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

/*** 弹窗：open 信号驱动显隐，点遮罩、× 或 Esc 触发 onClose；Tab 焦点陷阱 + 关闭归还焦点 ***/
export function modal(props: ModalProps, ...children: unknown[]): HTMLElement {
  const close = () => {
    if (!props.open()) return; // 卫语句：已关闭不重复触发回调
    props.open(false); // 写回信号触发隐藏
    props.onClose?.();
  };
  const overlay = h('div', {
    class: 'ua-modal-overlay',
    onClick: (e: Event) => {
      if (e.target === overlay) close(); // 卫语句：仅点遮罩本身关闭
    },
  });
  const box = h(
    'div',
    { class: `ua-modal ua-modal-${props.size ?? 'md'}`, role: 'dialog', 'aria-modal': 'true' }, // 对话框语义，供读屏识别
    h('div', { class: 'ua-modal-head' }, h('h3', { class: 'ua-modal-title' }, props.title), h('button', { type: 'button', class: 'ua-modal-close', 'aria-label': '关闭弹窗', onClick: close }, '×')),
    h('div', { class: 'ua-modal-body' }, ...children),
    props.footer ? h('div', { class: 'ua-modal-foot' }, props.footer) : null, // 底部操作区：右对齐，仅传了才渲染
  );
  overlay.append(box);
  let lastFocus: HTMLElement | null = null; // 打开前焦点宿主，关闭时归还
  const focusables = (): HTMLElement[] =>
    Array.from(box.querySelectorAll<HTMLElement>('button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'))
      .filter((el) => !el.hasAttribute('disabled')); // 弹窗内可聚焦元素（排除禁用）
  effect(() => {
    const open = props.open();
    overlay.classList.toggle('ua-open', open); // 显隐跟随信号
    if (open) {
      lastFocus = document.activeElement as HTMLElement | null; // 记录打开前焦点
      (box.querySelector('button, input, textarea') as HTMLElement | null)?.focus(); // 打开时聚焦首个可交互元素
    } else if (lastFocus) {
      lastFocus.focus(); // 关闭时归还焦点
      lastFocus = null;
    }
  });
  overlay.addEventListener('keydown', (e: KeyboardEvent) => {
    if (e.key !== 'Tab' || !props.open()) return; // 仅处理打开中的 Tab
    const els = focusables();
    if (els.length === 0) { e.preventDefault(); return; } // 无可聚焦元素：拦截 Tab 防焦点逃逸
    const first = els[0];
    const last = els[els.length - 1];
    if (e.shiftKey && (document.activeElement === first || !box.contains(document.activeElement))) {
      e.preventDefault(); last.focus(); // Shift+Tab 到首位时回绕到末尾
    } else if (!e.shiftKey && (document.activeElement === last || !box.contains(document.activeElement))) {
      e.preventDefault(); first.focus(); // Tab 到末位时回绕到开头
    }
  });
  document.addEventListener('keydown', (e: KeyboardEvent) => {
    if (e.key === 'Escape' && props.open()) close(); // Esc 关闭当前打开的弹窗
  });
  return overlay;
}