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

# Non-interactive Btrfs installer using the flake in this repo.
# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus

DISK="${DISK:-/dev/vda}"
TARGET_HOST="${TARGET_HOST:-nanuqsaurus}"

SCRIPT_DIR="$(cd -- "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd -- "$SCRIPT_DIR/.." && pwd)"

MNT=/mnt
EFI_SIZE=550M

have() { command -v "$1" >/dev/null 2>&1; }

die() {
  echo "ERROR: $*" >&2
  exit 1
}

confirm_disk() {
  echo "About to DESTROY ALL DATA on ${DISK}"
  lsblk "$DISK" || die "Disk not found: $DISK"
  echo "Continuing in 5 seconds… (Ctrl+C to abort)"
  sleep 5
}

clear
confirm_disk

echo "[1/7] Partitioning ${DISK}"
sfdisk "$DISK" <<EOF
label: gpt
,${EFI_SIZE},U
,,L
EOF

echo "[2/7] Formatting filesystems"
mkfs.fat -F32 "${DISK}1"
mkfs.btrfs -f "${DISK}2"

echo "[3/7] Creating Btrfs subvolumes"
mkdir -p "$MNT"
mount "${DISK}2" "$MNT"

for subvol in root home nix; do
  btrfs subvolume create "$MNT/$subvol"
done

umount "$MNT"

echo "[4/7] Mounting subvolumes"
mount -o compress=zstd,subvol=root "${DISK}2" "$MNT"
mkdir -p "$MNT"/{home,nix,boot}

mount -o compress=zstd,subvol=home "${DISK}2" "$MNT/home"
mount -o compress=zstd,subvol=nix  "${DISK}2" "$MNT/nix"
mount "${DISK}1" "$MNT/boot"

echo "[5/7] Copying flake to /etc/nixos"
mkdir -p "$MNT/etc/nixos"

EXCLUDES=(--exclude=.git --exclude=result --exclude=node_modules)

if have rsync; then
  rsync -a "${EXCLUDES[@]}" "$REPO_ROOT/" "$MNT/etc/nixos/"
else
  (cd "$REPO_ROOT" && tar -cf - "${EXCLUDES[@]/#/--exclude=}" .) \
    | (cd "$MNT/etc/nixos" && tar -xf -)
fi

echo "[6/7] Generating hardware config"
HOSTS_DIR="$MNT/etc/nixos/hosts"
mkdir -p "$HOSTS_DIR"

HW_FILE="$HOSTS_DIR/local-${TARGET_HOST}-hardware.nix"
HOST_FILE="$HOSTS_DIR/local-${TARGET_HOST}.nix"

nixos-generate-config --root "$MNT" --show-hardware-config > "$HW_FILE"

if [[ ! -e "$HOST_FILE" ]]; then
  cat > "$HOST_FILE" <<EOF
{ inputs, ... }:

{
  imports = [
    inputs.lix-module.nixosModules.lixFromNixpkgs
    ../modules/system/base.nix
    ../modules/system/packages.nix
    ../modules/system/home-manager-skel.nix
    ../modules/desktop/gnome-minimal.nix
    ../modules/users/admin.nix
    ./local-${TARGET_HOST}-hardware.nix
  ];

  networking.hostName = "${TARGET_HOST}";
}
EOF
fi

echo "[7/7] Installing ${TARGET_HOST} via flake"
LOG=/tmp/nixos-install.log
nixos-install \
  --root "$MNT" \
  --flake "$MNT/etc/nixos#local-${TARGET_HOST}" \
  --no-root-passwd |& tee "$LOG"

echo "Install log saved to $LOG"
echo "Install complete. You can reboot now."