from functools import partial

from twisted.internet.defer import inlineCallbacks, returnValue, maybeDeferred, Deferred

from ..error import NoRouteForTask, RejectRecipient

from ..model.offer import offers
from ..model.job import exJobs

from .pool  import taskPool

class Task:
    '''one single part of a job.
    a task is one message to one recipient
    '''
    def __init__(self, recipient, job):
        self.recipient = recipient
        self.job = job
        self.status = None
        self.error = False

    def setStatus(self,status):
        self.status = status
        return status

    def setError(self, error):
        self.status = error
        self.error = True
        return error

    def start(self):
        self.d = Deferred()
        self.d.addCallback(self.setStatus)
        self.d.addCallback(partial(self.job.setStatus,self))
        self.d.addErrback(self.setError)
        self.d.addErrback(partial(self.job.setError,self))
        taskPool.run(self._run)
        return self.d

    def _run(self):
        os= (i for i in self.job.offers)
        def n():
            try:
                offer = os.next()
                d = maybeDeferred(offers[offer],self.recipient,self.job.message)
                d.addCallback(self.d.callback)
                d.addErrback(addErr)
                d.addErrback(self.d.errback)
                return d
            except StopIteration:
                self.d.errback(NoRouteForTask())

        def addErr(failure):
            failure.trap(RejectRecipient)
            return n()
        
        n()


@inlineCallbacks
def createJob(user,recipients, msg, offers, info=None):
    job = yield exJobs.create(user, recipients, msg, offers, info)
    for r in recipients:
        task = Task(r,job)
        job.addTask(task)
        task.start()
    returnValue(job)