refactor(nix): cleanup package

nix/package.nix

@@ -0,0 +1,68 @@
+{
+  lib,
+  stdenv,
+  go,
+  rustPlatform,
+  lto ? !optimizeSize,
+  optimizeSize ? false,
+}:
+
+let
+  fs = lib.fileset;
+  toRustFlags = flags: toString (lib.mapAttrsToList (name: value: "-C ${name}=${value}") flags);
+in
+assert lib.assertMsg (lto -> !optimizeSize) "`lto` and `optimizeSize` are mutually exclusive";
+rustPlatform.buildRustPackage rec {
+  pname = "refraction";
+  inherit (passthru.cargoToml.package) version;
+
+  src = fs.toSource {
+    root = ../.;
+    fileset = fs.intersection (fs.gitTracked ../.) (
+      fs.unions [
+        ../src
+        ../build.rs
+        ../Cargo.lock
+        ../Cargo.toml
+        ../tags
+      ]
+    );
+  };
+
+  cargoLock.lockFile = ../Cargo.lock;
+
+  # `panic=abort` breaks tests womp womp
+  doCheck = stdenv.buildPlatform.canExecute stdenv.hostPlatform && !optimizeSize;
+
+  env = {
+    RUSTFLAGS = toRustFlags (
+      lib.optionalAttrs lto {
+        lto = "thin";
+        embed-bicode = "yes";
+      }
+      // lib.optionalAttrs optimizeSize {
+        codegen-units = "1";
+        opt-level = "s";
+        panic = "abort";
+        strip = "symbols";
+      }
+    );
+  };
+
+  passthru = {
+    cargoToml = lib.importTOML ../Cargo.toml;
+    # For container images
+    dockerArchitecture = go.GOARCH;
+  };
+
+  meta = {
+    description = "Discord bot for Prism Launcher";
+    homepage = "https://github.com/PrismLauncher/refraction";
+    license = lib.licenses.gpl3Plus;
+    maintainers = with lib.maintainers; [
+      getchoo
+      Scrumplex
+    ];
+    mainProgram = "refraction";
+  };
+}