import assert from "node:assert/strict";
import test from "node:test";

import {
  clampSessionLimit,
  compareSessionCursor,
  encodeSessionCursor,
  nextSessionCursor,
  parseSessionCursor,
  SESSION_PAGE_SIZE,
} from "../src/lib/session-cursor.ts";

const leftId = "11111111-1111-4111-8111-111111111111";
const rightId = "22222222-2222-4222-8222-222222222222";
const stamp = "2026-09-06T04:00:00.000Z";

test("encodeSessionCursor round-trips a valid pair", () => {
  const encoded = encodeSessionCursor(stamp, leftId);
  assert.deepEqual(parseSessionCursor(encoded), { updatedAt: stamp, id: leftId });
});

test("parseSessionCursor returns null for illegal strings", () => {
  assert.equal(parseSessionCursor(null), null);
  assert.equal(parseSessionCursor(""), null);
  assert.equal(parseSessionCursor("not-a-date,11111111-1111-4111-8111-111111111111"), null);
  assert.equal(parseSessionCursor(`${stamp},not-a-uuid`), null);
  assert.equal(parseSessionCursor(stamp), null);
});

test("compareSessionCursor uses id when the timestamp is the same", () => {
  const sameTime = compareSessionCursor(
    { updatedAt: stamp, id: leftId },
    { updatedAt: stamp, id: rightId },
  );
  assert.ok(sameTime > 0);
  const newerTime = compareSessionCursor(
    { updatedAt: "2026-09-06T05:00:00.000Z", id: leftId },
    { updatedAt: stamp, id: rightId },
  );
  assert.ok(newerTime < 0);
});

test("clampSessionLimit defaults to 40 and clamps 1–100", () => {
  assert.equal(clampSessionLimit(null), SESSION_PAGE_SIZE);
  assert.equal(clampSessionLimit("0"), 1);
  assert.equal(clampSessionLimit("101"), 100);
  assert.equal(clampSessionLimit("40"), 40);
});

test("nextSessionCursor is null when the page is short, else encodes the limit-th row", () => {
  const rows = [
    { id: leftId, updated_at: stamp },
    { id: rightId, updated_at: stamp },
  ];
  assert.equal(nextSessionCursor(rows, 40), null);
  assert.equal(nextSessionCursor(rows, 1), encodeSessionCursor(stamp, leftId));
});