#!/usr/bin/env bash
# Copyright (C) 2023  Umorpha Systems
# SPDX-License-Identifier: AGPL-3.0-or-later

# Dependencies:
#  - /usr/bin/env   (coreutils, busybox)
#  - cat            (coreutils, busybox)
#  - dd             (coreutils, busybox)
#  - install        (coreutils, busybox)
#  - mkdir          (coreutils, busybox)
#  - mktemp         (coreutils, busybox)
#  - rm             (coreutils, busybox)
#  - rmdir          (coreutils, busybox)
#  - losetup        (util-linux, busybox)
#  - umount         (util-linux, busybox)
#  - blkid          (util-linux)
#  - mount          (util-linux)
#  - bash           (bash)
#  - systemd-repart (systemd)
#  - lvcreate       (lvm2)
#  - pvcreate       (lvm2)
#  - vgchange       (lvm2)
#  - vgcreate       (lvm2)
#  - pv             (pv)
#  - mkfs.ext4      (e2fsprogs)
#  - arch-chroot    (arch-install-scripts)
#
# Dependencies of arch-chroot (as of v28):
#  - cat        (coreutils, busybox)
#  - chroot     (coreutils, busybox)
#  - install    (coreutils, busybox)
#  - ln         (coreutils, busybox)
#  - readlink   (coreutils, busybox)
#  - touch      (coreutils, busybox)
#  - mountpoint (util-linux, busybox)
#  - umount     (util-linux, busybox)
#  - unshare    (util-linux, busybox)
#  - mount      (util-linux)
#  - grep       (grep, busybox)
#  - bash       (bash)
set -euE -o pipefail
set -x

main() {
	local device rootfs
	device=$1
	rootfs=$2

	echo ":: Installing '${rootfs}' to '${device}'"

	cleanup=()
	trap 'for (( i=${#cleanup[@]}-1; i >= 0; i-- )); do eval "${cleanup[$i]}"; done' EXIT

	local tmpdir
	tmpdir="$(mktemp -dt "${0##*/}.XXXXXXXXXX")"
	cleanup+="rmdir -- ${tmpdir@Q}"

	########################################################################

	if [[ -f "$device" ]]; then
		echo "   file '${device}' is not a block device, setting up a loopback device..."
		device=$(losetup --find --show --partscan -- "$device")
		echo "   ... '${device}'"
		cleanup+=("losetup --detach ${device@Q}")
	fi
	local devicep="$device"
	if [[ "$devicep" == *[0-9] ]]; then
		devicep+='p'
	fi

	########################################################################

	echo ":: Setting up GPT"

	dd if=/dev/zero of="$device" bs=512 count=4

	cat >"$tmpdir/00-esp.conf" <<-EOF
		[Partition]
		Type=esp
		Format=vfat
		Label=Umorpha EFI System Partition
		SizeMinBytes=512M
		SizeMaxBytes=512M
	EOF
	cat >"$tmpdir/10-lvm.conf" <<-EOF
		[Partition]
		# https://en.wikipedia.org/w/index.php?title=User_talk:Claunia&diff=prev&oldid=1182832243
		Type=E6D6D379-F507-44C2-A23C-238F2A3DF928
		Label=Umorpha LVM Partition
	EOF

	systemd-repart \
		--empty=allow --dry-run=no \
		--no-pager \
		--definitions="$tmpdir" \
		"$device"

	rm -- "$tmpdir"/*.conf

	########################################################################

	echo ":: Setting up LVM"

	pvcreate "${devicep}2"
	vgcreate vg_umorpha "${devicep}2"
	cleanup+=("vgchange --activate=n vg_umorpha")

	lvcreate --name=lv_root_a --size="$(stat --format='%s' -- "$rootfs")b" vg_umorpha
	pv -- "$rootfs" >/dev/mapper/vg_umorpha-lv_root_a

	lvcreate --name=lv_root_overlay --size=1G vg_umorpha
	mkfs.ext4 /dev/mapper/vg_umorpha-lv_root_overlay

	########################################################################

	echo ":: Configuring boot"

	local selector_boot selector_root selector_overlay
	selector_boot="$(   blkid --output=export "${devicep}1"                          | grep ^UUID=)"
	selector_root="$(   blkid --output=export /dev/mapper/vg_umorpha-lv_root_a       | grep ^UUID=)"
	selector_overlay="$(blkid --output=export /dev/mapper/vg_umorpha-lv_root_overlay | grep ^UUID=)"

	mkdir "$tmpdir/root"
	cleanup+=("rmdir -- ${tmpdir@Q}/root")
	mount -o ro -- /dev/mapper/vg_umorpha-lv_root_a "$tmpdir/root"
	cleanup+=("umount ${tmpdir@Q}/root")

	mkdir "$tmpdir/overlay"
	cleanup+=("rmdir -- ${tmpdir@Q}/overlay")
	mount -- /dev/mapper/vg_umorpha-lv_root_overlay "$tmpdir/overlay"
	cleanup+=("umount ${tmpdir@Q}/overlay")

	mkdir  "$tmpdir/mnt" "$tmpdir/overlay/upperdir" "$tmpdir/overlay/workdir"
	cleanup+=("rmdir -- ${tmpdir@Q}/mnt")
	mount -t overlay -o "lowerdir=${tmpdir}/root,upperdir=${tmpdir}/overlay/upperdir,workdir=${tmpdir}/overlay/workdir" umorpha-rootfs \
	      "${tmpdir}/mnt"
	cleanup+=("umount ${tmpdir@Q}/mnt")

	mount -- "${devicep}1" "$tmpdir/mnt/boot"
	cleanup+=("umount ${tmpdir@Q}/mnt/boot")

	mkdir -p "$tmpdir/mnt/etc/kernel"
	echo root=$selector_root overlay_root=$selector_overlay boot=$selector_boot rw >"$tmpdir/mnt/etc/kernel/cmdline"

	mkdir -p -- "$tmpdir/mnt/boot/EFI/Linux"
	arch-chroot -- "$tmpdir/mnt" sh -c "printf '%s\n' usr/lib/modules/*/vmlinuz | /usr/share/libalpm/scripts/mkinitcpio install"
	install -D "$tmpdir/mnt/usr/lib/systemd/boot/efi/systemd-bootx64.efi" "$tmpdir/mnt/boot/EFI/BOOT/BOOTX64.EFI"
}

main "$@"