*part3" [by-uuid]="bbd2dd10-4209-4879-a1e2-5ee1eff8ff5c")'
	for key in "${!dev_map[@]}"; do
		dev_path=$(find -L "/dev/disk/${key}" -name "${dev_map[$key]}")
		if [ -n "$dev_path" ]; then
			echo "${dev_path}"
			break
		fi
	done
}

get_usb_efi_part()
{
	echo "/dev/$(lsblk -ndo pkname "$1")2"
}

get_usb_root_part()
{
	lsblk -no path "$1" | grep root
}

usb_mount()
{
	cryptsetup open "${USB_LUKS_PART}" adatausb || exit $?
	vgchange -a y > /dev/null || exit $?

	usb_dev_root=$(get_usb_root_part "${USB_LUKS_PART}")

	echo -e "Mounting /\t${usb_dev_root}"
	mount "${usb_dev_root}" /mnt/usb
	exit_code=$?
	if [ $exit_code -ne 0 ]; then
		cryptsetup close "${USB_LUKS_PART}"
		exit $exit_code
	fi

	echo -e "Mounting /efi\t${USB_DEV_EFI}"
	mount "${USB_DEV_EFI}" /mnt/usb/efi
	exit_code=$?
	if [ $exit_code -ne 0 ]; then
		umount /mnt/usb
		cryptsetup close "${USB_LUKS_PART}"
		exit $exit_code
	fi
	if [ $RUN_CHROOT == true ]; then
		arch-chroot /mnt/usb
	fi
}

usb_umount()
{
	usb_dev_root=$(get_usb_root_part "${USB_LUKS_PART}")
	umount "${USB_DEV_EFI}" "${usb_dev_root}" # || exit $?
	vgchange -a n --quiet adata > /dev/null # || exit $?
	cryptsetup close adatausb
}

# Auto-detect, in case we don't provide a device
if [ -z "${USB_LUKS_PART}" ]; then
	USB_LUKS_PART=$(get_archy_usb_dev_path)
	if [ -z "${USB_LUKS_PART}" ]; then
		printf "Device not found!\nUse %s </dev/path/to/LUKS_device>\n" "$0"
		exit 1
	fi
fi

USB_DEV_EFI=$(get_usb_efi_part "${USB_LUKS_PART}")
if [ -n "${usb_def_efi}" ]; then
	echo "EFI device not found!"
	exit 1
fi

usb_$ACTION