/**
 * Function Utils
 *
 * 函数工具
 */

/**
 * 防抖函数
 */
export function debounce<T extends (...args: any[]) => any>(
  func: T,
  wait: number
): (...args: Parameters<T>) => void {
  let timeout: ReturnType<typeof setTimeout> | null = null;

  return function (this: any, ...args: Parameters<T>) {
    if (timeout) {
      clearTimeout(timeout);
    }

    timeout = setTimeout(() => {
      func.apply(this, args);
    }, wait);
  };
}

/**
 * 节流函数
 */
export function throttle<T extends (...args: any[]) => any>(
  func: T,
  wait: number
): (...args: Parameters<T>) => void {
  let timeout: ReturnType<typeof setTimeout> | null = null;
  let previous = 0;

  return function (this: any, ...args: Parameters<T>) {
    const now = Date.now();

    if (!previous) previous = now;

    const remaining = wait - (now - previous);

    if (remaining <= 0 || remaining > wait) {
      if (timeout) {
        clearTimeout(timeout);
        timeout = null;
      }
      previous = now;
      func.apply(this, args);
    } else if (!timeout) {
      timeout = setTimeout(() => {
        previous = Date.now();
        timeout = null;
        func.apply(this, args);
      }, remaining);
    }
  };
}