import { DecodedValueMap, QueryParamConfigMap, EncodedValueMap } from './types';

/**
 * Convert the values in query to strings via the encode functions configured
 * in paramConfigMap
 *
 * @param paramConfigMap Map from query name to { encode, decode } config
 * @param encodedQuery Query updates mapping param name to decoded value
 */
export function decodeQueryParams<QPCMap extends QueryParamConfigMap>(
  paramConfigMap: QPCMap,
  encodedQuery: Partial<EncodedValueMap<QPCMap>>
): DecodedValueMap<QPCMap> {
  const decodedQuery: Partial<DecodedValueMap<QPCMap>> = {};

  // iterate over all keys in the config (#30)
  const paramNames = Object.keys(paramConfigMap);

  // ensure any non configured keys that are in the URL are also included
  for (const encodedKey of Object.keys(encodedQuery)) {
    if (paramConfigMap[encodedKey] == null) {
      paramNames.push(encodedKey);
    }
  }

  for (const paramName of paramNames) {
    const encodedValue = encodedQuery[paramName];

    if (!paramConfigMap[paramName]) {
      if (process.env.NODE_ENV === 'development') {
        console.warn(
          `Passing through parameter ${paramName} during decoding since it was not configured.`
        );
      }

      // NOTE: we could just not include it, but it is probably convenient to have
      // it default to be a string type.
      (decodedQuery as any)[paramName] = encodedValue;
    } else {
      decodedQuery[paramName as keyof QPCMap] = paramConfigMap[
        paramName
      ].decode(encodedValue);
    }
  }

  return decodedQuery as DecodedValueMap<QPCMap>;
}