staging again

modules/npm.nix

@@ -0,0 +1,38 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}: let
+  npmConf = pkgs.writeText "npmrc" ''
+    prefix=${config.environment.variables.NPM_CONFIG_PREFIX}
+    cache=$HOME/.npm
+    init-module=$HOME/.npm-init.js
+    node-linker=hoisted
+  '';
+in {
+  options.npm = {
+    enable = lib.mkEnableOption "System NPM Environment";
+  };
+  config = lib.mkIf config.npm.enable {
+    environment.systemPackages = with pkgs; [
+      nodejs
+      nodePackages.npm
+    ];
+    environment.variables = {
+      NPM_CONFIG_PREFIX = "$HOME/.npm-global";
+      PATH = ["$HOME/.npm-global/bin"];
+      NPM_CONFIG_USERCONFIG = "${npmConf}";
+    };
+    system.userActivationScripts.setupNpm = ''
+      mkdir -p $HOME/.npm-global/bin
+      mkdir -p $HOME/.npm
+      if [ ! -f "$HOME/.npmrc" ]; then
+        cp ${npmConf} $HOME/.npmrc
+      fi
+      if [ -d "$HOME/.npm-global" ]; then
+        chmod -R +rw $HOME/.npm-global
+      fi
+    '';
+  };
+}