import { h } from '@ui-arch/frame';
import type { NotificationProps } from './types.js';

let host: HTMLElement | null = null; // 右下角堆叠容器：首条通知出现时懒创建
const MAX_STACK = 3; // 同屏最多条数，超出挤掉最早一条

/*** 确保堆叠容器存在：fixed 挂 body 末尾，与右上角 toast 分区不打架 ***/
function ensureHost(): HTMLElement {
  if (host) return host;
  host = h('div', { class: 'ua-notice-host' });
  document.body.appendChild(host);
  return host;
}

/*** 退场并移除：摘 ua-open 触发过渡，transitionend 与 320ms 超时二选一兜底 ***/
function dismiss(item: HTMLElement): void {
  item.classList.remove('ua-open');
  item.addEventListener('transitionend', () => item.remove(), { once: true });
  window.setTimeout(() => item.isConnected && item.remove(), 320); // reduced-motion 下不触发 transition
}

/*** 通知卡片：标题 + 描述 + 可选操作区，返回 { el, close } 句柄；duration 为 0 表示常驻，非 0 时悬停 / 聚焦自动暂停计时 ***/
export function notification(props: NotificationProps): { el: HTMLElement; close: () => void } {
  // —— 状态集中声明 ——
  const duration = props.duration ?? 0; // 缺省常驻：通知通常需要用户读完
  const closable = props.closable ?? true; // 缺省带关闭按钮
  let timer = 0; // 自动关闭计时器句柄
  let remain = duration; // 剩余毫秒：暂停时扣减，续计时接着走
  let startedAt = 0; // 本轮计时起点，用于折算暂停前已流逝的时间
  let paused = false; // 是否因悬停 / 聚焦而暂停
  const closeBtn = h('button', { type: 'button', class: 'ua-notice-close', 'aria-label': '关闭通知' }, '×') as HTMLButtonElement; // 关闭按钮，回调在下方绑定
  const el = h(
    'div',
    { class: `ua-notice ua-notice-${props.variant ?? 'info'}`, role: 'alert' },
    h(
      'div',
      { class: 'ua-notice-head' },
      h('span', { class: 'ua-notice-dot', 'aria-hidden': 'true' }),
      h('span', { class: 'ua-notice-title' }, props.title),
      closable ? closeBtn : null,
    ),
    props.description ? h('div', { class: 'ua-notice-desc' }, props.description) : null,
    props.action ? h('div', { class: 'ua-notice-action' }, props.action) : null,
  ) as HTMLElement;

  /*** 关闭：清计时器后走退场动画 ***/
  const close = () => {
    window.clearTimeout(timer);
    dismiss(el);
  };
  closeBtn.addEventListener('click', () => close());

  /*** 起表：按剩余毫秒设定时器 ***/
  const arm = () => { if (remain <= 0) return; startedAt = Date.now(); timer = window.setTimeout(() => dismiss(el), remain); };
  /*** 暂停计时：扣掉已流逝部分，剩余时间留给续计 ***/
  const pause = () => { if (paused || remain <= 0) return; paused = true; window.clearTimeout(timer); remain -= Date.now() - startedAt; };
  /*** 续计：离开后按剩余毫秒重新起表 ***/
  const resume = () => { if (!paused) return; paused = false; arm(); };
  el.addEventListener('pointerenter', pause); // 悬停阅读时不倒计时
  el.addEventListener('pointerleave', resume);
  el.addEventListener('focusin', pause); // 键盘聚焦到关闭/操作按钮同样暂停
  el.addEventListener('focusout', resume);

  const stack = ensureHost();
  if (stack.childElementCount >= MAX_STACK) stack.firstElementChild?.remove(); // 超出上限挤掉最早一条
  stack.appendChild(el);
  requestAnimationFrame(() => el.classList.add('ua-open')); // 下一帧入场，保证过渡生效
  if (duration > 0) arm(); // 常驻（0）不设定时器
  return { el, close };
}