From 69e6eb5a898234dad82176b3c69bbc491ac5930d Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Fri, 14 Jul 2023 16:53:36 +0100
Subject: [PATCH] accept attr args to pppoe service, and typecheck them

We use (abuse, arguably) the nixos module system for typechecking.  Un
the plus side, it gives us documentation of the options and their
expected types. On the downside, the error message doesn't tell us
the file in which the error was encountered.

(This is subject to change, if I can find a better way)
---
 examples/rotuer.nix                     |  3 ++-
 modules/ppp.nix                         |  2 +-
 pkgs/liminix-tools/networking/pppoe.nix | 23 ++++++++++++++++++-----
 3 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/examples/rotuer.nix b/examples/rotuer.nix
index 06d5fef..3be133e 100644
--- a/examples/rotuer.nix
+++ b/examples/rotuer.nix
@@ -191,7 +191,8 @@ in rec {
 
   services.wan =
     let iface = config.hardware.networkInterfaces.wan;
-    in config.system.service.pppoe iface {
+    in config.system.service.pppoe {
+      interface = iface;
       ppp-options = [
         "debug" "+ipv6" "noauth"
         "name" secrets.l2tp.name
diff --git a/modules/ppp.nix b/modules/ppp.nix
index 08519e4..b1b19ea 100644
--- a/modules/ppp.nix
+++ b/modules/ppp.nix
@@ -6,7 +6,7 @@ let
 in {
   options = {
     system.service.pppoe = mkOption {
-      type = types.functionTo (types.functionTo types.package);
+      type = types.functionTo types.package;
     };
   };
   config = {
diff --git a/pkgs/liminix-tools/networking/pppoe.nix b/pkgs/liminix-tools/networking/pppoe.nix
index 1fbf776..238ad17 100644
--- a/pkgs/liminix-tools/networking/pppoe.nix
+++ b/pkgs/liminix-tools/networking/pppoe.nix
@@ -8,13 +8,26 @@
 } :
 let
   inherit (liminix.services) longrun;
+  inherit (lib)
+    mergeDefinitions
+    mkEnableOption mkOption isType types isDerivation hasAttr;
+  t = {
+    interface = mkOption {
+      type = types.package;     # actually a service
+      description = "ethernet interface to run PPPoE over";
+    };
+    ppp-options = mkOption {
+      type = types.listOf types.str;
+    };
+  };
+  t' = types.submodule { options = t; };
+  typeChecked = type: value:
+    let defs = [{ file = "pppoe.nix"; inherit value; }];
+    in (lib.mergeDefinitions [ ] type defs).mergedValue;
 in
-interface: {
-  synchronous ? false
-, ppp-options ? []
-, ...
-} @ args:
+params:
 let
+  inherit (typeChecked t' params) ppp-options interface;
   name = "${interface.device}.pppoe";
   ip-up = writeAshScript "ip-up" {} ''
     . ${serviceFns}