import { useEffect, useRef } from "react";
import type { Organization } from "fhir/r4";
import { useAuthServiceContext } from "../services/AuthService";
import { useOrganizationServiceContext } from "../services/OrganizationService";

// A save replaces the whole Organization, so saves run one at a time, each built from the last
// confirmed version: a slow save can never land after, and overwrite, a newer one.
export const useSerializedOrganizationSave = () => {
  const { currentOrganization, setWpOrganization } = useAuthServiceContext();
  const { updateOrganization } = useOrganizationServiceContext();
  const confirmed = useRef<Organization | null>(currentOrganization);
  const queue = useRef<Promise<unknown>>(Promise.resolve());

  useEffect(() => {
    confirmed.current = currentOrganization;
  }, [currentOrganization]);

  return (build: (base: Organization) => Organization): Promise<Organization> => {
    const run = queue.current.then(async () => {
      const base = confirmed.current;
      if (!base) throw new Error("The organization is not loaded.");
      const saved = await updateOrganization(build(base));
      confirmed.current = saved;
      setWpOrganization(saved);
      return saved;
    });
    queue.current = run.catch(() => undefined);
    return run;
  };
};