from datetime import datetime, timedelta, date
from datetime import time as dtime
import logging
import re

from adjacent import Client
from django.core.cache import cache
from django.core.urlresolvers import reverse
from django.db import models, transaction
from django.db.models import TextField
from django.template.loader import render_to_string
from django.utils import timezone

from boards import settings
from boards.mdx_neboard import bbcode_extended
from boards.models import PostImage
from boards.models.base import Viewable
from boards.models.thread import Thread
from boards.utils import datetime_to_epoch


WS_NOTIFICATION_TYPE_NEW_POST = 'new_post'
WS_NOTIFICATION_TYPE = 'notification_type'

WS_CHANNEL_THREAD = "thread:"

APP_LABEL_BOARDS = 'boards'

CACHE_KEY_PPD = 'ppd'
CACHE_KEY_POST_URL = 'post_url'

POSTS_PER_DAY_RANGE = 7

BAN_REASON_AUTO = 'Auto'

IMAGE_THUMB_SIZE = (200, 150)

TITLE_MAX_LENGTH = 200

# TODO This should be removed
NO_IP = '0.0.0.0'

# TODO Real user agent should be saved instead of this
UNKNOWN_UA = ''

REGEX_REPLY = re.compile(r'\[post\](\d+)\[/post\]')

PARAMETER_TRUNCATED = 'truncated'
PARAMETER_TAG = 'tag'
PARAMETER_OFFSET = 'offset'
PARAMETER_DIFF_TYPE = 'type'
PARAMETER_BUMPABLE = 'bumpable'
PARAMETER_THREAD = 'thread'
PARAMETER_IS_OPENING = 'is_opening'
PARAMETER_MODERATOR = 'moderator'
PARAMETER_POST = 'post'
PARAMETER_OP_ID = 'opening_post_id'
PARAMETER_NEED_OPEN_LINK = 'need_open_link'

DIFF_TYPE_HTML = 'html'
DIFF_TYPE_JSON = 'json'

PREPARSE_PATTERNS = {
    r'>>(\d+)': r'[post]\1[/post]',  # Reflink ">>123"
    r'^>([^>].+)': r'[quote]\1[/quote]',  # Quote ">text"
    r'^//(.+)': r'[comment]\1[/comment]',  # Comment "//text"
}


class PostManager(models.Manager):
    @transaction.atomic
    def create_post(self, title: str, text: str, image=None, thread=None,
                    ip=NO_IP, tags: list=None):
        """
        Creates new post
        """

        if not tags:
            tags = []

        posting_time = timezone.now()
        if not thread:
            thread = Thread.objects.create(bump_time=posting_time,
                                           last_edit_time=posting_time)
            new_thread = True
        else:
            new_thread = False

        pre_text = self._preparse_text(text)

        post = self.create(title=title,
                           text=pre_text,
                           pub_time=posting_time,
                           thread_new=thread,
                           poster_ip=ip,
                           poster_user_agent=UNKNOWN_UA,  # TODO Get UA at
                           # last!
                           last_edit_time=posting_time)

        logger = logging.getLogger('boards.post.create')

        logger.info('Created post {} by {}'.format(
            post, post.poster_ip))

        if image:
            # Try to find existing image. If it exists, assign it to the post
            # instead of createing the new one
            image_hash = PostImage.get_hash(image)
            existing = PostImage.objects.filter(hash=image_hash)
            if len(existing) > 0:
                post_image = existing[0]
            else:
                post_image = PostImage.objects.create(image=image)
                logger.info('Created new image #{} for post #{}'.format(
                            post_image.id, post.id))
            post.images.add(post_image)

        thread.replies.add(post)
        list(map(thread.add_tag, tags))

        if new_thread:
            Thread.objects.process_oldest_threads()
        else:
            thread.bump()
            thread.last_edit_time = posting_time
            thread.save()

        self.connect_replies(post)

        return post

    def delete_posts_by_ip(self, ip):
        """
        Deletes all posts of the author with same IP
        """

        posts = self.filter(poster_ip=ip)
        for post in posts:
            post.delete()

    def  connect_replies(self, post):
        """
        Connects replies to a post to show them as a reflink map
        """

