import type { ContactPoint, Patient } from "fhir/r4";

/** The first two values of one kind, primary then secondary, blank where absent. */
export const telecomSlots = (telecom: ContactPoint[] | undefined, system: "phone" | "email"): [string, string] => {
  const values = (telecom ?? []).filter((point) => point.system === system).map((point) => point.value ?? "");
  return [values[0] ?? "", values[1] ?? ""];
};

/** The use (mobile, home, work...) of the same two entries, blank where none is recorded. */
export const telecomUseSlots = (telecom: ContactPoint[] | undefined, system: "phone" | "email"): [string, string] => {
  const uses = (telecom ?? []).filter((point) => point.system === system).map((point) => point.use ?? "");
  return [uses[0] ?? "", uses[1] ?? ""];
};

/**
 * Write primary and secondary values for one kind. Existing entries keep their other fields (use,
 * rank), entries past the second are left alone, other kinds are untouched, and a cleared slot is
 * removed rather than stored empty. A use given for a slot replaces that entry's use; a blank one
 * clears it.
 */
export const setTelecomSlots = (
  draft: Patient,
  system: "phone" | "email",
  values: [string, string],
  uses?: [string, string],
): void => {
  const all = draft.telecom ?? [];
  const same = all.filter((point) => point.system === system);
  const others = all.filter((point) => point.system !== system);
  const slots: ContactPoint[] = [];
  values.forEach((raw, index) => {
    const value = raw.trim();
    if (!value) return;
    const slot: ContactPoint = same[index] ? { ...same[index], value } : { system, value, rank: index + 1 };
    if (uses) {
      const use = uses[index] as ContactPoint["use"] | "";
      if (use) slot.use = use;
      else delete slot.use;
    }
    slots.push(slot);
  });
  const telecom = [...others, ...slots, ...same.slice(2)];
  draft.telecom = telecom.length ? telecom : undefined;
};