from __future__ import absolute_import

import datetime
import logging

from django.db import models

from documents.models import Document
from history.api import create_history

from .exceptions import DocumentNotCheckedOut
from .literals import STATE_CHECKED_OUT, STATE_CHECKED_IN
from .events import HISTORY_DOCUMENT_CHECKED_IN

logger = logging.getLogger(__name__)


class DocumentCheckoutManager(models.Manager):
    def checked_out_documents(self):
        return Document.objects.filter(pk__in=self.model.objects.all().values_list('document__pk', flat=True))
        
    def expired_check_outs(self):
        expired_list = Document.objects.filter(pk__in=self.model.objects.filter(expiration_datetime__lte=datetime.datetime.now()).values_list('document__pk', flat=True))
        logger.debug('expired_list: %s' % expired_list)
        return expired_list

    def check_in_expired_check_outs(self):
        for document in self.expired_check_outs():
            document.check_in()

    def is_document_checked_out(self, document):
        if self.model.objects.filter(document=document):
            return True
        else:
            return False
            
    def check_in_document(self, document, user=None):
        try:
            document_checkout = self.model.objects.get(document=document)
        except self.model.DoesNotExist:
            raise DocumentNotCheckedOut
        else:
            if user:
                create_history(HISTORY_DOCUMENT_CHECKED_IN, source_object=document, data={'user': user, 'document': document})
            document_checkout.delete()
            
    def document_checkout_info(self, document):
        try:
            return self.model.objects.get(document=document)
        except self.model.DoesNotExist:
            raise DocumentNotCheckedOut

    def document_checkout_state(self, document):
        if self.is_document_checked_out(document):
            return STATE_CHECKED_OUT
        else:
            return STATE_CHECKED_IN

    def is_document_new_versions_allowed(self, document):
        try:
            return not self.document_checkout_info(document).block_new_version
        except DocumentNotCheckedOut:
            return True