Script to activate or rollback Nix Home Manager profile on macOS 15

nix-manager-adm

#!/usr/bin/env bash

# SPDX-License-Identifier: MIT
# SPDX-FileCopyrightText: 2025 Sébastien L.
# Description: Script to activate or rollback Nix Home Manager profile on macOS.
#  Script d’administration pour activer ou restaurer un environnement Nix Home Manager sous macOS.
#  Il vérifie l’utilisateur, la présence du flake et sécurise les opérations avec gestion des sauvegardes.
# Version: 0.1 (2025-06-25)
# Author: Sebastien L.

set -euo pipefail

EXPECTED_USER="user.local"

FLAKE_DIR="$HOME/.config/home-manager"

if [ "$(whoami)" != "$EXPECTED_USER" ]; then
  echo "❌ Error: This script must be run as user '$EXPECTED_USER'."
  exit 1
fi

if [ ! -f "$FLAKE_DIR/flake.nix" ]; then
  echo "❌ Error: No flake.nix found in $FLAKE_DIR."
  exit 1
fi

ACTION="${1:-}"

confirm() {
  echo -n "Are you sure you want to proceed? (yes/no): "
  read -r response
  if [[ "$response" != "yes" ]]; then
    echo "❌ Operation cancelled by user."
    exit 0
  fi
}

activate() {
  confirm
  echo "==> Activating Nix Home Manager profile..."
  cd "$FLAKE_DIR"
  nix run github:nix-community/home-manager -- switch -b backup --flake .#$EXPECTED_USER
  echo -e "\n✅ Nix environment activated."
  echo "💡 Please open a new terminal session to apply the changes."
}

rollback() {
  if [ ! -f ~/.bashrc.backup ] || [ ! -f ~/.profile.backup ]; then
    echo "❌ No backup files found. Rollback is not possible."
    exit 1
  fi

  confirm
  echo "==> Rolling back to pre-Nix state..."
  mv -v ~/.bashrc.backup ~/.bashrc
  mv -v ~/.profile.backup ~/.profile
  rm -v ~/.bash_profile || true
  rm -v ~/.bashrc.d/custom.bash || true
  echo -e "\n✅ Rollback complete. You can restart your terminal."
}

case "$ACTION" in
  activate)
    activate
    ;;
  rollback)
    rollback
    ;;
  *)
    echo "Usage: $0 {activate|rollback}"
    exit 1
    ;;
esac