class Gem::GemRunner

def do_configuration(args)
  Gem.configuration = @config_file_class.new(args)
  Gem.use_paths Gem.configuration[:gemhome], Gem.configuration[:gempath]
  Gem::Command.extra_args = Gem.configuration[:gem]
end

def extract_build_args(args) # :nodoc:
  return [] unless offset = args.index("--")
  build_args = args.slice!(offset...args.length)
  build_args.shift
  build_args
end

def initialize
  @command_manager_class = Gem::CommandManager
  @config_file_class = Gem::ConfigFile
end

def run(args)
  validate_encoding args
  build_args = extract_build_args args
  do_configuration args
  begin
    Gem.load_env_plugins
  rescue StandardError
    nil
  end
  Gem.load_plugins
  cmd = @command_manager_class.instance
  cmd.command_names.each do |command_name|
    config_args = Gem.configuration[command_name]
    config_args = case config_args
                  when String
                    config_args.split " "
                  else
                    Array(config_args)
    end
    Gem::Command.add_specific_extra_args command_name, config_args
  end
  cmd.run Gem.configuration.args, build_args
end

def validate_encoding(args)
  invalid_arg = args.find {|arg| !arg.valid_encoding? }
  if invalid_arg
    raise Gem::OptionParser::InvalidArgument.new("'#{invalid_arg.scrub}' has invalid encoding")
  end
end