import { id, Unit } from "../../../main";
import { AsyncState } from "../../async/state";
import { Coroutine } from "../../coroutines/state";
import { replaceWith } from "../../fun/domains/updater/domains/replaceWith/state";
import {
  ValueInfiniteStreamState,
  ValueInfiniteStreamWritableState,
  ValueStreamPosition,
} from "../state";
import { ValueStreamCo } from "./builder";

export const ValueInfiniteStreamLoader = (maxRetries = 3) => {
  const Co = ValueStreamCo();
  const updaters = ValueInfiniteStreamState.Updaters;
  const attemptLoad = (
    retryCount = 0,
  ): Coroutine<
    ValueInfiniteStreamWritableState,
    ValueInfiniteStreamWritableState,
    Unit
  > =>
    Co.GetState().then((current) => {
      return current.loadingMore.kind === "loaded"
        ? Co.Return(true)
        : Co.Await(
            () => current.getChunk([current.position]),
            () => "error" as const,
          ).then((apiResult) => {
            return Co.GetState().then((current) => {
              return apiResult.kind == "l"
                ? Co.SetState(
                    updaters.Core.loadingMore(
                      replaceWith(AsyncState.Default.loaded({})),
                    )
                      .then(
                        updaters.Coroutine.addLoadedChunk(
                          current.position.chunkIndex,
                          apiResult.value,
                        ).then(
                          updaters.Core.position(
                            ValueStreamPosition.Updaters.Core.shouldLoad(
                              replaceWith<ValueStreamPosition["shouldLoad"]>(
                                false,
                              ),
                            ),
                          ),
                        ),
                      )
                      .then(
                        updaters.Core.position(
                          ValueStreamPosition.Updaters.Core.nextStart(
                            current.position.disallowParamsChange
                              ? id
                              : replaceWith(apiResult.value.to),
                          ),
                        ).then(
                          updaters.Core.position(
                            ValueStreamPosition.Updaters.Core.disallowParamsChange(
                              replaceWith(false),
                            ),
                          ),
                        ),
                      ),
                  )
                : retryCount < maxRetries
                  ? Co.Wait(500).then(() => attemptLoad(retryCount + 1))
                  : Co.Return(false);
            });
          });
    });

  return Co.Seq([
    Co.SetState(
      updaters.Core.loadingMore(replaceWith(AsyncState.Default.loading())),
    ),
    attemptLoad(),
    Co.GetState().then((current) =>
      current.loadingMore.kind !== "loaded"
        ? Co.SetState(
            updaters.Core.loadingMore(
              replaceWith(AsyncState.Default.error("max retries reached")),
            ),
          )
        : Co.Wait(0),
    ),
  ]);
};