import { afterEach, describe, expect, it, vi } from "vitest";
import { uuidv7 } from "../../src/harness/session/uuid.ts";

const UUID_V7_RE = /^[0-9a-f]{8}-[0-9a-f]{4}-7[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/;
const TIMESTAMP = 0x0123456789ab;

function parseTimestamp(uuid: string): number {
	return Number.parseInt(uuid.replaceAll("-", "").slice(0, 12), 16);
}

afterEach(() => {
	vi.unstubAllGlobals();
});

describe("uuidv7", () => {
	it("uses the RFC 9562 layout and preserves monotonic order", () => {
		const randomValues = [
			new Uint8Array([0, 0, 0, 0, 0, 0, 0xff, 0xff, 0xff, 0xfe, 0x01, 0x11, 0x22, 0x33, 0x44, 0x55]),
			new Uint8Array(16),
			new Uint8Array(16),
		];
		const getRandomValues = vi.fn((bytes: Uint8Array) => {
			bytes.set(randomValues.shift() ?? new Uint8Array(bytes.length));
			return bytes;
		});
		vi.stubGlobal("crypto", { getRandomValues });
		const dateNow = vi.spyOn(Date, "now").mockReturnValue(TIMESTAMP);

		try {
			const first = uuidv7();
			const second = uuidv7();
			const third = uuidv7();

			expect(first).toBe("01234567-89ab-7fff-bfff-f91122334455");
			expect(second).toBe("01234567-89ab-7fff-bfff-fc0000000000");
			expect(third).toBe("01234567-89ac-7000-8000-000000000000");
			expect(first).toMatch(UUID_V7_RE);
			expect(second).toMatch(UUID_V7_RE);
			expect(third).toMatch(UUID_V7_RE);
			expect(parseTimestamp(first)).toBe(TIMESTAMP);
			expect(parseTimestamp(second)).toBe(TIMESTAMP);
			expect(parseTimestamp(third)).toBe(TIMESTAMP + 1);
			expect(first < second).toBe(true);
			expect(second < third).toBe(true);
			expect(getRandomValues).toHaveBeenCalledTimes(3);
		} finally {
			dateNow.mockRestore();
		}
	});
});