import { describe, it, expect } from 'vitest';
import { base64ToBytes, BufferReader } from '../src/parser';

describe('base64ToBytes', () => {
  it('decodes a simple base64 string', () => {
    const bytes = base64ToBytes('aGVsbG8='); // "hello"
    expect(Array.from(bytes)).toEqual([104, 101, 108, 108, 111]);
  });

  it('handles empty string', () => {
    const bytes = base64ToBytes('');
    expect(bytes).toBeInstanceOf(Uint8Array);
    expect(bytes.length).toBe(0);
  });
});

describe('BufferReader', () => {
  it('readByte and peekByte advance/inspect correctly', () => {
    const buf = new Uint8Array([1, 2, 3]);
    const r = new BufferReader(buf);
    expect(r.peekByte()).toBe(1);
    expect(r.readByte()).toBe(1);
    expect(r.peekByte()).toBe(2);
  });

  it('readBytes with and without length', () => {
    const buf = new Uint8Array([10, 11, 12, 13]);
    const r = new BufferReader(buf);
    const a = r.readBytes(2);
    expect(Array.from(a)).toEqual([10, 11]);
    const b = r.readBytes();
    expect(Array.from(b)).toEqual([12, 13]);
  });

  it('hasMore and remainingBytes reflect position', () => {
    const buf = new Uint8Array([5, 6]);
    const r = new BufferReader(buf);
    expect(r.hasMore()).toBe(true);
    expect(r.remainingBytes()).toBe(2);
    r.readByte();
    expect(r.remainingBytes()).toBe(1);
    r.readByte();
    expect(r.hasMore()).toBe(false);
  });

  it('reads little-endian unsigned ints', () => {
    const r16 = new BufferReader(new Uint8Array([0x34, 0x12]));
    expect(r16.readUint16LE()).toBe(0x1234);

    const r32 = new BufferReader(new Uint8Array([0x78, 0x56, 0x34, 0x12]));
    expect(r32.readUint32LE()).toBe(0x12345678);
  });

  it('reads signed ints with two/four bytes (negative)', () => {
    const r16 = new BufferReader(new Uint8Array([0xff, 0xff]));
    expect(r16.readInt16LE()).toBe(-1);

    const r32 = new BufferReader(new Uint8Array([0xff, 0xff, 0xff, 0xff]));
    expect(r32.readInt32LE()).toBe(-1);
  });

  it('readTimestamp returns Date with seconds->ms conversion', () => {
    const r = new BufferReader(new Uint8Array([0x01, 0x00, 0x00, 0x00]));
    const d = r.readTimestamp();
    expect(d.getTime()).toBe(1000);
  });
});