#!/usr/bin/env bash
set -euo pipefail

# To run this, do:
## curl -o bootstrap https://bootstrap.dougthompson.co.uk
## chmod +x bootstrap
## export USEFUL_HOST=yourhostnamehere
## ./bootstrap

echo "=== useful arch bootstrapper @ {{REF}} ==="

log() {
	echo "[useful] $@" >/dev/stderr
}

log "pre-flight checks"
FAIL=0

if ! curl -fsS ping.archlinux.org >/dev/null; then
	log "no internet connectivity, aborting."
	log "(hint: ip link, iwctl)"
	FAIL=1
fi

if ! timedatectl | grep 'synchronized: yes'; then
	log "clock is out of sync, aborting."
	log "(hint: timedatectl)"
	FAIL=1
fi

if [ -z "${USEFUL_HOST:-}" ]; then
	log "please set USEFUL_HOST"
	FAIL=1
fi

if [ -z "${USEFUL_DISK:-}" ]; then
	USEFUL_DISK=/dev/nvme0n1
fi
if [ "$USEFUL_DISK" = /dev/nvme0n1 ]; then
	USEFUL_ESP=/dev/nvme0n1p1
	USEFUL_LUKS=/dev/nvme0n1p2
elif [ "$USEFUL_DISK" = /dev/vda ]; then
	USEFUL_ESP=/dev/vda1
	USEFUL_LUKS=/dev/vda2
elif [ -z "${USEFUL_ESP}:-}" ] || [ -z "${USEFUL_LUKS}" ]; then
	log "USEFUL_DISK is set, but not sure what to call partition devices."
	log "please additionally set USEFUL_ESP, USEFUL_LUKS."
	FAIL=1
fi

[ "$FAIL" = 1 ] && exit 1

log "=> OK"

# You should've already done this, but doing it again for good measure before password entry:
loadkeys uk

mkdir -p /tmp/useful

PASSWORD=''
if [ -f /tmp/useful/password ]; then
	log "using cached /tmp/useful/password"
	PASSWORD="$(cat /tmp/useful/password)"
else
	PASSWORD_OK=0
	while [ "$PASSWORD_OK" != 1 ]; do
		PASSWORD_CONFIRM=''
		read -p "Set system password: " -s PASSWORD
		echo
		read -p "   Confirm password: " -s PASSWORD_CONFIRM
		echo

		if [ "$PASSWORD" == "$PASSWORD_CONFIRM" ]; then
			PASSWORD_OK=1
		else
			echo "Passwords don't match!"
		fi
	done
	echo -n "$PASSWORD" >/tmp/useful/password
fi

log "installing on $USEFUL_DISK"

echo "=== THIS COMPUTER IS ABOUT TO BE WIPED ==="
echo "The partition table (if any) on $USEFUL_DISK is about to be DESTROYED."
while true; do
	read -p "Are you completely sure? [y/n]: " yn
	case $yn in
	[Yy]*)
		break
		;;
	*)
		log "aborted."
		exit 1
		;;
	esac
done

log "cleaning up any previous install attempt"
umount -R /mnt >/dev/null 2>&1 || true
lvremove arch -y >/dev/null 2>&1 || true
vgremove arch -y >/dev/null 2>&1 || true
cryptsetup luksClose crypt >/dev/null 2>&1 || true

log "creating partition table"
echo -n "label: gpt
start=, size=1G, type=uefi, name=arch, bootable
start=, size=+, type=empty, name=luks
" | sfdisk "$USEFUL_DISK" --wipe always --wipe-partitions always

log "creating luks partition"
echo -n "$PASSWORD" | cryptsetup -q luksFormat --type luks2 --key-file - "$USEFUL_LUKS"
echo -n "$PASSWORD" | cryptsetup -q luksOpen --allow-discards --persistent --key-file - "$USEFUL_LUKS" crypt

