import { describe, expect, it } from "vitest";
import { getNearestPageNumber } from "../src/preview-page";

const pages = [
  { top: 0, bottom: 100 },
  { top: 124, bottom: 224 },
  { top: 248, bottom: 348 }
];

describe("getNearestPageNumber", () => {
  it("返回视口中心所在的页面", () => {
    expect(getNearestPageNumber(180, pages)).toBe(2);
  });

  it("在页间空隙中返回距离最近的页面", () => {
    expect(getNearestPageNumber(110, pages)).toBe(1);
    expect(getNearestPageNumber(116, pages)).toBe(2);
  });

  it("没有页面或中心坐标无效时返回 0", () => {
    expect(getNearestPageNumber(20, [])).toBe(0);
    expect(getNearestPageNumber(Number.NaN, pages)).toBe(0);
  });
});