NewsBlur-viq/apps/reader/models.py

import datetime
import time
import redis
import hashlib
import mongoengine as mongo
from utils import log as logging
from utils import json_functions as json
from django.db import models, IntegrityError
from django.conf import settings
from django.contrib.auth.models import User
from mongoengine.queryset import OperationError
from apps.reader.managers import UserSubscriptionManager
from apps.rss_feeds.models import Feed, MStory, DuplicateFeed
from apps.analyzer.models import MClassifierFeed, MClassifierAuthor, MClassifierTag, MClassifierTitle
from apps.analyzer.models import apply_classifier_titles, apply_classifier_feeds, apply_classifier_authors, apply_classifier_tags
from utils.feed_functions import add_object_to_folder

class UserSubscription(models.Model):
    """
    A feed which a user has subscrubed to. Carries all of the cached information
    about the subscription, including unread counts of the three primary scores.
    
    Also has a dirty flag (needs_unread_recalc) which means that the unread counts
    are not accurate and need to be calculated with `self.calculate_feed_scores()`.
    """
    UNREAD_CUTOFF = datetime.datetime.utcnow() - datetime.timedelta(days=settings.DAYS_OF_UNREAD)
    
    user = models.ForeignKey(User, related_name='subscriptions')
    feed = models.ForeignKey(Feed, related_name='subscribers')
    user_title = models.CharField(max_length=255, null=True, blank=True)
    active = models.BooleanField(default=False)
    last_read_date = models.DateTimeField(default=UNREAD_CUTOFF)
    mark_read_date = models.DateTimeField(default=UNREAD_CUTOFF)
    unread_count_neutral = models.IntegerField(default=0)
    unread_count_positive = models.IntegerField(default=0)
    unread_count_negative = models.IntegerField(default=0)
    unread_count_updated = models.DateTimeField(default=datetime.datetime.now)
    oldest_unread_story_date = models.DateTimeField(default=datetime.datetime.now)
    needs_unread_recalc = models.BooleanField(default=False)
    feed_opens = models.IntegerField(default=0)
    is_trained = models.BooleanField(default=False)
    
    objects = UserSubscriptionManager()

    def __unicode__(self):
        return '[%s (%s): %s (%s)] ' % (self.user.username, self.user.pk, 
                                        self.feed.feed_title, self.feed.pk)
        
    class Meta:
        unique_together = ("user", "feed")
    
    def canonical(self, full=False, include_favicon=True, classifiers=None):
        feed               = self.feed.canonical(full=full, include_favicon=include_favicon)
        feed['feed_title'] = self.user_title or feed['feed_title']
        feed['ps']         = self.unread_count_positive
        feed['nt']         = self.unread_count_neutral
        feed['ng']         = self.unread_count_negative
        feed['active']     = self.active
        feed['feed_opens'] = self.feed_opens
        feed['subscribed'] = True
        if classifiers:
            feed['classifiers'] = classifiers
        if not self.active and self.user.profile.is_premium:
            feed['active'] = True
            self.active = True
            self.save()

        return feed
            
    def save(self, *args, **kwargs):
        user_title_max = self._meta.get_field('user_title').max_length
        if self.user_title and len(self.user_title) > user_title_max:
            self.user_title = self.user_title[:user_title_max]
        if not self.active and self.user.profile.is_premium:
            self.active = True
        try:
            super(UserSubscription, self).save(*args, **kwargs)
        except IntegrityError:
            duplicate_feeds = DuplicateFeed.objects.filter(duplicate_feed_id=self.feed_id)
            for duplicate_feed in duplicate_feeds:
                already_subscribed = UserSubscription.objects.filter(user=self.user, feed=duplicate_feed.feed)
                if not already_subscribed:
                    self.feed = duplicate_feed.feed
                    super(UserSubscription, self).save(*args, **kwargs)
                    break
            else:
                self.delete()
    
    def sync_redis(self, skip_feed=False):
        r = redis.Redis(connection_pool=settings.REDIS_STORY_POOL)
        
        if not skip_feed:
            self.feed.sync_redis()
        
        userstories = MUserStory.objects.filter(feed_id=self.feed_id, user_id=self.user_id)
        for userstory in userstories:
            userstory.sync_redis(r=r)
        
    def get_stories(self, offset=0, limit=6, order='newest', read_filter='all', withscores=False):
        r = redis.Redis(connection_pool=settings.REDIS_STORY_POOL)
        ignore_user_stories = False
        
