presenterm: fix linking to libsixel on darwin & refactor (#418671)

pkgs/by-name/pr/presenterm/package.nix

@@ -3,12 +3,15 @@
   stdenv,
   rustPlatform,
   fetchFromGitHub,
+  makeBinaryWrapper,
   lld,
   libsixel,
   versionCheckHook,
   nix-update-script,
 }:
-
+let
+  inherit (stdenv.hostPlatform) isDarwin isx86_64;
+in
 rustPlatform.buildRustPackage (finalAttrs: {
   pname = "presenterm";
   version = "0.14.0";
@@ -20,9 +23,13 @@ rustPlatform.buildRustPackage (finalAttrs: {
     hash = "sha256-vBEHk0gQe4kUTtH4qtc0jVfDvYGabnkJrwPxmxt10hs=";
   };
 
-  nativeBuildInputs = lib.optionals (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) [
-    lld
-  ];
+  nativeBuildInputs =
+    lib.optionals isDarwin [
+      makeBinaryWrapper
+    ]
+    ++ lib.optionals (isDarwin && isx86_64) [
+      lld
+    ];
 
   buildInputs = [
     libsixel
@@ -35,7 +42,7 @@ rustPlatform.buildRustPackage (finalAttrs: {
   useFetchCargoVendor = true;
   cargoHash = "sha256-u0wOWKAfzi1Fxmx6x2ckrIv/PKgtqKrDiDauD4/BY24=";
 
-  env = lib.optionalAttrs (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isx86_64) {
+  env = lib.optionalAttrs (isDarwin && isx86_64) {
     NIX_CFLAGS_LINK = "-fuse-ld=lld";
   };
 
@@ -48,6 +55,12 @@ rustPlatform.buildRustPackage (finalAttrs: {
     "--skip=external_snippet"
   ];
 
+  # sixel-sys is dynamically linked to libsixel
+  postInstall = lib.optionalString isDarwin ''
+    wrapProgram $out/bin/presenterm \
+      --prefix DYLD_LIBRARY_PATH : "${lib.makeLibraryPath [ libsixel ]}"
+  '';
+
   nativeInstallCheckInputs = [
     versionCheckHook
   ];