A wrapper around retrofit2.Callback

RetrofitCallback.kt

abstract class RetrofitCallback<T> : retrofit2.Callback<T> {

    final override fun onResponse(call: Call<T>, response: Response<T>) =
            if (response.isSuccessful) onSuccess(response.body())
            else
                onError(when (response.code()) {
                    401 -> Failure.Unauthorized()
                    404 -> Failure.NotFound()
                    409 -> Failure.Conflict()
                    500 -> Failure.InternalServerError()
                    else -> Failure.Generic()
                })

    final override fun onFailure(call: Call<T>, t: Throwable) =
            onError(t)

    protected abstract fun onSuccess(t: T)

    protected abstract fun onError(t: Throwable)
}