import { useEffect, useState } from 'react';

interface PromiseFactory<T> {
  (): Promise<T>;
}

/**
 * Accepts a function that returns a Promise.
 * Returns `undefined` or the settled value of the Promise.
 * If the provided function does not handle Promise rejection, it will be lost.
 */
export function usePromise<T>(factory: PromiseFactory<T>, deps?: any[]) {
  const [ value, setValue ] = useState<T>();
  const [ loading, setLoading ] = useState(false);
  useEffect(() => {
    let doSetValue = true;
    setLoading(true);
    factory().then(value => {
      if (doSetValue) {
        setValue(value);
        setLoading(false);
      }
    });
    return () => { doSetValue = false };
  }, deps);
  return { value, loading };
}