From 236ddddffc611783fb54ca2bfcf733f96498637f Mon Sep 17 00:00:00 2001
From: chn <chn@chn.moe>
Date: Thu, 1 Feb 2024 10:55:47 +0800
Subject: [PATCH] rewrite system.nix

---
 modules/system/nix.nix | 129 +++++++++++++++++++++++------------------
 1 file changed, 72 insertions(+), 57 deletions(-)

diff --git a/modules/system/nix.nix b/modules/system/nix.nix
index 5e7fdb5d..43783bee 100644
--- a/modules/system/nix.nix
+++ b/modules/system/nix.nix
@@ -8,63 +8,78 @@ inputs:
     substituters = mkOption { type = types.nullOr (types.listOf types.nonEmptyStr); default = null; };
     autoOptimiseStore = mkOption { type = types.bool; default = false; };
   };
-  config =
-    let
-      inherit (inputs.config.nixos.system) nix;
-    in
+  config = let inherit (inputs.config.nixos.system) nix; in inputs.lib.mkMerge
+  [
+    # general nix config
+    {
+      nix.settings =
       {
-        nix =
-        {
-          settings =
-          {
-            system-features = [ "big-parallel" "nixos-test" "benchmark" ] ++ (map
-              (march: "gccarch-${march}")
-              (
-                if nix.marches == null then
-                  (with inputs.config.nixos.system.nixpkgs; if march == null then [] else [ march ])
-                else nix.marches
-              ));
-            experimental-features = [ "nix-command" "flakes" ];
-            keep-outputs = nix.includeBuildDependencies;
-            keep-failed = true;
-            auto-optimise-store = nix.autoOptimiseStore;
-            substituters = if nix.substituters == null then [ "https://cache.nixos.org/" ] else nix.substituters;
-            max-substitution-jobs = 1;
-            trusted-public-keys = [ "chn:Cc+nowW1LIpe1kyXOZmNaznFDiH1glXmpb4A+WD/DTE=" ];
-            show-trace = true;
-            max-jobs = 1;
-            cores = 0;
-            keep-going = true;
-          };
-          daemonIOSchedClass = "idle";
-          daemonCPUSchedPolicy = "idle";
-          registry =
-          {
-            nixpkgs.flake = inputs.topInputs.nixpkgs;
-            nixpkgs-unstable.flake = inputs.topInputs.nixpkgs-unstable;
-            nixos.flake = inputs.topInputs.self;
-          };
-          nixPath = [ "nixpkgs=${inputs.topInputs.nixpkgs}" ];
-        };
-        systemd.services.nix-daemon =
-        {
-          serviceConfig = { CacheDirectory = "nix"; Slice = "-.slice"; Nice = "19"; };
-          environment = { TMPDIR = "/var/cache/nix"; };
-        };
-        environment =
-        {
-          etc =
-          {
-            "channels/nixpkgs".source = inputs.topInputs.nixpkgs.outPath;
-            "channels/nixpkgs-unstable".source = inputs.topInputs.nixpkgs-unstable.outPath;
-            "nixos".source = inputs.topInputs.self.outPath;
-          };
-          variables.COMMA_NIXPKGS_FLAKE = "nixpkgs-unstable";
-        };
-        system.includeBuildDependencies = nix.includeBuildDependencies;
-        # environment.pathsToLink = [ "/include" ];
-        # environment.variables.CPATH = "/run/current-system/sw/include";
-        # environment.variables.LIBRARY_PATH = "/run/current-system/sw/lib";
-        # gui.enable
+        system-features = [ "big-parallel" "nixos-test" "benchmark" ];
+        experimental-features = [ "nix-command" "flakes" ];
+        keep-failed = true;
+        max-substitution-jobs = 1;
+        trusted-public-keys = [ "chn:Cc+nowW1LIpe1kyXOZmNaznFDiH1glXmpb4A+WD/DTE=" ];
+        show-trace = true;
+        max-jobs = 1;
+        cores = 0;
+        keep-going = true;
       };
+      systemd.services.nix-daemon = { serviceConfig.CacheDirectory = "nix"; environment.TMPDIR = "/var/cache/nix"; };
+    }
+    # nix daemon use lower io/cpu priority
+    {
+      nix = { daemonIOSchedClass = "idle"; daemonCPUSchedPolicy = "idle"; };
+      systemd.services.nix-daemon.serviceConfig = { Slice = "-.slice"; Nice = "19"; };
+    }
+    # nix channel & nix flake registry
+    {
+      nix =
+      {
+        registry =
+        {
+          nixpkgs.flake = inputs.topInputs.nixpkgs;
+          nixpkgs-unstable.flake = inputs.topInputs.nixpkgs-unstable;
+          nixos.flake = inputs.topInputs.self;
+        };
+        nixPath = [ "nixpkgs=${inputs.topInputs.nixpkgs}" ];
+      };
+      environment =
+      {
+        etc =
+        {
+          "channels/nixpkgs".source = inputs.topInputs.nixpkgs.outPath;
+          "channels/nixpkgs-unstable".source = inputs.topInputs.nixpkgs-unstable.outPath;
+          "nixos".source = inputs.topInputs.self.outPath;
+        };
+        variables.COMMA_NIXPKGS_FLAKE = "nixpkgs-unstable";
+      };
+    }
+    # marches
+    {
+      nix.settings.system-features = map
+        (march: "gccarch-${march}")
+        (
+          if nix.marches == null then
+            (with inputs.config.nixos.system.nixpkgs; if march == null then [] else [ march ])
+          else nix.marches
+        );
+    }
+    # includeBuildDependencies
+    {
+      nix.settings.keep-outputs = nix.includeBuildDependencies;
+      system.includeBuildDependencies = nix.includeBuildDependencies;
+    }
+    # substituters
+    {
+      nix.settings.substituters = if nix.substituters == null then [ "https://cache.nixos.org/" ] else nix.substituters;
+    }
+    # autoOptimiseStore
+    {
+      nix.settings.auto-optimise-store = nix.autoOptimiseStore;
+    }
+    # c++ include path
+    # environment.pathsToLink = [ "/include" ];
+    # environment.variables.CPATH = "/run/current-system/sw/include";
+    # environment.variables.LIBRARY_PATH = "/run/current-system/sw/lib";
+  ];
 }