Helper for packaging/grabbing osx apps; use it for OBS, keycastr, vlc

nix/system/worktop/darwin-configuration.nix

@@ -1,5 +1,35 @@
 { config, pkgs, ... }:
+let
+  obs-studio = pkgs.callPackage ./makeApp.nix rec {
+    name = "OBS";
+    version = "29.1.1";
+    src = pkgs.fetchurl {
+      url = "https://cdn-fastly.obsproject.com/downloads/obs-studio-${version}-macos-arm64.dmg";
+      sha256 = "07rhswgx3zqpn32n4ipf34zjjm2cx8fmrb7gliiw6hskwcbbs3yi";
+    };
+  };
 
+  vlc =
+    pkgs.callPackage ./makeApp.nix rec {
+      name = "VLC";
+      version = "3.0.18";
+      sourceRoot = "${name}.app";
+      src = pkgs.fetchurl {
+        url = "https://get.videolan.org/vlc/3.0.18/macosx/vlc-${version}-arm64.dmg";
+        sha256 = "0iwgcrwcfyw0r41kjx4hx1sy37mzx5q8nlbzh58gs8ajpjymkhlr";
+      };
+    };
+
+  keycastr =
+    pkgs.callPackage ./makeApp.nix rec {
+      name = "KeyCastr";
+      version = "0.9.13";
+      src = pkgs.fetchurl {
+        url = "https://github.com/keycastr/keycastr/releases/download/v${version}/KeyCastr.app.zip";
+        sha256 = "1pp0gslq53azhbbyxp12gjy9iaysrf56l16swqdaf4z21p7iag7k";
+      };
+    };
+in
 {
 
   nixpkgs.config.allowUnfree = true;
@@ -15,9 +45,11 @@
       pkgs.slack
       pkgs._1password
       pkgs.tailscale
+      obs-studio
+      vlc
+      keycastr
+
       # wishlist
-      # LICEcap
-      # keycastr
       # todo (unsupported on aarch64-darwin):
       # pkgs.spotify
       # pkgs.firefox

nix/system/worktop/makeApp.nix

@@ -0,0 +1,51 @@
+{ name
+, appname ? name
+, version
+, src
+, sourceRoot ? "."
+, # from nix
+  pkgs
+, stdenv
+, unzip
+, ...
+}:
+if stdenv.isDarwin then
+  pkgs.stdenv.mkDerivation
+  {
+    name = "${name}-${version}";
+    version = "${version}";
+    src = src;
+
+    sourceRoot = "${appname}.app";
+    phases = [ "unpackPhase" "installPhase" ];
+    unpackCmd = ''
+      echo "File to unpack: $curSrc"
+      if ! [[ "$curSrc" =~ \.dmg$ ]]; then return 1; fi
+      mnt=$(mktemp -d -t ci-XXXXXXXXXX)
+
+      function finish {
+        echo "Detaching $mnt"
+        /usr/bin/hdiutil detach $mnt -force
+        rm -rf $mnt
+      }
+      trap finish EXIT
+
+      echo "Attaching $mnt"
+      /usr/bin/hdiutil attach -nobrowse -readonly $src -mountpoint $mnt
+
+      echo "What's in the mount dir"?
+      ls -la $mnt/
+
+      echo "Copying contents"
+      shopt -s extglob
+      DEST="$PWD"
+      (cd "$mnt"; cp -a !(Applications) "$DEST/")
+    '';
+    nativeBuildInputs = [ pkgs.unzip ];
+    installPhase = ''
+      mkdir -p $out/Applications/${appname}.app
+      cp -a ./. $out/Applications/${appname}.app/
+    '';
+  }
+else
+  { }