fluxer/fluxer_app/src/features/messaging/utils/MessagePaginationUtils.test.ts

// SPDX-License-Identifier: AGPL-3.0-or-later

import {describe, expect, it} from 'vitest';
import {calculateAroundPaginationState, getAroundWindowCounts} from './MessagePaginationUtils';

describe('MessagePaginationUtils', () => {
	it('splits around windows with the newer side receiving the extra item for even limits', () => {
		expect(getAroundWindowCounts(0)).toEqual({newer: 0, older: 0});
		expect(getAroundWindowCounts(1)).toEqual({newer: 0, older: 0});
		expect(getAroundWindowCounts(2)).toEqual({newer: 1, older: 0});
		expect(getAroundWindowCounts(50)).toEqual({newer: 25, older: 24});
		expect(getAroundWindowCounts(51)).toEqual({newer: 25, older: 25});
	});

	it('keeps newer pagination open when an oldest-edge around response fills the newer side', () => {
		const state = calculateAroundPaginationState({
			limit: 50,
			messageCount: 26,
			targetIndex: 25,
			newestFetchedMessageId: '26',
			knownLatestMessageId: '100',
		});
		expect(state).toMatchObject({
			expectedNewer: 25,
			expectedOlder: 24,
			messagesNewer: 25,
			messagesOlder: 0,
			hasMoreBefore: false,
			hasMoreAfter: true,
		});
	});

	it('closes newer pagination when the fetched page reaches the known latest message', () => {
		const state = calculateAroundPaginationState({
			limit: 50,
			messageCount: 25,
			targetIndex: 0,
			newestFetchedMessageId: '100',
			knownLatestMessageId: '100',
		});
		expect(state.hasMoreBefore).toBe(true);
		expect(state.hasMoreAfter).toBe(false);
	});
});