log "creating lvm on luks"
pvcreate /dev/mapper/crypt
vgcreate arch /dev/mapper/crypt
lvcreate --name swap -L 8G arch
lvcreate --name root -l 100%FREE arch

log "formatting lvm partitions"
mkfs.vfat "$USEFUL_ESP"
mkswap /dev/arch/swap
mkfs.ext4 -L root /dev/arch/root

log "mounting partitions"
mount /dev/arch/root /mnt
mount --mkdir "$USEFUL_ESP" /mnt/boot

log "running pacstrap"
# Note some of these will be removed in later bootstrapping.
PACKAGES='
	base
	amd-ucode
	intel-ucode
	linux
	linux-firmware
	linux-headers
	exfatprogs
	e2fsprogs
	dosfstools
	lvm2
	cryptsetup
	dracut
	networkmanager
	neovim
	plasma-meta
	fish
	git
	mesa
	epiphany
'

pacstrap -K /mnt $PACKAGES

log "configuring system"

echo "$USEFUL_HOST" > /etc/hostname

# Technically not the same file at this point, but doesn't matter.
ln -s /usr/share/zoneinfo/Europe/London /mnt/etc/localtime

echo 'en_GB.UTF-8 UTF-8' > /mnt/etc/locale.gen
echo 'LANG=en_GB.UTF-8' > /mnt/etc/locale.conf
echo 'KEYMAP=uk' > /mnt/etc/vconsole.conf

UUID_ESP="$(blkid -o value -s UUID $USEFUL_ESP)"
UUID_LUKS="$(blkid -o value -s UUID $USEFUL_LUKS)"
UUID_LVM_ROOT="$(blkid -o value -s UUID /dev/arch/root)"
UUID_LVM_SWAP="$(blkid -o value -s UUID /dev/arch/swap)"

# NOTE: continuous TRIM is purposefully enabled for swap only.
echo -n "
UUID=$UUID_LVM_ROOT / ext4 rw,noatime 0 1
UUID=$UUID_ESP /boot vfat rw,noatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,utf8,errors=remount-ro 0 2
UUID=$UUID_LVM_SWAP none swap defaults,discard 0 0
" >> /mnt/etc/fstab

echo "crypt UUID=$UUID_LUKS none luks,initramfs" >> /mnt/etc/crypttab
echo 'install_items+=" /etc/crypttab "' > /mnt/etc/dracut.conf.d/10-useful.conf

# Most of the below config will be overwritten later - it's just "good enough"
# to get us booting to a desktop.

mkdir -p /mnt/boot/loader/entries
echo -n '
timeout 5
default arch.conf
' > /mnt/boot/loader/loader.conf

# Taking the firehose approach to the kernel cmdline here.
# Note 'quiet splash' is absent for now, would prefer to know if there are issues on first boot.
echo -n "
title Arch Linux (bootstrapping)
linux /vmlinuz-linux
initrd /initramfs-linux.img
options root=UUID=$UUID_LVM_ROOT rd.auto rd.retry=10 rd.luks.allow-discards rd.dm=0 rd.md=0 ro amdgpu.dcdebugmask=0x10 amdgpu.runpm=0
" > /mnt/boot/loader/entries/arch.conf

log "finalising config in chroot"
arch-chroot /mnt bash -c "
	set -euo pipefail

	log() {
		echo \"[useful][chroot] \$@\"
	}

	log 'adding user'
	useradd -m -G users,wheel,video,storage doug
	log 'setting user passwords'
	printf '%s\n' \"$PASSWORD\" \"$PASSWORD\" | passwd
	printf '%s\n' \"$PASSWORD\" \"$PASSWORD\" | passwd doug

	log 'setting hardware clock'
	hwclock --systohc
	log 'activating ntp'
	timedatectl set-ntp true
	log 'generating locales'
	locale-gen

	log 'running dracut'
	dracut -v -f /boot/initramfs-linux.img
	log 'installing bootloader'
	bootctl install
"

log "done - ready to reboot."