        for reply_number in re.finditer(REGEX_REPLY, post.get_raw_text()):
            post_id = reply_number.group(1)
            ref_post = self.filter(id=post_id)
            if ref_post.count() > 0:
                referenced_post = ref_post[0]
                referenced_post.referenced_posts.add(post)
                referenced_post.last_edit_time = post.pub_time
                referenced_post.build_refmap()
                referenced_post.save(update_fields=['refmap', 'last_edit_time'])

                referenced_thread = referenced_post.get_thread()
                referenced_thread.last_edit_time = post.pub_time
                referenced_thread.save(update_fields=['last_edit_time'])

    def get_posts_per_day(self):
        """
        Gets average count of posts per day for the last 7 days
        """

        day_end = date.today()
        day_start = day_end - timedelta(POSTS_PER_DAY_RANGE)

        cache_key = CACHE_KEY_PPD + str(day_end)
        ppd = cache.get(cache_key)
        if ppd:
            return ppd

        day_time_start = timezone.make_aware(datetime.combine(
            day_start, dtime()), timezone.get_current_timezone())
        day_time_end = timezone.make_aware(datetime.combine(
            day_end, dtime()), timezone.get_current_timezone())

        posts_per_period = float(self.filter(
            pub_time__lte=day_time_end,
            pub_time__gte=day_time_start).count())

        ppd = posts_per_period / POSTS_PER_DAY_RANGE

        cache.set(cache_key, ppd)
        return ppd

    def _preparse_text(self, text):
        """
        Preparses text to change patterns like '>>' to a proper bbcode
        tags.
        """

        for key, value in PREPARSE_PATTERNS.items():
            text = re.sub(key, value, text, flags=re.MULTILINE)

        return text


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

    objects = PostManager()

    class Meta:
        app_label = APP_LABEL_BOARDS
        ordering = ('id',)

    title = models.CharField(max_length=TITLE_MAX_LENGTH)
    pub_time = models.DateTimeField()
    text = TextField(blank=True, null=True)
    _text_rendered = TextField(blank=True, null=True, editable=False)

    images = models.ManyToManyField(PostImage, null=True, blank=True,
                                    related_name='ip+', db_index=True)

    poster_ip = models.GenericIPAddressField()
    poster_user_agent = models.TextField()

    thread_new = models.ForeignKey('Thread', null=True, default=None,
                                   db_index=True)
    last_edit_time = models.DateTimeField()

    referenced_posts = models.ManyToManyField('Post', symmetrical=False,
                                              null=True,
                                              blank=True, related_name='rfp+',
                                              db_index=True)
    refmap = models.TextField(null=True, blank=True)

    def __str__(self):
        return 'P#{}/{}'.format(self.id, self.title)

    def get_title(self) -> str:
        """
        Gets original post title or part of its text.
        """

        title = self.title
        if not title:
            title = self.get_text()

        return title

    def build_refmap(self) -> None:
        """
        Builds a replies map string from replies list. This is a cache to stop
        the server from recalculating the map on every post show.
        """
        map_string = ''

        first = True
        for refpost in self.referenced_posts.all():
            if not first:
                map_string += ', '
            map_string += '<a href="%s">&gt;&gt;%s</a>' % (refpost.get_url(),
                                                           refpost.id)
            first = False

        self.refmap = map_string

    def get_sorted_referenced_posts(self):
        return self.refmap

    def is_referenced(self) -> bool:
        if not self.refmap:
            return False
        else:
            return len(self.refmap) > 0

    def is_opening(self) -> bool:
        """
        Checks if this is an opening post or just a reply.
        """

        return self.get_thread().get_opening_post_id() == self.id

    @transaction.atomic
    def add_tag(self, tag):
        edit_time = timezone.now()

        thread = self.get_thread()
        thread.add_tag(tag)
        self.last_edit_time = edit_time
        self.save(update_fields=['last_edit_time'])

        thread.last_edit_time = edit_time
        thread.save(update_fields=['last_edit_time'])

    def get_url(self, thread=None):
        """
        Gets full url to the post.
        """

        cache_key = CACHE_KEY_POST_URL + str(self.id)
        link = cache.get(cache_key)

        if not link:
            if not thread:
                thread = self.get_thread()

            opening_id = thread.get_opening_post_id()

            if self.id != opening_id:
                link = reverse('thread', kwargs={
                    'post_id': opening_id}) + '#' + str(self.id)
            else:
                link = reverse('thread', kwargs={'post_id': self.id})

            cache.set(cache_key, link)

