RetrofitApiFactory.kt

interface RetrofitApi {
    fun create(): Retrofit
}

class ProductionRetrofitApi : RetrofitApi {
    override fun create(): Retrofit {
        val retrofit = Retrofit.Builder()
            .baseUrl("https://production-api.com")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        return retrofit
    }
}

class StagingRetrofitApi : RetrofitApi {
    override fun create(): Retrofit {
        val retrofit = Retrofit.Builder()
            .baseUrl("https://staging-api.com")
            .addConverterFactory(GsonConverterFactory.create())
            .build()
        return retrofit
    }
}

class RetrofitApiFactory {
    companion object {
        fun createRetrofitApi(apiType: String): RetrofitApi? {
            return when (apiType) {
                "production" -> ProductionRetrofitApi()
                "staging" -> StagingRetrofitApi()
                else -> null
            }
        }
    }
}

val productionApi = RetrofitApiFactory.createRetrofitApi("production")?.create()
val stagingApi = RetrofitApiFactory.createRetrofitApi("staging")?.create()