import os
import re
from django.db import models
from django.utils import timezone
import time

from neboard import settings
from markupfield.fields import MarkupField

import thumbs

NO_PARENT = -1
NO_IP = '0.0.0.0'
UNKNOWN_UA = ''


def update_image_filename(instance, filename):
    """Get unique image filename"""

    path = 'images/'
    new_name = str(int(time.mktime(time.gmtime()))) + '_' + filename
    return os.path.join(path, new_name)


class PostManager(models.Manager):
    def create_post(self, title, text, image=None, parent_id=NO_PARENT,
                    ip=NO_IP, tags=None):
        post = self.create(title=title,
                           text=text,
                           pub_time=timezone.now(),
                           parent=parent_id,
                           image=image,
                           poster_ip=ip,
                           poster_user_agent=UNKNOWN_UA,
                           last_edit_time=timezone.now())

        if tags:
            for tag in tags:
                post.tags.add(tag)

        if parent_id != NO_PARENT:
            self._bump_thread(parent_id)
        else:
            self._delete_old_threads()

        return post

    def delete_post(self, post):
        children = self.filter(parent=post.id)
        for child in children:
            self.delete_post(child)
        post.delete()

    def delete_posts_by_ip(self, ip):
        posts = self.filter(poster_ip=ip)
        for post in posts:
            self.delete_post(post)

    def get_threads(self, tag=None):
        if tag:
            threads = self.filter(parent=NO_PARENT, tags=tag)
        else:
            threads = self.filter(parent=NO_PARENT)
        threads = list(threads.order_by('-last_edit_time'))

        return threads

    def get_thread(self, opening_post_id):
        opening_post = self.get(id=opening_post_id)

        if opening_post.parent == NO_PARENT:
            replies = self.filter(parent=opening_post_id)

            thread = [opening_post]
            thread.extend(replies)

            return thread

    def exists(self, post_id):
        posts = self.filter(id=post_id)

        return len(posts) > 0

    def _delete_old_threads(self):
        """
        Preserves maximum thread count. If there are too many threads,
        delete the old ones.
        """

        # TODO Try to find a better way to get the active thread count.

        # TODO Move old threads to the archive instead of deleting them.
        # Maybe make some 'old' field in the model to indicate the thread
        # must not be shown and be able for replying.

        threads = self.get_threads()
        thread_count = len(threads)

        if thread_count > settings.MAX_THREAD_COUNT:
            num_threads_to_delete = thread_count - settings.MAX_THREAD_COUNT
            old_threads = threads[-num_threads_to_delete:]

            for thread in old_threads:
                self.delete_post(thread)

    def _bump_thread(self, thread_id):
        thread = self.get(id=thread_id)

        replies_count = len(self.get_thread(thread_id))
        if replies_count <= settings.MAX_POSTS_PER_THREAD:
            thread.last_edit_time = timezone.now()
            thread.save()


class TagManager(models.Manager):
    def get_not_empty_tags(self):
        all_tags = self.all().order_by('name')
        tags = []
        for tag in all_tags:
            if not tag.is_empty():
                tags.append(tag)

        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()

    name = models.CharField(max_length=100)
    # TODO Connect the tag to its posts to check the number of threads for
    # the tag.

    def __unicode__(self):
        return self.name

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

    def get_post_count(self):
        posts_with_tag = Post.objects.get_threads(tag=self)
        return len(posts_with_tag)


class Post(models.Model):
    """A post is a message."""

    objects = PostManager()

    title = models.CharField(max_length=50)
    pub_time = models.DateTimeField()
    text = MarkupField(default_markup_type='markdown', escape_html=True)
    image = thumbs.ImageWithThumbsField(upload_to=update_image_filename,
                                        blank=True, sizes=((200, 150),))
    poster_ip = models.IPAddressField()
    poster_user_agent = models.TextField()
    parent = models.BigIntegerField()
    tags = models.ManyToManyField(Tag)
    last_edit_time = models.DateTimeField()

    def __unicode__(self):
        return self.title + ' (' + self.text.raw + ')'

    def _get_replies(self):
        return Post.objects.filter(parent=self.id)

    def get_reply_count(self):
        return len(self._get_replies())

    def get_images_count(self):
        images_count = 1 if self.image else 0
        for reply in self._get_replies():
            if reply.image:
                images_count += 1

        return images_count

    def get_gets_count(self):
        gets_count = 1 if self.is_get() else 0
        for reply in self._get_replies():
            if reply.is_get():
                gets_count += 1

        return gets_count

    def is_get(self):
        """If the post has pretty id (1, 1000, 77777), than it is called GET"""

        first = self.id == 1

        # TODO Compile regexes

        id_str = str(self.id)
        pretty = re.match(r'^\d(0)+$', id_str)
        same_digits = re.match(r'^(.)\1+$', id_str)
        return first or pretty or same_digits


class Admin(models.Model):
    """
    Model for admin users
    """
    name = models.CharField(max_length=100)
    password = models.CharField(max_length=100)

    def __unicode__(self):
        return self.name + '/' + '*' * len(self.password)