Refactor UCI

Convert all options that go to UCI as an intermediate attrset
at config.uci.settings before generating the batch script.

lib/modules/dropbear.nix

@@ -9,8 +9,8 @@ in {
         See <link xlink:href="https://openwrt.org/docs/guide-user/base-system/dropbear"/>'';
     };
 
-  config.uci.batch = lib.toUciBatch {
-    config = "dropbear";
+  config.uci.settings.dropbear."" = {
     type = "dropbear";
-  } cfg.settings;
+    inherit (cfg) settings;
+  };
 }

lib/modules/system.nix

@@ -24,9 +24,9 @@ in {
 
   };
 
-  config.uci.batch = lib.toUciBatch {
-    config = "system";
+  config.uci.settings.system."" = {
     type = "system";
-  } cfg.settings;
+    inherit (cfg) settings;
+  };
 
 }

lib/modules/uci.nix

@@ -2,19 +2,30 @@
 with lib;
 let cfg = config.uci;
 in {
-  options.uci.batch = mkOption {
-    type = types.lines;
-    description = "UCI script to execute on first boot.";
-    example = ''
-      set system.@system[0].hostname='testap'
-      set dropbear.@dropbear[0].RootPasswordAuth='off'
+  options.uci.settings = mkOption {
+    default = { };
+    description = ''
+      See <link xlink:href="https://openwrt.org/docs/guide-user/base-system/uci#uci_dataobject_model"/>.
     '';
+    type = with types;
+      attrsOf (attrsOf (submodule {
+        options = {
+          type = mkOption { type = str; };
+          settings = mkOption { type = uciSection; };
+        };
+      }));
   };
+
   config.extraFiles."/etc/uci-defaults/99-config.uci.batch".text =
-    mkIf (cfg.batch != "") ''
+    mkIf (cfg.settings != { }) ''
       uci -q batch << NIX_EOI
-      ${cfg.batch}
-      uci commit
+      ${ # Flatten all the UCI settings into a batch script.
+      lib.strings.concatStringsSep "\n" (lib.lists.flatten
+        (lib.attrsets.mapAttrsToList (config: attrs:
+          (lib.attrsets.mapAttrsToList (section:
+            { type, settings }:
+            lib.toUciBatch { inherit config section type settings; }) attrs)
+          ++ [ "commit ${config}" ]) cfg.settings))}
       NIX_EOI
     '';
 }

lib/modules/wireless.nix

@@ -36,16 +36,12 @@ in {
       };
     };
 
+    # TODO: assert that device and interfaces name are mutually unique.
   };
 
-  config.uci.batch = let
+  config.uci.settings.wireless = let
     toUci' = type:
-      (lib.attrsets.mapAttrsToList (section: settings:
-        lib.toUciBatch {
-          config = "wireless";
-          inherit section type;
-        } settings));
-  in lib.strings.concatStringsSep "\n"
-  ((toUci' "wifi-device" cfg.devices) ++ (toUci' "wifi-iface" cfg.interfaces));
+      lib.attrsets.mapAttrs (_: settings: { inherit type settings; });
+  in (toUci' "wifi-device" cfg.devices) // (toUci' "wifi-iface" cfg.interfaces);
 
 }

lib/uci.nix

@@ -2,17 +2,25 @@ final: prev:
 let lib = prev;
 in {
 
-  types = lib.types
-    // (with lib.types; { uciSection = attrsOf (oneOf [ bool int str ]); });
+  types = lib.types // (with lib.types; {
+    uciSection = let atom = oneOf [ bool int str ];
+    in attrsOf (either atom (listOf atom));
+  });
 
-  toUciBatch = with builtins;
-    let toAtom = v: if isBool v then (if v then "0" else "1") else (toString v);
-    in { config, type, section ? "@${type}[0]" }:
-    attrs:
+  toUciBatch = { config, type, section, settings }:
+    with builtins;
     let
-      cmds = [ "set ${config}.${section}=${type}" ]
-        ++ (lib.attrsets.mapAttrsToList (option: value:
-          "set ${config}.${section}.${option}='${toAtom value}'") attrs);
+      section' = if section == "" then "@${type}[0]" else section;
+      toAtom = v: if isBool v then (if v then "1" else "0") else (toString v);
+      toCmd = option: value:
+        if isList value then
+          map
+          (elem: "add_list '${config}.${section'}.${option}'='${toAtom elem}'")
+          value
+        else
+          "set '${config}.${section'}.${option}'='${toAtom value}'";
+      cmds = [ "set '${config}.${section'}'='${type}'" ]
+        ++ (lib.attrsets.mapAttrsToList toCmd settings);
 
-    in lib.strings.concatStringsSep "\n" cmds;
+    in lib.strings.concatStringsSep "\n" (lib.lists.flatten cmds);
 }