const NEW_LINE_EXP = /\n(?!$)/g;

/**
 * @param highlightedCode - A string with new line breaks; the line numbers will be added before each line.
 * @param start - The number to start the line numbering from; default is 1
 * @returns A string with line numbers added before each line
 */
export function addLineNumbers(highlightedCode: string, start = 1): string {
  const codeLines = highlightedCode.split(NEW_LINE_EXP);

  return codeLines
    .map((line, i) => {
      return `<span class='line' data-line-number='${start + i}'>${line}</span>`;
    })
    .join('\n');
}