{
  pkgs,
  username,
  ...
}:
let
  config.boot.kernelPackages = pkgs.linuxPackages_latest;
in
{
  system.stateVersion = "25.11";

  imports = [
    ./hardware-configuration.nix

    ../../system/core
    ../../programs/ssh.nix
    ../../programs/utility.nix
    ../../programs/shell.nix
    ../../programs/docker.nix
    ../../programs/v4l2.nix
    ../../programs/desktop/hyprland.nix
    ../../programs/fcitx.nix
    ../../programs/steam.nix
  ];
  environment.systemPackages = with pkgs; [
    cargo
    rustc
    rustfmt
    openssl
    vulkan-tools
    android-tools
    android-file-transfer

    bluez
    bluez-tools
    bluetuith
    obexftp
    fzf
    ghq
  ];
  environment.sessionVariables.NIXOS_OZONE_WL = "1";

  programs.nix-ld.enable = true;

  services.openssh.enable = true;

  services.udisks2.enable = true;

  services.keyd.enable = true;

  services.keyd.keyboards.default = {
    ids = [ "*" ];
    settings = {
      main = {
        capslock = "C-space";
      };
    };
  };

  networking.firewall.allowedTCPPorts = [
    22
    19132
    25565
  ];
  networking.firewall.allowedUDPPorts = [ ];

  services.udev.extraRules = "";

  hardware.bluetooth = {
    enable = true;
    package = pkgs.bluez;
    powerOnBoot = true;
    settings = {
      General = {
        ControllerMode = "dual";
        Experimental = true;
        KernelExperimental = true;
        FastConnectable = true;
        # セキュリティレベルを調整
        Class = "0x000100";
        # ペアリングタイムアウトを延長
        PairableTimeout = 0;
      };
      Policy = {
        AutoEnable = true;
      };
    };
  };

  boot.kernelPackages = config.boot.kernelPackages;
  boot.extraModulePackages = [ config.boot.kernelPackages.v4l2loopback ];
  boot.kernelModules = [
    "v4l2loopback"
  ];

  # Bootloader.
  boot.loader.systemd-boot.enable = false;
  boot.loader.efi.canTouchEfiVariables = true;
  boot.loader.efi.efiSysMountPoint = "/boot";

  boot.loader.grub = {
    enable = true;
    efiSupport = true;
    devices = [ "nodev" ];
    useOSProber = true;

    copyKernels = true;
    configurationLimit = 10;
  };

  cornflake.greeter.monitors = [
    "DP-1, disable"
    "DP-2, disable"
    "DP-3, 1920x1080@240, 0x0"
  ];
}