        stories_key         = 'F:%s' % (self.feed_id)
        read_stories_key    = 'RS:%s:%s' % (self.user_id, self.feed_id)
        unread_stories_key  = 'U:%s:%s' % (self.user_id, self.feed_id)

        if not r.exists(stories_key):
            print " ---> No stories on feed: %s" % self
            return []
        elif read_filter != 'unread' or not r.exists(read_stories_key):
            ignore_user_stories = True
            unread_stories_key = stories_key
        else:
            r.sdiffstore(unread_stories_key, stories_key, read_stories_key)
        sorted_stories_key          = 'zF:%s' % (self.feed_id)
        unread_ranked_stories_key   = 'zU:%s:%s' % (self.user_id, self.feed_id)
        r.zinterstore(unread_ranked_stories_key, [sorted_stories_key, unread_stories_key])
        
        current_time    = int(time.time() + 60*60*24)
        mark_read_time  = int(time.mktime(self.mark_read_date.timetuple()))
        if order == 'oldest':
            byscorefunc = r.zrangebyscore
            min_score = mark_read_time
            max_score = current_time
        else:
            byscorefunc = r.zrevrangebyscore
            min_score = current_time
            max_score = mark_read_time

        if settings.DEBUG:
            print " ---> Unread all stories: %s" % r.zrevrange(unread_ranked_stories_key, 0, -1)
        story_ids = byscorefunc(unread_ranked_stories_key, min_score, 
                                  max_score, start=offset, num=limit,
                                  withscores=withscores)

        r.expire(unread_ranked_stories_key, 24*60*60)
        if not ignore_user_stories:
            r.delete(unread_stories_key)
        
        return story_ids
        
    @classmethod
    def feed_stories(cls, user_id, feed_ids, offset=0, limit=6, order='newest', read_filter='all'):
        r = redis.Redis(connection_pool=settings.REDIS_STORY_POOL)
        
        if order == 'oldest':
            range_func = r.zrange
        else:
            range_func = r.zrevrange
            
        if not isinstance(feed_ids, list):
            feed_ids = [feed_ids]

        unread_ranked_stories_keys  = 'zU:%s' % (user_id)
        if offset and r.exists(unread_ranked_stories_keys):
            story_guids = range_func(unread_ranked_stories_keys, offset, limit)
            return story_guids
        else:
            r.delete(unread_ranked_stories_keys)

        for feed_id in feed_ids:
            us = cls.objects.get(user=user_id, feed=feed_id)
            story_guids = us.get_stories(offset=0, limit=200, 
                                         order=order, read_filter=read_filter, 
                                         withscores=True)

            if story_guids:
                r.zadd(unread_ranked_stories_keys, **dict(story_guids))
            
        story_guids = range_func(unread_ranked_stories_keys, offset, limit)
        r.expire(unread_ranked_stories_keys, 24*60*60)
        
        return story_guids
        
    @classmethod
    def add_subscription(cls, user, feed_address, folder=None, bookmarklet=False, auto_active=True):
        feed = None
        us = None
    
        logging.user(user, "~FRAdding URL: ~SB%s (in %s)" % (feed_address, folder))
    
        feed = Feed.get_feed_from_url(feed_address)

        if not feed:    
            code = -1
            if bookmarklet:
                message = "This site does not have an RSS feed. Nothing is linked to from this page."
            else:
                message = "This address does not point to an RSS feed or a website with an RSS feed."
        else:
            us, subscription_created = cls.objects.get_or_create(
                feed=feed, 
                user=user,
                defaults={
                    'needs_unread_recalc': True,
                    'active': auto_active,
                }
            )
            code = 1
            message = ""
    
        if us:
            user_sub_folders_object, created = UserSubscriptionFolders.objects.get_or_create(
                user=user,
                defaults={'folders': '[]'}
            )
            if created:
                user_sub_folders = []
            else:
                user_sub_folders = json.decode(user_sub_folders_object.folders)
            user_sub_folders = add_object_to_folder(feed.pk, folder, user_sub_folders)
            user_sub_folders_object.folders = json.encode(user_sub_folders)
            user_sub_folders_object.save()
            
            if auto_active:
                us.active = True
            else:
                feed_count = cls.objects.filter(user=user).count()
                if feed_count < 64 or user.profile.is_premium:
                    us.active = True
            us.save()
        
            if feed.last_update < datetime.datetime.utcnow() - datetime.timedelta(days=1):
                feed = feed.update()
            
            from apps.social.models import MActivity
            MActivity.new_feed_subscription(user_id=user.pk, feed_id=feed.pk, feed_title=feed.title)
            feed.setup_feed_for_premium_subscribers()
        
        return code, message, us
    
    @classmethod
    def feeds_with_updated_counts(cls, user, feed_ids=None, check_fetch_status=False):
        feeds = {}
        
