chore: initial commit

lib/template/default.nix

@@ -0,0 +1,50 @@
+{ core-inputs
+, user-inputs
+, snowfall-lib
+}:
+
+let
+  inherit (builtins) baseNameOf;
+  inherit (core-inputs.nixpkgs.lib) assertMsg foldl;
+
+  user-templates-root = snowfall-lib.fs.get-file "templates";
+in
+{
+  template = {
+    # Create flake templates.
+    # Type: Attrs -> Attrs
+    # Usage: create-templates { src = ./my-templates; overrides = { inherit another-template; default = "my-template"; }; }
+    #   result: { another-template = ...; my-template = ...; default = ...; }
+    create-templates =
+      { src ? user-templates-root
+      , overrides ? { }
+      }:
+      let
+        user-templates = snowfall-lib.fs.get-directories src;
+        create-template-metadata = template: {
+          name = builtins.unsafeDiscardStringContext (baseNameOf template);
+          path = template;
+        };
+        templates-metadata = builtins.map create-template-metadata user-templates;
+        merge-templates = templates: metadata:
+          templates // {
+            ${metadata.name} = (overrides.${metadata.name} or { }) // {
+              inherit (metadata) path;
+            };
+          };
+        templates-without-default = foldl merge-templates { } templates-metadata;
+        default-template =
+          if overrides.default or null == null then
+            { }
+          else if builtins.isAttrs overrides.default then
+            { default = overrides.default; }
+          else if templates-without-default.${overrides.default} or null != null then
+            { default = templates-without-default.${overrides.default}; }
+          else
+            { };
+        overrides-without-default = builtins.removeAttrs overrides [ "default" ];
+        templates = templates-without-default // default-template // overrides-without-default;
+      in
+      templates;
+  };
+}