feat: automatically populate meta from env variables if they have a desc

lib/modules/env.nix

@@ -4,7 +4,18 @@
   config,
   ...
 }: let
-  inherit (lib) filter assertMsg head length escapeShellArg types mkOption concatStringsSep;
+  inherit
+    (lib)
+    filter
+    filterAttrs
+    assertMsg
+    head
+    length
+    escapeShellArg
+    types
+    mkOption
+    concatStringsSep
+    ;
 
   envToBash = {
     name,
@@ -37,7 +48,11 @@
       then ''unset ${name}''
       else throw "[devshell] BUG in the env module. This should never be reached.";
 
-  envType = types.submodule ({name, ...}: {
+  envType = types.submodule ({
+    config,
+    name,
+    ...
+  }: {
     options = {
       name = mkOption {
         type = types.str;
@@ -46,7 +61,7 @@
           Name of the environment variable, usually already set to `<name>`.
         '';
       };
-      desc = mkOption {
+      description = mkOption {
         type = types.nullOr types.str;
         default = null;
         description = ''
@@ -55,7 +70,7 @@
       };
       visible = mkOption {
         type = types.bool;
-        default = true;
+        default = config.description != null;
         description = ''
           Whether to include this env var and it's description in the menu.
         '';
@@ -120,16 +135,12 @@ in {
     env = {
       "XDG_DATA_DIRS".eval = "$DEVSHELL_DIR/share:\${XDG_DATA_DIRS-}";
     };
-    enterShellCommands."env".text = concatStringsSep "\n" (map envToBash (builtins.attrValues config.env));
-    # TODO: collect all env vars, then add them to the menu if they have a description and "visibile == true"
-
-    meta = {
-      sections."Environment Variables".color = "red";
-      entries."XDG_DATA_DIRS" = {
-        description = "Hello world";
-        section = "Environment Variables";
-        subEntries."Usage" = "hello world";
-      };
-    };
+    enterShellCommands."env".text =
+      concatStringsSep "\n" (map envToBash (builtins.attrValues config.env));
+    # meta entries for the menu
+    meta.entries = builtins.mapAttrs (_name: env: {
+      inherit (env) description;
+      section = "Environment Variables";
+    }) (filterAttrs (_name: env: env.visible) config.env);
   };
 }