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

# Non-interactive Btrfs installer using disko-install.
# Defaults: DISK=/dev/vda TARGET_HOST=nanuqsaurus
# If FLAKE is unset and /etc/nixos/flake.nix exists, it uses /etc/nixos.
# Otherwise, set FLAKE to a flake URI like:
#   - git+https://codeberg.org/<owner>/<repo>.git
#   - github:<owner>/<repo>

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

MNT=/mnt

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
}

resolve_flake() {
  if [[ -n "$FLAKE" ]]; then
    return 0
  fi

  if [[ -e /etc/nixos/flake.nix ]]; then
    FLAKE=/etc/nixos
    return 0
  fi

  die "FLAKE is unset. Set FLAKE to a flake URI (or run from an ISO that provides /etc/nixos)."
}

clear
confirm_disk
resolve_flake

echo "[1/1] Installing ${TARGET_HOST} via disko-install"
LOG=/tmp/nixos-install.log

nix \
  --experimental-features "nix-command flakes" \
  run "github:nix-community/disko/latest#disko-install" -- \
  --mode format \
  --flake "${FLAKE}#${TARGET_HOST}" \
  --disk main "${DISK}" \
  --mount-point "$MNT" \
  --system-config '{"users":{"users":{"root":{"hashedPassword":"!"}}}}' |& tee "$LOG"

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