Add nix shell aliases

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/user/console/nix-direnv/default.nix

@@ -5,11 +5,29 @@
 { inputs, ... }:
 {
   home-manager.users.${user} = {
-    programs.direnv = {
-      enable = true;
-      silent = true;
-      nix-direnv.enable = true;
-      enableZshIntegration = true;
+    programs = {
+      direnv = {
+        enable = true;
+        silent = true;
+        nix-direnv.enable = true;
+        enableZshIntegration = true;
+      };
+
+      zsh = {
+        shellAliases.nde = "nix-direnv";
+
+        initExtra = ''
+          nix-direnv() {
+            if [ -z "$1" ]; then
+              echo "Usage: nix-direnv <shell>"
+              return 1
+            fi
+
+            echo "use $1" > .envrc
+            direnv allow
+          }
+        '';
+      };
     };
 
     # https://github.com/direnv/direnv/wiki/Customizing-cache-location