import { describe, expect, it } from "vitest";

describe("sliding selection scheduling", () => {
  it("re-arms transitions when a StrictMode effect cleanup cancels the first frame", async () => {
    const selectionModule = await import("../src/renderer/ui/SlidingSelection");
    const schedule = Reflect.get(selectionModule, "scheduleSelectionTransitions");

    expect(schedule).toBeTypeOf("function");

    let transitionsEnabled = false;
    let nextFrame = 0;
    const pending = new Map<number, FrameRequestCallback>();
    const requestFrame = (callback: FrameRequestCallback): number => {
      nextFrame += 1;
      pending.set(nextFrame, callback);
      return nextFrame;
    };
    const cancelFrame = (frame: number): void => {
      pending.delete(frame);
    };

    const firstFrame = schedule(false, 0, () => { transitionsEnabled = true; }, requestFrame, cancelFrame);
    cancelFrame(firstFrame);
    const secondFrame = schedule(false, 0, () => { transitionsEnabled = true; }, requestFrame, cancelFrame);

    expect(transitionsEnabled).toBe(false);
    expect(pending.has(firstFrame)).toBe(false);
    pending.get(secondFrame)?.(0);
    expect(transitionsEnabled).toBe(true);
  });

  it("applies the first mounted selection before scheduling later movements", async () => {
    const selectionModule = await import("../src/renderer/ui/SlidingSelection");
    const schedule = Reflect.get(selectionModule, "scheduleSelectionLayout");

    expect(schedule).toBeTypeOf("function");

    const events: string[] = [];
    const pending: { callback?: FrameRequestCallback } = {};
    const requestFrame = (callback: FrameRequestCallback): number => {
      events.push("request");
      pending.callback = callback;
      return 9;
    };
    const cancelFrame = (frame: number): void => {
      events.push(`cancel:${frame}`);
    };
    const apply = (): void => {
      events.push("apply");
    };
    const enableTransitions = (): void => {
      events.push("enable");
    };

    expect(schedule(false, 0, apply, requestFrame, cancelFrame, enableTransitions)).toBe(9);
    expect(events).toEqual(["apply", "request"]);

    pending.callback?.(0);
    expect(events).toEqual(["apply", "request", "enable"]);

    events.length = 0;
    expect(schedule(true, 4, apply, requestFrame, cancelFrame)).toBe(9);
    expect(events).toEqual(["cancel:4", "request"]);

    pending.callback?.(0);
    expect(events).toEqual(["cancel:4", "request", "apply"]);
  });
});