// @flow

export function addTitleToMarkdown(md: string, title: string): string {
  let frontmatter = ''
  let body = md
  const match = md.match(/^---\n.*?---/ms)
  if (match instanceof Array && match.length > 0 && match.index === 0) {
    frontmatter = match[0]
    body = md.substr(frontmatter.length).trimLeft()
  }
  const linebreaks = body.split('\n', 1)[0].length === 0 ? '\n' : '\n\n'
  return frontmatter.length > 0
    ? `${frontmatter}\n# ${title}${linebreaks}${body}`
    : `# ${title}${linebreaks}${md}`
}