import os
from zope.interface import implementer

from twisted.application import service

application = service.Application("SMTP Server Tutorial")

from twisted.application import internet
from twisted.internet import protocol, defer

smtpServerFactory = protocol.ServerFactory()

from twisted.mail import smtp

@implementer(smtp.IMessage)
class FileMessage(object):
    def __init__(self, fileObj):
        self.fileObj = fileObj

    def lineReceived(self, line):
        self.fileObj.write(line + '\n')

    def eomReceived(self):
        self.fileObj.close()
        return defer.succeed(None)

    def connectionLost(self):
        self.fileObj.close()
        os.remove(self.fileObj.name)

class TutorialESMTP(smtp.ESMTP):
    counter = 0

    def validateTo(self, user):
        fileName = 'tutorial-smtp.' + str(self.counter)
        self.counter += 1
        return lambda: FileMessage(open(fileName, 'w'))

    def validateFrom(self, helo, origin):
        return origin

    def receivedHeader(self, helo, origin, recipients):
        return 'Received: Tutorially.'


smtpServerFactory.protocol = TutorialESMTP

smtpServerService = internet.TCPServer(2025, smtpServerFactory)
smtpServerService.setServiceParent(application)