createCheckbox.ts

import { Position, Range, TextEditor, TextEditorEdit, TextLine } from 'vscode';
import * as helpers from './helpers';

/** Create a new checkbox at selected lines or the current cursor position */
export const createCheckbox = async (editor: TextEditor) => {
  const selection = editor.selection;

  for (let r = selection.start.line; r <= selection.end.line; r++) {
    const line = editor.document.lineAt(r);
    await createCheckboxOfLine(editor, line);
  }
};

const createCheckboxOfLine = (
  editor: TextEditor,
  line: TextLine
): Thenable<boolean> => {
  const withBulletPoint = helpers.getConfig<boolean>('withBulletPoint');
  const typeOfBulletPoint = helpers.getConfig<string>('typeOfBulletPoint');
  const hasBullet = helpers.lineHasBulletPointAlready(line);

  const checkboxOfLine = helpers.getCheckboxOfLine(line);
  const checkboxCharacters = '[ ] ';

  return editor.edit((editBuilder: TextEditorEdit) => {
    if (!checkboxOfLine) {
      editBuilder.insert(
        new Position(line.lineNumber, hasBullet.pos),
        (withBulletPoint && !hasBullet.bullet ? typeOfBulletPoint + ' ' : '') +
          checkboxCharacters
      );
    } else {
      editBuilder.delete(
        new Range(
          new Position(line.lineNumber, hasBullet.pos),
          new Position(
            line.lineNumber,
            hasBullet.pos + checkboxCharacters.length
          )
        )
      );
    }
  });
};