Abstract Factory for Retro APIs

RetroDoggo.kt

interface RetroDogApi {
  @GET("/dogs/{doggoName}")
  Flowable<Dog> getDoggo(@Path("doggoName") String doggoName);
}

interface DogApi {
  Flowable<Dog> getDoggo(String doggoName);
}

interface UrlInfoApi {
  Flowable<String> getBaseUrl()
}

interface RetroDogApiFactory {
  fun createRetroDogApi(baseUrl: String): RetroDogApi
}

class RealRetroDogApiFactory: RetroDogApiFactory {
  fun createRetroDogApi(baseUrl: String) {
    val retrofit = Retrofit.Builder()
      .baseUrl(baseUrl)
      .build()
    return retrofit.create(RetroDogApi::class.java)
  }
}

class DogClient(val retroDogApiFactory: DogApiFactory, val urlInfoApi: UrlInfoApi): DogApi {  
  Flowable<Dog> getDoggo(String doggoName) {
    return urlInfoApi.getBaseUrl()
      .flatMap((baseUrl) -> {
        return dogApiFactory.createRetroDogApi(baseUrl)
      })
      .flatMap((retroDogApi) -> {
        return retroDogApi.getDog(doggoName)
      })
  }
}

class UseIt {
  fun use() {
    val retroDogApiFactory = RealRetroDogApiFactory()
    val urlInfoApi = UrlInfoClient() // need to create this implementation
    val dogApi = DogClient(retroDogApiFactory, urlInfoApi)
    dogApi.getDoggo("fido")
      .subscribeOn(...)
      .observeOn(...)
      .subscribe(...)
  }
}