import path from 'path'
import fs from 'fs'
import url from 'url'

// Make sure any symlinks in the project folder are resolved:
// https://github.com/facebookincubator/create-react-app/issues/637
const appDirectory = fs.realpathSync(process.cwd())
const resolveApp = relativePath => path.resolve(appDirectory, relativePath)

const envPublicUrl = process.env.PUBLIC_URL

function ensureSlash(path, needsSlash) {
  const hasSlash = path.endsWith('/')
  if (hasSlash && !needsSlash) {
    return path.substr(path, path.length - 1)
  } else if (!hasSlash && needsSlash) {
    return `${path}/`
  } else {
    return path
  }
}

const getPublicUrl = appPackageJson =>
  envPublicUrl || require(appPackageJson).homepage

// We use `PUBLIC_URL` environment variable or "homepage" field to infer
// "public path" at which the app is served.
// Webpack needs to know it to put the right <script> hrefs into HTML even in
// single-page apps that may serve index.html for nested URLs like /todos/42.
// We can't use a relative path in HTML because we don't want to load something
// like /todos/42/static/js/bundle.7289d.js. We have to know the root.
function getServedPath(appPackageJson) {
  const publicUrl = getPublicUrl(appPackageJson)
  const servedUrl =
    envPublicUrl || (publicUrl ? url.parse(publicUrl).pathname : '/')
  return ensureSlash(servedUrl, true)
}

export const dotenv = resolveApp('.env')
export const appBuild = resolveApp('build')
export const appPublic = resolveApp('public')
export const appHtml = resolveApp('public/index.html')
// standalone
export const appIndexJs = resolveApp('src/index.tsx')
// main usage
export const appIndexExports = resolveApp('src/index.tsx')
// app
export const appPackageJson = resolveApp('package.json')
export const appSrc = resolveApp('src')
export const yarnLockFile = resolveApp('yarn.lock')
export const testsSetup = resolveApp('src/setupTests.ts')
export const appNodeModules = resolveApp('node_modules')
export const appTsConfig = resolveApp('tsconfig.json')
export const appTsLint = resolveApp('tslint.json')
export const publicUrl = getPublicUrl(resolveApp('package.json'))
export const servedPath = getServedPath(resolveApp('package.json'))

export const paths = {
  dotenv,
  appBuild,
  appPublic,
  appHtml,
  appIndexJs,
  appIndexExports,
  appPackageJson,
  appSrc,
  yarnLockFile,
  testsSetup,
  appNodeModules,
  appTsConfig,
  appTsLint,
  publicUrl,
  servedPath,
}
export default paths