import type { Extension, PractitionerRole } from "fhir/r4";

// Appointment setup saved without publishing. It rides on the role so it survives a reload; it is not
// availability - nothing books from it, and role extensions reach patients only through an allow-list.
export const APPOINTMENT_SETUP_DRAFT_EXTENSION_URL =
  "https://akashichealthrecords.com/fhir/StructureDefinition/practitioner-role-appointment-setup-draft";

export type AppointmentSetupDraft = {
  serviceIds: string[];
  locationId: string;
  days: string[];
  start: string;
  end: string;
};

export const EMPTY_APPOINTMENT_SETUP: AppointmentSetupDraft = { serviceIds: [], locationId: "", days: [], start: "", end: "" };

const idOf = (reference: string | undefined, type: string): string =>
  reference?.startsWith(`${type}/`) ? reference.slice(type.length + 1) : "";

export const appointmentSetupDraftOf = (role?: PractitionerRole | null): AppointmentSetupDraft | null => {
  const draft = role?.extension?.find((extension) => extension.url === APPOINTMENT_SETUP_DRAFT_EXTENSION_URL);
  if (!draft) return null;
  const parts = (url: string) => (draft.extension ?? []).filter((part) => part.url === url);
  return {
    serviceIds: parts("service").map((part) => idOf(part.valueReference?.reference, "HealthcareService")).filter(Boolean),
    locationId: idOf(parts("location")[0]?.valueReference?.reference, "Location"),
    days: parts("day").map((part) => part.valueCode ?? "").filter(Boolean),
    start: parts("start")[0]?.valueString ?? "",
    end: parts("end")[0]?.valueString ?? "",
  };
};

// Replaces any earlier draft; null removes it once the schedule is published.
export const withAppointmentSetupDraft = (role: PractitionerRole, draft: AppointmentSetupDraft | null): PractitionerRole => {
  const others = (role.extension ?? []).filter((extension) => extension.url !== APPOINTMENT_SETUP_DRAFT_EXTENSION_URL);
  if (!draft) return { ...role, extension: others };
  const parts: Extension[] = [
    ...draft.serviceIds.map((id) => ({ url: "service", valueReference: { reference: `HealthcareService/${id}` } })),
    ...(draft.locationId ? [{ url: "location", valueReference: { reference: `Location/${draft.locationId}` } }] : []),
    ...draft.days.map((day) => ({ url: "day", valueCode: day })),
    ...(draft.start ? [{ url: "start", valueString: draft.start }] : []),
    ...(draft.end ? [{ url: "end", valueString: draft.end }] : []),
  ];
  return { ...role, extension: [...others, { url: APPOINTMENT_SETUP_DRAFT_EXTENSION_URL, extension: parts }] };
};

const keyOf = (setup: AppointmentSetupDraft): string =>
  JSON.stringify([[...setup.serviceIds].sort(), setup.locationId, [...setup.days].sort(), setup.start, setup.end]);
export const sameAppointmentSetup = (a: AppointmentSetupDraft, b: AppointmentSetupDraft): boolean => keyOf(a) === keyOf(b);