usePromise.ts

import { useEffect, useReducer } from 'react';

type PromiseState<T> = {
  isPending: false;
  isResolved: false;
  isError: false;
} | {
  isPending: true;
  isResolved: false;
  isError: false;
} | {
  isPending: false;
  isResolved: true;
  isError: true;
  error: Error;
} | {
  isPending: false;
  isResolved: true;
  isError: false;
  value: T;
};

interface Reset {
  type: 'RESET';
}

interface StartResolve {
  type: 'START_RESOLVE';
}

interface ReceiveResult<T> {
  type: 'RECEIVE_RESULT';
  result: T;
}

interface ResultFailed {
  type: 'RESULT_FAILED';
  error: Error;
}

type PromiseActions<T> = Reset | StartResolve | ReceiveResult<T> | ResultFailed;

function usePromise<T>(
  toResolve: () => Promise<T>,
): PromiseState<T>  {
  const [state, dispatch] = useReducer(
    (state: PromiseState<T>, action: PromiseActions<T>): PromiseState<T> => {
      switch (action.type) {
        case 'START_RESOLVE':
          return {
            isPending: true,
            isResolved: false,
            isError: false,
          };
        case 'RECEIVE_RESULT':
          return {
            isPending: false,
            isResolved: true,
            isError: false,
            value: action.result,
          };
        case 'RESULT_FAILED':
          return {
            isPending: false,
            isResolved: true,
            isError: true,
            error: action.error,
          };
        case 'RESET':
          return {
            isPending: false,
            isResolved: false,
            isError: false,
          };
        default:
          return state;
      }
    },
    {
      isPending: false,
      isResolved: false,
      isError: false,
    },
  );

  useEffect(
    () => dispatch({ type: 'RESET' }),
    [toResolve]
  );

  useEffect(
    () => {
      if (!state.isPending && !state.isResolved) {
        dispatch({ type: 'START_RESOLVE' });

        toResolve()
          .then(result => dispatch({ type: 'RECEIVE_RESULT', result }))
          .catch(error => dispatch({ type: 'RESULT_FAILED', error }));
      }
    },
    [toResolve, state.isPending, state.isResolved],
  );

  return state;
}

export default usePromise;