import type { Reference } from 'fhir/r4';

/**
 * WHAT TO CALL THE OTHER PARTY WHEN NOBODY CAN NAME THEM - and never their id.
 *
 * A resource id is not an answer to a reader. `senderLabel.ts` exists because a clinical message was
 * attributed to a hex string; this is the same defect on the thread ROW rather than the message, where
 * `getCounterpartyDisplay` ended `counterpartyId || directDisplay || "Unknown"` and printed the id as
 * the person's name in the patient's own inbox.
 *
 * AND THE ROW STILL HAS TO SAY SOMETHING. Hiding the name is worse than an imperfect one, so this
 * answers with the role-shaped word the same screen already shows beneath it: honest about what is not
 * known, and still telling the reader who they are talking to.
 *
 * IT LIVES HERE RATHER THAN IN THE PAGE for the reason `counterparty.ts` gives in its own header: the
 * two counterparty helpers drifted precisely because each surface kept its own copy. Pure and
 * reference-only, so it is testable without rendering the page.
 *
 * @param counterparty the other party's reference, or `undefined` on a pool or visit thread
 * @param practitionerRoleSummary the caller's role lookup - it already answers "Staff" when a
 * practitioner's roles cannot be resolved, so this never has to invent a second fallback
 */
export function counterpartyRoleWord(
    counterparty: Reference | undefined,
    practitionerRoleSummary: (practitionerId?: string) => string,
): string {
    const [resourceType, id] = (counterparty?.reference ?? '').split('/');

    if (resourceType === 'Practitioner') {
        return practitionerRoleSummary(id || undefined);
    }

    return resourceType === 'Patient' ? 'Patient' : 'Staff';
}