# NixOS integration for punktfunk — the declarative equivalent of everything the RPM/deb do in
# their %install + %post (packaging/rpm/punktfunk.spec, packaging/debian/build-deb.sh):
# the systemd *user* service, the uinput/uhid/vhci udev rules, the vhci-hcd autoload, the 32 MB
# UDP socket-buffer sysctls, the firewall openers, the `input`-group membership for virtual
# gamepads, the management web console (`services.punktfunk.web`, on by default with the host — the
# RPM/deb Recommends), and the opt-in plugin/script runner (`services.punktfunk.scripting`).
#
# Usage (flake):
#   { inputs.punktfunk.url = "git+https://git.unom.io/unom/punktfunk";
#     outputs = { punktfunk, nixpkgs, ... }: {
#       nixosConfigurations.myhost = nixpkgs.lib.nixosSystem {
#         modules = [ punktfunk.nixosModules.default
#                     { services.punktfunk.host.enable = true;
#                       services.punktfunk.host.users = [ "alice" ]; } ];
#       };
#     };
#   }
#
# The host is fundamentally a per-user, in-graphical-session service (it drives the live
# compositor, PipeWire and the desktop portals), so it ships as a `systemd.user` unit. Enable it
# for a session with `systemctl --user enable --now punktfunk-host` (or set `autoStart = true` for a
# headless appliance with `users.users.<u>.linger = true`).
self:
{ config, lib, pkgs, ... }:
let
  inherit (lib)
    mkEnableOption mkOption mkIf mkMerge mkDefault types
    optional optionals optionalString literalExpression
    concatStringsSep mapAttrsToList genAttrs;

  cfg = config.services.punktfunk;
  system = pkgs.stdenv.hostPlatform.system;

  # host.env rendering: booleans → 1/0 (what PUNKTFUNK_* knobs expect), everything else verbatim.
  renderVal = v:
    if lib.isBool v then (if v then "1" else "0")
    else toString v;
  renderEnv = attrs:
    concatStringsSep "\n" (mapAttrsToList (k: v: "${k}=${renderVal v}") attrs) + "\n";

  hostSettingsFile = pkgs.writeText "punktfunk-host.env" (renderEnv cfg.host.settings);

  # Native punktfunk/1 ports (control plane + discovery + mgmt API). The media data plane is an
  # ephemeral per-session UDP port the host hole-punches, so nothing fixed to open (see
  # packaging/linux/punktfunk.ufw).
  nativeTCP = [ 47990 ]; # mgmt/library REST API (HTTPS + mTLS)
  nativeUDP = [ 9777 5353 ]; # QUIC control plane + mDNS
  # GameStream/Moonlight-compat fixed ports (opt-in with `host.gamestream`).
  gamestreamTCP = [ 47984 47989 48010 ];
  gamestreamUDP = [ 47998 47999 48000 ];
in
{
  options.services.punktfunk = {
    host = {
      enable = mkEnableOption "the punktfunk streaming host (systemd --user service + system wiring)";

      package = mkOption {
        type = types.package;
        default = self.packages.${system}.punktfunk-host;
        defaultText = literalExpression "punktfunk.packages.\${system}.punktfunk-host";
        description = "The punktfunk-host package (bundles punktfunk-host + punktfunk-tray).";
      };

      gamestream = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Advertise the GameStream/Moonlight-compatible planes (`serve --gamestream`) so a stock
          Moonlight client can pair. Set to `false` for a native-only, more secure host (no
          plain-HTTP pairing / legacy GCM path) and drop the GameStream firewall ports.
        '';
      };

      autoStart = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Start the host automatically in every user's graphical session (adds it to the user
          `default.target`). For a login-less appliance, also enable lingering for the host user
          (`users.users.<name>.linger = true`) so the user service comes up at boot.
        '';
      };

      users = mkOption {
        type = types.listOf types.str;
        default = [ ];
        example = [ "alice" ];
        description = ''
          Users to add to the `input` group — required for the virtual gamepads the host creates
          (`/dev/uinput`, `/dev/uhid`, and the usbip/vhci virtual Steam Deck). The host runs as
          these users' `systemd --user` service.
        '';
      };

