shell.nix: Update dependencies and add Gradle

Update OpenJDK to version 17, Android build tools to 33.0.1 and platform to 33.
These are required to build with Gradle.

Add Gradle to the environment, which must be wrapped to fix a
permissions issue. Setting `GRADLE_OPTS` has no effect as it seems not
to be passed down to the daemon.

CONTRIBUTING.md

@@ -28,6 +28,8 @@ Building the debug apk:
 ./gradlew assembleDebug
 ```
 
+Nix users can call gradle directly: `gradle assembleDebug`.
+
 If the build succeeds, the debug apk is located in `build/outputs/apk/debug/app-debug.apk`.
 
 ## Debugging on your phone

shell.nix

@@ -1,19 +1,33 @@
 { pkgs ? import <nixpkgs> {
   config.android_sdk.accept_license = true;
   config.allowUnfree = true;
-  } }:
+} }:
 
 let
-  jdk = pkgs.openjdk8;
+  jdk = pkgs.openjdk17;
+  build_tools_version = "33.0.1";
 
   android = pkgs.androidenv.composeAndroidPackages {
-    buildToolsVersions = [ "30.0.3" ];
-    platformVersions = [ "30" ];
+    buildToolsVersions = [ build_tools_version ];
+    platformVersions = [ "33" ];
     abiVersions = [ "armeabi-v7a" ];
   };
 
-in
-pkgs.mkShell {
-  buildInputs = [ pkgs.findutils jdk android.androidsdk pkgs.fontforge ];
-  ANDROID_HOME = "${android.androidsdk}/libexec/android-sdk";
+  ANDROID_SDK_ROOT = "${android.androidsdk}/libexec/android-sdk";
+
+  # Without this option, aapt2 fails to run with a permissions error.
+  gradle_wrapped = pkgs.runCommandLocal "gradle-wrapped" {
+    nativeBuildInputs = with pkgs; [ makeBinaryWrapper ];
+  } ''
+    mkdir -p $out/bin
+    ln -s ${pkgs.gradle}/bin/gradle $out/bin/gradle
+    wrapProgram $out/bin/gradle \
+    --add-flags "-Dorg.gradle.project.android.aapt2FromMavenOverride=${ANDROID_SDK_ROOT}/build-tools/${build_tools_version}/aapt2"
+  '';
+
+in pkgs.mkShell {
+  buildInputs =
+    [ pkgs.findutils pkgs.fontforge jdk android.androidsdk gradle_wrapped ];
+  JAVA_HOME = jdk.home;
+  inherit ANDROID_SDK_ROOT;
 }