        # Get subscriptions for user
        user_subs = cls.objects.select_related('feed').filter(user=user, active=True)
        feed_ids = [f for f in feed_ids if f and not f.startswith('river')]
        if feed_ids:
            user_subs = user_subs.filter(feed__in=feed_ids)
        
        
        UNREAD_CUTOFF = datetime.datetime.utcnow() - datetime.timedelta(days=settings.DAYS_OF_UNREAD)

        for i, sub in enumerate(user_subs):
            # Count unreads if subscription is stale.
            if (sub.needs_unread_recalc or 
                sub.unread_count_updated < UNREAD_CUTOFF or 
                sub.oldest_unread_story_date < UNREAD_CUTOFF):
                sub = sub.calculate_feed_scores(silent=True)
            if not sub: continue # TODO: Figure out the correct sub and give it a new feed_id

            feed_id = sub.feed_id
            feeds[feed_id] = {
                'ps': sub.unread_count_positive,
                'nt': sub.unread_count_neutral,
                'ng': sub.unread_count_negative,
                'id': feed_id,
            }
            if not sub.feed.fetched_once or check_fetch_status:
                feeds[feed_id]['fetched_once'] = sub.feed.fetched_once
                feeds[feed_id]['not_yet_fetched'] = not sub.feed.fetched_once # Legacy. Dammit.
            if sub.feed.favicon_fetching:
                feeds[feed_id]['favicon_fetching'] = True
            if sub.feed.has_feed_exception or sub.feed.has_page_exception:
                feeds[feed_id]['has_exception'] = True
                feeds[feed_id]['exception_type'] = 'feed' if sub.feed.has_feed_exception else 'page'
                feeds[feed_id]['feed_address'] = sub.feed.feed_address
                feeds[feed_id]['exception_code'] = sub.feed.exception_code

        return feeds
        
    def mark_feed_read(self):
        now = datetime.datetime.utcnow()
        
        # Use the latest story to get last read time.
        latest_story = MStory.objects(story_feed_id=self.feed.pk).order_by('-story_date').only('story_date')
        if latest_story:
            latest_story_date = latest_story[0]['story_date']\
                                + datetime.timedelta(seconds=1)
        else:
            latest_story_date = now
        
        self.last_read_date = latest_story_date
        self.mark_read_date = latest_story_date
        self.unread_count_negative = 0
        self.unread_count_positive = 0
        self.unread_count_neutral = 0
        self.unread_count_updated = now
        self.oldest_unread_story_date = now
        self.needs_unread_recalc = False
        
        # No longer removing old user read stories, since they're needed for social,
        # and they get cleaned up automatically when new stories come in.
        # MUserStory.delete_old_stories(self.user_id, self.feed_id)
        
        self.save()
        
    def mark_story_ids_as_read(self, story_ids, request=None):
        data = dict(code=0, payload=story_ids)
        
        if not request:
            request = self.user
    
        if not self.needs_unread_recalc:
            self.needs_unread_recalc = True
            self.save()
    
        if len(story_ids) > 1:
            logging.user(request, "~FYRead %s stories in feed: %s" % (len(story_ids), self.feed))
        else:
            logging.user(request, "~FYRead story in feed: %s" % (self.feed))
        
        for story_id in set(story_ids):
            try:
                story = MStory.objects.get(story_feed_id=self.feed_id, story_guid=story_id)
            except MStory.DoesNotExist:
                # Story has been deleted, probably by feed_fetcher.
                continue
            except MStory.MultipleObjectsReturned:
                story = MStory.objects.filter(story_feed_id=self.feed_id, story_guid=story_id)[0]
            now = datetime.datetime.utcnow()
            date = now if now > story.story_date else story.story_date # For handling future stories
            m = MUserStory(story=story, user_id=self.user_id, 
                           feed_id=self.feed_id, read_date=date, 
                           story_id=story_id, story_date=story.story_date)
            try:
                m.save()
            except OperationError, e:
                original_m = MUserStory.objects.get(user_id=self.user_id, feed_id=self.feed_id, story_id=story_id)
                logging.user(request, "~BRMarked story as read error: %s" % (e))
                logging.user(request, "~BRMarked story as read: %s" % (story_id))
                logging.user(request, "~BROrigin story as read: %s" % (m.story.story_guid))
                logging.user(request, "~BRMarked story id:   %s" % (original_m.story_id))
                logging.user(request, "~BROrigin story guid: %s" % (original_m.story.story_guid))
                logging.user(request, "~BRRead now date: %s, original read: %s, story_date: %s." % (m.read_date, original_m.read_date, story.story_date))
                original_m.story_id = story_id
                original_m.read_date = date
                original_m.story_date = story.story_date
                original_m.save()
            except OperationError, e:
                logging.user(request, "~BR~SKCan't even save: %s" % (original_m.story_id))
                pass
                
