import { describe, it, expect } from 'vitest'
import { getByteLength, truncateToMaxBytes } from '../../src/utils/byteUtils.js'

describe('byteUtils', () => {
  it('counts ASCII bytes', () => {
    expect(getByteLength('hello')).toBe(5)
    expect(getByteLength('')).toBe(0)
  })

  it('counts UTF-8 multibyte characters', () => {
    expect(getByteLength('中')).toBe(3)
    expect(getByteLength('hello世界')).toBe(11)
  })

  it('returns original string when within limit', () => {
    expect(truncateToMaxBytes('hello', 10)).toBe('hello')
  })

  it('truncates by bytes without breaking multibyte chars', () => {
    const text = 'a'.repeat(10) + '中'
    const truncated = truncateToMaxBytes(text, 11)
    expect(getByteLength(truncated)).toBeLessThanOrEqual(11)
    expect(truncated).not.toContain('中')
  })

  it('handles exact byte boundary', () => {
    expect(truncateToMaxBytes('ab', 2)).toBe('ab')
    expect(truncateToMaxBytes('abc', 2)).toBe('ab')
  })
})