Migrate nix and nix registry configuration to home manager module

There is an existing module.
Existing manually written and linked files are replaced with usage of
the module.

This has the advantage that I don't need to know where to place the
files and which format to use.
Furthermore, the module will check whether I've typos in options and
whether values match expected types.

home.nix

@@ -25,6 +25,10 @@
   # Let Home Manager install and manage itself.
   programs.home-manager.enable = true;
 
+  nix = import ./home/programs/nix.nix {
+    inherit pkgs;
+  };
+
   # Install packages
   # Some are installed via `programs` below, as they are also configured.
   # Some packages don't have a module for configuration, and are configured via `home.file` below.
@@ -136,9 +140,6 @@
     "phpactor/phpactor.yml".source = ./home/files/phpactor.yml;
     "tig/config".source = ./home/files/tig;
 
-    "nix/nix.conf".source = ./home/files/nix/nix.conf;
-    "nix/registry.json".source = ./home/files/nix/registry.json;
-
     "cmus/smyckblue.theme".source = ./home/files/cmus/smyckblue.theme;
     "cmus/rc".source = ./home/files/cmus/rc;
 

home/files/nix/nix.conf

@@ -1,3 +0,0 @@
-experimental-features = nix-command flakes
-substituters = https://cache.nixos.org https://fossar.cachix.org
-trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= fossar.cachix.org-1:Zv6FuqIboeHPWQS7ysLCJ7UT7xExb4OE8c4LyGb5AsE=

home/files/nix/registry.json

@@ -1,15 +0,0 @@
-{
-  "flakes": [
-    {
-      "from": {
-        "id": "cp",
-        "type": "indirect"
-      },
-      "to": {
-        "path": "/home/daniels/.config/nixpkgs/registries/customer-projects",
-        "type": "path"
-      }
-    }
-  ],
-  "version": 2
-}

home/programs/nix.nix

@@ -0,0 +1,39 @@
+{ pkgs }:
+
+{
+  enable = true;
+
+  package = pkgs.nix;
+
+  settings = {
+
+    experimental-features = [
+      "nix-command"
+      "flakes"
+    ];
+
+    substituters = [
+      "https://cache.nixos.org"
+      "https://fossar.cachix.org"
+    ];
+
+    trusted-public-keys = "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= fossar.cachix.org-1:Zv6FuqIboeHPWQS7ysLCJ7UT7xExb4OE8c4LyGb5AsE=";
+
+  };
+
+  registry = {
+
+    customer-projects = {
+      from = {
+        id = "cp";
+        type = "indirect";
+      };
+      to = {
+        path = toString ./../../registries/customer-projects;
+        type = "path";
+      };
+    };
+
+  };
+
+}