hosts/default.nix: change mkSystem

hosts/default.nix

@@ -3,42 +3,72 @@
   inputs,
   ...
 }: let
-  inherit (inputs.self) lib;
-  inherit (lib.extendedLib.builders) mkSystem;
-  inherit (lib.extendedLib.modules) mkModuleTree';
+  inherit (inputs) self;
+  inherit (self) lib;
+  # inherit (lib.extendedLib.builders) mkSystem;
+  # inherit (lib.extendedLib.modules) mkModuleTree';
   inherit (lib.lists) concatLists flatten singleton;
-
+  inherit (lib) mkDefault nixosSystem recursiveUpdate;
+  inherit (builtins) filter map toString;
+  inherit (lib.filesystem) listFilesRecursive;
+  inherit (lib.strings) hasSuffix;
   # NOTE: This was inspired by raf, and I find this
   # to be quite a sane way of managing all modules in my flake.
 
-  mkModulesFor = hostname:
-    flatten (
-      concatLists [
-        # Derive host specific module path from the first argument of the
-        # function. Should be a string, obviously.
-        (singleton ./${hostname}/default.nix)
-
-        # Recursively import all module trees (i.e. directories with a `module.nix`)
-        # for given moduleTree directories
-        (mkModuleTree' {path = ../modules;})
-      ]
+  mkSystem = {
+    withSystem,
+    system,
+    hostname,
+    ...
+  } @ args:
+    withSystem system (
+      {
+        inputs',
+        self',
+        ...
+      }:
+        nixosSystem {
+          inherit system;
+          specialArgs =
+            recursiveUpdate
+            {
+              inherit lib;
+              inherit inputs inputs';
+              inherit self self';
+            }
+            (args.specialArgs or {});
+          modules = concatLists [
+            # This is used to pre-emptively set the hostPlatform for nixpkgs.
+            # Also, we set the system hostname here.
+            (singleton {
+              networking.hostName = args.hostname;
+              nixpkgs.hostPlatform = mkDefault args.system;
+            })
+            (flatten (
+              concatLists [
+                (singleton ./${hostname}/default.nix)
+                (
+                  filter (hasSuffix "module.nix") (
+                    map toString (listFilesRecursive ../modules)
+                  )
+                )
+              ]
+            ))
+          ];
+        }
     );
 in {
   flake.nixosConfigurations = {
     temperance = mkSystem {
       inherit withSystem;
       system = "x86_64-linux";
-
       hostname = "temperance";
-      modules = mkModulesFor "temperance";
     };
 
     hermit = mkSystem {
       inherit withSystem;
       system = "x86_64-linux";
-
       hostname = "hermit";
-      modules = mkModulesFor "hermit";
     };
   };
 }