'''
Models for the Polls application.
'''

import datetime
from django.db import models
from django.db.models import Q


class PollManager(models.Manager):
   """Manager for the Poll model"""

   def get_current_polls(self):
      now = datetime.datetime.now()
      return self.filter(
            Q(is_enabled=True),
            Q(start_date__lte=now),
            Q(end_date__isnull=True) | Q(end_date__gte=now))

   def get_old_polls(self):
      now = datetime.datetime.now()
      return self.filter(
            Q(is_enabled=True),
            Q(end_date__isnull=False),
            Q(end_date__lt=now))


class Poll(models.Model):
   """Model to represent polls"""
   start_date = models.DateTimeField(db_index=True,
         help_text='Date/time the poll will be eligible for voting.',)
   end_date = models.DateTimeField(blank=True, null=True, db_index=True,
         help_text='Date/time the poll will be ineligible for voting. '\
            'Leave blank for an open ended poll.')
   is_enabled = models.BooleanField(default=True, db_index=True,
         help_text='Check to allow the poll to be viewed on the site.')
   question = models.CharField(max_length=200)

   objects = PollManager()

   def __unicode__(self):
      return self.question

   class Meta:
      ordering = ('-start_date', )
      get_latest_by = 'start_date'

   @models.permalink
   def get_absolute_url(self):
      return ('polls.views.poll_detail', [str(self.id)])

   def results(self):
      """
      Returns a tuple; element 0 is the total votes, element 1 is a list of
      {choice, votes, pct}
      """
      choices = []
      total_votes = 0
      for choice in self.choice_set.all():
         total_votes += choice.votes
         choices.append({'choice': choice.choice, 'votes': choice.votes, 'pct': 0.0})

      if total_votes > 0:
         for choice in choices:
            choice['pct'] = float(choice['votes']) / total_votes * 100.0

      return (total_votes, choices)

   def is_open(self):
      now = datetime.datetime.now()
      return self.start_date <= now and (not self.end_date or now <= self.end_date)

   def can_comment_on(self):
      return self.is_open()


class Choice(models.Model):
   """Model for poll choices"""
   poll = models.ForeignKey(Poll)
   choice = models.CharField(max_length = 200)
   votes = models.IntegerField(default = 0)

   def __unicode__(self):
      return self.choice