text: 'use strict'
  
  const BB = require('bluebird')
  
  const crypto = require('crypto')
  const figgyPudding = require('figgy-pudding')
  const log = require('npmlog')
  const npm = require('../npm.js')
  const pack = require('../pack.js')
  const path = require('path')
  
  const npmSession = npm.session = crypto.randomBytes(8).toString('hex')
  log.verbose('npm-session', npmSession)
  
  const SCOPE_REGISTRY_REGEX = /@.*:registry$/gi
  const NpmConfig = figgyPudding({}, {
    other (key) {
      return key.match(SCOPE_REGISTRY_REGEX)
    }
  })
  
  let baseConfig
  
  module.exports = mkConfig
  function mkConfig (...providers) {
    if (!baseConfig) {
      baseConfig = NpmConfig(npm.config, {
        // Add some non-npm-config opts by hand.
        cache: path.join(npm.config.get('cache'), '_cacache'),
        // NOTE: npm has some magic logic around color distinct from the config
        // value, so we have to override it here
        color: !!npm.color,
        dirPacker: pack.packGitDep,
        hashAlgorithm: 'sha1',
        includeDeprecated: false,
        log,
        'npm-session': npmSession,
        'project-scope': npm.projectScope,
        refer: npm.referer,
        dmode: npm.modes.exec,
        fmode: npm.modes.file,
        umask: npm.modes.umask,
        npmVersion: npm.version,
        tmp: npm.tmp,
        Promise: BB
      })
      const ownerStats = calculateOwner()
      if (ownerStats.uid != null || ownerStats.gid != null) {
        baseConfig = baseConfig.concat(ownerStats)
      }
    }
    let conf = baseConfig.concat(...providers)
    // Adapt some other configs if missing
    if (npm.config.get('prefer-online') === undefined) {
      conf = conf.concat({
        'prefer-online': npm.config.get('cache-max') <= 0
      })
    }
    if (npm.config.get('prefer-online') === undefined) {
      conf = conf.concat({
        'prefer-online': npm.config.get('cache-min') >= 9999
      })
    }
    return conf
  }
  
  let effectiveOwner
  function calculateOwner () {
    if (!effectiveOwner) {
      effectiveOwner = { uid: 0, gid: 0 }
  
      // Pretty much only on windows
      if (!process.getuid) {
        return effectiveOwner
      }
  
      effectiveOwner.uid = +process.getuid()
      effectiveOwner.gid = +process.getgid()
  
      if (effectiveOwner.uid === 0) {
        if (process.env.SUDO_UID) effectiveOwner.uid = +process.env.SUDO_UID
        if (process.env.SUDO_GID) effectiveOwner.gid = +process.env.SUDO_GID
      }
    }
  
    return effectiveOwner
  }
  