import { describe, expect, it } from "vitest";
import { dayRangeNairobi, isBusinessDate, startOfMonthNairobi, todayNairobi } from "@/lib/server/businessDay";

describe("Nairobi business day", () => {
  it("rolls over at midnight EAT, not midnight UTC", () => {
    // 00:30 EAT on 12 Oct = 21:30 UTC on 11 Oct.
    expect(todayNairobi(new Date("2026-10-11T21:30:00Z"))).toBe("2026-10-12");
    // 23:30 EAT on 11 Oct = 20:30 UTC on 11 Oct.
    expect(todayNairobi(new Date("2026-10-11T20:30:00Z"))).toBe("2026-10-11");
  });

  it("maps a business date to the UTC range 21:00 -> 21:00", () => {
    const { start, end } = dayRangeNairobi("2026-10-12");
    expect(start.toISOString()).toBe("2026-10-11T21:00:00.000Z");
    expect(end.toISOString()).toBe("2026-10-12T21:00:00.000Z");
  });

  it("starts the month on the 1st at 00:00 EAT", () => {
    expect(startOfMonthNairobi(new Date("2026-10-31T22:00:00Z")).toISOString()).toBe("2026-10-31T21:00:00.000Z");
    expect(startOfMonthNairobi(new Date("2026-10-15T10:00:00Z")).toISOString()).toBe("2026-09-30T21:00:00.000Z");
  });

  it("rejects malformed dates", () => {
    expect(isBusinessDate("2026-02-30")).toBe(false);
    expect(isBusinessDate("2026-2-3")).toBe(false);
    expect(isBusinessDate("2026-02-28")).toBe(true);
    expect(() => dayRangeNairobi("nope")).toThrow();
  });
});