import feedparser
import httplib2
import logging
import calendar
import xml.etree.ElementTree as ET

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, GlobalId, KeyPair
from boards.models.post import TITLE_MAX_LENGTH
from boards.models.post.sync import SyncManager, TAG_ID, TAG_UPDATE_TIME
from boards.settings import SECTION_EXTERNAL
from boards.utils import get_tripcode_from_text
from boards import settings

DELIMITER_TAGS = ','

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


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

    name = models.TextField()
    timestamp = models.DateTimeField(blank=True, null=True)
    url = models.TextField()
    tags = models.TextField(blank=True)
    query_split_limit = models.IntegerField()

    def __str__(self):
        return self.name

    @transaction.atomic
    def run_sync(self):
        logger = logging.getLogger('boards.sync')

        tags = []
        if self.tags:
            tags = self.tags.split(DELIMITER_TAGS)

        timestamp = None
        if self.timestamp:
            timestamp = self.timestamp

        new_timestamp = timezone.now()

        list_url = '{}api/sync/list/'.format(self.url)
        get_url = '{}api/sync/get/'.format(self.url)
        file_url = self.url[:-1]

        xml = SyncManager.generate_request_list(
            tags=tags,
            timestamp_from=timestamp).encode()

        logger.info('Running LIST request for {}...'.format(self.name))
        h = httplib2.Http()
        response, content = h.request(list_url, method="POST", body=xml)
        if response.status != 200:
            raise Exception('Server returned error {}'.format(response.status))

        logger.info('Processing response...')

        root = ET.fromstring(content)
        status = root.findall('status')[0].text
        if status == 'success':
            ids_to_sync = list()

            models = root.findall('models')[0]
            for model in models:
                self.add_to_sync_list(ids_to_sync, logger, model)
            logger.info('Starting sync...')

            if len(ids_to_sync) > 0:
                if self.query_split_limit > 0:
                    limit = min(self.query_split_limit, len(ids_to_sync))
                else:
                    limit = len(ids_to_sync)

                for offset in range(0, len(ids_to_sync), limit):
                    xml = SyncManager.generate_request_get(
                        ids_to_sync[offset:offset + limit])
                    h = httplib2.Http()
                    logger.info('Running GET request...')
                    response, content = h.request(get_url, method="POST",
                                                  body=xml)
                    logger.info('Processing response...')

                    SyncManager.parse_response_get(content, file_url)

                    logger.info('Sync completed successfully for {}'.format(self.name))
            else:
                logger.info('Nothing to get for {}, everything synced'.format(self.name))
        else:
            raise Exception('Invalid response status')

        self.timestamp = new_timestamp
        self.save(update_fields=['timestamp'])

    def add_to_sync_list(self, ids_to_sync, logger, model):
        tag_id = model.find(TAG_ID)
        global_id, exists = GlobalId.from_xml_element(tag_id)
        from_this_board = self._is_from_this_board(global_id)
        if from_this_board:
            # If the post originates from this board, no need to process
            # it again, nobody else could modify it
            logger.debug('NO SYNC Processed post {}'.format(global_id))
        else:
            tag_update_time = model.find(TAG_UPDATE_TIME)
            if tag_update_time:
                update_time = tag_update_time.text
            else:
                update_time = None
            if not exists or update_time is None or global_id.post.last_edit_time < parse_datetime(
                    update_time):
                logger.debug('SYNC Processed post {}'.format(global_id))
                ids_to_sync.append(global_id)
            else:
                logger.debug('NO SYNC Processed post {}'.format(global_id))

    def _is_from_this_board(self, global_id):
        from_this_board = KeyPair.objects.filter(
            key_type=global_id.key_type,
            public_key=global_id.key).exists()
        return from_this_board