import { readFileSync } from 'node:fs';
import { describe, expect, it } from 'vitest';
import { blake3 } from '../src/blake3.js';

const vectors = JSON.parse(
  readFileSync(
    new URL('../../../test/fixtures/blake3-vectors.json', import.meta.url),
    'utf8',
  ),
);

/** Official BLAKE3 vector inputs are the repeating byte pattern i % 251. */
function vectorInput(/** @type {number} */ len) {
  const bytes = new Uint8Array(len);
  for (let i = 0; i < len; i++) bytes[i] = i % 251;
  return bytes;
}

function toHex(/** @type {Uint8Array} */ bytes) {
  return Array.from(bytes)
    .map((b) => b.toString(16).padStart(2, '0'))
    .join('');
}

describe('blake3', () => {
  it('matches the official vectors at 32-byte output', () => {
    for (const c of vectors.cases) {
      const out = blake3(vectorInput(c.input_len), 32);
      expect(toHex(out), `input_len=${c.input_len}`).toBe(c.hash.slice(0, 64));
    }
  });

  it('matches the official vectors at extended output length', () => {
    for (const c of vectors.cases) {
      const outLen = c.hash.length / 2;
      const out = blake3(vectorInput(c.input_len), outLen);
      expect(toHex(out), `input_len=${c.input_len} outLen=${outLen}`).toBe(
        c.hash,
      );
    }
  });

  it('produces 2048 bytes for LtHash expansion', () => {
    const out = blake3(new TextEncoder().encode('a'), 2048);
    expect(out.length).toBe(2048);
  });

  it('defaults to 32 bytes', () => {
    expect(blake3(new Uint8Array(0)).length).toBe(32);
  });
});