eslint_import_resolver.js

/**
 * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * Adapted from node resolver: https://github.com/benmosher/eslint-plugin-import/tree/master/resolvers/node
 *
 */

'use strict';

const resolve = require('resolve');
const path = require('path');

const log = require('debug')('eslint-plugin-import:resolver:node');

module.exports.interfaceVersion = 2;

module.exports.resolve = function(source, file, config) {
  log('Resolving:', source, 'from:', file);
  let resolvedPath;

  if (resolve.isCore(source)) {
    log('resolved to core');
    return {found: true, path: null};
  }

  source = applyModuleNameMapper(source, config);

  try {
    resolvedPath = resolve.sync(source, opts(file, config));
    log('Resolved to:', resolvedPath);
    return {found: true, path: resolvedPath};
  } catch (err) {
    log('resolve threw error:', err);
    return {found: false};
  }
};

function opts(file, config) {
  return Object.assign(
    {
      // more closely matches Node (#333)
      extensions: ['.js', '.json'],
    },
    config,
    {
      // path.resolve will handle paths relative to CWD
      basedir: path.dirname(path.resolve(file)),
      packageFilter,
    }
  );
}

function packageFilter(pkg) {
  if (pkg['jsnext:main']) {
    pkg['main'] = pkg['jsnext:main'];
  }
  return pkg;
}

function applyModuleNameMapper(source, config) {
  Object.keys(config.moduleNameMapper).forEach(regex => {
    const mappedModuleName = config.moduleNameMapper[regex];

    if (source.match(regex)) {
      const matches = source.match(regex);
      if (!matches) {
        source = mappedModuleName;
      } else {
        source = mappedModuleName.replace(
          /\$([0-9]+)/g,
          (_, index) => matches[parseInt(index, 10)]
        );
      }
      source = path.resolve(source);
    }
  });

  return source;
}