// 数据扁平化
export function treeToFlat(data: any[], Id = 'Id', key = 'ParentId', children = 'Children') {
  // <!-- 此处需要使用function，不能使用箭头函数，否则下方的arguments存在异常 -->
  const result = data.reduce(function fn(prev: {}[], curr: { [x: string]: any; }) {
    let obj = {};
    for (var c in curr) {
      if (c !== children) Object.assign(obj, { [c]: curr[c] });
    }
    prev.push(obj);
    curr[children] &&
      curr[children].forEach((v: { [x: string]: any; }) => {
        v[key] = curr['Id'] || curr[Id];
        fn(prev, v);
      });
    return prev;
  }, []);
  return result;
}
// 数据反扁平化
export function flatToTree(data: any[], key = 'ParentId', children = 'Children') {
  const result = data.reduce(function (prev, curr, i, arr) {
    curr[children] = arr.filter((v) => v[key] === curr['Id'])
    curr[children] = curr[children].length ? curr[children] : undefined;
    if (!curr[key]) {
      prev.push(curr);
    }
    return prev;
  }, []);
  return result;
}