From ea620730a66c34986d161f76d06cbc068451ff13 Mon Sep 17 00:00:00 2001
From: Manuel Thalmann <m@nuth.ch>
Date: Wed, 1 May 2024 15:06:31 +0200
Subject: [PATCH] Improve readability of `custom-build-vm` code

---
 lib/config/custom-build-vm.nix | 106 +++++++++++++++++----------------
 1 file changed, 56 insertions(+), 50 deletions(-)

diff --git a/lib/config/custom-build-vm.nix b/lib/config/custom-build-vm.nix
index 13ec1c7..00936a2 100644
--- a/lib/config/custom-build-vm.nix
+++ b/lib/config/custom-build-vm.nix
@@ -118,68 +118,74 @@ in {
             };
           };
 
-        virtualisation = config.virtualisation;
+        inherit (config.virtualisation)
+          vmVariant
+          vmVariantWithBootLoader
+        ;
       in {
-        vmVariant = extendVMConfig virtualisation.vmVariant;
-        vmVariantWithBootLoader = extendVMConfig virtualisation.vmVariantWithBootLoader;
+        vmVariant = extendVMConfig vmVariant;
+        vmVariantWithBootLoader = extendVMConfig vmVariantWithBootLoader;
       };
 
     system.build =
       {
         vm = lib.mkForce (
-          (
-            vm:
-              if (vm.name == packageName)
-              then
-                vm
-              else
-                let
-                  originalCommand = "${vm}/bin/run-${config.system.name}-vm";
+          let
+            vm = vanillaVM;
+          in
+            if (vm.name == packageName)
+            then
+              vm
+            else
+              let
+                originalCommand = "${vm}/bin/run-${config.system.name}-vm";
 
-                  # Have the command run in background if requested
-                  suffix =
-                    lib.concatStringsSep " " (
-                      lib.optional config.virtualisation.qemu.runInBackground "&");
+                # Have the command run in background if requested
+                suffix =
+                  lib.concatStringsSep " " (
+                    lib.optional config.virtualisation.qemu.runInBackground "&");
 
-                  shellApp = pkgs.writeShellApplication {
-                    name = "run-${config.system.name}-vm";
-                    text = lib.strings.concatLines (
-                      [
-                        "${originalCommand} ${suffix}"
-                      ] ++ (
-                        let
-                          # Run `remote-viewer` as normal user to limit access
-                          viewerPrefix = "sudo -Eu\"#$SUDO_UID\" ";
-                          spice = config.virtualisation.qemu.spice;
-                        in
-                          (
-                            lib.optionals
-                              config.virtualisation.virt-viewer
+                vmRunner = pkgs.writeShellApplication {
+                  name = "run-${config.system.name}-vm";
+
+                  text = lib.strings.concatLines (
+                    [
+                      "${originalCommand} ${suffix}"
+                    ] ++ (
+                      # Run `remote-viewer` as normal user to limit access
+                      (
+                        lib.optionals
+                          config.virtualisation.virt-viewer (
+                            let
+                              spice = config.virtualisation.qemu.spice;
+                              remoteAddress = "spice://${lib.escapeShellArg spice.bindAddress}:${toString spice.port}";
+                              viewerPrefix = "sudo -Eu\"#$SUDO_UID\" ";
+                            in
                               [
-                                "${viewerPrefix}${pkgs.virt-viewer}/bin/remote-viewer spice://${lib.escapeShellArg spice.bindAddress}:${toString spice.port}"
+                                "${viewerPrefix}${pkgs.virt-viewer}/bin/remote-viewer ${remoteAddress}"
                                 # Kill QEMU after `remote-viewer` finished running
                                 "kill %1"
-                              ])));
-                  };
+                              ]))));
+                };
 
-                  # Run VM as root if requested
-                  wrapped =
-                    if !config.virtualisation.runAsRoot
-                    then
-                      shellApp
-                    else
-                      pkgs.writeShellApplication {
-                        name = shellApp.name;
-                        text = ''
-                          sudo -E ${shellApp}/bin/${shellApp.name}
-                        '';
-                      };
-                in
-                  pkgs.symlinkJoin {
-                    name = packageName;
-                    paths = [ wrapped ];
-                  })
-          vanillaVM);
+                # Run VM as root if requested
+                wrapped =
+                  if !config.virtualisation.runAsRoot
+                  then
+                    vmRunner
+                  else
+                    pkgs.writeShellApplication {
+                      inherit (vmRunner) name;
+                      
+                      text = ''
+                        sudo -E "${vmRunner}/bin/${vmRunner.name}"
+                      '';
+                    };
+              in
+                pkgs.symlinkJoin {
+                  name = packageName;
+                  paths = [ wrapped ];
+                });
       };
   };
 }