{pkgs, config, ...}:

with pkgs.lib;

let
  efiBootStubBuilder = pkgs.substituteAll {
    src = ./efi-boot-stub-builder.sh;
    isExecutable = true;
    inherit (pkgs) bash;
    path = [pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.glibc] ++ (pkgs.stdenv.lib.optionals config.boot.loader.efiBootStub.runEfibootmgr [pkgs.efibootmgr pkgs.module_init_tools]);
    inherit (config.boot.loader.efiBootStub) installStartupNsh;

    inherit (config.boot.loader.efi) efiSysMountPoint;

    inherit (config.boot.loader.efi.efibootmgr) efiDisk efiPartition postEfiBootMgrCommands;

    runEfibootmgr = config.boot.loader.efi.efibootmgr.enable;

    efiShell = if config.boot.loader.efiBootStub.installShell then
      if pkgs.stdenv.isi686 then
        pkgs.fetchurl {
          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/Ia32/Shell_Full.efi";
          sha256 = "1gv6kyaspczdp7x8qnx5x76ilriaygkfs99ay7ihhdi6riclkhfl";
        }
      else
        pkgs.fetchurl {
          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/X64/Shell_Full.efi";
          sha256 = "1g18z84rlavxr5gsrh2g942rfr6znv9fs3fqww5m7dhmnysgyv8p";
        }
    else
      null;

    kernelFile = platform.kernelTarget;
    targetArch = if pkgs.stdenv.isi686 then
      "IA32"
    else if pkgs.stdenv.isx86_64 then
      "X64"
    else
      throw "Unsupported architecture";
  };

  # Temporary check, for nixos to cope both with nixpkgs stdenv-updates and trunk
  platform = pkgs.stdenv.platform;
in
{
  options = {
    boot = {
      loader = {
        efiBootStub = {

          enable = mkOption {
            default = false;
            description = ''
              Whether to use the linux kernel as an EFI bootloader.
              When enabled, the kernel, initrd, and an EFI shell script
              to boot the system are copied to the EFI system partition.
            '';
          };

          installStartupNsh = mkOption {
            default = false;
            description = ''
              Whether to install a startup.nsh in the root of the EFI system partition.
              For now, it will just boot the latest version when run, the eventual goal
              is to have a basic menu-type interface.
            '';
          };

          installShell = mkOption {
            default = false;
            description = ''
              Whether to install an EFI shell in \EFI\BOOT.
              This _should_ only be needed for removable devices
              (CDs, usb sticks, etc.), but it may be an option for broken
              systems where efibootmgr doesn't work. Particularly useful in
              conjunction with installStartupNsh
            '';
          };

        };
      };
    };
  };

  config = mkIf config.boot.loader.efiBootStub.enable {
    assertions = [ { assertion = ! config.boot.kernelPackages.kernel ? features || config.boot.kernelPackages.kernel.features ? efiBootStub; message = "This kernel does not support the EFI boot stub"; } ];
  
    system = {
      build.installBootLoader = efiBootStubBuilder;
      boot.loader.id = "efiBootStub";
      boot.loader.kernelFile = platform.kernelTarget;
      requiredKernelConfig = with config.lib.kernelConfig; [
        (isYes "EFI_STUB")
      ];
    };
  };

}