# nix build .#nixosConfigurations.rpi3.config.system.build.sdImage
{
  description = "Minimal NixOS Raspberry Pi 3B Flake";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };

  outputs =
    { self, nixpkgs, ... }@inputs:
    {
      nixosConfigurations.rpi3 = nixpkgs.lib.nixosSystem {
        system = "aarch64-linux";
        modules = [
          # Include the official SD card image builder module
          "${nixpkgs}/nixos/modules/installer/sd-card/sd-image-aarch64.nix"

          ({ lib, pkgs, ... }: {
            # System basic configuration
            system.stateVersion = "24.11";
            networking.hostName = "nixos-pi3";

            # Enable necessary hardware firmware
            hardware.enableRedistributableFirmware = true;

            # Create a default user so you can log in
            users.users.root.initialHashedPassword = ""; # Or set a password/SSH key
            users.users.nixos = {
              isNormalUser = true;
              extraGroups = [ "wheel" ]; # Enable ‘sudo’
              initialPassword = "changeme";
            };

            # Enable SSH for remote access on first boot
            services.openssh = {
              enable = true;
              settings.PermitRootLogin = "yes"; # Change or use keys for security
            };

            # Expand root partition automatically on first boot
            # services.growpart.enable = true;
          })
        ];
      };
    };
}