/** pick up to random N elements from array.
 *  just shuffle it if N is unspecified or greater than the length of the array.
 *  the original array remains unmodified. */
export function sample<T>(arr: T[], n: number = arr.length): T[] {
  if (n > arr.length) return sample(arr, arr.length);
  const copy = [...arr];
  for (let i = 0; i < n; i++) {
    const j = i + Math.floor(Math.random() * (copy.length - i));
    [copy[i], copy[j]] = [copy[j] as T, copy[i] as T];
  }
  return copy.slice(0, n);
}

/** sleep for N milliseconds */
export const sleep = (msec: number) =>
  new Promise((resolve) => setTimeout(resolve, msec));

/** normalize user-visible text and neutralize accidental mentions/tags */
export const sanitizeText = (text: string) =>
  text
    .replaceAll(/\r\n?/g, "\n")
    .replaceAll(/\n[\t ]+/g, "\n")
    .replaceAll(/\n{3,}/g, "\n\n")
    .trim()
    .replaceAll("@", "＠")
    .replaceAll("#", "＃");

const POLITE_ENDING =
  /(?:です|ます|ません|でした|ました|でしょう|ください)(?:ね|よ|か)?$/u;

export function isPoliteEnough(text: string) {
  const sentences = text
    .split(/[。！？]+/u)
    .map((sentence) => sentence.trim())
    .filter(Boolean);
  return (
    sentences.length > 0 &&
    sentences.some((sentence) => POLITE_ENDING.test(sentence))
  );
}