import { Dict } from '../common';

/**
 * Function to be used to construct an update object. If value is null or undefined - property will not be updated. Example:
 *
 * ```ts
    await update('table_name',
      {
        title: element.title,
        ...optional(element.description, val => ({ description: val })),
      },
      { id: elementId },
    ).run(ctx);
 * ```
 *
 * @param val value to be used to update a property
 * @param map mapping function that will return an update object for the property
 */
export const optional = <T>(
  val: T,
  map: (val: T) => Dict<T>,
): false | Dict<T> => {
  return val !== undefined && val !== null && map(val);
};

/**
 * Function to be used to construct an update object. If value is undefined - property will not be updated. If value is null - it will be set. Useful for Date properties. Example:
 *
 * ```ts
    await update('table_name',
      {
        title: element.title,
        ...nullable(element.released, val => ({ released: val })),
      },
      { id: elementId },
    ).run(ctx);
 * ```
 *
 * @param val value to be used to update a property
 * @param map mapping function that will return an update object for the property
 */
export const nullable = <T>(
  val: T,
  map: (val: T) => Dict<T>,
): false | Dict<T> => {
  return val !== undefined && map(val);
};