import { Appointment, Location } from "fhir/r4";
import { isVirtualLocation } from "./roomLocation";

// FHIR R4 has no `Appointment.location` element - the site rides in `participant[].actor` as a
// `Location/<id>` reference, next to the Practitioner, PractitionerRole and Patient actors. The
// patient-facing appointment cards used to ignore it entirely and print the logged-in
// organization's name in the location slot, so an appointment booked at "West Burlington Hospital"
// displayed as "Great River Health Center" (the org). The data was always correct; nothing read it.
//
// This matters beyond tidiness now that a telehealth visit IS a Location: showing the
// org there would tell a patient booked into a Video Visit to attend a physical building.

/** The `Location/...` participant on an appointment, if it has one. */
const findLocationParticipant = (appointment: Appointment) =>
  appointment.participant?.find((participant) =>
    // Anchored on the prefix on purpose. The sibling practitioner lookup in these cards matches with
    // `reference.includes("Practitioner")`; copying that here would let any reference that merely
    // CONTAINS "Location" win.
    participant.actor?.reference?.startsWith("Location/"),
  );

/**
 * The name to show in an appointment's location slot.
 *
 * Falls back to `organizationName` when the appointment names no location - appointments booked
 * before locations were captured have no Location participant, and the owning organization is the
 * best "where" we have for them. A Location participant with no usable display falls back the same
 * way: a blank where the site should be reads as deliberate, which is worse than naming the org.
 */
export const getAppointmentLocationName = (
  appointment: Appointment,
  organizationName: string | undefined,
  locations: readonly Location[] = [],
): string => {
  const participant = findLocationParticipant(appointment);
  // A virtual Location's name is the admin's label for it; the visit itself is a video visit.
  const id = participant?.actor?.reference?.split("/")[1];
  const location = id ? locations.find((candidate) => candidate.id === id) : undefined;
  if (location && isVirtualLocation(location)) return "Video visit";
  const locationDisplay = participant?.actor?.display?.trim();

  return locationDisplay || organizationName?.trim() || "";
};