import type { Appointment as FhirAppointment } from "fhir/r4";
import { holdDelete, holdWrite } from "../../../utils/writeThroughHold";

// Realtime appointment-broadcast helpers for the receptionist overview ( / AHR-225).
//
// The appointment.{created,updated,deleted} broadcast bundle already carries the full Appointment resource, so
// the receptionist list can be updated straight from the payload - immediately consistent. The previous handler
// instead re-fetched via a HealthLake search, which is eventually consistent: for ~1-2s after the POST the new
// Appointment isn't searchable, so a patient self-booking appeared only after a manual refresh.

/**
 * Pull the Appointment resource out of a broadcast CloudEvent's bundle (entries can also contain Slots).
 * Returns undefined if the payload is absent/malformed (caller falls back to a refetch).
 */
export function extractAppointmentFromBroadcast(cloudEvent: unknown): FhirAppointment | undefined {
    const data = (cloudEvent as { data?: { entry?: Array<{ resource?: { resourceType?: string } }> } })?.data;
    const match = (data?.entry ?? []).find((entry) => entry.resource?.resourceType === "Appointment");
    return match?.resource as FhirAppointment | undefined;
}

/**
 * Merge a broadcast Appointment into the receptionist's appointment list, de-duped by id: remove on a delete
 * event, otherwise insert-or-replace at the front. Order is irrelevant - every consumer memo re-sorts by start
 * time - so a plain front insert keeps the merge simple and idempotent.
 */
export function mergeBroadcastAppointment(
    current: FhirAppointment[],
    appointment: FhirAppointment,
    isDelete: boolean,
): FhirAppointment[] {
    const withoutThis = current.filter((existing) => existing.id !== appointment.id);
    return isDelete ? withoutThis : [appointment, ...withoutThis];
}

/**
 * Hold a broadcast appointment in the shared hold until the search can see it, as a booking made on this screen
 * is held. A patient's online booking arrives only as a broadcast, and the search that follows it lags by minutes.
 * A delete is held as one, so the lagging search cannot show it again. Returns false when the payload carries no
 * appointment.
 */
export function holdBroadcastAppointment(cloudEvent: unknown, now = Date.now()): boolean {
    const appointment = extractAppointmentFromBroadcast(cloudEvent);
    if (!appointment?.id) return false;
    if ((cloudEvent as { type?: string })?.type === "com.akashichealthrecords.fhir.appointment.deleted") {
        holdDelete({ resourceType: "Appointment", id: appointment.id }, now);
    } else {
        holdWrite(appointment, now);
    }
    return true;
}