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

export NIX_CONFIG="${NIX_CONFIG:-}
experimental-features = nix-command flakes
accept-flake-config = false
warn-dirty = false
"

ensure_nix_profile() {
  if [ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]; then
    . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
  elif [ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]; then
    . "$HOME/.nix-profile/etc/profile.d/nix.sh"
  fi
}

install_nix_if_missing() {
  if command -v nix >/dev/null 2>&1; then
    return
  fi

  echo "Nix not found. Installing Nix..."

  if [ "$(id -u)" -eq 0 ]; then
    echo "Running as root; preparing nixbld users for container/Codex environment..."

    if ! getent group nixbld >/dev/null; then
      groupadd -r nixbld
    fi

    for i in $(seq 1 10); do
      if ! id "nixbld$i" >/dev/null 2>&1; then
        useradd \
          -r \
          -g nixbld \
          -G nixbld \
          -d /var/empty \
          -s /usr/sbin/nologin \
          "nixbld$i" || true
      fi
    done

    mkdir -p /etc/nix
    cat > /etc/nix/nix.conf <<'EOF'
experimental-features = nix-command flakes
accept-flake-config = false
warn-dirty = false
build-users-group = nixbld
EOF

    sh <(curl -L https://nixos.org/nix/install) --no-daemon
  else
    sh <(curl -L https://nixos.org/nix/install) --no-daemon
  fi

  ensure_nix_profile
}

install_nix_if_missing
ensure_nix_profile

mkdir -p "$HOME/.config/nix"
cat > "$HOME/.config/nix/nix.conf" <<'EOF'
experimental-features = nix-command flakes
accept-flake-config = false
warn-dirty = false
EOF

echo "Nix version:"
nix --version

echo "Installing jq if unavailable..."
if ! command -v jq >/dev/null 2>&1; then
  nix profile install nixpkgs#jq
fi

echo "Available NixOS hosts:"
hosts="$(nix eval --json --no-use-registries --no-accept-flake-config .#nixosConfigurations --apply builtins.attrNames | jq -r '.[]')"
echo "$hosts"

echo "Evaluating all host toplevel derivations..."
for host in $hosts; do
  echo "==> Evaluating $host"
  nix eval --raw --no-use-registries --no-accept-flake-config ".#nixosConfigurations.${host}.config.system.build.toplevel.drvPath"
done

echo "Codex setup complete."