export const DEFAULT_SESSION_RENEW_THRESHOLD_MS = 10 * 60 * 1000;
export const DEFAULT_SESSION_RENEW_THROTTLE_MS = 30 * 1000;

export type SessionRenewDecisionParams = {
  expiresAtSec?: number | null;
  nowMs: number;
  isEnabled: boolean;
  isAuthenticated: boolean;
  isLoading: boolean;
  isRenewInFlight: boolean;
  lastAttemptAtMs: number;
  thresholdMs?: number;
  throttleMs?: number;
};

function hasRenewPreconditions({
  isAuthenticated,
  isLoading,
  isRenewInFlight,
}: SessionRenewDecisionParams) {
  return isAuthenticated && !isLoading && !isRenewInFlight;
}

function isRenewWindowOpen({
  expiresAtSec,
  nowMs,
  lastAttemptAtMs,
  thresholdMs = DEFAULT_SESSION_RENEW_THRESHOLD_MS,
  throttleMs = DEFAULT_SESSION_RENEW_THROTTLE_MS,
}: SessionRenewDecisionParams) {
  if (typeof expiresAtSec !== "number") {
    return false;
  }

  const remainingMs = expiresAtSec * 1000 - nowMs;
  if (remainingMs <= 0 || remainingMs > thresholdMs) {
    return false;
  }

  if (nowMs - lastAttemptAtMs < throttleMs) {
    return false;
  }

  return true;
}

export function shouldAttemptSlidingSessionRenew(
  params: SessionRenewDecisionParams,
) {
  if (!params.isEnabled || !hasRenewPreconditions(params)) {
    return false;
  }

  return isRenewWindowOpen(params);
}

export function shouldAttemptUnlimitedSessionRenew(
  params: SessionRenewDecisionParams,
) {
  if (params.isEnabled || !hasRenewPreconditions(params)) {
    return false;
  }

  return isRenewWindowOpen(params);
}