Function extractLinkAtCursor

packages/app-core/src/lib/internal-links.ts:145–169

(doc: string, pos: number)

 * link's URL, or a bare URL. Returns null when the offset isn't inside a link.
 */
export function extractLinkAtCursor(doc: string, pos: number): string | null {
  const lineStart = doc.lastIndexOf('\n', pos - 1) + 1
  const lineEnd = doc.indexOf('\n', pos)
  const line = doc.slice(lineStart, lineEnd === -1 ? undefined : lineEnd)
  const col = pos - lineStart
  const wikiRe = /\[\[([^\]|]+?)(?:\|[^\]]+)?\]\]/g
  let m: RegExpExecArray | null
  while ((m = wikiRe.exec(line)) !== null) {
    if (col >= m.index && col < m.index + m[0].length) return m[1]
  }
  // Angle-bracketed URLs can contain `)` so match them specifically first.
  const mdAngleRe = /\[([^\]]*)\]\(<([^>]+)>\)/g
  while ((m = mdAngleRe.exec(line)) !== null) {
    if (col >= m.index && col < m.index + m[0].length) return m[2]
  }
  const mdRe = /\[([^\]]*)\]\(([^)]+)\)/g
  while ((m = mdRe.exec(line)) !== null) {
    if (col >= m.index && col < m.index + m[0].length) return unwrapMdUrl(m[2])
  }
  const urlRe = /https?:\/\/[^\s)>\]]+/g
  while ((m = urlRe.exec(line)) !== null) {
    if (col >= m.index && col < m.index + m[0].length) return m[0]
  }
  return null
}

/**
 * The Markdown link `[label](href)` covering a document offset, with its full