        return data
    
    def calculate_feed_scores(self, silent=False, stories_db=None):
        # now = datetime.datetime.strptime("2009-07-06 22:30:03", "%Y-%m-%d %H:%M:%S")
        now = datetime.datetime.now()
        UNREAD_CUTOFF = now - datetime.timedelta(days=settings.DAYS_OF_UNREAD)

        if self.user.profile.last_seen_on < UNREAD_CUTOFF:
            # if not silent:
            #     logging.info(' ---> [%s] SKIPPING Computing scores: %s (1 week+)' % (self.user, self.feed))
            return
        
        if not self.feed.fetched_once:
            if not silent:
                logging.info(' ---> [%s] NOT Computing scores: %s' % (self.user, self.feed))
            self.needs_unread_recalc = False
            self.save()
            return
            
        feed_scores = dict(negative=0, neutral=0, positive=0)
        
        # Two weeks in age. If mark_read_date is older, mark old stories as read.
        date_delta = UNREAD_CUTOFF
        if date_delta < self.mark_read_date:
            date_delta = self.mark_read_date
        else:
            self.mark_read_date = date_delta

        read_stories = MUserStory.objects(user_id=self.user_id,
                                          feed_id=self.feed_id,
                                          read_date__gte=self.mark_read_date)
        # if not silent:
        #     logging.info(' ---> [%s]    Read stories: %s' % (self.user, datetime.datetime.now() - now))
        read_stories_ids = [us.story_id for us in read_stories]
        stories_db = stories_db or MStory.objects(story_feed_id=self.feed_id,
                                                  story_date__gte=date_delta)
        # if not silent:
        #     logging.info(' ---> [%s]    MStory: %s' % (self.user, datetime.datetime.now() - now))
        oldest_unread_story_date = now
        unread_stories_db = []
        for story in stories_db:
            if story.story_date < date_delta:
                continue
            if hasattr(story, 'story_guid') and story.story_guid not in read_stories_ids:
                unread_stories_db.append(story)
                if story.story_date < oldest_unread_story_date:
                    oldest_unread_story_date = story.story_date
        stories = Feed.format_stories(unread_stories_db, self.feed_id)
        # if not silent:
        #     logging.info(' ---> [%s]    Format stories: %s' % (self.user, datetime.datetime.now() - now))
        
        classifier_feeds   = list(MClassifierFeed.objects(user_id=self.user_id, feed_id=self.feed_id, social_user_id=0))
        classifier_authors = list(MClassifierAuthor.objects(user_id=self.user_id, feed_id=self.feed_id))
        classifier_titles  = list(MClassifierTitle.objects(user_id=self.user_id, feed_id=self.feed_id))
        classifier_tags    = list(MClassifierTag.objects(user_id=self.user_id, feed_id=self.feed_id))

        # if not silent:
        #     logging.info(' ---> [%s]    Classifiers: %s (%s)' % (self.user, datetime.datetime.now() - now, classifier_feeds.count() + classifier_authors.count() + classifier_tags.count() + classifier_titles.count()))
            
        scores = {
            'feed': apply_classifier_feeds(classifier_feeds, self.feed),
        }
        
        for story in stories:
            scores.update({
                'author' : apply_classifier_authors(classifier_authors, story),
                'tags'   : apply_classifier_tags(classifier_tags, story),
                'title'  : apply_classifier_titles(classifier_titles, story),
            })
            
            max_score = max(scores['author'], scores['tags'], scores['title'])
            min_score = min(scores['author'], scores['tags'], scores['title'])
            if max_score > 0:
                feed_scores['positive'] += 1
            elif min_score < 0:
                feed_scores['negative'] += 1
            else:
                if scores['feed'] > 0:
                    feed_scores['positive'] += 1
                elif scores['feed'] < 0:
                    feed_scores['negative'] += 1
                else:
                    feed_scores['neutral'] += 1
                
