gramps-graphql/gramps

const omit = key => ['Subscription'].includes(key);

const maybeMap = (key, fn, obj) =>
  omit(key) ? obj[key] : fn(obj[key], key, obj);

const mapObj = fn => obj => {
  if (obj.constructor.name === 'Object') {
    return Object.keys(obj).reduce(
      (acc, key) => ({
        ...acc,
        [key]: maybeMap(key, fn, obj),
      }),
      {},
    );
  } else {
    return obj;
  }
};

const checkFn = (fn, fieldName) => {
  if (typeof fn !== 'function') {
    throw new Error(
      `Expected Function for ${fieldName} resolver but received ${typeof fn}`,
    );
  }
};

const wrapFn = namespace => (fn, fieldName) => {
  checkFn(fn, fieldName);
  return (root, args, context, info) =>
    fn(root, args, context[namespace], info);
};

export default (namespace, resolvers) => {
  if (resolvers instanceof Object) {
    return mapObj(mapObj(wrapFn(namespace)))(resolvers);
  }
};