From d69a07436699e1b6d0d77bde6ef58d897c4c39a4 Mon Sep 17 00:00:00 2001
From: Johannes Kirschbauer <hsjobeki@gmail.com>
Date: Tue, 1 Apr 2025 17:28:52 +0200
Subject: [PATCH] chore(buildClan): make buildClan and flake-parts return
 identical outputs

---
 flakeModules/clan.nix      | 35 +++++++++++++++++++++++----------
 lib/build-clan/default.nix | 40 ++++++++++++++++++++------------------
 lib/build-clan/module.nix  |  2 +-
 lib/build-clan/public.nix  | 17 ++++++++++++++++
 4 files changed, 64 insertions(+), 30 deletions(-)
 create mode 100644 lib/build-clan/public.nix

diff --git a/flakeModules/clan.nix b/flakeModules/clan.nix
index e50192dee..07e84dbf4 100644
--- a/flakeModules/clan.nix
+++ b/flakeModules/clan.nix
@@ -11,9 +11,24 @@ let
   inherit (lib) types;
 
   buildClanModule = clan-core.clanLib.buildClanModule;
+
+  publicAttrs = import ../lib/build-clan/public.nix;
+  # Create output options only for listed attributes
+  outputModule = {
+    clan = lib.genAttrs publicAttrs.clan (
+      name:
+      config.clan.clanInternals.${name}
+        or (throw "Output: clanInternals.${name} not found. Check: ${config.file}")
+    );
+    topLevel = {
+      options = lib.genAttrs publicAttrs.topLevel (_: lib.mkOption { });
+      config = lib.genAttrs publicAttrs.topLevel (
+        name: config.clan.${name} or (throw "Output: clan.${name} not found. See: ${config.file}")
+      );
+    };
+  };
 in
 {
-
   options.clan = lib.mkOption {
     default = { };
     type = types.submoduleWith {
@@ -27,16 +42,16 @@ in
     };
   };
 
-  options.flake = flake-parts-lib.mkSubmoduleOptions {
-    clan = lib.mkOption { type = types.raw; };
-    clanInternals = lib.mkOption { type = types.raw; };
-  };
+  options.flake =
+    flake-parts-lib.mkSubmoduleOptions {
+      clan = lib.mkOption { type = types.raw; };
+    }
+    // outputModule.topLevel.options;
   config = {
-    flake.clan = {
-      inherit (config.clan.clanInternals) templates;
-    };
-    flake.clanInternals = config.clan.clanInternals;
-    flake.nixosConfigurations = config.clan.nixosConfigurations;
+    flake = {
+      clan = outputModule.clan;
+    } // outputModule.topLevel.config;
   };
+
   _file = __curPos.file;
 }
diff --git a/lib/build-clan/default.nix b/lib/build-clan/default.nix
index b94bba48e..35a0d7753 100644
--- a/lib/build-clan/default.nix
+++ b/lib/build-clan/default.nix
@@ -5,14 +5,7 @@
   lib,
   nixpkgs,
 }:
-let
-  clanResultAttributes = [
-    "clanInternals"
-    "nixosConfigurations"
-  ];
-in
 {
-  inherit clanResultAttributes;
   flakePartsModule = {
     imports = [
       ./interface.nix
@@ -25,6 +18,7 @@ in
 
     # Arguments of the first function
     - clan-core: Self, provided by our flake-parts module
+    - publicAttrs: { clan :: List Str, topLevel :: List Str } Publicly exported attribute names
 
     # Arguments of the second function (aka 'buildClan')
     - self: Reference to the users flake
@@ -34,13 +28,13 @@ in
 
     # Returns
 
-    A module evaluation containing '.config' and '.options'
-
-    NOTE:
-    The result might export all kinds of options at the '.config' top level.
+    Public attributes of buildClan. As specified in publicAttrs.
   */
   buildClanWith =
-    { clan-core }:
+    {
+      clan-core,
+      publicAttrs ? import ./public.nix,
+    }:
     {
       ## Inputs
       self ? lib.warn "Argument: 'self' must be set when using 'buildClan'." null, # Reference to the current flake
@@ -65,12 +59,20 @@ in
         inherit specialArgs;
       };
       rest = builtins.removeAttrs attrs [ "specialArgs" ];
+      result = eval {
+        imports = [
+          rest
+          # implementation
+          ./module.nix
+        ];
+      };
     in
-    eval {
-      imports = [
-        rest
-        # implementation
-        ./module.nix
-      ];
-    };
+    {
+      clan = lib.genAttrs publicAttrs.clan (
+        name:
+        result.clanInternals.${name}
+          or (throw "Output: clanInternals.${name} not found. Check: ${result.file}")
+      );
+    }
+    // lib.filterAttrs (name: _v: builtins.elem name publicAttrs.topLevel) result;
 }
diff --git a/lib/build-clan/module.nix b/lib/build-clan/module.nix
index 29eafe838..9311c53c4 100644
--- a/lib/build-clan/module.nix
+++ b/lib/build-clan/module.nix
@@ -208,7 +208,7 @@ in
     # TODO: unify this interface
     # We should have only clan.modules. (consistent with clan.templates)
     inherit (clan-core) clanModules clanLib;
-    modules = clan-core.modules;
+    modules = clan-core.clanModules;
 
     inherit inventoryFile;
     inventoryValuesPrios =
diff --git a/lib/build-clan/public.nix b/lib/build-clan/public.nix
new file mode 100644
index 000000000..493ac1cc0
--- /dev/null
+++ b/lib/build-clan/public.nix
@@ -0,0 +1,17 @@
+/**
+  Publicly exported attribute names
+  These are mapped from 'options.clan.{name}' into 'flake.{name}'
+  For example "clanInternals" will be exposed as "flake.clan.clanInternals"
+  This list is used to guarantee equivalent attribute sets for both flake-parts and buildClan users.
+*/
+{
+  # flake.clan.{name} <- clanInternals.{name}
+  clan = [
+    "templates"
+  ];
+  # flake.{name} <- clan.{name}
+  topLevel = [
+    "clanInternals"
+    "nixosConfigurations"
+  ];
+}