From f6745d06f5dc6c357e9bc101f524a5ced3562921 Mon Sep 17 00:00:00 2001
From: Nathaniel Glen <njag2202@gmail.com>
Date: Fri, 23 Oct 2020 13:36:56 -0400
Subject: [PATCH] nixos/pipewire: cleanup module

---
 nixos/modules/services/desktops/pipewire.nix | 53 +++++++++-----------
 1 file changed, 23 insertions(+), 30 deletions(-)

diff --git a/nixos/modules/services/desktops/pipewire.nix b/nixos/modules/services/desktops/pipewire.nix
index d527343966d7..ed1b15380ffe 100644
--- a/nixos/modules/services/desktops/pipewire.nix
+++ b/nixos/modules/services/desktops/pipewire.nix
@@ -9,6 +9,10 @@ let
                            && pkgs.stdenv.isx86_64
                            && pkgs.pkgsi686Linux.pipewire != null;
 
+  # The package doesn't output to $out/lib/pipewire directly so that the
+  # overlays can use the outputs to replace the originals in FHS environments.
+  #
+  # This doesn't work in general because of missing development information.
   jack-libs = pkgs.runCommand "jack-libs" {} ''
     mkdir -p "$out/lib"
     ln -s "${pkgs.pipewire.jack}/lib" "$out/lib/pipewire"
@@ -37,41 +41,16 @@ in {
       };
 
       alsa = {
-        enable = mkOption {
-          default = false;
-          type = types.bool;
-          description = ''
-            Route audio to/from generic ALSA-using applications via the ALSA PIPEWIRE PCM plugin.
-          '';
-        };
-
-        support32Bit = mkOption {
-          default = false;
-          type = types.bool;
-          description = ''
-            Whether to support sound for 32-bit ALSA applications on a 64-bit system.
-          '';
-        };
+        enable = mkEnableOption "ALSA support";
+        support32Bit = mkEnableOption "32-bit ALSA support on 64-bit systems";
       };
 
       jack = {
-        enable = mkOption {
-          default = false;
-          type = types.bool;
-          description = ''
-            Enable transparent JACK audio emulation using LD_LIBRARY_PATH.
-          '';
-        };
+        enable = mkEnableOption "JACK audio emulation";
       };
 
       pulse = {
-        enable = mkOption {
-          default = false;
-          type = types.bool;
-          description = ''
-            Enable transparent PulseAudio emulation using LD_LIBRARY_PATH.
-          '';
-        };
+        enable = mkEnableOption "PulseAudio emulation";
       };
     };
   };
@@ -79,12 +58,25 @@ in {
 
   ###### implementation
   config = mkIf cfg.enable {
+    assertions = [
+      {
+        assertion = cfg.pulse.enable -> !config.hardware.pulseaudio.enable;
+        message = "PipeWire based PulseAudio emulation doesn't use the PulseAudio service";
+      }
+      {
+        assertion = cfg.jack.enable -> !config.services.jack.jackd.enable;
+        message = "PIpeWire based JACK emulation doesn't use the JACK service";
+      }
+    ];
+
     environment.systemPackages = [ pkgs.pipewire ]
                                  ++ lib.optional cfg.jack.enable jack-libs
                                  ++ lib.optional cfg.pulse.enable pulse-libs;
 
     systemd.packages = [ pkgs.pipewire ];
 
+    # PipeWire depends on DBUS but doesn't list it. Without this booting
+    # into a terminal results in the service crashing with an error.
     systemd.user.sockets.pipewire.wantedBy = lib.mkIf cfg.socketActivation [ "sockets.target" ];
     systemd.user.services.pipewire.bindsTo = [ "dbus.service" ];
     services.udev.packages = [ pkgs.pipewire ];
@@ -107,6 +99,7 @@ in {
     environment.etc."alsa/conf.d/50-pipewire.conf" = mkIf cfg.alsa.enable {
       source = "${pkgs.pipewire}/share/alsa/alsa.conf.d/50-pipewire.conf";
     };
-    environment.sessionVariables.LD_LIBRARY_PATH = [ "/run/current-system/sw/lib/pipewire" ];
+    environment.sessionVariables.LD_LIBRARY_PATH =
+      lib.optional (cfg.alsa.enable || cfg.jack.enable || cfg.pulse.enable) "/run/current-system/sw/lib/pipewire";
   };
 }