import { describe, expect, it } from "vitest";
import { nextOccurrences } from "./occurrences_extra.js";

const ISO = (o: { fireAtUtc: number }) => new Date(o.fireAtUtc).toISOString().replace(".000Z", "Z");

describe("count boundary semantics", () => {
  it("never returns more than count", () => {
    for (const count of [1, 2, 5, 17]) {
      const out = nextOccurrences({ cron: "*/15 * * * *", timezone: "America/New_York" }, "2024-03-09T00:00:00Z", count);
      expect(out.length).toBe(count);
    }
  });
  it("stops at the collapse edge with the latest collapsed label", () => {
    // Exclusive from 05:00Z (== 00:00 local): the first slot is 00:15. The
    // eighth occurrence is the collapse edge — nominal slots 02:00..03:00 all
    // materialize onto 07:00Z — and it carries the LATEST label (03:00), with
    // nothing beyond the edge emitted.
    const out = nextOccurrences({ cron: "*/15 * * * *", timezone: "America/New_York" }, "2024-03-10T05:00:00Z", 8);
    expect(out.length).toBe(8);
    expect(out.map(ISO)[7]).toBe("2024-03-10T07:00:00Z");
    expect(out[7]!.nominalLocal).toBe("2024-03-10T03:00");
    // The same result whether the boundary is reached with 8 or 80 requested,
    // because generation stops at the first slot after the boundary instant.
    const wide = nextOccurrences({ cron: "*/15 * * * *", timezone: "America/New_York" }, "2024-03-10T05:00:00Z", 80);
    expect(wide[7]!.nominalLocal).toBe("2024-03-10T03:00");
  });
});