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

const hosts = new Map<string, HTMLElement>(); // 每个角落一个堆叠容器，首次用到该角落时懒创建
const byKey = new Map<string, NotificationHandle>(); // 同 key 只留一张卡，二次调用走原地更新
const MAX_STACK = 3; // 同一角落最多条数，超出挤掉最早一条

/*** 确保指定角落的堆叠容器存在：fixed 挂 body 末尾，与 toast 的右上角分区不打架 ***/
function ensureHost(place: string): HTMLElement {
  const hit = hosts.get(place);
  if (hit) return hit;
  const el = h('div', { class: `ua-notice-host is-${place}` });
  document.body.appendChild(el);
  hosts.set(place, el);
  return el;
}

/*** 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, update } 句柄；duration 为 0 表示常驻，非 0 时悬停 / 聚焦自动暂停计时；带 key 时二次调用原地更新同一张卡 ***/
export function notification(props: NotificationProps): NotificationHandle {
  const dup = props.key ? byKey.get(props.key) : undefined;
  if (dup) { dup.update(props); return dup; } // 同 key：只更新内容，不新增一条

  // —— 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 titleEl = h('span', { class: 'ua-notice-title' }, props.title) as HTMLElement;
  const actionEl = props.action ? h('div', { class: 'ua-notice-action' }, props.action) : null;
  let descEl = props.description ? h('div', { class: 'ua-notice-desc' }, props.description) : null;

  /*** 换语义色：整串重设 class，保住已挂上的入场态 ***/
  const paint = (variant: string): void => {
    el.className = `ua-notice ua-notice-${variant}${el.classList.contains('ua-open') ? ' ua-open' : ''}`;
  };
  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' }), titleEl, closable ? closeBtn : null),
    descEl,
    actionEl,
  ) as HTMLElement;

  /*** 关闭：清计时器后走退场动画，顺手释放 key 登记 ***/
  const close = () => {
    window.clearTimeout(timer);
    if (props.key && byKey.get(props.key) === handle) byKey.delete(props.key);
    dismiss(el);
  };
  closeBtn.addEventListener('click', () => close());

  /*** 原地更新：改标题 / 描述 / 语义色；描述按需插入到操作区之前 ***/
  const update = (next: Partial<NotificationProps>): void => {
    if (next.title != null) titleEl.textContent = next.title;
    if (next.variant) paint(next.variant);
    if (next.description != null) {
      if (!descEl) { // 首次补描述：插在操作区之前，没有操作区就追加
        descEl = h('div', { class: 'ua-notice-desc' });
        if (actionEl) el.insertBefore(descEl, actionEl); else el.appendChild(descEl);
      }
      descEl.textContent = next.description;
    }
  };

  /*** 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(props.placement ?? 'bottom-right'); // 缺省右下，与右上角 toast 错开
  if (stack.childElementCount >= MAX_STACK) stack.firstElementChild?.remove(); // 超出上限挤掉最早一条
  stack.appendChild(el);
  const handle: NotificationHandle = { el, close, update };
  if (props.key) byKey.set(props.key, handle);
  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 handle;
}