text: 'use strict'
  
  var scopedPackagePattern = new RegExp('^(?:@([^/]+?)[/])?([^/]+?)$')
  var builtins = require('builtins')
  var blacklist = [
    'node_modules',
    'favicon.ico',
  ]
  
  function validate (name) {
    var warnings = []
    var errors = []
  
    if (name === null) {
      errors.push('name cannot be null')
      return done(warnings, errors)
    }
  
    if (name === undefined) {
      errors.push('name cannot be undefined')
      return done(warnings, errors)
    }
  
    if (typeof name !== 'string') {
      errors.push('name must be a string')
      return done(warnings, errors)
    }
  
    if (!name.length) {
      errors.push('name length must be greater than zero')
    }
  
    if (name.match(/^\./)) {
      errors.push('name cannot start with a period')
    }
  
    if (name.match(/^_/)) {
      errors.push('name cannot start with an underscore')
    }
  
    if (name.trim() !== name) {
      errors.push('name cannot contain leading or trailing spaces')
    }
  
    // No funny business
    blacklist.forEach(function (blacklistedName) {
      if (name.toLowerCase() === blacklistedName) {
        errors.push(blacklistedName + ' is a blacklisted name')
      }
    })
  
    // Generate warnings for stuff that used to be allowed
  
    // core module names like http, events, util, etc
    builtins({ version: '*' }).forEach(function (builtin) {
      if (name.toLowerCase() === builtin) {
        warnings.push(builtin + ' is a core module name')
      }
    })
  
    if (name.length > 214) {
      warnings.push('name can no longer contain more than 214 characters')
    }
  
    // mIxeD CaSe nAMEs
    if (name.toLowerCase() !== name) {
      warnings.push('name can no longer contain capital letters')
    }
  
    if (/[~'!()*]/.test(name.split('/').slice(-1)[0])) {
      warnings.push('name can no longer contain special characters ("~\'!()*")')
    }
  
    if (encodeURIComponent(name) !== name) {
      // Maybe it's a scoped package name, like @user/package
      var nameMatch = name.match(scopedPackagePattern)
      if (nameMatch) {
        var user = nameMatch[1]
        var pkg = nameMatch[2]
        if (encodeURIComponent(user) === user && encodeURIComponent(pkg) === pkg) {
          return done(warnings, errors)
        }
      }
  
      errors.push('name can only contain URL-friendly characters')
    }
  
    return done(warnings, errors)
  }
  
  var done = function (warnings, errors) {
    var result = {
      validForNewPackages: errors.length === 0 && warnings.length === 0,
      validForOldPackages: errors.length === 0,
      warnings: warnings,
      errors: errors,
    }
    if (!result.warnings.length) {
      delete result.warnings
    }
    if (!result.errors.length) {
      delete result.errors
    }
    return result
  }
  
  module.exports = validate
  