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

/*** 文件选择：点击或拖拽入列，已选清单可逐个移除；只负责选文件并回传，不内置上传请求（网络层交给调用方） ***/
export function upload(props: UploadProps): HTMLElement {
  // —— 状态集中声明 ——
  const files: File[] = []; // 已选文件（顺序即选择顺序）
  const input = h('input', { type: 'file', class: 'ua-upload-input' }) as HTMLInputElement; // 隐藏的原生选择器
  if (props.accept) input.accept = props.accept;
  if (props.multiple) input.multiple = true;
  const listEl = h('div', { class: 'ua-upload-list' }) as HTMLElement; // 已选文件清单

  /*** 按字节数换算可读体积 ***/
  const size = (bytes: number) =>
    bytes < 1024 ? `${bytes} B` : bytes < 1024 * 1024 ? `${(bytes / 1024).toFixed(1)} KB` : `${(bytes / 1048576).toFixed(1)} MB`;

  /*** 移除指定下标的文件 ***/
  const remove = (i: number) => {
    files.splice(i, 1);
    sync();
  };

  /*** 重绘清单并回传（选择/拖拽/移除都走这里，保证单一出口） ***/
  const sync = () => {
    listEl.replaceChildren(
      ...files.map((file, i) =>
        h(
          'div',
          { class: 'ua-upload-item' },
          h('span', { class: 'ua-upload-name' }, file.name),
          h('span', { class: 'ua-upload-size' }, size(file.size)),
          h('button', { type: 'button', class: 'ua-upload-remove', 'aria-label': `移除 ${file.name}`, onclick: () => remove(i) }, '×'),
        ),
      ),
    );
    props.onChange?.(files.slice()); // 回传副本，避免调用方改动内部数组
  };

  /*** 追加文件：单选模式直接替换，多选模式追加并去重（同名同大小视为同一个） ***/
  const add = (picked: FileList | File[]) => {
    for (const file of Array.from(picked)) {
      const dup = files.some((f) => f.name === file.name && f.size === file.size);
      if (dup) continue; // 卫语句：重复文件跳过
      if (props.multiple) files.push(file);
      else files.splice(0, files.length, file); // 单选：只留最新一个
    }
    sync();
  };

  const zone = h(
    'div',
    {
      class: props.disabled ? 'ua-upload-zone ua-upload-disabled' : 'ua-upload-zone',
      tabindex: props.disabled ? '-1' : '0',
      role: 'button',
      'aria-label': '选择文件',
      onclick: () => { if (!props.disabled) input.click(); },
      onkeydown: (e: KeyboardEvent) => {
        if (props.disabled) return; // 卫语句：禁用不响应
        if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); input.click(); } // 键盘等效点击
      },
      ondragover: (e: Event) => {
        if (props.disabled) return; // 卫语句：禁用不接受拖拽
        e.preventDefault();
        (e.currentTarget as HTMLElement).classList.add('ua-upload-over');
      },
      ondragleave: (e: Event) => (e.currentTarget as HTMLElement).classList.remove('ua-upload-over'),
      ondrop: (e: Event) => {
        const ev = e as DragEvent;
        ev.preventDefault();
        (ev.currentTarget as HTMLElement).classList.remove('ua-upload-over');
        if (props.disabled || !ev.dataTransfer?.files?.length) return; // 卫语句：无文件或已禁用
        add(ev.dataTransfer.files);
      },
    },
    h('span', { class: 'ua-upload-icon', 'aria-hidden': 'true' }, '⤒'),
    h('span', { class: 'ua-upload-hint' }, props.hint ?? '点击或拖拽文件到此处'),
    input,
  );

  input.addEventListener('change', () => {
    if (input.files?.length) add(input.files);
    input.value = ''; // 清空以便重复选择同一文件也能触发 change
  });

  return h('div', { class: 'ua-upload' }, zone, listEl);
}