from functools import partial

from twisted.internet import defer

from ..error import NoRoute, RejectRecipient

from ..model.offer import getPossibleOffers
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

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

    def _run(self):
        for offer in getPossibleOffers(self.recipient,self.job.offers):
            try:
                return offer.send(self.recipient,self.job.message)
            except RejectRecipient:
                continue
        else:
            raise NoRoute()


def createJob(user,recipients, msg, offers, info=None):
    d = defer.maybeDeferred(exJobs.create,user, recipients, msg, offers, info)
    def _(job):
        for r in recipients:
            task = Task(r,job)
            job.addTask(task)
            task.start()
        return job
    d.addCallback(_)
    return d