#start here: https://help.ubuntu.com/community/ManualFullSystemEncryption
# This is a butchering of the script the guide gets you to run.
# Made to be exactly what I want without any extras or prompts.


#findPartitions					# The various partitions.
# I'm just manually entering what I want
declare -gr DATA_PARTITION_CHOSEN=false
declare -gr SWAP_PARTITION_CHOSEN=false
declare -gr HIBERNATION_CHOSEN=${SWAP_PARTITION_CHOSEN}
#declare -gr SWAP_PARTITION_SIZE=65536
declare -gr PARTITION_SYSTEM=/dev/sdc1
#PARTITION_ESP= this is EFI and so I don't need this
#	findBootloader					# The bootloader.
#declare -gr BOOTLOADER=/dev/??? #not sure I need this either
#	findPassphrases					# The passphrases (and password note).
declare -gr PASSPHRASE_SYSTEM=""

#preInstallationProcess					# Do the pre-installation
# Encrypt the system partition.
encryptPartition System ${PARTITION_SYSTEM} "${PASSPHRASE_SYSTEM}"

# Unlock the system partition.
unlockPartition System system ${PARTITION_SYSTEM} "${PASSPHRASE_SYSTEM}"

setUpLvm System system				# Set up the system LVM.

setUpLogicalVolume Boot boot system 512M	# Create /boot.
formatVolume Boot system-boot ext4 boot		# Format /boot.

setUpLogicalVolume Root root system '100%FREE'	# Create root.
formatVolume Root system-root ext4 root		# Format root.

#runInstaller						# Run the installer.
echo "just manually run the installer and follow the guide"
echo "https://help.ubuntu.com/community/ManualFullSystemEncryption/DetailedProcessInstallUbuntu"
read -rp 'Press Enter to continue once installer finished, or press Ctrl+C to cancel: '


#---------------------------------------------------------------------------------------------------
#-------- Functions --------------------------------------------------------------------------------
#---------------------------------------------------------------------------------------------------

function inputSummary ()
{
	cat <<-END

		$Summary

		Partition ${PARTITION_SYSTEM} will be used for your System partition (root).
		                      Passphrase: ${PASSPHRASE_SYSTEM}


		Please check the details carefully before deciding whether or not to proceed.


		Are you sure that these details are correct?

	END

	# Confirm permission.
	local ANSWER=''
	read -rp "Type Y to proceed, or anything else to cancel, and press Enter: " ANSWER

	if [[ "${ANSWER,}" != 'y' ]]
	then
		echo
		echo 'Terminated. I did nothing.'
		echo
		exit 3					# Terminate if incorrect.
	fi
} #inputSummary

#---------------------------------------------------------------------------------------------------
#	Encrypt a partition
#
# Parameters
#	1	Human-readable name for the partition
#	2	The partition, e.g. /dev/sda2, nvme0n1p2
#	3	The passphrase
#---------------------------------------------------------------------------------------------------


function encryptPartition ()
{
	local -r HUMAN_NAME=${1}
	local -r PARTITION=${2}
	local -r PASSPHRASE="${3}"

	echo
	echo "Encrypting the ${HUMAN_NAME} partition..."

	# Encrypt the partition.
	echo -n "${PASSPHRASE}" | sudo cryptsetup luksFormat --hash=sha512 --key-size=512 --key-file=- ${PARTITION}

	local -ir RET=${?}				# Catch the return code.

	(( RET )) && error "There was an error encrypting the ${HUMAN_NAME} partition." ${RET}

} # encryptPartition


#---------------------------------------------------------------------------------------------------
#	Unlock a partition
#
# Parameters
#	1	Human-readable name for the partition
#	2	Partition label
#	3	The partition, e.g. /dev/sda2, /dev/nvme0n1p2
#	4	The passphrase
#---------------------------------------------------------------------------------------------------


function unlockPartition ()
{
	local -r HUMAN_NAME=${1}
	local -r LABEL=${2}
	local -r PARTITION=${3}
	local -r PASSPHRASE="${4}"

	echo
	echo "Unlocking the ${HUMAN_NAME} partition..."

