/**
 * AriaEngine CRC32 单元测试
 */
import { crc32, crc32Continue } from '../../src/engine/aria/crc32';

const enc = new TextEncoder();

function bytes(s: string): Uint8Array {
  return enc.encode(s);
}

describe('CRC32', () => {
  test('标准测试向量：空串 = 0', () => {
    expect(crc32(new Uint8Array(0))).toBe(0x00000000);
  });

  test('标准测试向量：123456789 = 0xCBF43926（IEEE 802.3 参考值）', () => {
    expect(crc32(bytes('123456789'))).toBe(0xcbf43926);
  });

  test('标准测试向量：The quick brown fox... = 0x414FA339', () => {
    expect(crc32(bytes('The quick brown fox jumps over the lazy dog'))).toBe(0x414fa339);
  });

  test('确定性：相同输入多次计算一致', () => {
    const data = bytes('metona-sqlark aria engine');
    const a = crc32(data);
    const b = crc32(data);
    expect(a).toBe(b);
  });

  test('区分性：不同输入不同校验和', () => {
    expect(crc32(bytes('hello'))).not.toBe(crc32(bytes('hellp')));
    expect(crc32(bytes('abc'))).not.toBe(crc32(bytes('abd')));
  });

  test('单字节翻转可被检测', () => {
    const original = bytes('metona-sqlark aria engine');
    const flipped = new Uint8Array(original);
    flipped[10] ^= 0xff;
    expect(crc32(original)).not.toBe(crc32(flipped));
  });

  test('分段计算与一次性计算一致（crc32Continue）', () => {
    const data = bytes('The quick brown fox jumps over the lazy dog');
    const whole = crc32(data);

    // 按 1 字节分段
    let seg = 0;
    for (let i = 0; i < data.length; i++) {
      seg = crc32Continue(seg, data.subarray(i, i + 1));
    }
    expect(seg).toBe(whole);

    // 按 5 字节分段
    let seg2 = 0;
    for (let i = 0; i < data.length; i += 5) {
      seg2 = crc32Continue(seg2, data.subarray(i, i + 5));
    }
    expect(seg2).toBe(whole);
  });

  test('seed 参数与 crc32Continue 等价', () => {
    const data = bytes('metona-sqlark aria engine');
    const head = data.subarray(0, 7);
    const tail = data.subarray(7);
    const whole = crc32(data);
    const split = crc32(tail, crc32(head));
    expect(split).toBe(whole);
  });

  test('中文 UTF-8 字节正确参与计算', () => {
    const data = bytes('玥玥的测试数据：大段中文内容');
    expect(crc32(data)).toBe(crc32(new Uint8Array(data)));
  });

  test('大缓冲区（1MB 随机字节）稳定计算', () => {
    const data = new Uint8Array(1024 * 1024);
    let x = 12345;
    for (let i = 0; i < data.length; i++) {
      x = (x * 1103515245 + 12345) & 0x7fffffff;
      data[i] = x & 0xff;
    }
    const a = crc32(data);
    const b = crc32(data);
    expect(a).toBe(b);
    expect(a).not.toBe(0);
  });
});