import type { HumanName } from 'fhir/r4';
import type { ActingAsTarget, IUser } from '../../services/AuthService.tsx';
import { getDisplayName } from '../../utils/fhirHumanName';

export interface AgreementSubject {
    subjectName: string;
    guardianName?: string;
}

// Whose agreements these are when a helper has switched into someone else's record; none for oneself.
export const agreementSubject = (
    actingAs: ActingAsTarget | null | undefined,
    user: IUser | null | undefined,
): AgreementSubject | undefined => {
    if (!actingAs) return undefined;
    const ownName = user?.fhir && 'name' in user.fhir
        ? getDisplayName(user.fhir.name as HumanName[] | undefined)
        : '';
    return {
        subjectName: actingAs.subjectName?.trim() || 'the person you are acting for',
        guardianName: ownName.trim() || undefined,
    };
};

// The Patient these agreements are about: the one acted for, or the signed-in patient. Never a Patient merely
// loaded on the page, which can still be the previous one; undefined when neither is proven.
export const agreementPatientId = (
    actingAs: ActingAsTarget | null | undefined,
    user: IUser | null | undefined,
): string | undefined => {
    if (actingAs) return actingAs.subjectPatientId || undefined;
    return user?.fhir?.resourceType === 'Patient' ? user.fhir.id || undefined : undefined;
};