index.js

'use strict';

var path = require('path');
var resolve = require('./lib/resolve');

function getConfig(moduleName) {
  try {
    return require(resolve(path.join(moduleName, 'package.json')));
  } catch (e) {
    return {};
  }
}

function getFullPath(originalPath) {
  var fullPath = originalPath;
  if (path.dirname(originalPath) === '.') {
    // There are no subfolders, so node will try to use file specified by the
    // "main" key in the package.json. We need the es6 version though, so
    // let's lookup the "jsnext:main" key instead, if it's present.
    var config = getConfig(originalPath);
    if (config['jsnext:main']) {
      fullPath = path.join(originalPath, config['jsnext:main']);
    }
  }
  return getModulePath(fullPath);
}

function getModulePath(name) {
  try {
    return resolve(name);
  } catch (e) {
    // If a module wasn't found with this name, just return the original path.
    console.warn('Module with name "' + name + '" could not be found by node."', e.message);
    return name;
  }
}

function renameAlias(originalPath, filename) {
  var result = originalPath;
  if (originalPath[0] !== '.' && originalPath[0] !== '/' && originalPath.indexOf(':') === -1) {
    var fullPath = getFullPath(originalPath);
    result = path.join(path.dirname(fullPath), path.basename(fullPath, '.js'));

    // babel uses 'unknown' as a special value for filename when the transformed
    // source can't be traced to a file (e.g., transformed string)
    // https://github.com/babel/babel/blob/d2e7e6a/packages/babel-core/src/transformation/file/options/config.js
    if (filename && filename !== 'unknown') {
      result = path.relative(path.dirname(filename), result);
    }
    else {
      console.warn('Warning: missing source path leads to wrong / absolute import path.');
    }
  }
  return result.replace(/\\/g, '/');
}

module.exports = {
  resolveModuleSource: renameAlias
};