        return link

    def get_thread(self) -> Thread:
        """
        Gets post's thread.
        """

        return self.thread_new

    def get_referenced_posts(self):
        return self.referenced_posts.only('id', 'thread_new')

    def get_view(self, moderator=False, need_open_link=False,
                 truncated=False, *args, **kwargs):
        """
        Renders post's HTML view. Some of the post params can be passed over
        kwargs for the means of caching (if we view the thread, some params
        are same for every post and don't need to be computed over and over.
        """

        is_opening = kwargs.get(PARAMETER_IS_OPENING, self.is_opening())
        thread = kwargs.get(PARAMETER_THREAD, self.get_thread())
        can_bump = kwargs.get(PARAMETER_BUMPABLE, thread.can_bump())

        if is_opening:
            opening_post_id = self.id
        else:
            opening_post_id = thread.get_opening_post_id()

        return render_to_string('boards/post.html', {
            PARAMETER_POST: self,
            PARAMETER_MODERATOR: moderator,
            PARAMETER_IS_OPENING: is_opening,
            PARAMETER_THREAD: thread,
            PARAMETER_BUMPABLE: can_bump,
            PARAMETER_NEED_OPEN_LINK: need_open_link,
            PARAMETER_TRUNCATED: truncated,
            PARAMETER_OP_ID: opening_post_id,
        })

    def get_search_view(self, *args, **kwargs):
        return self.get_view(args, kwargs)

    def get_first_image(self) -> PostImage:
        return self.images.earliest('id')

    def delete(self, using=None):
        """
        Deletes all post images and the post itself. If the post is opening,
        thread with all posts is deleted.
        """

        for image in self.images.all():
            image_refs_count = Post.objects.filter(images__in=[image]).count()
            if image_refs_count == 1:
                image.delete()

        if self.is_opening():
            self.get_thread().delete()
        else:
            thread = self.get_thread()
            thread.last_edit_time = timezone.now()
            thread.save()

        super(Post, self).delete(using)

        logging.getLogger('boards.post.delete').info(
            'Deleted post {}'.format(self))

    def get_post_data(self, format_type=DIFF_TYPE_JSON, request=None,
                      include_last_update=False):
        """
        Gets post HTML or JSON data that can be rendered on a page or used by
        API.
        """

        if format_type == DIFF_TYPE_HTML:
            params = dict()
            params['post'] = self
            if PARAMETER_TRUNCATED in request.GET:
                params[PARAMETER_TRUNCATED] = True

            return render_to_string('boards/api_post.html', params)
        elif format_type == DIFF_TYPE_JSON:
            post_json = {
                'id': self.id,
                'title': self.title,
                'text': self._text_rendered,
                }
            if self.images.exists():
                post_image = self.get_first_image()
                post_json['image'] = post_image.image.url
                post_json['image_preview'] = post_image.image.url_200x150
            if include_last_update:
                post_json['bump_time'] = datetime_to_epoch(
                    self.thread_new.bump_time)
            return post_json

    def send_to_websocket(self, request, recursive=True):
        """
        Sends post HTML data to the thread web socket.
        """

        if not settings.WEBSOCKETS_ENABLED:
            return

        client = Client()

        thread = self.get_thread()
        thread_id = thread.id
        channel_name = WS_CHANNEL_THREAD + str(thread.get_opening_post_id())
        client.publish(channel_name, {
            WS_NOTIFICATION_TYPE: WS_NOTIFICATION_TYPE_NEW_POST,
        })
        client.send()

        logger = logging.getLogger('boards.post.websocket')

        logger.info('Sent notification from post #{} to channel {}'.format(
            self.id, channel_name))

        if recursive:
            for reply_number in re.finditer(REGEX_REPLY, self.get_raw_text()):
                post_id = reply_number.group(1)
                ref_post = Post.objects.filter(id=post_id)[0]

                # If post is in this thread, its thread was already notified.
                # Otherwise, notify its thread separately.
                if ref_post.thread_new_id != thread_id:
                    ref_post.send_to_websocket(request, recursive=False)

    def save(self, force_insert=False, force_update=False, using=None,
             update_fields=None):
        self._text_rendered = bbcode_extended(self.get_raw_text())

        super().save(force_insert, force_update, using, update_fields)

    def get_text(self) -> str:
        return self._text_rendered

    def get_raw_text(self) -> str:
        return self.text