# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.


from twisted.trial import unittest
from twisted.protocols import loopback
from twisted.protocols import basic
from twisted.internet import protocol, abstract

from io import BytesIO

class BufferingServer(protocol.Protocol):
    buffer = b''

    def dataReceived(self, data):
        self.buffer += data

class FileSendingClient(protocol.Protocol):
    def __init__(self, f):
        self.f = f


    def connectionMade(self):
        s = basic.FileSender()
        d = s.beginFileTransfer(self.f, self.transport, lambda x: x)
        d.addCallback(lambda r: self.transport.loseConnection())

class FileSenderTests(unittest.TestCase):
    def testSendingFile(self):
        testStr = b'xyz' * 100 + b'abc' * 100 + b'123' * 100
        s = BufferingServer()
        c = FileSendingClient(BytesIO(testStr))

        d = loopback.loopbackTCP(s, c)
        d.addCallback(lambda x : self.assertEqual(s.buffer, testStr))
        return d


    def testSendingEmptyFile(self):
        fileSender = basic.FileSender()
        consumer = abstract.FileDescriptor()
        consumer.connected = 1
        emptyFile = BytesIO(b'')

        d = fileSender.beginFileTransfer(emptyFile, consumer, lambda x: x)

        # The producer will be immediately exhausted, and so immediately
        # unregistered
        self.assertIsNone(consumer.producer)

        # Which means the Deferred from FileSender should have been called
        self.assertTrue(d.called, 
                        'producer unregistered with deferred being called')