refactor: phase1 modularizing the host config for workplace

Following the great example of gh/Misterio77, I start to split out the
host configuration of the workplace into a `common/core` part, present on
all systems and a `common/optional` part, to include only on selected
modules. In difference to Misterio77 repo, I do not only manage Linux
systems, but darwin as well. Therefore this repo will also have a
`common/darwin` folder.

hosts/common/core/default.nix

@@ -0,0 +1,34 @@
+{
+  pkgs,
+  inputs,
+  ...
+}: {
+  imports = [
+    ./nix.nix
+    ./fonts.nix
+  ];
+
+  environment = {
+    systemPackages = [
+      pkgs.coreutils
+      pkgs.neovim-unwrapped
+      pkgs.git
+    ];
+
+    shells = [
+      pkgs.bash
+      pkgs.zsh
+    ];
+  };
+
+  programs.zsh = {
+    enable = true;
+    enableCompletion = true;
+  };
+
+  home-manager.useGlobalPkgs = true;
+  home-manager.useUserPackages = true;
+  home-manager.extraSpecialArgs = {
+    inherit pkgs inputs;
+  };
+}

hosts/common/core/fonts.nix

@@ -0,0 +1,12 @@
+{pkgs, ...}: {
+  fonts = {
+    packages = [
+      (pkgs.nerdfonts.override {
+        fonts = [
+          "JetBrainsMono"
+          "Meslo"
+        ];
+      })
+    ];
+  };
+}

hosts/common/core/nix.nix

@@ -0,0 +1,33 @@
+{...}: {
+  nix = {
+    # package = pkgs.nixVersions.nix_2_16;
+    checkConfig = true;
+    configureBuildUsers = true;
+    settings = {
+      # Necessary for using flakes on this system.
+      experimental-features = [
+        "nix-command"
+        "flakes"
+      ];
+      allowed-users = [
+        "@admin"
+      ];
+      # disable it, enabling leads to some symlink problems
+      # on macOS
+      auto-optimise-store = false;
+      cores = 6;
+      extra-sandbox-paths = [];
+      max-jobs = "auto";
+      require-sigs = true;
+      sandbox = false;
+      # substituters = [];
+      # trusted-public-keys = [];
+      trusted-users = [
+        "@admin"
+      ];
+    };
+  };
+
+  # Auto upgrade nix package and the daemon service.
+  services.nix-daemon.enable = true;
+}

hosts/common/darwin/core/default.nix

@@ -0,0 +1,3 @@
+{...}: {
+  environment.systemPath = ["/opt/homebrew/bin"];
+}

hosts/common/users/refnode/default.nix

@@ -0,0 +1,3 @@
+{config, ...}: {
+  home-manager.users.refnode = import ../../../../users/refnode/default.nix;
+}

hosts/defiant/default.nix

@@ -7,65 +7,11 @@
 }: {
   imports = [
     inputs.home-manager.darwinModules.home-manager
+    ../common/core
+    ../common/darwin/core
+    ../common/users/refnode
   ];
 
-  # List packages installed in system profile. To search by name, run:
-  # $ nix-env -qaP | grep wget
-  environment = {
-    systemPackages = [
-      pkgs.coreutils
-      pkgs.vim
-      pkgs.git
-    ];
-
-    shells = [
-      pkgs.bash
-      pkgs.zsh
-    ];
-  };
-
-  fonts = {
-    packages = [
-      (pkgs.nerdfonts.override {
-        fonts = [
-          "JetBrainsMono"
-          "Meslo"
-        ];
-      })
-    ];
-  };
-
-  # Auto upgrade nix package and the daemon service.
-  services.nix-daemon.enable = true;
-
-  nix = {
-    # package = pkgs.nixVersions.nix_2_16;
-    checkConfig = true;
-    configureBuildUsers = true;
-    settings = {
-      # Necessary for using flakes on this system.
-      experimental-features = "nix-command flakes";
-      allowed-users = [
-        "@admin"
-      ];
-      # disable it, enabling leads to some symlink problems
-      # on macOS
-      auto-optimise-store = false;
-      cores = 6;
-      extra-sandbox-paths = [];
-      max-jobs = "auto";
-      require-sigs = true;
-      sandbox = false;
-      # substituters = [];
-      # trusted-public-keys = [];
-      trusted-users = [
-        "@admin"
-      ];
-    };
-  };
-
-  programs.zsh.enable = true;
-
   # TODO https://discourse.nixos.org/t/give-name-label-comment-to-generations/45355
   system.configurationRevision = flake.rev or flake.dirtyRev or null;
 
@@ -83,10 +29,5 @@
     localHostName = "defiant";
   };
 
-  home-manager = {
-    useGlobalPkgs = true;
-    useUserPackages = true;
-    extraSpecialArgs = {inherit pkgs;};
-    users.refnode = import ../../users/refnode;
-  };
+  # home-manager.users.refnode = import ../../users/refnode;
 }