import os
from random import random
import re
import time
import math

from django.db import models
from django.http import Http404
from django.utils import timezone
from markupfield.fields import MarkupField
from threading import Thread

from neboard import settings
import thumbs

IMAGE_THUMB_SIZE = (200, 150)

TITLE_MAX_LENGTH = 50

DEFAULT_MARKUP_TYPE = 'markdown'

NO_PARENT = -1
NO_IP = '0.0.0.0'
UNKNOWN_UA = ''
ALL_PAGES = -1
OPENING_POST_POPULARITY_WEIGHT = 2
IMAGES_DIRECTORY = 'images/'
FILE_EXTENSION_DELIMITER = '.'

RANK_ADMIN = 0
RANK_MODERATOR = 10
RANK_USER = 100


class PostManager(models.Manager):
    def create_post(self, title, text, image=None, parent_id=NO_PARENT,
                    ip=NO_IP, tags=None, user=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(),
                           user=user)

        if tags:
            map(post.tags.add, tags)

        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)

        map(self.delete_post, children)
        post.delete()

    def delete_posts_by_ip(self, ip):
        posts = self.filter(poster_ip=ip)
        map(self.delete_post, posts)

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

            # TODO Throw error 404 if no threads for tag found?
        else:
            threads = self.filter(parent=NO_PARENT)

        threads = threads.order_by(order_by)

        if page != ALL_PAGES:
            thread_count = len(threads)

            if page < self.get_thread_page_count(tag=tag):
                start_thread = page * settings.THREADS_PER_PAGE
                end_thread = min(start_thread + settings.THREADS_PER_PAGE,
                                 thread_count)
                threads = threads[start_thread:end_thread]

        return threads

    def get_thread(self, opening_post_id):
        try:
            opening_post = self.get(id=opening_post_id, parent=NO_PARENT)
        except Post.DoesNotExist:
            raise Http404

        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 posts.count() > 0

    def get_thread_page_count(self, tag=None):
        if tag:
            threads = self.filter(parent=NO_PARENT, tags=tag)
        else:
            threads = self.filter(parent=NO_PARENT)

        return int(math.ceil(threads.count() / float(
            settings.THREADS_PER_PAGE)))

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

        # 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[thread_count - num_threads_to_delete:]

            map(self.delete_post, old_threads)

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

        if thread.can_bump():
            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

    def get_popular_tags(self):
        all_tags = self.get_not_empty_tags()

        sorted_tags = sorted(all_tags, key=lambda tag: tag.get_popularity(),
                             reverse=True)

        return sorted_tags[:settings.POPULAR_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)

    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 posts_with_tag.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


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

    objects = PostManager()

    def _update_image_filename(self, filename):
        """Get unique image filename"""

        path = IMAGES_DIRECTORY
        new_name = str(int(time.mktime(time.gmtime())))
        new_name += str(int(random() * 1000))
        new_name += FILE_EXTENSION_DELIMITER
        new_name += filename.split(FILE_EXTENSION_DELIMITER)[-1:][0]

        return os.path.join(path, new_name)

    title = models.CharField(max_length=TITLE_MAX_LENGTH)
    pub_time = models.DateTimeField()
    text = MarkupField(default_markup_type=DEFAULT_MARKUP_TYPE,
                       escape_html=False)

    image_width = models.IntegerField(default=0)
    image_height = models.IntegerField(default=0)

    image = thumbs.ImageWithThumbsField(upload_to=_update_image_filename,
                                        blank=True, sizes=(IMAGE_THUMB_SIZE,),
                                        width_field='image_width',
                                        height_field='image_height')

    poster_ip = models.GenericIPAddressField()
    poster_user_agent = models.TextField()
    parent = models.BigIntegerField()
    tags = models.ManyToManyField(Tag)
    last_edit_time = models.DateTimeField()
    user = models.ForeignKey('User', null=True, default=None)

    def __unicode__(self):
        return '#' + str(self.id) + ' ' + self.title + ' (' + \
               self.text.raw[:50] + ')'

    def get_title(self):
        title = self.title
        if len(title) == 0:
            title = self.text.raw[:20]

        return title

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

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

    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 can_bump(self):
        """Check if the thread can be bumped by replying"""

        replies_count = len(Post.objects.get_thread(self.id))

        return replies_count <= settings.MAX_POSTS_PER_THREAD

    def get_last_replies(self):
        if settings.LAST_REPLIES_COUNT > 0:
            reply_count = self.get_reply_count()

            if reply_count > 0:
                reply_count_to_show = min(settings.LAST_REPLIES_COUNT,
                                          reply_count)
                last_replies = self._get_replies()[reply_count
                                                   - reply_count_to_show:]

                return last_replies


class User(models.Model):

    user_id = models.CharField(max_length=50)
    rank = models.IntegerField()

    registration_time = models.DateTimeField()
    last_access_time = models.DateTimeField()

    fav_tags = models.ManyToManyField(Tag, null=True, blank=True)
    fav_threads = models.ManyToManyField(Post, related_name='+', null=True,
                                         blank=True)

    def save_setting(self, name, value):
        setting, created = Setting.objects.get_or_create(name=name, user=self)
        setting.value = value
        setting.save()

        return setting

    def get_setting(self, name):
        settings = Setting.objects.filter(name=name, user=self)
        if len(settings) > 0:
            setting = settings[0]
        else:
            setting = None

        if setting:
            setting_value = setting.value
        else:
            setting_value = None

        return setting_value

    def is_moderator(self):
        return RANK_MODERATOR >= self.rank

    def get_sorted_fav_tags(self):
        return self.fav_tags.order_by('name')

    def __unicode__(self):
        return self.user_id + '(' + str(self.rank) + ')'


class Setting(models.Model):

    name = models.CharField(max_length=50)
    value = models.CharField(max_length=50)
    user = models.ForeignKey(User)


class Ban(models.Model):
    ip = models.GenericIPAddressField()

    def __unicode__(self):
        return self.ip