	# Unlock the partition.
	echo -n "${PASSPHRASE}" | sudo cryptsetup open --type=luks --key-file=- ${PARTITION} ${LABEL}

	local -ir RET=${?}				# Catch the return code.

	(( RET )) && error "There was an error unlocking the ${HUMAN_NAME} partition." ${RET}

} # unlockPartition


#---------------------------------------------------------------------------------------------------
#	Set up LVM for the partition.
#
# Parameters
#	1	Human-readable name for the partition
#	2	Partition label
#---------------------------------------------------------------------------------------------------


function setUpLvm ()
{
	local -r HUMAN_NAME=${1}
	local -r LABEL=${2}

	echo
	echo "Set up ${HUMAN_NAME} physical volume for ${LABEL}..."

	sudo pvcreate /dev/mapper/${LABEL}		# Initialise the physical volume.

	local -i RET=${?}				# Catch the return code.

	(( RET )) && error "There was an error initialising the physical volume for LVM on the ${HUMAN_NAME} partition." ${RET}

	echo
	echo "Set up ${HUMAN_NAME} volume group for ${LABEL}..."

	sudo vgcreate ${LABEL} /dev/mapper/${LABEL}	# Set up the volume group.

	RET=${?}					# Catch the return code.

	(( RET )) && error "There was an error setting up the volume group for LVM on the ${HUMAN_NAME} partition." ${RET}

} # setUpLvm


#---------------------------------------------------------------------------------------------------
#	Set up the logical volume for a partition.
#
# Parameters
#	1	Human-readable name for the partition
#	2	Partition label
#	3	Partition to set up
#	4	Size, including the modifier, e.g. 512M and 100%FREE
#---------------------------------------------------------------------------------------------------


function setUpLogicalVolume ()
{
	local -r HUMAN_NAME=${1}			# Human-readable name.
	local -r LABEL=${2}				# The logical volumne name.
	local -r PARTITION=${3}				# The partition where to create it.
	local -r SIZE=${4}				# The required size.

	echo
	echo "Set up logical volume ${HUMAN_NAME} for ${LABEL} in ${PARTITION} size ${SIZE}..."

	if [[ ${SIZE} == '100%FREE' ]]
	then
		local -r OPTION=extents
	else
		local -r OPTION=size
	fi

	sudo lvcreate --${OPTION}=${SIZE} --name=${LABEL} ${PARTITION}

	local -i RET=${?}				# Catch the return code.

	(( RET )) && error "There was an error initialising the logical volume for LVM on the ${HUMAN_NAME} partition." ${RET}

} # setUpLogicalVolume


#---------------------------------------------------------------------------------------------------
#	Format a volume.
#
# Parameters
#	1	Human-readable name for the partition
#	2	Partition to be formatted
#	3	Type of format, specifically swap or ext4
#	4	Lbel for the partition
#---------------------------------------------------------------------------------------------------


function formatVolume ()
{
	local -r HUMAN_NAME="${1}"
	local -r PARTITION=${2}
	local -r TYPE=${3}
	local -r LABEL="${4}"

	echo
	echo "Format ${HUMAN_NAME} partition ${PARTITION} (${LABEL}) as ${TYPE}..."

	# Format the partition.
	if [[ ${TYPE} == 'swap' ]]
	then
		sudo mkswap --label=${LABEL} /dev/mapper/${PARTITION}
	else
		sudo mkfs.ext4 -L ${LABEL} /dev/mapper/${PARTITION}
	fi

	local -ir RET=${?}				# Catch the return code.

	(( RET )) && error "Error formatting the ${HUMAN_NAME} partition in ${PARTITION}." ${RET}

} # formatVolume





postInstallationProcess					# Do the post-installation work.
go to https://help.ubuntu.com/community/ManualFullSystemEncryption/DetailedProcessCheckAndFinalise