feat(flake)!: convert to fs-defined modules

Place all modules in either:
    - `modules/${manager}/${module}.nix`
    - `modules/${manager}/${module}/default.nix`

- `${manager}` - One of `nixos`, `nix-on-droid`, `nix-darwin` or `home-manager`
- `${module}` - Module name (autoimported by configurations, used for exporting)

modules/home-manager/README.md

@@ -0,0 +1,5 @@
+Add your reusable home-manager modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/home-manager/default.nix

@@ -1,10 +0,0 @@
-# Add your reusable home-manager modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  reo101-shell = import ./reo101-shell;
-  reo101-river = import ./reo101-river;
-  reo101-wezterm = import ./reo101-wezterm;
-}

modules/nix-darwin/README.md

@@ -0,0 +1,5 @@
+Add your reusable nix-darwin modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nix-darwin/default.nix

@@ -1,10 +0,0 @@
-# Add your reusable nix-darwin modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  brew = import ./brew;
-  yabai = import ./yabai;
-  system = import ./system;
-}

modules/nix-on-droid/README.md

@@ -0,0 +1,5 @@
+Add your reusable nix-on-droid modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nix-on-droid/default.nix

@@ -1,7 +0,0 @@
-# Add your reusable nix-on-droid modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-}

modules/nixos/README.md

@@ -0,0 +1,5 @@
+Add your reusable NixOS modules to this directory (<https://nixos.wiki/wiki/Module>)
+
+These are considered modules:
+- files, ending in `.nix` (excluding `default.nix`)
+- directories, containing `default.nix`

modules/nixos/default.nix

@@ -1,8 +0,0 @@
-# Add your reusable NixOS modules to this directory, on their own file (https://nixos.wiki/wiki/Module).
-# These should be stuff you would like to share with others, not your personal configurations.
-
-{
-  # List your module files here
-  # my-module = import ./my-module.nix;
-  jellyfin = import ./jellyfin.nix;
-}

util/default.nix

@@ -7,7 +7,12 @@ let
   inherit (lib.attrsets) filterAttrs;
 in
 rec {
-  # Directory walker
+  # Boolean helpers
+  and = lib.all lib.id;
+  or  = lib.any lib.id;
+  eq  = x: y: x == y;
+
+  # Directory walking helpers
   recurseDir = dir:
     mapAttrs
       (file: type:
@@ -17,27 +22,19 @@ rec {
       )
       (builtins.readDir dir);
 
-  # NOTE: Implying `attrs` is the output of `recurseDir`
+  allSatisfy = predicate: attrs: attrset:
-  hasFiles = files: attrs:
+    and
-    builtins.all
-      lib.id
       (builtins.map
-        (file:
+        (attr:
-          builtins.hasAttr file attrs &&
+          builtins.hasAttr attr attrset &&
-          builtins.getAttr file attrs == "regular")
+          predicate (builtins.getAttr attr attrset))
-        files);
+        attrs);
 
-  # NOTE: Implying `attrs` is the output of `recurseDir`
+  # NOTE: Implying last argument is the output of `recurseDir`
-  hasDirectories = directories: attrs:
+  hasFiles = allSatisfy (eq "regular");
-    builtins.all
-      lib.id
-      (builtins.map
-        (directory:
-          builtins.hasAttr directory attrs &&
-          lib.isAttrs (builtins.getAttr directory attrs))
-        directories);
 
-  and = lib.all lib.id;
+  # NOTE: Implying last argument is the output of `recurseDir`
+  hasDirectories = allSatisfy lib.isAttrs;
 
   # pkgs helpers
   forEachSystem = lib.genAttrs [
@@ -53,11 +50,61 @@ rec {
       (system:
         f nixpkgs.legacyPackages.${system});
 
+  # Modules helpers
+  createModules = baseDir: { passthru ? { inherit inputs outputs; }, ... }:
+    lib.pipe baseDir [
+      # Read given directory
+      builtins.readDir
+      # Map each entry to a module
+      (lib.mapAttrs'
+        (name: type:
+          let
+            moduleDir = baseDir + "/${name}";
+          in
+          if and [
+            (type == "directory")
+            (hasFiles ["default.nix"] (builtins.readDir moduleDir))
+          ] then
+            # Classic module in a directory
+            lib.nameValuePair
+              name
+              (import moduleDir)
+          else if and [
+            (type == "regular")
+            (lib.hasSuffix ".nix" name)
+          ] then
+            # Classic module in a file
+            lib.nameValuePair
+              (lib.removeSuffix ".nix" name)
+              (import moduleDir)
+          else
+            # Invalid module
+            lib.nameValuePair
+              name
+              null))
+      # Filter invalid modules
+      (lib.filterAttrs
+        (moduleName: module:
+          module != null))
+      # Passthru if needed
+      (lib.mapAttrs
+        (moduleName: module:
+          if and [
+            (builtins.isFunction
+              module)
+            (eq
+              (lib.pipe module [builtins.functionArgs builtins.attrNames])
+              (lib.pipe passthru [builtins.attrNames]))
+          ]
+          then module passthru
+          else module))
+    ];
+
   # Modules
-  nixosModules = import ../modules/nixos;
+  nixosModules       = createModules ../modules/nixos        { };
-  nixOnDroidModules = import ../modules/nix-on-droid;
+  nixOnDroidModules  = createModules ../modules/nix-on-droid { };
-  nixDarwinModules = import ../modules/nix-darwin;
+  nixDarwinModules   = createModules ../modules/nix-darwin   { };
-  homeManagerModules = import ../modules/home-manager;
+  homeManagerModules = createModules ../modules/home-manager { };
 
   # Machines
   machines = recurseDir ../machines;
@@ -72,8 +119,8 @@ rec {
 
     modules = [
       (root + "/configuration.nix")
-      inputs.home-manager.nixosModules.home-manager
       inputs.nur.nixosModules.nur
+      inputs.home-manager.nixosModules.home-manager
       {
         home-manager = {
           useGlobalPkgs = false;
@@ -87,6 +134,9 @@ rec {
           };
         };
       }
+      {
+        networking.hostName = hostname;
+      }
     ] ++ (builtins.attrValues nixosModules);
 
     specialArgs = {
@@ -166,7 +216,7 @@ rec {
       (builtins.attrValues
         (builtins.mapAttrs
           (system: hosts:
-            lib.attrsets.filterAttrs
+            lib.filterAttrs
               (host: config:
                 config != null)
               (builtins.mapAttrs