import { h } from '@ui-arch/frame';
import { button } from './button.js';
import { textField } from './textField.js';
import type { FormItemHandle, FormItemProps, FormProps, FormRule } from './types.js';

/*** 执行单条规则：null 通过，字符串为错误消息 ***/
function checkRule(value: string, rule: FormRule): string | null {
  if (rule.required && !value.trim()) return rule.message ?? '该项为必填项';
  if (!value) return null; // 非必填且为空：其余规则跳过
  if (rule.min !== undefined && value.length < rule.min) return rule.message ?? `至少 ${rule.min} 个字符`;
  if (rule.max !== undefined && value.length > rule.max) return rule.message ?? `最多 ${rule.max} 个字符`;
  if (rule.pattern && !rule.pattern.test(value)) return rule.message ?? '格式不正确';
  if (rule.validator) {
    const r = rule.validator(value);
    if (r !== true) return typeof r === 'string' ? r : rule.message ?? '校验未通过';
  }
  return null;
}

/*** 表单字段：label + 控件插槽 + 错误区；返回句柄供 form 聚合校验 ***/
export function formItem(props: FormItemProps, control: HTMLElement): FormItemHandle {
  // —— 状态集中声明 ——
  const mode = props.validateOn ?? 'blur'; // 校验时机；缺省失焦校验
  const rules = [...(props.required ? [{ required: true }] : []), ...(props.rules ?? [])];
  const error = h('div', { class: 'ua-form-error' });
  const label = h('label', { class: 'ua-form-label' }, props.label, props.required ? h('i', { class: 'ua-form-req' }, '*') : null);
  const el = h('div', { class: 'ua-form-item' }, label, h('div', { class: 'ua-form-control' }, control, error));

  /*** 错误态落点：控件根 + 内部原生控件，保证 select / checkbox 这类包裹式控件也能标红 ***/
  const marked = (): HTMLElement[] => [
    control,
    ...Array.from(control.querySelectorAll<HTMLElement>('input, textarea, select, .ua-select-trigger')),
  ];

  /*** 执行全部规则：返回首个错误消息，同时同步错误区、控件态与 aria-invalid ***/
  const validate = () => {
    const value = props.value();
    let msg: string | null = null;
    for (const rule of rules) {
      msg = checkRule(value, rule);
      if (msg) break; // 首个失败即停止
    }
    error.textContent = msg ?? '';
    control.classList.toggle('ua-invalid', !!msg);
    for (const node of marked()) node.setAttribute('aria-invalid', String(!!msg)); // 读屏同步错误态
    return msg;
  };

  control.addEventListener('input', () => {
    if (mode === 'input' || error.textContent) validate(); // input 模式即时校验；其余模式仅清已报错误
  });
  control.addEventListener('change', () => {
    if (mode === 'input') validate(); // select / checkbox / radio 变更即校验（原生 input 事件不冒泡）
  });
  control.addEventListener('focusout', () => {
    if (mode !== 'submit') validate(); // 用会冒泡的 focusout 取代 blur，包裹式控件同样生效
  });
  return { el, validate };
}

/*** 表单容器：布局 + 原生 submit 拦截 + 聚合校验（全部通过才触发 onSubmit） ***/
export function form(props: FormProps, items: FormItemHandle[]): HTMLElement {
  // —— 状态集中声明 ——
  /*** 整体提交：逐项校验，聚焦首个出错项并中止 ***/
  const submit = () => {
    for (const item of items) {
      if (item.validate()) {
        (item.el.querySelector('input, textarea, select') as HTMLElement | null)?.focus();
        return; // 卫语句：有错误不提交
      }
    }
    props.onSubmit?.();
  };
  const submitBtn = button({ label: props.submitText ?? '提交', onClick: submit });
  const resetBtn = props.resetText ? button({ label: props.resetText, variant: 'ghost', onClick: props.onReset }) : null;
  const actions = h('div', { class: 'ua-form-actions' }, submitBtn, resetBtn);
  const el = h(
    'form',
    { class: props.layout === 'horizontal' ? 'ua-form ua-form-h' : 'ua-form' },
    ...items.map((i) => i.el),
    actions,
  );
  el.addEventListener('submit', (e) => {
    e.preventDefault(); // 拦截原生提交，走校验流程
    submit();
  });
  return el;
}