import feedparser
import logging
import calendar

from time import mktime
from datetime import datetime

from django.db import models, transaction
from django.utils.dateparse import parse_datetime
from django.utils.timezone import utc
from django.utils import timezone
from django.utils.html import strip_tags

from boards.models import Post
from boards.models.post import TITLE_MAX_LENGTH
from boards.settings import SECTION_EXTERNAL
from boards.utils import get_tripcode_from_text
from boards import settings


SOURCE_TYPE_MAX_LENGTH = 100
SOURCE_TYPE_RSS = 'RSS'
TYPE_CHOICES = (
        (SOURCE_TYPE_RSS, SOURCE_TYPE_RSS),
)


class ThreadSource(models.Model):
    class Meta:
        app_label = 'boards'

    name = models.TextField()
    thread = models.ForeignKey('Thread', on_delete=models.CASCADE)
    timestamp = models.DateTimeField()
    source = models.TextField()
    source_type = models.CharField(max_length=SOURCE_TYPE_MAX_LENGTH,
            choices=TYPE_CHOICES)

    def __str__(self):
        return self.name

    @transaction.atomic
    def fetch_latest_posts(self):
        """Creates new posts with the info fetched since the timestamp."""
        logger = logging.getLogger('boards.source')

        if self.thread.is_archived():
            logger.error('The thread {} is archived, please try another one'.format(self.thread))
        else:
            tripcode = get_tripcode_from_text(
                    settings.get(SECTION_EXTERNAL, 'SourceFetcherTripcode'))
            start_timestamp = self.timestamp
            last_timestamp = start_timestamp
            logger.info('Start timestamp is {}'.format(start_timestamp))
            if self.thread.is_bumplimit():
                logger.warn('The thread {} has reached its bumplimit, please create a new one'.format(self.thread))
            if self.source_type == SOURCE_TYPE_RSS:
                feed = feedparser.parse(self.source)
                items = sorted(feed.entries, key=lambda entry: entry.published_parsed)
                for item in items:
                    title = self.strip_title(item.title, TITLE_MAX_LENGTH)
                    timestamp = datetime.fromtimestamp(calendar.timegm(item.published_parsed), tz=utc)
                    if not timestamp:
                        logger.error('Invalid timestamp {} for {}'.format(item.published, title))
                    else:
                        if timestamp > last_timestamp:
                            last_timestamp = timestamp
                        if timestamp > start_timestamp:
                            Post.objects.create_post(title=title, text=self.parse_text(item.description),
                                    thread=self.thread, file_urls=[item.link], tripcode=tripcode)
                            logger.info('Fetched item {} from {} into thread {}'.format(
                                title, self.name, self.thread))
            logger.info('New timestamp is {}'.format(last_timestamp))
            self.timestamp = last_timestamp
            self.save(update_fields=['timestamp'])

    def parse_text(self, text):
        return strip_tags(text)

    def strip_title(self, title, max_length):
        result = title
        if len(title) > max_length:
            result = title[:max_length - 1] + '…'
        return result