function createRatecardController({ messageTypes, requestConsumerTokenServiceOnce, sendRuntimeMessage,
  appendBackgroundRequestLog, openRatecardDrawer, closePlanDetailPopover, environment }) {
  const pending = new Map();
  async function request(planNumber) {
    const authorizations = await requestConsumerTokenServiceOnce();
    const response = await sendRuntimeMessage({ type: messageTypes.requestRatecardByPlan, planNumber,
      authorization: authorizations && authorizations.accountPlans });
    appendBackgroundRequestLog(response?.debugRequests);
    if (!response?.ok) throw new Error(response?.error || "Unable to load rate card.");
    return response.items;
  }

  async function showRatecard(plan, trigger) {
    closePlanDetailPopover();
    const handle = openRatecardDrawer(plan, trigger);
    if (!handle) return;
    try {
      const planNumber = String(plan.subPlanNum ?? "").trim();
      if (!planNumber) throw new Error("Plan number is unavailable for this account plan.");
      if (!pending.has(planNumber)) pending.set(planNumber, request(planNumber).finally(() => pending.delete(planNumber)));
      handle.showItems(await pending.get(planNumber));
    } catch (error) {
      handle.showError(error.message || "Unable to load rate card.");
    }
  }

  function createRatecardButton(plan) {
    const button = environment.document.createElement("button");
    button.type = "button";
    button.className = "opportunities-extension-ratecard-button";
    button.textContent = "Rate Card";
    button.title = "View rate card";
    button.setAttribute("aria-haspopup", "dialog");
    button.addEventListener("click", () => showRatecard(plan, button));
    return button;
  }
  return { createRatecardButton, showRatecard };
}