import { OrderByCondition } from 'typeorm';
import { OrderByDirection } from '@/types';
import { enumFromStringValue } from '@/utils';
import { PagesOrderBy, PagesOrderByField } from './types';

type Keys = string;

const FieldEnumToFieldNameMapper = new Map<PagesOrderByField, Keys>([
  [PagesOrderByField.FEATURED, 'featured'],
]);

/**
 * @returns {string} key for orderBy that contains a prefix if one is provided
 */
const optionallyPrefixedKey = (key: string, prefix?: string): string =>
  `${prefix ? `${prefix}.` : ''}${key}`;

/**
 * Given input for reports query, generate typeorm order field that can be
 * used to control sort direction
 * @default { featured: 'DESC' }
 */
export const convertOrderByGraphQLToTypeormOrder = (
  orderBy?: PagesOrderBy,
  prefix?: string
): OrderByCondition => {
  const defaultOrderBy: OrderByCondition = {
    [optionallyPrefixedKey('featured', prefix)]: 'DESC',
  };
  if (!orderBy) {
    return defaultOrderBy;
  }
  const fieldAsEnum = enumFromStringValue(PagesOrderByField, orderBy.field);
  if (!fieldAsEnum) {
    return defaultOrderBy;
  }
  const field = FieldEnumToFieldNameMapper.get(fieldAsEnum);
  if (!field) {
    return defaultOrderBy;
  }

  const direction = orderBy.direction === OrderByDirection.ASC ? 'ASC' : 'DESC';
  return {
    [optionallyPrefixedKey(field, prefix)]: {
      order: direction,
      nulls: 'NULLS LAST',
    },
  };
};