import {
  __resetTelemetryForTests,
  registerTelemetry,
  trackClick,
  withClickTracking,
} from "../telemetry";

describe("telemetry registry", () => {
  afterEach(() => __resetTelemetryForTests());

  it("is a no-op until a sink is registered", () => {
    // The whole point of the default: a consumer that never opts in must not
    // have this throw, buffer, or reach the network.
    expect(() => trackClick("login.submit")).not.toThrow();
  });

  it("forwards element and route to the registered sink", () => {
    const sink = { trackClick: jest.fn() };
    registerTelemetry(sink);

    trackClick("login.submit", "/login");

    expect(sink.trackClick).toHaveBeenCalledWith("login.submit", "/login");
  });

  it("swallows a sink that throws", () => {
    // A failing sink must never take down the press handler it is observing.
    registerTelemetry({
      trackClick: () => {
        throw new Error("collector unreachable");
      },
    });

    expect(() => trackClick("login.submit")).not.toThrow();
  });

  it("stops reporting once the sink is removed", () => {
    const sink = { trackClick: jest.fn() };
    registerTelemetry(sink);
    registerTelemetry(null);

    trackClick("login.submit");

    expect(sink.trackClick).not.toHaveBeenCalled();
  });

  describe("withClickTracking", () => {
    it("returns the original handler when there is no id", () => {
      // Identity, not a wrapper: an untagged control should not pay for a
      // closure on every render.
      const handler = jest.fn();
      expect(withClickTracking(undefined, handler)).toBe(handler);
    });

    it("reports before invoking the handler", () => {
      const order: string[] = [];
      registerTelemetry({ trackClick: () => order.push("tracked") });
      const wrapped = withClickTracking("login.submit", () => order.push("handled"));

      wrapped?.();

      expect(order).toEqual(["tracked", "handled"]);
    });

    it("still reports when there is no handler to call", () => {
      const sink = { trackClick: jest.fn() };
      registerTelemetry(sink);

      withClickTracking("login.submit", undefined)?.();

      expect(sink.trackClick).toHaveBeenCalledWith("login.submit", undefined);
    });

    it("passes arguments and the return value through", () => {
      registerTelemetry({ trackClick: jest.fn() });
      const wrapped = withClickTracking("row.select", (id: never) => `picked ${String(id)}`);

      expect(wrapped?.("abc" as never)).toBe("picked abc");
    });
  });
});