/**
 * The front desk's "checkout done" stamp on an appointment: who finished checkout and when. The visit
 * itself stays fulfilled; this only says the desk has nothing left to do for it.
 */
import type { Appointment, Encounter } from "fhir/r4";

export const APPOINTMENT_CHECKOUT_EXTENSION_URL =
  "https://akashichealthrecords.com/fhir/StructureDefinition/appointment-checkout-done";

export interface CheckoutDone {
  reference: string;
  display?: string;
  at: string;
}

export const readCheckoutDone = (appointment: Appointment | undefined): CheckoutDone | undefined => {
  for (const extension of appointment?.extension ?? []) {
    if (extension.url !== APPOINTMENT_CHECKOUT_EXTENSION_URL) continue;

    const children = extension.extension ?? [];
    const by = children.find((child) => child.url === "by")?.valueReference;
    const at = children.find((child) => child.url === "at")?.valueDateTime;

    if (!by?.reference || !at) continue;

    return by.display ? { reference: by.reference, display: by.display, at } : { reference: by.reference, at };
  }

  return undefined;
};

export const withCheckoutDone = (appointment: Appointment, done: CheckoutDone): Appointment => ({
  ...appointment,
  extension: [
    ...(appointment.extension ?? []).filter((extension) => extension.url !== APPOINTMENT_CHECKOUT_EXTENSION_URL),
    {
      url: APPOINTMENT_CHECKOUT_EXTENSION_URL,
      extension: [
        {
          url: "by",
          valueReference: done.display
            ? { reference: done.reference, display: done.display }
            : { reference: done.reference },
        },
        { url: "at", valueDateTime: done.at },
      ],
    },
  ],
});

/** A finished visit the desk has not yet marked checkout done for. */
export const awaitsCheckout = (appointment: Appointment | undefined, encounter: Encounter | undefined): boolean =>
  Boolean(appointment) && encounter?.status === "finished" && !readCheckoutDone(appointment);