import logging
from datetime import timedelta

from django.db import models, transaction
from django.db.models import Count, Sum, QuerySet, Q
from django.utils import timezone

import boards
from boards import settings
from boards.models import STATUS_BUMPLIMIT, STATUS_ACTIVE, STATUS_ARCHIVE
from boards.models.attachment import FILE_TYPES_IMAGE
from boards.models.post import Post
from boards.models.tag import Tag, TagAlias
from boards.settings import SECTION_VIEW
from boards.utils import cached_result, datetime_to_epoch

FAV_THREAD_NO_UPDATES = -1


__author__ = 'neko259'


logger = logging.getLogger(__name__)


WS_NOTIFICATION_TYPE_NEW_POST = 'new_post'
WS_NOTIFICATION_TYPE = 'notification_type'

WS_CHANNEL_THREAD = "thread:"

STATUS_CHOICES = (
        (STATUS_ACTIVE, STATUS_ACTIVE),
        (STATUS_BUMPLIMIT, STATUS_BUMPLIMIT),
        (STATUS_ARCHIVE, STATUS_ARCHIVE),
)


class ThreadManager(models.Manager):
    def process_old_threads(self):
        """
         Preserves maximum thread count. If there are too many threads,
         archive or delete the old ones.
         """
        old_time_delta = settings.get_int('Messages', 'ThreadArchiveDays')
        old_time = timezone.now() - timedelta(days=old_time_delta)
        old_ops = Post.objects.filter(opening=True, pub_time__lte=old_time).exclude(thread__status=STATUS_ARCHIVE)

        for op in old_ops:
            thread = op.get_thread()
            if settings.get_bool('Storage', 'ArchiveThreads'):
                self._archive_thread(thread)
            else:
                thread.delete()
            logger.info('Processed old thread {}'.format(thread))


    def _archive_thread(self, thread):
        thread.status = STATUS_ARCHIVE
        thread.last_edit_time = timezone.now()
        thread.update_posts_time()
        thread.save(update_fields=['last_edit_time', 'status'])

    def get_new_posts(self, last_posts):
        query = None
        for post in last_posts:
            if not post.get_thread().is_archived():
                q = Q(id=post.thread_id) & Q(replies__id__gt=post.id)
                if query is None:
                    query = q
                else:
                    query = query | q
        if query is not None:
            return self.filter(query).annotate(
                new_post_count=Count('replies'))

    def get_new_post_count(self, last_posts):
        new_posts = self.get_new_posts(last_posts)
        return new_posts.aggregate(total_count=Count('replies'))\
                ['total_count'] if new_posts else 0


def get_thread_max_posts():
    return settings.get_int('Messages', 'MaxPostsPerThread')


class Thread(models.Model):
    objects = ThreadManager()

    class Meta:
        app_label = 'boards'

    tags = models.ManyToManyField('Tag', related_name='thread_tags')
    bump_time = models.DateTimeField(db_index=True)
    last_edit_time = models.DateTimeField()
    max_posts = models.IntegerField(default=get_thread_max_posts)
    status = models.CharField(max_length=50, default=STATUS_ACTIVE,
            choices=STATUS_CHOICES, db_index=True)
    monochrome = models.BooleanField(default=False)
    stickerpack = models.BooleanField(default=False)

    def get_tags(self) -> QuerySet:
        """
        Gets a sorted tag list.
        """

        return self.tags.filter(aliases__in=TagAlias.objects.filter_localized(parent__thread_tags=self)).order_by('aliases__name')

    def bump(self):
        """
        Bumps (moves to up) thread if possible.
        """

        if self.can_bump():
            self.bump_time = self.last_edit_time

            self.update_bump_status()

            logger.info('Bumped thread %d' % self.id)

    def has_post_limit(self) -> bool:
        return self.max_posts > 0

    def update_bump_status(self, exclude_posts=None):
        if self.has_post_limit() and self.get_reply_count() >= self.max_posts:
            self.status = STATUS_BUMPLIMIT
            self.update_posts_time(exclude_posts=exclude_posts)

    def _get_cache_key(self):
        return [datetime_to_epoch(self.last_edit_time)]

    @cached_result(key_method=_get_cache_key)
    def get_reply_count(self) -> int:
        return self.get_replies().count()

    @cached_result(key_method=_get_cache_key)
    def get_images_count(self) -> int:
        return self.get_replies().filter(
            attachments__mimetype__in=FILE_TYPES_IMAGE)\
            .annotate(images_count=Count(
            'attachments')).aggregate(Sum('images_count'))['images_count__sum'] or 0

