import { describe, expect, it } from "vitest";
import {
  formatDateTimeLocal,
  parseLocalDateTime,
  resolveZonedDateTime,
  shiftTimestampByPeriods,
  zonedDateTimeCandidates,
} from "../../src/otp/time";

describe("TOTP time travel", () => {
  it("parses exact UTC wall-clock values", () => {
    const resolved = resolveZonedDateTime("2025-08-19T12:34:56", "UTC");
    expect(new Date(resolved.timestampMs).toISOString()).toBe(
      "2025-08-19T12:34:56.000Z",
    );
    expect(formatDateTimeLocal(resolved.timestampMs, "UTC")).toBe(
      "2025-08-19T12:34:56",
    );
    expect(
      resolveZonedDateTime("2025-08-19T12:34:56.125", "UTC").timestampMs,
    ).toBe(Date.UTC(2025, 7, 19, 12, 34, 56, 125));
  });

  it("respects seasonal IANA timezone offsets", () => {
    expect(
      new Date(
        resolveZonedDateTime("2024-01-15T12:00:00", "America/New_York")
          .timestampMs,
      ).toISOString(),
    ).toBe("2024-01-15T17:00:00.000Z");
    expect(
      new Date(
        resolveZonedDateTime("2024-07-15T12:00:00", "America/New_York")
          .timestampMs,
      ).toISOString(),
    ).toBe("2024-07-15T16:00:00.000Z");
  });

  it("rejects nonexistent DST times and exposes both repeated times", () => {
    expect(() =>
      resolveZonedDateTime("2024-03-10T02:30:00", "America/New_York"),
    ).toThrow(/does not exist/iu);

    const candidates = zonedDateTimeCandidates(
      "2024-11-03T01:30:00",
      "America/New_York",
    );
    expect(candidates.map((value) => new Date(value).toISOString())).toEqual([
      "2024-11-03T05:30:00.000Z",
      "2024-11-03T06:30:00.000Z",
    ]);
    expect(
      new Date(
        resolveZonedDateTime("2024-11-03T01:30:00", "America/New_York", "later")
          .timestampMs,
      ).toISOString(),
    ).toBe("2024-11-03T06:30:00.000Z");
  });

  it("handles non-hour timezone offsets", () => {
    expect(
      new Date(
        resolveZonedDateTime("2025-08-19T12:00:00", "Asia/Kathmandu")
          .timestampMs,
      ).toISOString(),
    ).toBe("2025-08-19T06:15:00.000Z");
  });

  it("validates calendar values, timezone names and bounded period shifts", () => {
    expect(() => parseLocalDateTime("2025-02-29T12:00:00")).toThrow(
      /valid calendar/iu,
    );
    expect(() =>
      resolveZonedDateTime("2025-01-01T00:00:00", "Mars/Base"),
    ).toThrow(/timezone/iu);
    expect(shiftTimestampByPeriods(90_000, 30, -2)).toBe(30_000);
    expect(() => shiftTimestampByPeriods(1_000, 30, -1)).toThrow(
      /outside supported time/iu,
    );
  });
});