import { Encounter, Reference } from 'fhir/r4';

/**
 * The visit a clinical record should be filed against when it is being recorded from inside one.
 *
 * Three rules, and the second and third are the ones worth having a function for:
 *
 *   inside a visit    a reference to THAT encounter, so the form shows what the write already does
 *   outside any       undefined - there is no visit to infer, and a default would be a guess
 *   an encounter      undefined - a reference built from a missing id is `Encounter/undefined`,
 *   with no id        which is a broken pointer that looks like a chosen one
 *
 * `toReference` is passed in rather than imported because building a FHIR reference needs the service
 * context, and a rule this small should be testable without one.
 */
export const activeEncounterDefault = (
    encounter: Encounter | undefined,
    toReference: (id: string) => Reference,
): Reference | undefined => (encounter?.id ? toReference(encounter.id) : undefined);