      settings = mkOption {
        type = types.attrsOf (types.oneOf [ types.str types.int types.bool ]);
        default = { };
        example = literalExpression ''
          {
            PUNKTFUNK_VIDEO_SOURCE = "virtual";
            PUNKTFUNK_COMPOSITOR = "kwin";
            PUNKTFUNK_444 = true;
            RUST_LOG = "info";
          }
        '';
        description = ''
          `host.env` key/value pairs passed to the service via `EnvironmentFile`. See
          `''${package}/share/punktfunk-host/host.env.example` for the full surface. Booleans render
          as `1`/`0`. Leave empty to rely on the host's per-connect auto-detection of the
          compositor + input backend. Do NOT put secrets here (world-readable in the store) — use
          `environmentFile` instead.
        '';
      };

      environmentFile = mkOption {
        type = types.nullOr types.path;
        default = null;
        example = "/run/secrets/punktfunk-host.env";
        description = ''
          Extra `EnvironmentFile` layered AFTER `settings` (its values win). For secrets such as
          `PUNKTFUNK_MGMT_TOKEN`. Loaded optionally (a missing file does not fail the unit).
        '';
      };

      openFirewall = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Open the host's inbound ports. Native punktfunk/1 always: UDP 9777 (QUIC) + 5353 (mDNS),
          TCP 47990 (mgmt API). With `gamestream = true` also TCP 47984/47989/48010 and UDP
          47998/47999/48000. The ephemeral media UDP port is hole-punched, so a default-deny
          firewall still streams (it just adds ~2.5 s at session start).
        '';
      };
    };

    client = {
      enable = mkEnableOption "the native punktfunk Linux client";

      package = mkOption {
        type = types.package;
        default = self.packages.${system}.punktfunk-client;
        defaultText = literalExpression "punktfunk.packages.\${system}.punktfunk-client";
        description = "The punktfunk-client package (bundles punktfunk-client + punktfunk-session).";
      };

      openFirewall = mkOption {
        type = types.bool;
        default = false;
        description = "Open UDP 5353 (mDNS) so the client can auto-discover hosts on the LAN.";
      };
    };

    # The management web console (SPAKE2 PIN pairing + host status) — the browser UI every client
    # needs. Ships by DEFAULT alongside the host (mirrors the RPM's `Recommends: punktfunk-web` and
    # the .deb the host package pulls in), auto-wired to the host's mgmt token + identity cert.
    web = {
      enable = mkOption {
        type = types.bool;
        default = cfg.host.enable;
        defaultText = literalExpression "config.services.punktfunk.host.enable";
        description = ''
          Run the management web console as a `systemd --user` service on TCP 47992 (HTTPS). Enabled
          by default whenever the host is enabled — set to `false` for a console-less host. It
          auto-wires to `~/.config/punktfunk/{mgmt-token,cert.pem,key.pem}` (written by the host's
          `serve`) and generates a login password on first start.
        '';
      };

      package = mkOption {
        type = types.package;
        default = self.packages.${system}.punktfunk-web;
        defaultText = literalExpression "punktfunk.packages.\${system}.punktfunk-web";
        description = "The punktfunk-web package (the bun-built Nitro SSR console bundle).";
      };

      openFirewall = mkOption {
        type = types.bool;
        default = cfg.host.openFirewall;
        defaultText = literalExpression "config.services.punktfunk.host.openFirewall";
        description = "Open TCP 47992 so the console is reachable from other devices on the LAN.";
      };

      autoStart = mkOption {
        type = types.bool;
        default = cfg.host.autoStart;
        defaultText = literalExpression "config.services.punktfunk.host.autoStart";
        description = ''
          Start the console automatically in every user's graphical session (adds it to the user
          `default.target`). Follows the host's `autoStart` by default — for a login-less appliance,
          enable lingering for the user as well.
        '';
      };
    };

    # The plugin/script runner — host automation on bun. Ships with the host (the RPM/deb Recommends
    # it), but running it is OPT-IN: the `systemd --user` unit is defined yet NOT added to
    # `default.target`, because the runner is inert until you add scripts/plugins. Turn it on with
    # `systemctl --user enable --now punktfunk-scripting`.
    scripting = {
      enable = mkOption {
        type = types.bool;
        default = cfg.host.enable;
        defaultText = literalExpression "config.services.punktfunk.host.enable";
        description = ''
          Install the plugin/script runner and define its `systemd --user` unit
          (`punktfunk-scripting`). Enabled by default whenever the host is — but the unit is not
          auto-started (see `autoStart`), since the runner does nothing until you add scripts to
          `~/.config/punktfunk/scripts` or install `punktfunk-plugin-*` packages under
          `~/.config/punktfunk/plugins`. A plugin auto-wires to the host's mgmt token + identity cert.
        '';
      };

