const nativeModule = require('module')
const path = require('path')
const fs = require('fs')

function createRequire (filename) {
 // Fallback to process.cwd() if no filename passed
 if (!filename) {
 filename = process.cwd()
 }

 // If filename is dir, createRequire goes with parent directory, so we need fakepath
 if (isDir(filename)) {
 filename = path.join(filename, 'index.js')
 }

 // Added in Node v12.2.0
 if (nativeModule.createRequire) {
 return nativeModule.createRequire(filename)
 }

 // Added in Node v10.12.0 and deprecated since Node v12.2.0
 if (nativeModule.createRequireFromPath) {
 return nativeModule.createRequireFromPath(filename)
 }

 // Polyfill
 return _createRequire(filename)
}

// Polyfill
function _createRequire (filename) {
 const mod = new nativeModule.Module(filename, null)
 mod.filename = filename
 mod.paths = nativeModule.Module._nodeModulePaths(path.dirname(filename))
 mod._compile('module.exports = require;', filename)
 return mod.exports
}

function isDir (path) {
 try {
 const stat = fs.lstatSync(path)
 return stat.isDirectory()
 } catch (e) {
 // lstatSync throws an error if path doesn't exist
 return false
 }
}

module.exports = createRequire