Move functions to helper.nix

helpers.nix

@@ -0,0 +1,57 @@
+inputs:
+with inputs;
+with inputs.nixpkgs.lib; {
+  mergeHosts = lists.foldl' (
+    a: b: attrsets.recursiveUpdate a b
+  ) {};
+
+  mkHost = hostname: {
+    platform ? "x86_64-linux",
+    suite,
+    user ? "fern",
+    extraModules ? [],
+  }: {
+    nixosConfigurations.${hostname} = nixosSystem rec {
+      system = platform;
+
+      pkgs = import nixpkgs {
+        inherit system;
+        config = {
+          allowUnfree = true;
+          permittedInsecurePackages = [
+            "dotnet-sdk-6.0.428"
+            "dotnet-runtime-6.0.36"
+          ];
+        };
+      };
+
+      specialArgs = {
+        inherit
+          hostname
+          nixpkgs
+          suite
+          platform
+          user
+          ; # Inherit variables.
+
+        userPackages = {
+          fluffychat = fluffychat-2_0_0.legacyPackages.${system}.fluffychat;
+          feishin = feishin-0_17_0.legacyPackages.${system}.feishin;
+          webone = pkgs.callPackage ./packages/webone {};
+        };
+
+        secrets = builtins.toString inputs.secrets; # Secrets directory.
+      };
+
+      modules =
+        [
+          nixvim.nixosModules.nixvim
+          ./suites/common.nix
+          ./suites/${suite}.nix
+          ./hosts/${suite}/${hostname}.nix
+        ]
+        ++ (filesystem.listFilesRecursive ./modules)
+        ++ extraModules;
+    };
+  };
+}