import hashlib
import re

from boards.models.attachment import FILE_TYPES_IMAGE
from django.template.loader import render_to_string
from django.db import models
from django.db.models import Count
from django.core.urlresolvers import reverse
from django.utils.translation import get_language

from boards.models import Attachment
from boards.models.base import Viewable
from boards.models.thread import STATUS_ACTIVE, STATUS_BUMPLIMIT, STATUS_ARCHIVE
from boards.utils import cached_result
import boards

__author__ = 'neko259'


RELATED_TAGS_COUNT = 5

REGEX_TAG_ALIAS = r'{}:(\w+),'


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

        return self.annotate(num_threads=Count('thread_tags')).filter(num_threads__gt=0)\
            .order_by('name')

    def get_tag_url_list(self, tags: list) -> str:
        """
        Gets a comma-separated list of tag links.
        """

        return ', '.join([tag.get_view() for tag in tags])

    def get_by_alias(self, alias):
        return self.filter(aliases__contains=":{},".format(alias)).first()


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, unique=True)
    required = models.BooleanField(default=False, db_index=True)
    description = models.TextField(blank=True)

    parent = models.ForeignKey('Tag', null=True, blank=True,
            related_name='children')
    aliases = models.TextField(blank=True)

    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, status=None) -> int:
        threads = self.get_threads()
        if status is not None:
            threads = threads.filter(status=status)
        return threads.count()

    def get_active_thread_count(self) -> int:
        return self.get_thread_count(status=STATUS_ACTIVE)

    def get_bumplimit_thread_count(self) -> int:
        return self.get_thread_count(status=STATUS_BUMPLIMIT)

    def get_archived_thread_count(self) -> int:
        return self.get_thread_count(status=STATUS_ARCHIVE)

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

    def get_threads(self):
        return self.thread_tags.order_by('-bump_time')

    def is_required(self):
        return self.required

    def get_view(self):
        locale = get_language()

        if self.aliases:
            match = re.search(REGEX_TAG_ALIAS.format(locale), self.aliases)
            if match:
                localized_tag_name = match.group(1)
        else:
            localized_tag_name = self.name

        link = '<a class="tag" href="{}">{}</a>'.format(
            self.get_absolute_url(), localized_tag_name)
        if self.is_required():
            link = '<b>{}</b>'.format(link)
        return link

    @cached_result()
    def get_post_count(self):
        return self.get_threads().aggregate(num_posts=Count('replies'))['num_posts']

    def get_description(self):
        return self.description

    def get_random_image_post(self, status=[STATUS_ACTIVE, STATUS_BUMPLIMIT]):
        posts = boards.models.Post.objects.filter(attachments__mimetype__in=FILE_TYPES_IMAGE)\
            .annotate(images_count=Count(
            'attachments')).filter(images_count__gt=0, thread__tags__in=[self])
        if status is not None:
            posts = posts.filter(thread__status__in=status)
        return posts.order_by('?').first()

    def get_first_letter(self):
        return self.name and self.name[0] or ''

    def get_related_tags(self):
        return set(Tag.objects.filter(thread_tags__in=self.get_threads()).exclude(
            id=self.id).order_by('?')[:RELATED_TAGS_COUNT])

    @cached_result()
    def get_color(self):
        """
        Gets color hashed from the tag name.
        """
        return hashlib.md5(self.name.encode()).hexdigest()[:6]

    def get_parent(self):
        return self.parent

    def get_all_parents(self):
        parents = list()
        parent = self.get_parent()
        if parent and parent not in parents:
            parents.insert(0, parent)
            parents = parent.get_all_parents() + parents

        return parents

    def get_children(self):
        return self.children

    def get_images(self):
        return Attachment.objects.filter(
            attachment_posts__thread__tags__in=[self]).filter(
            mimetype__in=FILE_TYPES_IMAGE).order_by('-attachment_posts__pub_time')