From 2c16b45a25d489a07749d075dabba47b59010d52 Mon Sep 17 00:00:00 2001
From: Fabrizio Cucci <fabriziocucci@meta.com>
Date: Fri, 15 Mar 2024 09:32:26 -0700
Subject: [PATCH] Fix auto-download of CMake

Summary:
Changelog: [Internal]

This is an attempt to fix [#39783](https://github.com/facebook/react-native/issues/39783).

It seems that when `configureBuildForHermes` runs (as part of `yarn android` in `rn-tester`) cmake may not be available and is not installed automatically:
* for 3p, even after installing the latest Android Studio, cmake 3.22.1 is not available by default but needs to be installed manually
* for Meta employees, same story when looking at the `ANDROID_HOME` set by the `setup_fb4a.sh` in the `.zshrc` file:
```
# added by setup_fb4a.sh
export ANDROID_SDK=/opt/android_sdk
export ANDROID_NDK_REPOSITORY=/opt/android_ndk
export ANDROID_HOME=${ANDROID_SDK}
export PATH=${PATH}:${ANDROID_SDK}/emulator:${ANDROID_SDK}/tools:${ANDROID_SDK}/tools/bin:${ANDROID_SDK}/platform-tools
```

This diff introduces an explicit task to install cmake.

### ALTERNATIVE 1

See D54897379.

### ALTERNATIVE 2

Suggested by cortinico:

> Create a mini module called :packages:react-native:ReactAndroid:hermes-engine:cmake-downloader which just triggers an empty cmake build via Android SDK

Differential Revision: D54859484
---
 .../hermes-engine/build.gradle.kts            | 51 +++++++++++++------
 1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts b/packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts
index 17eb24f355b5..1e2552ef6a7c 100644
--- a/packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts
+++ b/packages/react-native/ReactAndroid/hermes-engine/build.gradle.kts
@@ -20,22 +20,27 @@ group = "com.facebook.react"
 version = parent?.properties?.get("publishing_version")?.toString()!!
 
 val cmakeVersion = parent?.properties?.get("cmake_version")?.toString()!!
-
-/**
- * We use the bundled version of CMake in the Android SDK if available, to don't force Android users
- * to install CMake externally.
- */
-fun findCmakePath(cmakeVersion: String): String {
-  val cmakeRelativePath = "cmake/${cmakeVersion}/bin/cmake"
-  if (System.getenv("ANDROID_SDK_ROOT") != null &&
-      File("${System.getenv("ANDROID_SDK_ROOT")}/${cmakeRelativePath}").exists()) {
-    return "${System.getenv("ANDROID_SDK_ROOT")}/${cmakeRelativePath}"
+val cmakePath = "${getSDKPath()}/cmake/$cmakeVersion"
+val cmakeBinaryPath = "${cmakePath}/bin/cmake"
+
+fun getSDKPath(): String {
+  val androidSdkRoot = System.getenv("ANDROID_SDK_ROOT")
+  val androidHome = System.getenv("ANDROID_HOME")
+  return when {
+    !androidSdkRoot.isNullOrBlank() -> androidSdkRoot
+    !androidHome.isNullOrBlank() -> androidHome
+    else -> throw IllegalStateException("Neither ANDROID_SDK_ROOT nor ANDROID_HOME is set.")
   }
-  if (System.getenv("ANDROID_HOME") != null &&
-      File("${System.getenv("ANDROID_HOME")}/${cmakeRelativePath}").exists()) {
-    return "${System.getenv("ANDROID_HOME")}/${cmakeRelativePath}"
+}
+
+fun getSDKManagerPath(): String {
+  val metaSdkManagerPath = File("${getSDKPath()}/cmdline-tools/latest/bin/sdkmanager")
+  val ossSdkManagerPath = File("${getSDKPath()}/tools/bin/sdkmanager")
+  return when {
+    metaSdkManagerPath.exists() -> metaSdkManagerPath.absolutePath
+    ossSdkManagerPath.exists() -> ossSdkManagerPath.absolutePath
+    else -> throw GradleException("Could not find sdkmanager executable.")
   }
-  return "cmake"
 }
 
 val reactNativeRootDir = project(":packages:react-native:ReactAndroid").projectDir.parent
@@ -111,14 +116,28 @@ val unzipHermes by
       into(hermesDir)
     }
 
+// NOTE: ideally, we would like CMake to be installed automatically by the `externalNativeBuild`
+// below. To do that, we would need the various `ConfigureCMake*` tasks to run *before*
+// `configureBuildForHermes` and `buildHermesC` so that CMake is available for their run. But the
+// `ConfigureCMake*` tasks depend upon the `ImportHermesc.cmake` file which is actually generated by
+// the two tasks mentioned before, so we install CMake manually to break the circular dependency.
+
+val installCMake by
+    tasks.registering(Exec::class) {
+      onlyIf { !File(cmakePath).exists() }
+      commandLine(
+          windowsAwareCommandLine(getSDKManagerPath(), "--install", "cmake;${cmakeVersion}"))
+    }
+
 val configureBuildForHermes by
     tasks.registering(Exec::class) {
+      dependsOn(installCMake)
       workingDir(hermesDir)
       inputs.dir(hermesDir)
       outputs.files(hermesBuildOutputFileTree)
       commandLine(
           windowsAwareCommandLine(
-              findCmakePath(cmakeVersion),
+              cmakeBinaryPath,
               if (Os.isFamily(Os.FAMILY_WINDOWS)) "-GNMake Makefiles" else "",
               "-S",
               ".",
@@ -135,7 +154,7 @@ val buildHermesC by
       outputs.file(hermesCOutputBinary)
       commandLine(
           windowsAwareCommandLine(
-              findCmakePath(cmakeVersion),
+              cmakeBinaryPath,
               "--build",
               hermesBuildDir.toString(),
               "--target",