Initial MVP

2026-07-27 00:16:46 -04:00
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+# Reproducible build of the debug APK, written the way a nixpkgs package would be.
+#
+# Two hard problems this file solves:
+#   1. The Android SDK  -> supplied via `androidSdk` (built by androidenv in flake.nix)
+#                          and exposed through ANDROID_HOME.
+#   2. Gradle's network  -> `gradle` with `mitmCache` intercepts Gradle's HTTP(S)
+#      dependency fetches   traffic and replays it from a hash-locked `deps.json`,
+#                           so the build itself runs fully offline & reproducibly.
+#
+# Regenerate deps.json whenever dependencies change:
+#   nix build .#default.mitmCache.updateScript && ./result
+{
+  lib,
+  stdenv,
+  gradle,
+  makeWrapper,
+  androidSdk,
+  androidHome,
+  buildToolsVersion ? "35.0.0",
+}:
+
+stdenv.mkDerivation (finalAttrs: {
+  pname = "music-remote";
+  version = "0.1.0";
+
+  src = ./.;
+
+  nativeBuildInputs = [
+    gradle
+    androidSdk
+    makeWrapper
+  ];
+
+  ANDROID_HOME = androidHome;
+  # Some tooling still reads the deprecated variable; set both to be safe.
+  ANDROID_SDK_ROOT = androidHome;
+
+  # Gradle downloads a prebuilt aapt2 from Maven that isn't patched for NixOS's
+  # loader. Point AGP at the aapt2 that androidenv already patched instead.
+  gradleFlags = [
+    "-Pandroid.aapt2FromMavenOverride=${androidHome}/build-tools/${buildToolsVersion}/aapt2"
+  ];
+
+  # Build the (unsigned) debug APK. `assembleRelease` would additionally need a
+  # signing keystore, which is out of scope for a hello-world.
+  gradleBuildTask = "assembleDebug";
+
+  # Run the JVM unit tests as the derivation's check phase.
+  doCheck = true;
+  gradleCheckTask = "testDebugUnitTest";
+
+  mitmCache = gradle.fetchDeps {
+    # `pkg` (rather than the manual's `inherit pname`) is what an out-of-tree
+    # flake package must pass: the manual's shorthand resolves `pkgs.<pname>`,
+    # which only exists for packages that live inside nixpkgs itself.
+    pkg = finalAttrs.finalPackage;
+    data = ./deps.json;
+  };
+
+  installPhase = ''
+    runHook preInstall
+    install -Dm644 app/build/outputs/apk/debug/app-debug.apk \
+      "$out/music-remote.apk"
+    runHook postInstall
+  '';
+
+  meta = {
+    description = "Hello-world Kotlin / Jetpack Compose (Material 3) Android app";
+    platforms = lib.platforms.linux;
+    license = lib.licenses.mit;
+  };
+})