Бесконечный скролл RxKotlin Android

EndlessList.kt

class EndlessList {
    companion object {
        fun <T> get(recyclerView: RecyclerView, next: (Int) -> Observable<Response<T>>): Observable<Response<T>> {
            var loading = false
            var hasNextPage = true
            return Observable.create<Int> {
                        val lm = recyclerView.layoutManager
                        val getLastVisible = if (lm is LinearLayoutManager) {
                            fun() = lm.findLastVisibleItemPosition()
                        } else if (lm is GridLayoutManager) {
                            fun() = lm.findLastVisibleItemPosition()
                        } else {
                            throw Exception("LayoutManager must be Linear or Grid")
                        }

                        if (lm.itemCount == 0) {
                            it.onNext(0)
                        }

                        val scrollListener = object : RecyclerView.OnScrollListener() {
                            override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
                                super.onScrolled(recyclerView, dx, dy)
                                if (dy <= 0) return
                                if (!hasNextPage) {
                                    it.onCompleted(); recyclerView?.removeOnScrollListener(this); return
                                }
                                val position = getLastVisible()
                                val updatePos = lm.itemCount - 3
                                if (!loading && position > updatePos) {
                                    it.onNext(lm.itemCount)
                                }
                            }
                        }
                        recyclerView.addOnScrollListener(scrollListener)
                    }
                    .doOnNext {
                        loading = true
                        //fixme cleanup log
                        Log.i("EndlessList", "offset $it")
                    }
                    .switchMap(next)
                    .doOnNext {
                        loading = false
                        hasNextPage = it.hasNextPage
                        var size = 1
                        if (it.data is List<*>) {
                            size = it.data.size
                        }
                        Log.i("EndlessList", "next $size ${it.hasNextPage}")
                    }
        }
    }
}