/**
 * 功能：管理资源页头像的鉴权读取、本地预览、清除和保存前上传。
 * 版本：v1.0.0
 */
import { Message } from '@arco-design/web-vue';
import { onBeforeUnmount, ref } from 'vue';
import { avatarApi } from '@/api/avatar';
import { DEFAULT_USER_AVATAR } from '@/constants/avatar';
import { createAvatarUploadCache } from './avatar-upload-cache';

export function useResourceAvatar() {
  const url = ref(DEFAULT_USER_AVATAR);
  const file = ref<File>();
  const cleared = ref(false);
  const canClear = ref(false);
  const uploadCache = createAvatarUploadCache(avatarApi.upload);
  let objectURL = '';

  function revoke() {
    if (objectURL) URL.revokeObjectURL(objectURL);
    objectURL = '';
  }

  /** 加载现有受保护头像，记录没有头像时继续使用默认图。 */
  async function load(resource: string, identity: string) {
    revoke();
    uploadCache.reset();
    url.value = DEFAULT_USER_AVATAR;
    canClear.value = false;
    file.value = undefined;
    cleared.value = false;
    if (!identity) return;
    const blob = await avatarApi.load(resource, identity);
    if (!blob) return;
    objectURL = URL.createObjectURL(blob);
    url.value = objectURL;
    canClear.value = true;
  }

  /** 校验并预览用户选择的新头像。 */
  function select(next: File) {
    if (
      !['image/jpeg', 'image/png'].includes(next.type) ||
      next.size <= 0 ||
      next.size > 2 * 1024 * 1024
    ) {
      Message.warning('请选择不超过 2 MB 的 JPG 或 PNG 图片');
      return;
    }
    revoke();
    uploadCache.reset();
    objectURL = URL.createObjectURL(next);
    url.value = objectURL;
    file.value = next;
    cleared.value = false;
    canClear.value = true;
  }

  /** 标记清除头像，真正写入空值发生在保存资料时。 */
  function clear() {
    revoke();
    uploadCache.reset();
    url.value = DEFAULT_USER_AVATAR;
    file.value = undefined;
    cleared.value = true;
    canClear.value = false;
  }

  /** 将头像变化写入资源更新载荷。 */
  async function applyToPayload(payload: Record<string, unknown>) {
    if (file.value) payload.avatar = await uploadCache.resolve(file.value);
    else if (cleared.value) payload.avatar = '';
  }

  function marker() {
    return file.value
      ? `${file.value.name}:${file.value.size}:${file.value.lastModified}`
      : cleared.value
        ? 'clear'
        : 'unchanged';
  }

  onBeforeUnmount(revoke);
  return {
    url,
    file,
    cleared,
    canClear,
    load,
    select,
    clear,
    applyToPayload,
    marker,
  };
}