{ config, lib, ... }:

{
  options.modules.nvidia = {
    enable = lib.mkEnableOption "NVIDIA proprietary drivers";

    open = lib.mkOption {
      type = lib.types.bool;
      default = true;
      description = ''
        Use the open-source NVIDIA kernel module.
        Set to true for Turing (RTX 20-series) and newer.
        Set to false for older architectures.
      '';
    };

    package = lib.mkOption {
      type = lib.types.package;
      default = config.boot.kernelPackages.nvidiaPackages.stable;
      defaultText = lib.literalExpression
        "config.boot.kernelPackages.nvidiaPackages.stable";
      description = "The NVIDIA driver package to use.";
    };

    prime = {
      enable = lib.mkEnableOption "NVIDIA Optimus PRIME (hybrid graphics)";

      mode = lib.mkOption {
        type = lib.types.enum [ "offload" "sync" "reverse-sync" ];
        default = "offload";
        description = ''
          Which PRIME mode to use.
            offload      — iGPU handles everything; dGPU used on demand (best battery)
            sync         — dGPU always active; best performance, less tearing
            reverse-sync — experimental; dGPU primary, iGPU for outputs
        '';
      };

      intelBusId = lib.mkOption {
        type = lib.types.str;
        default = "";
        example = "PCI:0:2:0";
        description = "PCI bus ID of the Intel iGPU (from lshw -c display).";
      };

      amdBusId = lib.mkOption {
        type = lib.types.str;
        default = "";
        example = "PCI:54:0:0";
        description = "PCI bus ID of the AMD iGPU (from lshw -c display). Leave empty if Intel.";
      };

      nvidiaBusId = lib.mkOption {
        type = lib.types.str;
        default = "";
        example = "PCI:14:0:0";
        description = "PCI bus ID of the NVIDIA dGPU (from lshw -c display).";
      };
    };
  };

  config = lib.mkIf config.modules.nvidia.enable {
    hardware.graphics.enable = true;

    services.xserver.videoDrivers =
      if config.modules.nvidia.prime.enable
        && config.modules.nvidia.prime.mode == "offload"
      then [
        (if config.modules.nvidia.prime.amdBusId != "" then "amdgpu" else "modesetting")
        "nvidia"
      ]
      else [ "nvidia" ];

    hardware.nvidia = {
      modesetting.enable = true;
      open = config.modules.nvidia.open;
      nvidiaSettings = true;
      package = config.modules.nvidia.package;

      powerManagement.enable = false;
      powerManagement.finegrained = false;

      prime = lib.mkIf config.modules.nvidia.prime.enable (
        let
          busIds = lib.filterAttrs (_: v: v != "") {
            intelBusId  = config.modules.nvidia.prime.intelBusId;
            amdgpuBusId = config.modules.nvidia.prime.amdBusId;
            nvidiaBusId = config.modules.nvidia.prime.nvidiaBusId;
          };
          modeConfig =
            if config.modules.nvidia.prime.mode == "offload" then {
              offload.enable = true;
              offload.enableOffloadCmd = true;
            } else if config.modules.nvidia.prime.mode == "sync" then {
              sync.enable = true;
            } else {
              reverseSync.enable = true;
              allowExternalGpu = false;
            };
        in busIds // modeConfig
      );
    };
  };
}