Function insertIntoFile

lib/utilities/insert-into-file.js:50–123

Inserts the given content into a file. If the `contentsToInsert` string is already present in the current contents, the file will not be changed unless `force` option is passed. If `options.before` is specified, `contentsToInsert` will be inserted before the first instance of that string.

(fullPath, contentsToInsert, providedOptions)

  @return {Promise}
*/
async function insertIntoFile(fullPath, contentsToInsert, providedOptions) {
  let options = providedOptions || {};

  let returnValue = {
    path: fullPath,
    originalContents: '',
    contents: '',
    inserted: false,
  };

  let exists = fs.existsSync(fullPath);

  if (exists || (!exists && options.create !== false)) {
    let originalContents = '';

    if (exists) {
      originalContents = fs.readFileSync(fullPath, { encoding: 'utf8' });
    }

    let contentsToWrite = originalContents;

    let alreadyPresent = originalContents.indexOf(contentsToInsert) > -1;
    let insert = !alreadyPresent;
    let insertBehavior = 'end';

    if (options.before) {
      insertBehavior = 'before';
    }
    if (options.after) {
      insertBehavior = 'after';
    }

    if (options.force) {
      insert = true;
    }

    if (insert) {
      if (insertBehavior === 'end') {
        contentsToWrite += contentsToInsert;
      } else {
        let contentMarker = options[insertBehavior];
        if (contentMarker instanceof RegExp) {
          let matches = contentsToWrite.match(contentMarker);
          if (matches) {
            contentMarker = matches[0];
          }
        }
        let contentMarkerIndex = contentsToWrite.indexOf(contentMarker);

        if (contentMarkerIndex !== -1) {
          let insertIndex = contentMarkerIndex;
          if (insertBehavior === 'after') {
            insertIndex += contentMarker.length;
          }

          contentsToWrite =
            contentsToWrite.slice(0, insertIndex) + contentsToInsert + EOL + contentsToWrite.slice(insertIndex);
        }