Function insertBeforeEachLine

core/src/utils/markdownUtils.ts:160–191

(
  selectedText: string,
  insertBefore: string | AlterLineFunction,
)

 * Inserts insertionString before each line
 */
export function insertBeforeEachLine(
  selectedText: string,
  insertBefore: string | AlterLineFunction,
): { modifiedText: string; insertionLength: number } {
  const lines = selectedText.split(/\n/);

  let insertionLength = 0;
  const modifiedText = lines
    .map((item, index) => {
      if (typeof insertBefore === 'string') {
        if (item.startsWith(insertBefore)) {
          insertionLength -= insertBefore.length;
          return item.slice(insertBefore.length);
        }
        insertionLength += insertBefore.length;
        return insertBefore + item;
      }
      if (typeof insertBefore === 'function') {
        if (item.startsWith(insertBefore(item, index))) {
          insertionLength -= insertBefore(item, index).length;
          return item.slice(insertBefore(item, index).length);
        }
        const insertionResult = insertBefore(item, index);
        insertionLength += insertionResult.length;
        return insertBefore(item, index) + item;
      }
      throw Error('insertion is expected to be either a string or a function');
    })
    .join('\n');

  return { modifiedText, insertionLength };
}