fmt/support/build.gradle

import java.nio.file.Paths

// General gradle arguments for root project
buildscript {    
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath "com.android.tools.build:gradle:9.0.0"
    }
}
repositories {
    google()
    mavenCentral()
}

// Project's root where CMakeLists.txt exists: rootDir/support/.cxx -> rootDir

def rootDir = Paths.get(project.buildDir.getParent()).getParent()
println("rootDir: ${rootDir}")

// Output: Shared library (.so) for Android

apply plugin: "com.android.library"
android {
    namespace = "dev.fmt"

    compileSdk 36   // Target Android 16 (API 36).

    /*  Target ABI
      - This option controls target platform of module
      - The platform might be limited by compiler's support
        some can work with Clang(default), but some can work only with GCC...
        if bad, both toolchains might not support it
    */

    ndkVersion = "28.2.13676358"

    defaultConfig {
        minSdk 21    // Android 5.0+
        targetSdkVersion 36 // Follow Compile SDK
        versionCode 34      // Follow release count
        versionName "7.1.2" // Follow Official version

        ndk{
            abiFilters "arm64-v8a", "armeabi-v7a", "x86_64"
        }

        externalNativeBuild {
            cmake {
                arguments "-DANDROID_STL=c++_shared"    // Specify Android STL
                arguments "-DBUILD_SHARED_LIBS=true"    // Build shared object
                arguments "-DFMT_TEST=false"            // Skip test
                arguments "-DFMT_DOC=false"             // Skip documentation
                cppFlags  "-std=c++17"
                targets   "fmt"
            }
        }
        println(externalNativeBuild.cmake.cppFlags)
        println(externalNativeBuild.cmake.arguments)
    }

    // External Native build
    //  - Use existing CMakeList.txt
    //  - Give path to CMake. This gradle file should be 
    //    neighbor of the top level cmake
    externalNativeBuild {
        cmake {
            version = "3.22.1"
            path "${rootDir}/CMakeLists.txt"
            // buildStagingDirectory "./build"  // Custom path for cmake output
        }
    }
    
    sourceSets{
        // Android Manifest for Gradle
        main {
            manifest.srcFile "AndroidManifest.xml"
        }
    }

    // https://developer.android.com/studio/build/native-dependencies#build_system_configuration
    buildFeatures {
        prefab = true
        prefabPublishing = true
    }
    prefab {
        fmt {
            headers = "${rootDir}/include"
        }
    }
}

assemble.doLast
{
    /*
    *- Instead of `ninja install`, Gradle will deploy the files.
    *- We are doing this since FMT is dependent to the ANDROID_STL after build
    */
    copy {
        from "build/intermediates/cmake"
        into "${rootDir}/libs"
    }
    // Copy debug binaries
    copy {
        from "${rootDir}/libs/debug/obj"
        into "${rootDir}/libs/debug"
    }
    // Copy Release binaries
    copy {
        from "${rootDir}/libs/release/obj"
        into "${rootDir}/libs/release"
    }
    // Remove empty directory
    delete "${rootDir}/libs/debug/obj"
    delete "${rootDir}/libs/release/obj"

    // Copy AAR files. Notice that the aar is named after the folder of this script.
    copy {
        from "build/outputs/aar/support-release.aar"
        into "${rootDir}/libs"
        rename "support-release.aar", "fmt-release.aar"
    }
    copy {
        from "build/outputs/aar/support-debug.aar"
        into "${rootDir}/libs"
        rename "support-debug.aar", "fmt-debug.aar"
    }
}