import type { ComponentType, RefObject, RefAttributes } from 'react';

import { useMemo, useState, useImperativeHandle, forwardRef } from 'react';

import type { Remote, WorkerModule } from '../rpc';

interface WorkerPoolProps {

  concurrency?: number;

}

const withPool = <T extends WorkerModule>(

  Component: ComponentType<RefAttributes<Remote<T>>>,

) => {

  const PoolComponent = forwardRef<Remote<T>[], WorkerPoolProps>(({

    concurrency = navigator.hardwareConcurrency,

  }, ref) => {

    const [workerRefs] = useState<RefObject<Remote<T>>[]>(() => Array.from(

      { length: concurrency },

      () => ({ current: null }),

    ));

    const workers = useMemo(() => workerRefs.map((ref, index) => (

      <Component key={index} ref={ref} />

    )), [workerRefs]);

    useImperativeHandle(ref, () => workerRefs.map(

      ({ current }) => current!

    ), [workerRefs]);

    return <>{workers}</>;

  });

  return PoolComponent;

};

export default withPool;