      package = mkOption {
        type = types.package;
        default = self.packages.${system}.punktfunk-scripting;
        defaultText = literalExpression "punktfunk.packages.\${system}.punktfunk-scripting";
        description = "The punktfunk-scripting package (the bun-bundled Effect SDK runner).";
      };

      autoStart = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Start the runner automatically in every user's graphical session (adds it to the user
          `default.target`). Off by default even when the host auto-starts — running arbitrary
          operator scripts/plugins is a deliberate opt-in; enable it once you have automation to run.
        '';
      };
    };
  };

  config = mkMerge [
    # --- shared: whenever either half is enabled -----------------------------------------------
    (mkIf (cfg.host.enable || cfg.client.enable) {
      assertions = [{
        assertion = system == "x86_64-linux";
        message = "services.punktfunk is x86_64-linux only (desktop NVENC host; no aarch64 build).";
      }];
      # The GPU driver libs the binaries dlopen at runtime (libcuda / libnvidia-encode / libEGL /
      # the Vulkan ICD) live under /run/opengl-driver/lib — provided by hardware.graphics.
      hardware.graphics.enable = mkDefault true;
      # 32 MB UDP socket buffers — without this the kernel clamps the host's SO_SNDBUF / client's
      # SO_RCVBUF and high-bitrate frames overflow (measured: 4 MB cap = 31.6 % loss at 2 Gbps).
      boot.kernel.sysctl = {
        "net.core.wmem_max" = mkDefault 33554432;
        "net.core.rmem_max" = mkDefault 33554432;
      };
    })

    # --- host ----------------------------------------------------------------------------------
    (mkIf cfg.host.enable {
      environment.systemPackages = [ cfg.host.package ];
      # 60-punktfunk.rules: /dev/uinput + /dev/uhid group access + the vhci sysfs perms.
      services.udev.packages = [ cfg.host.package ];
      # The vhci attach/detach rule shells out to chgrp/chmod (coreutils) — put them on udev's PATH.
      services.udev.path = [ pkgs.coreutils ];
      # uinput/uhid: the virtual X360 + DualSense nodes. vhci-hcd: the usbip transport that makes
      # the virtual Steam Deck a real USB device (Steam Input only adopts USB pads).
      boot.kernelModules = [ "uinput" "uhid" "vhci-hcd" ];

      # `input` group membership for the virtual-gamepad nodes (mirrors the RPM's usermod hint).
      users.groups.input = { };
      users.users = genAttrs cfg.host.users (_: { extraGroups = [ "input" ]; });

      # Status-tray autostart entry (self-gating: `--autostart` exits unless this user runs a host).
      environment.etc."xdg/autostart/io.unom.Punktfunk.Tray.desktop".source =
        "${cfg.host.package}/etc/xdg/autostart/io.unom.Punktfunk.Tray.desktop";

      networking.firewall = mkIf cfg.host.openFirewall {
        allowedTCPPorts = nativeTCP ++ optionals cfg.host.gamestream gamestreamTCP;
        allowedUDPPorts = nativeUDP ++ optionals cfg.host.gamestream gamestreamUDP;
      };

      systemd.user.services.punktfunk-host = {
        description = "punktfunk GameStream + punktfunk/1 streaming host";
        documentation = [ "https://git.unom.io/unom/punktfunk" ];
        # Soft ordering: the host listens immediately and only touches the compositor per session.
        after = [ "pipewire.service" ];
        wants = [ "pipewire.service" ];
        wantedBy = optional cfg.host.autoStart "default.target";
        # The host may exec external helpers (pw-dump, sh, and — for the gamescope/kwin backends —
        # the compositor). Extend this in your config for a headless gamescope/KWin appliance.
        path = [ pkgs.bash pkgs.coreutils pkgs.pipewire ];
        serviceConfig = {
          ExecStart = "${cfg.host.package}/bin/punktfunk-host serve"
            + optionalString cfg.host.gamestream " --gamestream";
          Restart = "on-failure";
          RestartSec = 2;
          EnvironmentFile =
            (optional (cfg.host.settings != { }) "${hostSettingsFile}")
            ++ (optional (cfg.host.environmentFile != null) "-${toString cfg.host.environmentFile}");
        };
      };
    })

    # --- client --------------------------------------------------------------------------------
    (mkIf cfg.client.enable {
      environment.systemPackages = [ cfg.client.package ];
      # 70-punktfunk-client.rules: hidraw access for the seated user's DualSense (SDL HIDAPI). The
      # rule is uaccess-tagged, so the active-seat user gets it with no group membership.
      services.udev.packages = [ cfg.client.package ];

      networking.firewall = mkIf cfg.client.openFirewall {
        allowedUDPPorts = [ 5353 ];
      };
    })

