refactor(flake): split assembly by concept

lib/default.nix

@@ -0,0 +1,9 @@
+{ lib }:
+let
+  files = import ./files.nix { inherit lib; };
+  network = import ./network.nix { inherit lib; };
+in
+{
+  inherit (files) collectNixFiles;
+  inherit (network) bridgeName deriveMac;
+}

lib/files.nix

@@ -0,0 +1,22 @@
+{ lib }:
+let
+  collectNixFiles =
+    dir:
+    lib.flatten (
+      lib.mapAttrsToList (
+        name: type:
+        let
+          path = dir + "/${name}";
+        in
+        if type == "directory" then
+          collectNixFiles path
+        else if type == "regular" && lib.hasSuffix ".nix" name then
+          [ path ]
+        else
+          [ ]
+      ) (builtins.readDir dir)
+    );
+in
+{
+  inherit collectNixFiles;
+}

lib/network.nix

@@ -0,0 +1,12 @@
+{ lib }:
+{
+  bridgeName = id: "br-vlan${toString id}";
+
+  deriveMac =
+    name:
+    let
+      hash = builtins.hashString "sha256" name;
+      octet = i: builtins.substring (i * 2) 2 hash;
+    in
+    lib.concatStringsSep ":" ([ "02" ] ++ map octet [ 0 1 2 3 4 ]);
+}