nixos/hosts/yarn/default.nix

{
  config,
  pkgs,
  lib,
  username,
  inputs,
  site_config,
  ...
}:
{
  imports = [
    ../../modules/desktop-common.nix
    ../../modules/no-rgb.nix
    ./disk.nix
    ./impermanence.nix
    ./vr.nix

    inputs.impermanence.nixosModules.impermanence
    inputs.jovian-nixos.nixosModules.default
  ];

  fileSystems."/media/games" = {
    device = "/dev/disk/by-uuid/1878136e-765d-4784-b204-3536ab4fdac8";
    fsType = "f2fs";
    options = [ "nofail" ];
  };

  systemd.targets = {
    sleep.enable = false;
    suspend.enable = false;
    hibernate.enable = false;
    hybrid-sleep.enable = false;
  };

  networking.hostId = "abf570f9";

  # Static IP for consistent SSH access
  networking.networkmanager.ensureProfiles.profiles.enp7s0-static = {
    connection = {
      id = "enp7s0-static";
      type = "ethernet";
      interface-name = "enp7s0";
      autoconnect = true;
    };
    ipv4 = {
      method = "manual";
      address1 = "${site_config.hosts.yarn.ip}/24,${site_config.lan.gateway}";
      dns = lib.concatMapStrings (n: "${n};") site_config.dns_servers;
    };
    ipv6.method = "disabled";
  };

  services.openssh = {
    enable = true;
    ports = [ 22 ];
    settings = {
      PasswordAuthentication = false;
      PermitRootLogin = "yes";
    };
  };

  users.users.${username}.openssh.authorizedKeys.keys = [
    site_config.ssh_keys.laptop
  ];

  users.users.root.openssh.authorizedKeys.keys = [
    site_config.ssh_keys.laptop
    site_config.ssh_keys.ci_deploy
  ];

  programs.steam = {
    remotePlay.openFirewall = true;
    localNetworkGameTransfers.openFirewall = true;
  };

  # LACT (Linux AMDGPU Configuration Tool): https://github.com/ilya-zlobintsev/LACT
  environment.systemPackages = with pkgs; [
    lact
    jovian-stubs
  ];
  systemd.packages = with pkgs; [ lact ];
  systemd.services.lactd.wantedBy = [ "multi-user.target" ];

  systemd.services.lactd.serviceConfig.ExecStartPre = "${lib.getExe pkgs.bash} -c \"sleep 3s\"";

  # root-level service that applies a pending update. Triggered by
  # steamos-update (via systemctl start) when the user accepts an update.
  # Runs as root so it can write the system profile and boot entry.
  systemd.services.pull-update-apply = {
    description = "Apply pending NixOS update pulled from binary cache";
    serviceConfig = {
      Type = "oneshot";
      ExecStart = pkgs.writeShellScript "pull-update-apply" ''
        set -uo pipefail
        export PATH=${
          pkgs.lib.makeBinPath [
            pkgs.curl
            pkgs.coreutils
            pkgs.nix
          ]
        }

        STORE_PATH=$(curl -sf --max-time 30 "${site_config.binary_cache.url}/deploy/yarn" || true)
        if [ -z "$STORE_PATH" ]; then
          echo "server unreachable"
          exit 1
        fi

        CURRENT=$(readlink -f /nix/var/nix/profiles/system)
        if [ "$CURRENT" = "$STORE_PATH" ]; then
          echo "already up to date: $STORE_PATH"
          exit 0
        fi

        echo "applying $STORE_PATH (was $CURRENT)"
        nix-store -r --add-root /nix/var/nix/gcroots/pull-update-apply-latest --indirect "$STORE_PATH" \
          || { echo "fetch failed"; exit 1; }
        nix-env -p /nix/var/nix/profiles/system --set "$STORE_PATH" \
          || { echo "profile set failed"; exit 1; }
        "$STORE_PATH/bin/switch-to-configuration" boot \
          || { echo "boot entry failed"; exit 1; }
        echo "update applied; reboot required"
      '';
    };
  };

  # Allow primary user to start pull-update-apply.service without a password
  security.polkit.extraConfig = ''
    polkit.addRule(function(action, subject) {
      if (action.id == "org.freedesktop.systemd1.manage-units" &&
          action.lookup("unit") == "pull-update-apply.service" &&
          subject.user == "${username}") {
        return polkit.Result.YES;
      }
    });
  '';

  nixpkgs.config.allowUnfreePredicate =
    pkg:
    builtins.elem (lib.getName pkg) [
      "steamdeck-hw-theme"
      "steam-jupiter-unwrapped"
      "steam"
      "steam-original"
      "steam-unwrapped"
      "steam-run"
    ];

  # Override jovian-stubs to disable steamos-update kernel check
  # This prevents Steam from requesting reboots for "system updates"
  # Steam client updates will still work normally
  nixpkgs.overlays = [
    (
      final: prev:
      let
        deploy-url = "${site_config.binary_cache.url}/deploy/yarn";

        steamos-update-script = final.writeShellScript "steamos-update" ''
          export PATH=${
            final.lib.makeBinPath [
              final.curl
              final.coreutils
              final.systemd
            ]
          }

          STORE_PATH=$(curl -sf --max-time 30 "${deploy-url}" || true)

          if [ -z "$STORE_PATH" ]; then
            >&2 echo "[steamos-update] server unreachable"
            exit 7
          fi

          CURRENT=$(readlink -f /nix/var/nix/profiles/system)
          if [ "$CURRENT" = "$STORE_PATH" ]; then
            >&2 echo "[steamos-update] no update available"
            exit 0
          fi

          # check-only mode: just report that an update exists
          if [ "''${1:-}" = "check" ] || [ "''${1:-}" = "--check-only" ]; then
            >&2 echo "[steamos-update] update available"
            exit 0
          fi

          # apply: trigger the root-running systemd service to install the update
          >&2 echo "[steamos-update] applying update..."
          if systemctl start --wait pull-update-apply.service; then
            >&2 echo "[steamos-update] update installed, reboot to apply"
            exit 0
          else
            >&2 echo "[steamos-update] apply failed; see 'journalctl -u pull-update-apply'"
            exit 1
          fi
        '';
      in
      {
        # Only replace holo-update (and its steamos-update alias) with our
        # binary-cache pull script. All other stubs (pkexec, sudo,
        # holo-reboot, holo-select-branch, …) come from upstream unchanged.
        jovian-stubs = prev.jovian-stubs.overrideAttrs (old: {
          buildCommand = (old.buildCommand or "") + ''
            install -D -m 755 ${steamos-update-script} $out/bin/holo-update
            install -D -m 755 ${steamos-update-script} $out/bin/steamos-update
          '';
        });
      }
    )
  ];

  jovian = {
    devices.steamdeck.enable = false;
    steam = {
      enable = true;
      autoStart = true;
      desktopSession = "niri";
      user = username;
    };
  };

  # Jovian-NixOS requires sddm
  # https://github.com/Jovian-Experiments/Jovian-NixOS/commit/52f140c07493f8bb6cd0773c7e1afe3e1fd1d1fa
  services.displayManager.sddm.wayland.enable = true;

  # Disable gamescope from common.nix to avoid conflict with jovian-nixos
  programs.gamescope.enable = lib.mkForce false;
}