import { effect } from './signal.js';

type Child = Node | string | number | boolean | null | undefined | (() => unknown);
type Props = Record<string, unknown>;

/*** 响应式属性绑定：函数值属性在依赖变化时自动写回 DOM ***/
function bindProp(el: HTMLElement, key: string, fn: () => unknown): void {
  effect(() => {
    const v = fn();
    if (key === 'value') (el as unknown as HTMLInputElement).value = String(v);
    else if (key === 'checked') (el as unknown as HTMLInputElement).checked = Boolean(v);
    else if (v === false || v == null) el.removeAttribute(key);
    else el.setAttribute(key, v === true ? '' : String(v));
  });
}

/*** 静态属性写入：false / null 移除属性，true 置空标记属性 ***/
function bindStatic(el: HTMLElement, key: string, value: unknown): void {
  if (value === false || value == null) el.removeAttribute(key);
  else if (value === true) el.setAttribute(key, '');
  else el.setAttribute(key, String(value));
}

/*** 挂载子节点：函数型子节点转为响应式文本节点 ***/
function appendChild(el: HTMLElement, child: unknown): void {
  if (child == null || child === false) return;
  if (typeof child === 'function') {
    const node = document.createTextNode('');
    effect(() => {
      node.textContent = String(child());
    });
    el.append(node);
  } else if (typeof child === 'object') {
    el.append(child as Node);
  } else {
    el.append(String(child));
  }
}

/*** hyperscript 入口：h(tag, props, ...children)；on* 为事件，函数值为响应式属性 ***/
export function h(tag: string, props?: Props | null, ...children: unknown[]): HTMLElement {
  const el = document.createElement(tag);
  for (const [key, value] of Object.entries(props ?? {})) {
    if (key.startsWith('on') && typeof value === 'function') {
      el.addEventListener(key.slice(2).toLowerCase(), value as EventListener);
    } else if (typeof value === 'function') {
      bindProp(el, key, value as () => unknown);
    } else if (key === 'class') {
      el.className = String(value);
    } else {
      bindStatic(el, key, value);
    }
  }
  for (const child of children.flat(Infinity)) appendChild(el, child);
  return el;
}

/*** 列表渲染：信号变化时整体替换容器子节点（tbody / 列表等场景） ***/
export function renderList(el: HTMLElement, fn: () => Node[]): void {
  effect(() => {
    el.replaceChildren(...fn());
  });
}

/*** 挂载视图到容器；容器不存在时静默跳过 ***/
export function mount(target: Element | string, view: () => Node): void {
  const root = typeof target === 'string' ? document.querySelector(target) : target;
  if (!root) return; // 卫语句：容器不存在
  root.replaceChildren(view());
}