command-not-found: Add ZSH Support

nixos/modules/module-list.nix

@@ -54,8 +54,8 @@
   ./misc/version.nix
   ./programs/atop.nix
   ./programs/bash/bash.nix
-  ./programs/bash/command-not-found.nix
   ./programs/blcr.nix
+  ./programs/command-not-found/command-not-found.nix
   ./programs/dconf.nix
   ./programs/environment.nix
   ./programs/info.nix

nixos/modules/programs/command-not-found/command-not-found.nix

@@ -44,6 +44,26 @@ in
       }
     '';
 
+  programs.zsh.interactiveShellInit =
+    ''
+      # This function is called whenever a command is not found.
+      command_not_found_handler() {
+        local p=/run/current-system/sw/bin/command-not-found
+        if [ -x $p -a -f /nix/var/nix/profiles/per-user/root/channels/nixos/programs.sqlite ]; then
+          # Run the helper program.
+          $p "$1"
+
+          # Retry the command if we just installed it.
+          if [ $? = 126 ]; then
+            "$@"
+          fi
+	else
+          # Indicate than there was an error so ZSH falls back to its default handler
+	  return 127
+        fi
+      }
+    '';
+
   environment.systemPackages = [ commandNotFound ];
 
   # TODO: tab completion for uninstalled commands! :-)