require 'common/domain'
require 'common/errors'

class User
  # A class representing a syntactically valid user; that is, an email
  # address. Once constructed, you can be sure that it's valid.

  @localpart = nil
  @domain = nil

  def domain()
    return @domain
  end

  def domainpart()
    return @domain.to_s()
  end

  def initialize(username)
    # Initialize this user object, but throw an error if either the
    # localpart or domainpart are invalid. The one argument is an
    # email address string.
    if not username.is_a?(String)
      msg =  'username must be a String '
      msg += "but a #{username.class.to_s()} was given"
      raise InvalidUserError.new(msg)
    end

    parts = username.split('@')

    if parts.length() < 2 then
      msg = "the username #{username} does not contain an '@' symbol"
      raise InvalidUserError.new(msg)
    end

    localpart = parts[0]

    if localpart.length() > 64 then
      msg = "the local part of #{username} cannot have more than 64 characters"
      raise InvalidUserError(msg)
    end

    if localpart.empty? then
      msg = "the local part of #{username} cannot be empty"
      raise InvalidUserError.new(msg)
    end

    @localpart = localpart
    @domain = Domain.new(parts[1])
  end

  def localpart()
    return @localpart
  end

  def to_s()
    return @localpart + '@' + @domain.to_s()
  end

  def ==(other)
    return self.to_s() == other.to_s()
  end

  def <=>(other)
    return self.to_s() <=> other.to_s()
  end
end