require 'test/unit'
require 'snmp'

class TimeoutManager  < SNMP::Manager
  attr_accessor :response_count
  
  def initialize(config)
    super(config)
    @response_count = 0
    @raise_on_send = false
    @raise_on_get = false
  end
  
  def raise_send_error
      @raise_on_send = true
  end

  def raise_get_error
      @raise_on_get = true
  end
  
  def send_request(request, community, host, port) 
      raise RuntimeError if @raise_on_send
  end

  def get_response(request) 
      @response_count += 1
      raise RuntimeError if @raise_on_get
      raise Timeout::Error, "testing retry count"
  end
end

class MismatchIdTransport
    def initialize
        @data = []
    end
    
    def close
    end
    
    def send(data, host, port)
        bad_id_data = data.dup
        bad_msg = SNMP::Message.decode(data)
        bad_msg.pdu.request_id -= 3  # corrupt request_id  
        @data << bad_msg.encode # insert corrupted PDU before real data
        @data << data
    end
    
    def recv(max_bytes)
        raise "receive queue is empty" unless @data.first
        SNMP::Message.decode(@data.shift).response.encode[0,max_bytes]
    end
end


class TestRetry < Test::Unit::TestCase 
    def test_retry_count
        assert_response_count(0, 1, SNMP::RequestTimeout)
        assert_response_count(1, 2, SNMP::RequestTimeout)
        assert_response_count(5, 6, SNMP::RequestTimeout)
    end

    def test_retry_on_error
        assert_response_count(5, 0, RuntimeError) { |m| m.raise_send_error }  
        old_verbose = $VERBOSE
        $VERBOSE = nil
        assert_response_count(5, 6, SNMP::RequestTimeout) { |m| m.raise_get_error }
        $VERBOSE = old_verbose
    end

    def assert_response_count(retry_count, response_count, exception) 
        m = TimeoutManager.new( :Retries => retry_count )
        yield m if block_given?
        assert_raise(exception) { m.get("1.2.3.4") }
        assert_equal(response_count, m.response_count)
    end
    
    def test_drop_mismatched_id
        m = SNMP::Manager.new(:Transport => MismatchIdTransport)
        m.get("1.2.3.4")
    end
end
