nix: add NixOS module

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I0d8e0ed21f7b565123312cbdffa8a5e36a6a6964

nix/modules/nixos.nix

@@ -0,0 +1,44 @@
+self: {
+  config,
+  pkgs,
+  lib,
+  ...
+}: let
+  inherit (lib.modules) mkIf;
+  inherit (lib.options) mkEnableOption mkPackageOption;
+  inherit (lib.strings) optionalString;
+
+  cfg = config.programs.eh;
+in {
+  options.programs.eh = {
+    enable = mkEnableOption "eh - Ergonomic Nix CLI helper";
+    package = mkPackageOption self.packages.${pkgs.hostPlatform.system} ["eh"] {};
+
+    hooks = {
+      bash.enable = mkEnableOption "Bash shell hook for EH" // {default = config.programs.bash.enable;};
+      zsh.enable = mkEnableOption "ZSH shell hook for EH" // {default = config.programs.zsh.enable;};
+    };
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [cfg.package];
+
+    programs = {
+      bash.interactiveShellInit = optionalString cfg.hooks.bash.enable ''
+        # Aliases added by EH
+        alias nr='eh run'
+        alias ns='eh shell'
+        alias nb='eh build'
+        alias nu='eh update'
+      '';
+
+      zsh.interactiveShellInit = optionalString cfg.hooks.zsh.enable ''
+        # Aliases added by EH
+        alias nr='eh run'
+        alias ns='eh shell'
+        alias nb='eh build'
+        alias nu='eh update'
+      '';
+    };
+  };
+}