    # --- web console ---------------------------------------------------------------------------
    # The declarative equivalent of the punktfunk-web .deb / RPM subpackage: the two systemd --user
    # units (the console + its first-run password generator) plus the firewall opener, all auto-wired
    # to the host's per-user mgmt token + identity cert (no env editing on a packaged install).
    (mkIf cfg.web.enable {
      environment.systemPackages = [ cfg.web.package ];

      networking.firewall = mkIf cfg.web.openFirewall {
        allowedTCPPorts = [ 47992 ]; # console HTTPS (packaging/linux/punktfunk-web.xml)
      };

      # First-run setup: generate the console login password once, in the user's config dir, and
      # surface it to the --user journal. Self-gates via ConditionPathExists (mirrors
      # scripts/punktfunk-web-init.service).
      systemd.user.services.punktfunk-web-init = {
        description = "punktfunk web console first-run setup (login password)";
        documentation = [ "https://git.unom.io/unom/punktfunk" ];
        unitConfig.ConditionPathExists = "!%h/.config/punktfunk/web-password";
        path = [ pkgs.coreutils ];
        serviceConfig = {
          Type = "oneshot";
          RemainAfterExit = true;
          ExecStart = "${cfg.web.package}/share/punktfunk-web/web-init.sh";
        };
      };

      # The console itself: Nitro SSR on bun, HTTPS on 47992 with the host's identity cert, proxying
      # the host's loopback mgmt API with the bearer token injected server-side. mgmt-token is
      # REQUIRED (the host's `serve` writes it) — if absent the unit fails and Restart retries until
      # the host has created it; web-password is optional ('-'). Mirrors scripts/punktfunk-web.service.
      systemd.user.services.punktfunk-web = {
        description = "punktfunk management web console";
        documentation = [ "https://git.unom.io/unom/punktfunk" ];
        after = [ "punktfunk-web-init.service" "punktfunk-host.service" ];
        wants = [ "punktfunk-web-init.service" ];
        wantedBy = optional cfg.web.autoStart "default.target";
        environment = {
          PUNKTFUNK_MGMT_URL = "https://127.0.0.1:47990";
          PORT = "47992";
          HOST = "0.0.0.0";
          # Serve HTTPS with the host's own identity cert (the anchor native clients already pin) and
          # mark the session cookie Secure. The host's `serve` writes these PEMs.
          PUNKTFUNK_UI_TLS_CERT = "%h/.config/punktfunk/cert.pem";
          PUNKTFUNK_UI_TLS_KEY = "%h/.config/punktfunk/key.pem";
          PUNKTFUNK_UI_SECURE = "1";
        };
        serviceConfig = {
          Type = "simple";
          EnvironmentFile = [
            "%h/.config/punktfunk/mgmt-token"
            "-%h/.config/punktfunk/web-password"
          ];
          ExecStart = "${cfg.web.package}/bin/punktfunk-web-server";
          Restart = "on-failure";
          RestartSec = 2;
        };
      };
    })

    # --- plugin/script runner ------------------------------------------------------------------
    # Installs the runner + defines its opt-in `systemd --user` unit (mirrors the deb/rpm
    # punktfunk-scripting subpackage). NOT auto-started unless `scripting.autoStart` is set.
    (mkIf cfg.scripting.enable {
      environment.systemPackages = [ cfg.scripting.package ];

      systemd.user.services.punktfunk-scripting = {
        description = "punktfunk plugin/script runner";
        documentation = [ "https://git.unom.io/unom/punktfunk" ];
        # Plugins talk to the host's loopback mgmt API; order after it (soft — the runner backs off
        # and retries per unit, so this is ordering only, not a hard requirement).
        after = [ "punktfunk-host.service" ];
        wantedBy = optional cfg.scripting.autoStart "default.target";
        serviceConfig = {
          Type = "simple";
          ExecStart = "${cfg.scripting.package}/bin/punktfunk-scripting";
          Restart = "on-failure";
          RestartSec = 2;
          # Deliver SIGTERM to the runner (it orchestrates the structural shutdown of its unit
          # fibers) and give it room to run their finalizers before the cgroup is reaped.
          KillMode = "mixed";
          KillSignal = "SIGTERM";
          TimeoutStopSec = 30;
        };
      };
    })
  ];
}