#!/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 (optional) (util-linux; the busybox one doesn't work)
#  - umount             (util-linux, busybox)
#  - blkid              (util-linux)
#  - mount              (util-linux)
#  - bash               (bash)
#  - systemd-repart     (systemd)
#  - lvcreate           (lvm2)
#  - pvcreate           (lvm2)
#  - vgchange           (lvm2)
#  - vgcreate           (lvm2)
#  - vgremove           (lvm2)
#  - pv                 (pv)
#  - mkfs.ext4          (e2fsprogs)
#  - mkfs.vfat          (dosfstools)
#  - arch-chroot        (arch-install-scripts)
#
# Dependencies of arch-chroot (as of v28):
#  - cat        (coreutils, busybox)
#  - install    (coreutils, busybox)
#  - ln         (coreutils, busybox)
#  - touch      (coreutils, busybox)
#  - chroot     (coreutils; the busybox one doesn't work)
#  - readlink   (coreutils; the busybox one doesn't work)
#  - mountpoint (util-linux, busybox)
#  - umount     (util-linux, busybox)
#  - unshare    (util-linux, busybox)
#  - mount      (util-linux)
#  - grep       (grep, busybox)
#  - bash       (bash)
#
# Of those, these are the ones that aren't already in an initcpio:
#  - arch-chroot    (arch-install-scripts)
#  - bash           (bash)
#  - chroot         (coreutils)
#  - readlink       (coreutils)
#  - pv             (pv)
#  - systemd-repart (systemd)
#  - mkfs.ext4      (e2fsprogs)
#  - mkfs.vfat      (dosfstools)
#  - pvcreate       (lvm2)
#  - vgchange       (lvm2)
#  - vgcreate       (lvm2)
#  - vgremove       (lvm2)
#  - lvcreate       (lvm2)

set -euE -o pipefail

v() {
	printf >&2 '  $ %s\n' "${*@Q}"
	"$@"
}

main() {
	local typ device rootfs
	typ=$1
	rootfs=$2
	device=$3

	echo ":: Installing '${rootfs}' to '${device}' for '${typ}'"
	if [[ "$rootfs" != *rootfs* ]]; then
		echo >&2 "!! Filename '${rootfs}' does not look like a rootfs filename"
		return 2
	fi
	case "$typ" in
		uefi|bios) :;;
		*)
			echo >&2 "!! Install type '${typ}' is not valid"
			return 2
			;;
	esac

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

	cleanup=()
	_do_cleanup() {
		if [[ $? == 0 ]]; then
			echo "::Cleaning up..."
		else
			echo >&2 "!! ERROR! Cleaning up..."
		fi
		for (( i=${#cleanup[@]}-1; i >= 0; i-- )); do
			eval "${cleanup[$i]}"
		done
	}
	trap '_do_cleanup' EXIT

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

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

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

	v vgremove --yes vg_umorpha || true

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

	echo ":: Setting up GPT"

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

	n=0
	cat >"$tmpdir/00-esp.conf" <<-EOF
		[Partition]
		Type=esp
		Format=vfat
		Label=Umorpha EFI System Partition
		SizeMinBytes=512M
		SizeMaxBytes=512M
	EOF
	n_esp=$((++n))
	if [[ $typ == bios ]]; then
		cat >"$tmpdir/05-bios.conf" <<-EOF
			[Partition]
			Type=21686148-6449-6E6F-744E-656564454649
			Label=Umorpha BIOS Boot Partition
			SizeMinBytes=1M
			SizeMaxBytes=1M
		EOF
		n_bios=$((++n))
	fi
	cat >"$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
	n_lvm=$((++n))

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

	rm -- "$tmpdir"/*.conf

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

	echo ":: Setting up LVM"

	v pvcreate "${devicep}${n_lvm}"
	v vgcreate vg_umorpha "${devicep}${n_lvm}"
	if $is_loop; then
		cleanup+=("v vgchange --activate=n vg_umorpha")
	fi

	# Use short `-c` instead of `--format` so this works with busybox.
	v lvcreate --zero=y --wipesignatures=y --yes --name=lv_root_a \
	        --size="$(stat -c '%s' -- "$rootfs")b" vg_umorpha
	v pv -- "$rootfs" >/dev/mapper/vg_umorpha-lv_root_a

	v lvcreate --zero=y --wipesignatures=y --yes \
	        --name=lv_root_overlay --size=1G vg_umorpha
	v 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}${n_esp}"                   | grep ^UUID=)"
	selector_root="$(   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=)"
	v declare -p selector_boot selector_root selector_overlay

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

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

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

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

	case "$typ" in
		uefi)
			mkdir -p -- "$tmpdir/mnt/etc/kernel"
			echo "root=$selector_root overlay_root=$selector_overlay boot=$selector_boot rw" >"$tmpdir/mnt/etc/kernel/cmdline"
			mkdir -p -- "$tmpdir/mnt/boot/EFI/Linux"
			v install -D "$tmpdir/mnt/usr/lib/systemd/boot/efi/systemd-bootx64.efi" "$tmpdir/mnt/boot/EFI/BOOT/BOOTX64.EFI"
			;;
		bios)
			v arch-chroot -- "$tmpdir/mnt" grub-install --target=i386-pc "$device"
			install -Dm600 /dev/stdin "$tmpdir/mnt/boot/grub/grub.cfg" <<-EOF
				insmod part_gpt
				insmod part_msdos
				if [ -s \$prefix/grubenv ]; then
				  load_env
				fi
				if [ -s \$prefix/grub_a.cfg ]; then
				  configfile \$prefix/grub_a.cfg
				fi
				if [ -s \$prefix/grub_b.cfg ]; then
				  configfile \$prefix/grub_b.cfg
				fi
			EOF
			{
				for krnl in "$tmpdir/mnt"/usr/lib/modules/*/vmlinuz; do
					pkgbase=$(cat -- ${krnl%vmlinuz}pkgbase)
					cat <<-EOF
						menuentry 'Parabola GNU/Linux-libre, slot a, ${pkgbase} kernel'
						  set search --no-floppy --fs-uuid --set=root ${selector_boot#UUID=}
						  echo 'Loading ${pkgbase} kernel...'
						  linux /vmlinuz-${pkgbase} root=$selector_root overlay_root=$selector_overlay boot=$selector_boot rw
						  echo 'Loading initial ramdisk...'
						  initrd /initramfs-${pkgbase}.img
						  echo 'Booting...'
						  boot
					EOF
				done
			} | install -Dm600 /dev/stdin "$tmpdir/mnt/boot/grub/grub_a.cfg" <<-EOF
			;;
	esac

	v arch-chroot -- "$tmpdir/mnt" sh -c "printf '%s\n' usr/lib/modules/*/vmlinuz | /usr/share/libalpm/scripts/mkinitcpio install"
	v arch-chroot -- "$tmpdir/mnt" ldconfig
	v arch-chroot -- "$tmpdir/mnt" systemd-machine-id-setup
	v arch-chroot -- "$tmpdir/mnt" update-ca-trust
}

main "$@"