get-distinctive-items-from-relations.ts

/**
 * Returns the list of distinctive
 * elements based on current relations.
 * @param items
 * @param relations
 * @returns string[]
 */
function getDistinctiveItemsFromRelations(
  items: Record<string, { type: string }>, 
  relations: Record<string, string[]>
): string[] {
  // We use Set data structure so
  // we make sure only unique elements will be added.
  const distinctiveItems = new Set<string>()
  
  for (const itemKey in relations) {
    if (relations.hasOwnProperty(itemKey) && items.hasOwnProperty(itemKey)) {
      distinctiveItems.add(itemKey)
      const relatedItemsKeys = relations[itemKey]
      if (relatedItemsKeys.isArray()) {
        relatedItemsKeys
          .filter((relatedItemKey) => items.hasOwnProperty(relatedItemKey))
          .forEach((relatedItemKey) => distinctiveItems.add(relatedItemKey))
      }
    }
  }
  
  return [...distinctiveItems]
}