/**
 * 코드 펜스 시작 줄을 파싱한다.
 * @param {string} line - 마크다운 줄
 * @returns {{ language: string, showLineNumbers: boolean }|null} 파싱 결과
 */
export const parseCodeFenceLine = (line) => {
  const trimmed = String(line ?? '').trim()

  if (!trimmed.startsWith('```')) {
    return null
  }

  const rest = trimmed.slice(3).trim()

  if (!rest) {
    return { language: '', showLineNumbers: true }
  }

  const noLineNumberTokens = ['nolinenos', 'no-linenos', 'no-line-numbers']
  const tokens = rest.split(/\s+/).filter(Boolean)
  const showLineNumbers = !tokens.some((token) => noLineNumberTokens.includes(token.toLowerCase()))
  const languageTokens = tokens.filter((token) => !noLineNumberTokens.includes(token.toLowerCase()))
  const language = languageTokens[0] || ''

  return { language, showLineNumbers }
}

/**
 * 코드 펜스 시작 줄을 만든다.
 * @param {{ language?: string, showLineNumbers?: boolean }} options - 옵션
 * @returns {string} 펜스 시작 줄
 */
export const buildCodeFenceOpener = (options = {}) => {
  const language = String(options.language ?? '').trim()
  const showLineNumbers = options.showLineNumbers !== false
  let opener = '```'

  if (language) {
    opener += language
  }

  if (!showLineNumbers) {
    opener += language ? ' nolinenos' : 'nolinenos'
  }

  return opener
}

/**
 * 코드 블록 마크다운 줄 배열을 만든다.
 * @param {{ language?: string, showLineNumbers?: boolean, body?: string }} options - 옵션
 * @returns {string[]} 마크다운 줄
 */
export const buildCodeBlockLines = (options = {}) => {
  const body = String(options.body ?? '').replace(/\r/g, '')
  const bodyLines = body.length ? body.split('\n') : ['']

  return [
    buildCodeFenceOpener(options),
    ...bodyLines,
    '```'
  ]
}