// The patient's three words for a plan, over FHIR Coverage.status (active | cancelled | draft |
// entered-in-error). FHIR has no "expired": a lapsed plan is active with a past period.end.
export type CoverageStatusChoice = 'active' | 'cancelled' | 'expired';

export const COVERAGE_STATUS_OPTIONS: { label: string; value: CoverageStatusChoice }[] = [
    { label: 'Active', value: 'active' },
    { label: 'Cancelled', value: 'cancelled' },
    { label: 'Expired', value: 'expired' },
];

/** True when a FHIR date has passed, by the same rule the list uses to badge a plan Expired. */
export const endHasPassed = (periodEnd: string | undefined, now: Date = new Date()): boolean =>
    !!periodEnd && new Date(periodEnd) < now;

export const statusChoiceOf = (fhirStatus: string | undefined, periodEnd: string | undefined, now?: Date): CoverageStatusChoice => {
    if (fhirStatus === 'cancelled') return 'cancelled';
    return endHasPassed(periodEnd, now) ? 'expired' : 'active';
};

/** Expired and Active both store `active`; the end date is what tells them apart. */
export const fhirStatusFor = (choice: CoverageStatusChoice): 'active' | 'cancelled' =>
    choice === 'cancelled' ? 'cancelled' : 'active';

/** Why the chosen status and the Effective To date disagree, or undefined when they agree. */
export const statusDateConflict = (choice: CoverageStatusChoice, periodEnd: string | undefined, now?: Date): string | undefined => {
    if (choice === 'expired' && !endHasPassed(periodEnd, now)) {
        return 'An expired plan needs the date it ended. Enter it in Effective To.';
    }
    if (choice === 'active' && endHasPassed(periodEnd, now)) {
        return 'Effective To has passed, so this plan has expired. Change the date, or set Status to Expired.';
    }
    return undefined;
};