import { useContext, useCallback, useState } from 'react';
import { HackleContext } from '../components';
import {
  Decision,
  LoadableResult,
  DEFAULT_VARIATION,
  DecisionReason,
} from '../models';
import { InputUtil } from '../utils';
import { useOnMount } from './useOnMount';

export function useLoadableVariationDetail(
  experimentKey: number
): LoadableResult<Decision> {
  const { hackle, userVersion } = useContext(HackleContext);
  const getVariationDetail = useCallback(() => {
    return (
      hackle
        ?.variationDetail(experimentKey)
        .then((decision) => Decision.withReactNativeDecision(decision)) ||
      Promise.resolve(
        Decision.of(DEFAULT_VARIATION, DecisionReason.SDK_NOT_READY)
      )
    );
  }, [experimentKey, hackle]);

  const [variationDetail, setVariationDetail] = useState(() => {
    if (!hackle) {
      return Promise.resolve(
        Decision.of(DEFAULT_VARIATION, DecisionReason.SDK_NOT_READY)
      );
    }
    return getVariationDetail();
  });

  const currentInput = {
    key: experimentKey,
    userVersion,
  };

  const [prevInput, setPrevInput] = useState(currentInput);

  if (!InputUtil.isInputEqual(prevInput, currentInput)) {
    setPrevInput(currentInput);
    setVariationDetail(getVariationDetail());
  }

  return useOnMount(
    variationDetail,
    Decision.of(DEFAULT_VARIATION, DecisionReason.SDK_NOT_READY)
  );
}