#!/usr/env/bin bash

set -euox pipefail

export DISK="/dev/vda"
export DISK_EXT="${DISK}"
 # The size is large because I'd like to be able to hibernate my laptop in its entirety. I have 64 GB of ram.
export SWAP_SIZE="32"
export SWAP_OFFSET="$(( SWAP_SIZE + 1 ))"

export LABEL_CRYPT_LUKS="NixOS-Crypt"
export LABEL_SWAP="NixOS-Swap"
export LABEL_BTRFS="NixOS-Primary"
export LABEL_BOOT="NixOS-Boot"

swapoff -a || true
umount /mnt/**/* || true
umount /mnt/* || true
umount /mnt || true
cryptsetup close enc || true
dd if=/dev/zero of="${DISK}" bs=512 count=1024 || true

### Partition The Disk
parted "${DISK}" -- mklabel gpt
# Boot partition
parted -a optimal "${DISK}" -- mkpart ESP fat32 1MiB 1GiB
parted "${DISK}" -- set 1 boot on
mkfs.vfat "${DISK_EXT}1"
fatlabel "${DISK_EXT}1" "${LABEL_BOOT}"
# Swap Partition
parted -a optimal "${DISK}" -- mkpart "${LABEL_SWAP}" linux-swap 1Gib "${SWAP_OFFSET}GB"
mkswap -L "${LABEL_SWAP}" "${DISK_EXT}2"
swapon "${DISK_EXT}2"
# Nix Partition, where the OS will reside with our data
parted -a optimal "${DISK}" -- mkpart "${LABEL_BTRFS}" "${SWAP_OFFSET}GiB" 100%

### Encrypt
cryptsetup --verify-passphrase -v luksFormat "${DISK_EXT}3"
cryptsetup config "${DISK_EXT}3" --label "${LABEL_CRYPT_LUKS}"
# Have to decrypt it so we can actually get other things setup
export CRYPT_OPEN_NAME="enc"
export CRYPT_PATH="/dev/mapper/${CRYPT_OPEN_NAME}"
cryptsetup open "${DISK_EXT}3" "${CRYPT_OPEN_NAME}"

### BTRFS Setup
# Go ahead and make the unerypted BTRFS
mkfs.btrfs -L "${LABEL_BTRFS}"  "${CRYPT_PATH}"

# Mount it
mount -t btrfs "${CRYPT_PATH}" /mnt

# Create our subvolumes
btrfs subvolume create "/mnt/@nix"
umount /mnt

### Final Mountings
# Mount tmpfs to mnt
mount -t tmpfs -o mode=755 none /mnt

# Create our directories
mkdir /mnt/{"boot","nix"}
# Mount our boot partition
mount -t vfat -o defaults,noatime "${DISK_EXT}1" /mnt/boot

# Mount our btrfs subvolumes individually with some btrfs options
# NOTE: On high performance NVME SSDs with a beefy CPU it may be worth considering ZLO compression instead of ZSTD. In
# many cases ZLO is more performant, especially when writing, than ZSTD while having a somewhat worse comrpession ratio.
# WARN: ZLO *may* be a good solution, it can be VERY slow on incompressible data. Something to keep in mind.
mount -t btrfs -o noatime,compress=zstd,subvol=@nix "${CRYPT_PATH}" /mnt/nix

mkdir -p /mnt/nix/persist
### Install NixOS
# Gotta make sure current working tree isn't dirty for the flake
git config --global user.email "m@m.com"; git config --global user.name "name"; git add .; git commit -m "Shit" >/dev/null 2>&1; \
# Clone the flake into place
git clone . /mnt/nix/persist/etc/nixos && cd /mnt/nix/persist/etc/nixos
# Finally, actually install NixOS
nixos-install --flake "git+file:.#orion"