treewide: start transitioning to nixpkgs package structure

pkgs/applications/misc/rat/default.nix

@@ -0,0 +1,47 @@
+{
+  pins,
+  lib,
+  disableHardening ? true,
+  fetchFromGitHub,
+  stdenv,
+  unixtools,
+}:
+assert disableHardening -> lib.warn "nyxpkgs/rat disables hardening to avoid segfaults. You may want to consider overriding the package if this is undesirable" true; let
+  pin = pins.rat;
+
+  pname = "rat";
+  version = "2.0.1";
+in
+  stdenv.mkDerivation {
+    inherit pname version;
+
+    src = fetchFromGitHub {
+      inherit (pin.repository) owner repo;
+      sha256 = pin.hash;
+      rev = pin.revision;
+    };
+
+    # the code is so unsafe, it doesn't work with even one of hardening flags
+    # lol
+    hardeningDisable = lib.optionals disableHardening ["all"];
+
+    buildInputs = [unixtools.xxd];
+    buildPhase = ''
+      runHook preBuild
+      make linux_audio
+      runHook postBuild
+    '';
+
+    installPhase = ''
+      runHook preInstall
+      mkdir -p $out/bin
+      install -Dm755 ./bin/rat -t "$out/bin/"
+      runHook postInstall
+    '';
+
+    meta = {
+      description = "rat";
+      homepage = "https://github.com/thinkingsand/rat";
+      maintainers = with lib.maintainers; [NotAShelf];
+    };
+  }