boards/models/tag.py

from boards.models import Post
from django.db import models
from django.db.models import Count

__author__ = 'neko259'

TAG_FONT_MULTIPLIER = 0.1
MAX_TAG_FONT = 10
OPENING_POST_POPULARITY_WEIGHT = 2


class TagManager(models.Manager):

    def get_not_empty_tags(self):
        tags = self.annotate(Count('threads')) \
            .filter(threads__count__gt=0).order_by('name')

        return tags


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

    objects = TagManager()

    class Meta:
        app_label = 'boards'

    name = models.CharField(max_length=100)
    threads = models.ManyToManyField('Post', null=True,
                                     blank=True, related_name='tag+')
    linked = models.ForeignKey('Tag', null=True, blank=True)

    def __unicode__(self):
        return self.name

    def is_empty(self):
        return self.get_post_count() == 0

    def get_post_count(self):
        return self.threads.count()

    def get_popularity(self):
        posts_with_tag = Post.objects.get_threads(tag=self)
        reply_count = 0
        for post in posts_with_tag:
            reply_count += post.get_reply_count()
            reply_count += OPENING_POST_POPULARITY_WEIGHT

        return reply_count

    def get_linked_tags(self):
        tag_list = []
        self.get_linked_tags_list(tag_list)

        return tag_list

    def get_linked_tags_list(self, tag_list=[]):
        """
        Returns the list of tags linked to current. The list can be got
        through returned value or tag_list parameter
        """

        linked_tag = self.linked

        if linked_tag and not (linked_tag in tag_list):
            tag_list.append(linked_tag)

            linked_tag.get_linked_tags_list(tag_list)

    def get_font_value(self):
        """Get tag font value to differ most popular tags in the list"""

        post_count = self.get_post_count()
        if post_count > MAX_TAG_FONT:
            post_count = MAX_TAG_FONT

        font_value = str(1 + (post_count - 1) * TAG_FONT_MULTIPLIER)

        return font_value