modules/nvidia.nix

{ pkgs, lib, username, ... }:
let
  prime-run = pkgs.writeScriptBin "prime-run" ''
    export __NV_PRIME_RENDER_OFFLOAD=1
    export __NV_PRIME_RENDER_OFFLOAD_PROVIDER=NVIDIA-G0
    export __GLX_VENDOR_LIBRARY_NAME=nvidia
    export __VK_LAYER_NV_optimus=NVIDIA_only
    exec "$@"
  '';
in
{
  config = {
    services.xserver.videoDrivers = [ "nvidia" ];
    hardware = {
      opengl.enable = true;
      nvidia = {
        modesetting.enable = true;
        powerManagement.enable = true;
        prime = {
          offload.enable = true;
          intelBusId = "PCI:0:2:0";
          nvidiaBusId = "PCI:1:0:0";
        };
      };
    };

    specialisation.nvidia-sync.configuration = {
      system.nixos.tags = [ "nvidia-sync" ];
      hardware.nvidia.powerManagement.enable = lib.mkForce false;
      hardware.nvidia.prime.offload.enable = lib.mkForce false;
      hardware.nvidia.prime.sync.enable = lib.mkForce true;
      services.xserver.dpi = 96;

      home-manager.users.${username}.home.file.".xinitrc".text = lib.mkBefore ''
        ${pkgs.xorg.xrandr}/bin/xrandr --setprovideroutputsource modesetting NVIDIA-0
        ${pkgs.xorg.xrandr}/bin/xrandr --output HDMI-0 --primary --mode 3840x2160 --pos 0x0 --rotate normal --output eDP-1-1 --mode 1920x1080 --pos 960x2160 --rotate normal
      '';
    };

    internal.allowUnfree = [ "nvidia-x11" "nvidia-settings" "cudatoolkit" ];
  };
  home.home.packages = [ pkgs.nvtop prime-run ];
}