    @cached_result(key_method=_get_cache_key)
    def get_attachment_count(self) -> int:
        return self.get_replies().annotate(attachment_count=Count('attachments'))\
                .aggregate(Sum('attachment_count'))['attachment_count__sum'] or 0

    def can_bump(self) -> bool:
        """
        Checks if the thread can be bumped by replying to it.
        """

        return self.get_status() == STATUS_ACTIVE

    def get_last_replies(self) -> QuerySet:
        """
        Gets several last replies, not including opening post
        """

        last_replies_count = settings.get_int(SECTION_VIEW, 'LastRepliesCount')

        if last_replies_count > 0:
            reply_count = self.get_reply_count()

            if reply_count > 0:
                reply_count_to_show = min(last_replies_count,
                                          reply_count - 1)
                replies = self.get_replies()
                last_replies = replies[reply_count - reply_count_to_show:]

                return last_replies

    def get_skipped_replies_count(self) -> int:
        """
        Gets number of posts between opening post and last replies.
        """
        reply_count = self.get_reply_count()
        last_replies_count = min(settings.get_int(SECTION_VIEW, 'LastRepliesCount'),
                                 reply_count - 1)
        return reply_count - last_replies_count - 1

    # TODO Remove argument, it is not used
    def get_replies(self, view_fields_only=True) -> QuerySet:
        """
        Gets sorted thread posts
        """
        query = self.replies.order_by('pub_time').prefetch_related(
            'attachments')
        return query

    def get_viewable_replies(self) -> QuerySet:
        """
        Gets replies with only fields that are used for viewing.
        """
        return self.get_replies().defer('text', 'last_edit_time')

    def get_top_level_replies(self) -> QuerySet:
        return self.get_replies().exclude(refposts__threads__in=[self])

    def get_replies_with_images(self, view_fields_only=False) -> QuerySet:
        """
        Gets replies that have at least one image attached
        """
        return self.get_replies(view_fields_only).filter(
            attachments__mimetype__in=FILE_TYPES_IMAGE).annotate(images_count=Count(
            'attachments')).filter(images_count__gt=0)

    def get_opening_post(self, only_id=False) -> Post:
        """
        Gets the first post of the thread
        """

        query = self.get_replies().filter(opening=True)
        if only_id:
            query = query.only('id')
        opening_post = query.first()

        return opening_post

    @cached_result()
    def get_opening_post_id(self) -> int:
        """
        Gets ID of the first thread post.
        """

        return self.get_opening_post(only_id=True).id

    def get_pub_time(self):
        """
        Gets opening post's pub time because thread does not have its own one.
        """

        return self.get_opening_post().pub_time

    def __str__(self):
        return 'T#{}/{}'.format(self.id, self.get_opening_post())

    def get_tag_url_list(self) -> list:
        return boards.models.Tag.objects.get_tag_url_list(self.get_tags().all())

    def update_posts_time(self, exclude_posts=None):
        last_edit_time = self.last_edit_time

        for post in self.replies.all():
            if exclude_posts is None or post not in exclude_posts:
                # Manual update is required because uids are generated on save
                post.last_edit_time = last_edit_time
                post.save(update_fields=['last_edit_time'])

    def get_absolute_url(self):
        return self.get_opening_post().get_absolute_url()

    def get_required_tags(self):
        return self.get_tags().filter(required=True)

    def get_sections_str(self):
        return Tag.objects.get_tag_url_list(self.get_required_tags())

    def get_replies_newer(self, post_id):
        return self.get_replies().filter(id__gt=post_id)

    def is_archived(self):
        return self.get_status() == STATUS_ARCHIVE

    def is_bumplimit(self):
        return self.get_status() == STATUS_BUMPLIMIT

    def get_status(self):
        return self.status

    def is_monochrome(self):
        return self.monochrome

    def is_stickerpack(self):
        return self.stickerpack

    # If tags have parent, add them to the tag list
    @transaction.atomic
    def refresh_tags(self):
        for tag in self.get_tags().all():
            parents = tag.get_all_parents()
            if len(parents) > 0:
                self.tags.add(*parents)

    def get_reply_tree(self):
        replies = self.get_replies().prefetch_related('refposts')
        tree = []
        for reply in replies:
            parents = reply.refposts.all()

            found_parent = False
            searching_for_index = False

            if len(parents) > 0:
                index = 0
                parent_depth = 0

                indexes_to_insert = []

                for depth, element in tree:
                    index += 1

                    # If this element is next after parent on the same level,
                    # insert child before it
                    if searching_for_index and depth <= parent_depth:
                        indexes_to_insert.append((index - 1, parent_depth))
                        searching_for_index = False

                    if element in parents:
                        found_parent = True
                        searching_for_index = True
                        parent_depth = depth

            if not found_parent:
                tree.append((0, reply))
            else:
                if searching_for_index:
                    tree.append((parent_depth + 1, reply))

                offset = 0
                for last_index, parent_depth in indexes_to_insert:
                    tree.insert(last_index + offset, (parent_depth + 1, reply))
                    offset += 1

        return tree