'use babel'

import {spawnSync} from 'child_process'
import os from 'os'

// Gets a dump of the user's configured shell environment.
//
// Returns the output of the `env` command or `undefined` if there was an error.
function getRawShellEnv () {
  let shell = getUserShell()

  // The `-ilc` set of options was tested to work with the OS X v10.11
  // default-installed versions of bash, zsh, sh, and ksh. It *does not*
  // work with csh or tcsh.
  let results = spawnSync(shell, ['-ilc', 'env'], {encoding: 'utf8'})
  if (results.error || !results.stdout || results.stdout.length <= 0) {
    return
  }

  return results.stdout
}

function getUserShell () {
  if (process.env.SHELL) {
    return process.env.SHELL
  }

  return '/bin/bash'
}

// Gets the user's configured shell environment.
//
// Returns a copy of the user's shell enviroment.
function getFromShell () {
  let shellEnvText = getRawShellEnv()
  if (!shellEnvText) {
    return
  }

  let env = {}

  for (let line of shellEnvText.split(os.EOL)) {
    if (line.includes('=')) {
      let components = line.split('=')
      if (components.length === 2) {
        env[components[0]] = components[1]
      } else {
        let k = components.shift()
        let v = components.join('=')
        env[k] = v
      }
    }
  }

  return env
}

function needsPatching (options = { platform: process.platform, env: process.env }) {
  if (options.platform === 'darwin' && !options.env.PWD) {
    let shell = getUserShell()
    if (shell.endsWith('csh') || shell.endsWith('tcsh') || shell.endsWith('fish')) {
      return false
    }
    return true
  }

  return false
}

// Fix for #11302 because `process.env` on Windows is a magic object that offers case-insensitive
// environment variable matching. By always cloning to `process.env` we prevent breaking the
// underlying functionality.
function clone (to, from) {
  for (var key in to) {
    delete to[key]
  }

  Object.assign(to, from)
}

function normalize (options = {}) {
  if (options && options.env) {
    clone(process.env, options.env)
  }

  if (!options.env) {
    options.env = process.env
  }

  if (!options.platform) {
    options.platform = process.platform
  }

  if (needsPatching(options)) {
    // Patch the `process.env` on startup to fix the problem first documented
    // in #4126. Retain the original in case someone needs it.
    let shellEnv = getFromShell()
    if (shellEnv && shellEnv.PATH) {
      process._originalEnv = Object.assign({}, process.env)
      clone(process.env, shellEnv)
    }
  }
}

function replace (env) {
  if (!env || !env.PATH) {
    return
  }

  clone(process.env, env)
}

export default { getFromShell, needsPatching, normalize, replace }