require "pam"

class PamWrapper
  def initialize
    @login    = nil
    @password = nil
  end

  def conv_callback
    password = @password ? @password : nil

    [PAM::Response.new(password, 0)]
  end

  def set_pairs(user=nil, password=nil)
    @user     = user
    @password = password
    self
  end

  def auth
    user = @user ? @user : nil
    conv = proc{conv_callback}
    conv_data = ""

    PAM.start("system-auth", user, conv, conv_data){|pam|
      begin
	pam.authenticate(0)
      rescue PAM::PAM_USER_UNKNOWN
	print("unknown user: #{pam.get_item(PAM::PAM_USER)}")
        raise pam.status.inspect
      rescue PAM::PAM_AUTH_ERR
        print("authentication error: #{pam.get_item(PAM::PAM_USER)}\n")
        print("error code = #{pam.status}\n")
        raise pam.status.inspect
      rescue PAM::PAMError
        print("error code = #{pam.status}\n")
        raise pam.status.inspect
      end

      print("\n",
            "authenticated!\n")
    }
  end
end