#
# lsblk
#
# -d, --nodeps      Do  not  print  holder  devices  or  slaves.
# -p, --paths       Print full device paths.
# -l, --list        Produce  output  in the form of a list.
# -n, --noheadings
# -x, --sort column
#
# lsblk --tree=PATH -o PATH,TYPE,PARTUUID

function get_uuid() {
  # arg $1: Partition
  # arg $2: Variable name to store UUID
  validate_args 2 "$@" || return $?
  local partition="${1}"
  local -n uuid_ptr=$2

  # shellcheck disable=SC2034
  uuid_ptr="$(blkid -o value -s UUID "${partition}")" || return $?
}

function get_partitions(){
  # arg $1: block device
  # arg $2: name of variable to store partitions
  validate_args 2 "$@" || return $?
  local block_device="$1"
  local -n partitions_ptr=$2

  # Remove first line of output (which is just the block device itself)
  # with sed: `sed 1d`
  # shellcheck disable=SC2034
  partitions_ptr="$(lsblk -pln -o name "${block_device}" | sed 1d)" || return $?

  newline_separated_to_array partitions_ptr partitions_ptr || return $?
}

function get_block_devices() {
  # arg $1: name of variable to store block devices
  validate_args 1 "$@" || return $?
  local -n block_devices_ptr=$1

  # Get list of devices, one per line
  # shellcheck disable=SC2034
  block_devices_ptr="$(lsblk -dplnx size -o name | grep -Ev 'boot|rpmb|loop' | tac)" || return $?

  newline_separated_to_array block_devices_ptr block_devices_ptr || return $?
}

function get_block_devices_with_size() {
  # Example: variable with name $1 has content ('/dev/nvme0n1' '1,9T')
  #
  # arg $1: name of variable to store block device paths and their sizes
  validate_args 1 "$@" || return $?
  local -n block_device_sizes_ptr=$1

  # Get list of devices and their sizes, one pair per line.
  # Use sed to remove multiple white spaces: sed 's|\s\s*| |'
  # shellcheck disable=SC2034
  block_device_sizes_ptr="$(lsblk -dplnx size -o name,size | grep -Ev 'boot|rpmb|loop' | sed 's|\s\s*| |' | tac)"  || return $?

  newline_to_space block_device_sizes_ptr || return $?
  space_separated_to_array block_device_sizes_ptr block_device_sizes_ptr || return $?
}

function partition() {
  # Creates two partitions:
  # - boot partition, by default 260MiB
  # - luks partition, rest of the device for (encrypted) data
  #
  # arg $1: target block device
  # arg $2: boot firmware: 'uefi' | 'bios'
  # arg $3: boot partition size in MiB: >=260 | 'none'
  # arg $4: name of variable to store boot partition
  # arg $5: name of variable to store luks partition
  validate_args 5 "$@" || return $?
  local target_block_device="${1}"
  local boot_firmware="${2}"
  local boot_part_size="${3}"
  local -n boot_part=$4
  local -n luks_part=$5

  local minimum=260
  # Check if too small
  if [ "${boot_part_size}" -lt "${minimum}" ]; then
    printf '%s\n' "boot_part_size should be >= ${minimum}"
    return 1
  fi

  # As our data partition is encrypted,
  # we need a separate boot partition!
  case "${boot_firmware}" in
	uefi)
	  # EFI boot partition
    #
    # Create a partition with fat32 as the file system type and set the
    # esp flag on it.
    sudo parted --script "${target_block_device}" -- mklabel gpt \
      mkpart ESP fat32 2Mib "${boot_part_size}MiB" \
      set 1 esp on \
      mkpart primary "${boot_part_size}MiB" 100% || return $?

    get_partitions "${target_block_device}" PARTITIONS || return $?
    boot_part="${PARTITIONS[0]}"
    luks_part="${PARTITIONS[1]}"
		;;
	bios)
	  # > On a BIOS/GPT configuration, a BIOS boot partition is required. GRUB embeds its `core.img`
	  # > into this partition.
	  # > For parted set/activate the flag bios_grub on the partition.
	  #
	  # archwiki -> GRUB#GUID_Partition_Table_(GPT)_specific_instructions
	  # https://www.gnu.org/software/grub/manual/grub/html_node/BIOS-installation.html#BIOS-installation
	  sudo parted --script "${target_block_device}" -- mklabel gpt \
      mkpart primary 1MiB 2MiB \
      set 1 bios_grub on \
      mkpart primary 2MiB "${boot_part_size}MiB" \
      mkpart primary "${boot_part_size}MiB" 100% || return $?

