from django.db import models
from django.http import Http404
from django.utils import timezone

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

class PostManager(models.Manager):

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

        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 is None:
            threads = self.filter(parent = NO_PARENT)
        else:
            threads = self.filter(parent = NO_PARENT, tag = tag)

        return threads

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


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
    """

    name = models.CharField(max_length = 100)


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

    objects = PostManager()

    title = models.CharField(max_length = 100)
    pub_time = models.DateTimeField()
    text = models.TextField()
    image = models.ImageField(upload_to = DIR_IMAGES, blank = True)
    poster_ip = models.IPAddressField()
    poster_user_agent = models.TextField()
    parent = models.BigIntegerField()
    tags = models.ManyToManyField(Tag)

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


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)