import { IHash } from '../../interfaces';
import base58 from '../libs/base58';
import converters from '../libs/converters';

function castFromBytesToBase58(bytes, sliceIndex) {
  bytes = Uint8Array.from(Array.prototype.slice.call(bytes, sliceIndex));
  return base58.encode(bytes);
}

function castFromStringToBase58(str: string) {
  return base58.encode(converters.stringToByteArray(str));
}

export function createRemapper(rules) {

  return function (data: IHash<any>): IHash<any> {

    return Object.keys({ ...data, ...rules }).reduce((result, key) => {

      const rule = rules[key];

      if (typeof rule === 'function') {
        // Process with a function
        result[key] = rule(data[key]);
      } else if (typeof rule === 'string') {
        // Rename a field with the rule name
        result[rule] = data[key];
      } else if (rule && typeof rule === 'object') {

        // Transform according to the rule
        if (rule.from === 'bytes' && rule.to === 'base58') {
          result[key] = castFromBytesToBase58(data[key], rule.slice || 0);
        } else if (rule.from === 'string' && rule.to === 'base58') {
          result[key] = castFromStringToBase58(data[key]);
        }


      } else if (rule !== null) {
        // Leave the data as is (or add some default value from the rule)
        result[key] = data[key] != null ? data[key] : rule;
      }

      return result;

    }, Object.create(null));
  };
}