from django.template.loader import render_to_string
from django.db import models
from django.db.models import Count, Sum
from django.core.urlresolvers import reverse

from boards.models import Thread
from boards.models.base import Viewable


__author__ = 'neko259'


class TagManager(models.Manager):

    def get_not_empty_tags(self):
        """
        Gets tags that have non-archived threads.
        """

        not_empty_tags = list()
        tags = self.order_by('-required', 'name')
        for tag in tags:
            if tag.get_thread_count() > 0:
                not_empty_tags.append(tag)

        return not_empty_tags


class Tag(models.Model, Viewable):
    """
    A tag is a text node assigned to the thread. The tag serves as a board
    section. There can be multiple tags for each thread
    """

    objects = TagManager()

    class Meta:
        app_label = 'boards'
        ordering = ('name',)

    name = models.CharField(max_length=100, db_index=True)
    required = models.BooleanField(default=False)

    def __str__(self):
        return self.name

    def is_empty(self) -> bool:
        """
        Checks if the tag has some threads.
        """

        return self.get_thread_count() == 0

    def get_thread_count(self) -> int:
        return self.get_threads().count()

    def get_post_count(self, archived=False):
        """
        Gets posts count for the tag's threads.
        """

        posts_count = 0

        threads = self.get_threads().filter(archived=archived)
        if threads.exists():
            posts_count = threads.annotate(posts_count=Count('replies')) \
                .aggregate(posts_sum=Sum('posts_count'))['posts_sum']

        if not posts_count:
            posts_count = 0

        return posts_count

    def get_url(self):
        return reverse('tag', kwargs={'tag_name': self.name})

    def get_threads(self):
        return Thread.objects.filter(tags__in=[self]).order_by('-bump_time')

    def is_required(self):
        return self.required

    def get_view(self):
        #prefix = '##' if self.is_required() else '#'
        link = '<a class="tag" href="{}">{}</a>'.format(
                self.get_url(), self.name)
        if self.is_required():
            link = '<b>{}</b>'.format(link)
        return link

    def get_search_view(self, *args, **kwargs):
        return render_to_string('boards/tag.html', {
                   'tag': self,
               })