from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.utils.translation import ugettext
from django.core.exceptions import ObjectDoesNotExist

from documents.models import Document

from literals import DOCUMENTQUEUE_STATE_STOPPED,\
    DOCUMENTQUEUE_STATE_CHOICES, QUEUEDOCUMENT_STATE_PENDING,\
    QUEUEDOCUMENT_STATE_CHOICES
from exceptions import AlreadyQueued

    
class DocumentQueueManager(models.Manager):
    def queue_document(self, document, queue_name='default'):
        document_queue = DocumentQueue.objects.get(name=queue_name)
        if QueueDocument.objects.filter(document_queue=document_queue, document=document).count():
            raise AlreadyQueued

        queue_document = QueueDocument(document_queue=document_queue, document=document)
        queue_document.save()    

        return document_queue


class DocumentQueue(models.Model):
    name = models.CharField(max_length=64, unique=True, verbose_name=_(u'name'))
    label = models.CharField(max_length=64, verbose_name=_(u'label'))
    state = models.CharField(max_length=4,
        choices=DOCUMENTQUEUE_STATE_CHOICES,
        default=DOCUMENTQUEUE_STATE_STOPPED,
        verbose_name=_(u'state'))
    
    objects = DocumentQueueManager()
    
    class Meta:
        verbose_name = _(u'document queue')
        verbose_name_plural = _(u'document queues')

    def __unicode__(self):
        return self.label
       

class QueueDocument(models.Model):
    document_queue = models.ForeignKey(DocumentQueue, verbose_name=_(u'document queue'))
    document = models.ForeignKey(Document, verbose_name=_(u'document'))
    datetime_submitted = models.DateTimeField(verbose_name=_(u'date time submitted'), auto_now_add=True, db_index=True)
    state = models.CharField(max_length=4,
        choices=QUEUEDOCUMENT_STATE_CHOICES,
        default=QUEUEDOCUMENT_STATE_PENDING,
        verbose_name=_(u'state'))
    result = models.TextField(blank=True, null=True, verbose_name=_(u'result'))
    
    class Meta:
        ordering = ('datetime_submitted',)
        verbose_name = _(u'queue document')
        verbose_name_plural = _(u'queue documents')

    def __unicode__(self):
        try:
            return unicode(self.document)
        except ObjectDoesNotExist:
            return ugettext(u'Missing document.')