import * as React from 'react';

export function useMemoArray<T>(
  entries: [item: T, deps: readonly unknown[]][]
): T[] {
  const previousRef = React.useRef<
    | {
        entries: { item: T; deps: readonly unknown[] }[];
        items: T[];
      }
    | undefined
  >(undefined);

  const previous = previousRef.current;
  const next = entries.map(([item, deps], index) => {
    const previousEntry = previous?.entries[index];
    const depsEqual =
      previousEntry &&
      previousEntry.deps.length === deps.length &&
      previousEntry.deps.every((it, index) => Object.is(it, deps[index]));

    return depsEqual ? previousEntry : { item, deps };
  });

  if (
    previous &&
    previous.entries.length === next.length &&
    next.every((entry, index) => entry === previous.entries[index])
  ) {
    return previous.items;
  }

  const items = next.map((entry) => entry.item);

  previousRef.current = {
    entries: next,
    items,
  };

  return items;
}