import * as R from 'ramda';


type BaseT = Record<string, any>;

export const pickAll = <T extends BaseT>(
  key: string,
  childKey: string,
  data: T[] | T,
): any[] => {
  const hasChildren = (node: T) => {
    return R.hasPath([childKey], node);
  };
  const Tree: any = {
    reduce: R.curry((reducerFn: any, init: any[], node: T) => {
      const acc = reducerFn(init, node);
      if (!hasChildren(node)) {
        const res = acc && acc.length ? R.map((item: any) => {
          return item[key] || item
        })(acc) : [];
        return res;
      }
      return node[childKey]
        ? node[childKey].reduce(Tree.reduce(reducerFn), acc)
        : acc;
    }),
    find: R.curry((findFn: any, init: any[], node: T[]) => {
      return R.pipe(R.map(Tree.reduce(findFn, init)), R.flatten)(node as T[]);
    })
  };
  const fn = (arr: any[], data: T) => {
    if (data[key]) {
      return arr.concat([R.omit([childKey], data)]);
    } else {
      return arr;
    }
  };


  const type = R.type(data);
  switch (type) {
    case 'Object': {
      return Tree.reduce(fn, [])(data);
    }
    case 'Array': {
      return Tree.find(fn, [])(data);
    }
    default: {
      return data as T[];
    }
  }
};