    get_partitions "${target_block_device}" PARTITIONS || return $?
    boot_part="${PARTITIONS[2]}"
    luks_part="${PARTITIONS[3]}"
		;;
	*)
		printf '%s\n'  "Expected uefi or bios but got ${boot_firmware} instead!"
		return 1
		;;
  esac

  printf '%s\n' "boot partition: ${boot_part}"
  printf '%s\n' "luks partition: ${luks_part}"
}

function format() {
  # Formats the `boot` and `luks` partitions.
  #
  # If FDE is enabled ('true'),
  # then $2 will be encrypted with password $3 and opened at $7.
  #
  # If FDE is disabled,
  # then $7 is identical with $2.
  #
  # arg $1: boot partition
  # arg $2: (encrypted) luks partition
  # arg $3: password of luks partition
  # arg $4: full-disk-encryption (FDE): 'true' | 'false'
  # arg $5: filesystem: 'BTRFS' | 'EXT4' | 'F2FS'
  # arg $6: name of variable to store partition of encrypted luks partition (if FDE='true').
  #         Set to /dev/mapper/$(basename $LUKS_PART)
  # arg $7: name of variable to store data partition
  #
  # @post
  #   boot partition formatted
  #   luks partition formatted and accessible under $7
  validate_args 7 "$@" || return $?
  local boot_part="${1}"
  local luks_part="${2}"
  local luks_pwd="${3}"
  local fde="${4}"
  local fs="${5}"
  # shellcheck disable=SC2034
  local -n luks_part_uuid=$6
  local -n data_part=$7

  printf '%s\n' 'Wiping old signatures from partitions ...'
  sudo wipefs --all "${boot_part}" || return $?
  sudo wipefs --all "${luks_part}" || return $?

  printf '%s\n' "Formatting boot partition ${boot_part} ..."
  sudo mkfs.fat -F32 "${boot_part}" || return $?

  case "${fde}" in
  true)
    # FDE:
    #   GRUB does support LUKS2 since this commit:
    #   https://git.savannah.gnu.org/cgit/grub.git/commit/?id=365e0cc3e7e44151c14dd29514c2f870b49f9755
    #   Using "--type luks1" is no longer required.
    printf '%s\n' "Creating encrypted luks partition ${luks_part} ..."
    printf '%s' "${luks_pwd}" | sudo cryptsetup luksFormat \
      --cipher aes-xts-plain64 --key-size 512 --hash sha512 \
      --iter-time 10000 --use-random "${luks_part}" || return $?

    get_uuid "${luks_part}" luks_part_uuid || return $?

    local luks_name
    luks_name="$(basename "${luks_part}")"
    data_part="/dev/mapper/${luks_name}"

    # Open luks partition
    printf '%s' "${luks_pwd}" | sudo cryptsetup luksOpen "${luks_part}" "${luks_name}" || return $?
    ;;
  false)
    data_part="${luks_part}"
    ;;
  *)
    printf '%s\n' "Invalid option: ${fde}"
    return 1
    ;;
  esac

  printf '%s\n' "Formatting the data partition ${data_part} ..."
  case "${fs}" in
	BTRFS)
      sudo mkfs.btrfs "${data_part}" || return $?
		;;
	EXT4)
      # https://wiki.archlinux.org/index.php/Ext4
  	  # If the CPU supports SSE 4.2, make sure the crc32c_intel kernel module is loaded
      sudo mkfs.ext4 -O metadata_csum "${data_part}" || return $?
		;;
	F2FS)
      # archwiki -> F2FS#Creating_a_F2FS_file_system
      # - requires f2fs-tools
      # - compression: "-O compression" and when mounting the filesystem, specify compress_algorithm=(lzo|lz4|zstd|lzo-rle)
      sudo mkfs.f2fs -O extra_attr,inode_checksum,sb_checksum,compression "${data_part}" || return $?
		;;
	*)
		printf '%s\n' "Filesystem ${fs} is not yet supported!"
		return 1
		;;
  esac
}