import { describe, expect, it } from 'vitest';
import { fromHex, hexPreview, toHex, toHexUpper } from '../src/hex';

describe('hex', () => {
    it('encodes only the selected byte view', () => {
        const bytes = Uint8Array.of(0xff, 0x01, 0xab, 0xff);
        expect(toHex(bytes.subarray(1, 3))).toBe('01ab');
        expect(toHexUpper(Buffer.from(bytes).subarray(1, 3))).toBe('01AB');
    });

    it('toHex / toHexUpper render bytes as zero-padded hex', () => {
        const b = Uint8Array.from([0x00, 0x0f, 0xa0, 0xff]);
        expect(toHex(b)).toBe('000fa0ff');
        expect(toHexUpper(b)).toBe('000FA0FF');
        expect(toHex(Uint8Array.of())).toBe('');
    });

    it('hexPreview appends "..." only past maxBytes', () => {
        const b = Uint8Array.from([1, 2, 3, 4, 5]);
        expect(hexPreview(b)).toBe('0102030405'); // under the default 64-byte cap
        expect(hexPreview(b, 5)).toBe('0102030405'); // exactly at the cap → no ellipsis
        expect(hexPreview(b, 2)).toBe('0102...'); // truncated
        expect(hexPreview(b, 0)).toBe('...'); // nothing shown, but bytes remain
    });

    it('fromHex round-trips toHex and rejects odd-length input', () => {
        const b = Buffer.from([0xde, 0xad, 0xbe, 0xef]);
        expect(fromHex(toHex(b)).equals(b)).toBe(true);
        expect(toHex(fromHex('00ffa0'))).toBe('00ffa0');
        expect(() => fromHex('abc')).toThrow();
    });
});