Android build gradle for react native with configurable versioning

android\app\build.gradle

apply plugin: "com.android.application"
apply from: project(':react-native-config').projectDir.getPath() + "/dotenv.gradle"

....

android {

...

    defaultConfig {
        applicationId "com.rnversioner"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode generateVersionCode()
        versionName generateVersionName()
    }
    
...

}


/**
 * Internal version number generator
 * Refer https://developer.android.com/google/play/publishing/multiple-apks.html#using-a-version-code-scheme
*/
private Integer generateVersionCode() {
  return rootProject.ext.minSdkVersion * 10000000 + project.env.get("MAJOR_VERSION").toInteger() * 10000 + project.env.get("MINOR_VERSION").toInteger() * 100 + project.env.get("PATCH_VERSION").toInteger()
}

/**
 * Internal version name generator
*/
private String generateVersionName() {
   String versionName = "${project.env.get("MAJOR_VERSION")}.${project.env.get("MINOR_VERSION")}.${project.env.get("PATCH_VERSION")}"
   if(project.env.get("PRE_RELEASE") != null && !project.env.get("PRE_RELEASE").isEmpty()) {
       versionName = versionName + "-" + project.env.get("PRE_RELEASE")
   }
   return versionName
}

...