/**
 * 将扁平数组转换成树结构
 * @param list 扁平数组
 * @param options 树解析map
 * @returns
 */
function transformTree(
  list: any[] = [],
  options = {
    keyField: 'id',
    childField: 'children',
    parentField: 'pid',
  },
) {
  const { keyField, childField, parentField } = options;

  const tree = [];
  const record: any = {};

  for (let i = 0, len = list.length; i < len; i++) {
    const item = list[i];
    const id = item[keyField];

    if (!id) {
      continue;
    }

    if (record[id]) {
      item[childField] = record[id];
    } else {
      item[childField] = record[id] = [];
    }

    if (item[parentField]) {
      const parentId = item[parentField];

      if (!record[parentId]) {
        record[parentId] = [];
      }

      record[parentId].push(item);
    } else {
      tree.push(item);
    }
  }

  return tree;
}

export default transformTree;