1 files changed, 80 insertions, 0 deletions
diff --git a/lib.nix b/lib.nix
new file mode 100644
index 0000000..f7f07f3
--- /dev/null
+++ b/lib.nix
@@ -0,0 +1,80 @@
+lib: {
+  self,
+  platforms ? {
+    "x86_64-linux" = {
+      os = "ubuntu-latest";
+      arch = "x64";
+    };
+
+    "aarch64-linux" = {
+      os = "ubuntu-latest";
+      arch = "aarch64";
+    };
+
+    "x86_64-darwin" = {
+      os = "macos-latest";
+      arch = "x64";
+    };
+  },
+  ...
+}: let
+  platforms' =
+    platforms
+    // {
+      fallback = lib.warn "an output in the job matrix is not supported!" {
+        os = null;
+        arch = null;
+      };
+    };
+
+  mkMatrixMulti = systems: output:
+    lib.flatten (
+      lib.mapAttrsToList (
+        system:
+          lib.mapAttrsToList (
+            attr: _: {
+              inherit (platforms'.${system} or platforms'.fallback) arch os;
+              attr = "${output}.${system}.${attr}";
+            }
+          )
+      )
+      (lib.getAttrs systems self.${output})
+    );
+
+  mkMatrixFlat = {
+    output,
+    suffix ? "",
+  }:
+    lib.mapAttrsToList (
+      attr: deriv: {
+        inherit (platforms'.${deriv.pkgs.system} or platforms'.fallback) os arch;
+        attr = "${output}.${attr}${suffix}";
+      }
+    )
+    self.${output};
+in {
+  inherit
+    mkMatrixMulti
+    mkMatrixFlat
+    ;
+
+  mkMatrix = {
+    output,
+    systems ? (builtins.attrNames platforms),
+  }: let
+    systemMatrix = mkMatrixFlat {
+      inherit output;
+      suffix = ".config.system.build.toplevel";
+    };
+  in
+    {
+      "nixosConfigurations" = systemMatrix;
+      "darwinConfigurations" = systemMatrix;
+      "homeConfigurations" = mkMatrixFlat {
+        inherit output;
+        suffix = ".activationPackage";
+      };
+    }
+    .${output}
+    or (mkMatrixMulti systems output);
+}