        
        # if not silent:
        #     logging.info(' ---> [%s]    End classifiers: %s' % (self.user, datetime.datetime.now() - now))

        self.unread_count_positive = feed_scores['positive']
        self.unread_count_neutral = feed_scores['neutral']
        self.unread_count_negative = feed_scores['negative']
        self.unread_count_updated = datetime.datetime.now()
        self.oldest_unread_story_date = oldest_unread_story_date
        self.needs_unread_recalc = False
        
        self.save()

        if (self.unread_count_positive == 0 and 
            self.unread_count_neutral == 0 and
            self.unread_count_negative == 0):
            self.mark_feed_read()
        
        if not silent:
            logging.info(' ---> [%s] Computing scores: %s (%s/%s/%s)' % (self.user, self.feed, feed_scores['negative'], feed_scores['neutral'], feed_scores['positive']))
            
        return self
    
    def switch_feed(self, new_feed, old_feed):
        # Rewrite feed in subscription folders
        try:
            user_sub_folders = UserSubscriptionFolders.objects.get(user=self.user)
        except Exception, e:
            logging.info(" *** ---> UserSubscriptionFolders error: %s" % e)
            return
    
        # Switch to original feed for the user subscription
        logging.info("      ===> %s " % self.user)
        self.feed = new_feed
        self.needs_unread_recalc = True
        try:
            self.save()
            user_sub_folders.rewrite_feed(new_feed, old_feed)
        except (IntegrityError, OperationError):
            logging.info("      !!!!> %s already subscribed" % self.user)
            self.delete()
            return
        
        # Switch read stories
        user_stories = MUserStory.objects(user_id=self.user_id, feed_id=old_feed.pk)
        if user_stories.count() > 0:
            logging.info(" ---> %s read stories" % user_stories.count())

        for user_story in user_stories:
            user_story.feed_id = new_feed.pk
            duplicate_story = user_story.story
            story_guid = duplicate_story.story_guid if hasattr(duplicate_story, 'story_guid') else duplicate_story.id
            original_story = MStory.objects(story_feed_id=new_feed.pk,
                                            story_guid=story_guid)
        
            if original_story:
                user_story.story = original_story[0]
                try:
                    user_story.save()
                except OperationError:
                    # User read the story in the original feed, too. Ugh, just ignore it.
                    pass
            else:
                logging.info(" ***> Can't find original story: %s" % duplicate_story.id)
                user_story.delete()
        
        def switch_feed_for_classifier(model):
            duplicates = model.objects(feed_id=old_feed.pk, user_id=self.user_id)
            if duplicates.count():
                logging.info(" ---> Switching %s %s" % (duplicates.count(), model))
            for duplicate in duplicates:
                duplicate.feed_id = new_feed.pk
                try:
                    duplicate.save()
                    pass
                except (IntegrityError, OperationError):
                    logging.info("      !!!!> %s already exists" % duplicate)
                    duplicate.delete()
        
        switch_feed_for_classifier(MClassifierTitle)
        switch_feed_for_classifier(MClassifierAuthor)
        switch_feed_for_classifier(MClassifierFeed)
        switch_feed_for_classifier(MClassifierTag)
    
    @classmethod
    def collect_orphan_feeds(cls, user):
        us = cls.objects.filter(user=user)
        try:
            usf = UserSubscriptionFolders.objects.get(user=user)
        except UserSubscriptionFolders.DoesNotExist:
            return
        us_feed_ids = set([sub.feed_id for sub in us])
        folders = json.decode(usf.folders)
        
        def collect_ids(folders, found_ids):
            for item in folders:
                # print ' --> %s' % item
                if isinstance(item, int):
                    # print ' --> Adding feed: %s' % item
                    found_ids.add(item)
                elif isinstance(item, dict):
                    # print ' --> Descending folder dict: %s' % item.values()
                    found_ids.update(collect_ids(item.values(), found_ids))
                elif isinstance(item, list):
                    # print ' --> Descending folder list: %s' % len(item)
                    found_ids.update(collect_ids(item, found_ids))
            # print ' --> Returning: %s' % found_ids
            return found_ids
        found_ids = collect_ids(folders, set())
        diff = len(us_feed_ids) - len(found_ids)
        if diff > 0:
            logging.info(" ---> Collecting orphans on %s. %s feeds with %s orphans" % (user.username, len(us_feed_ids), diff))
            orphan_ids = us_feed_ids - found_ids
            folders.extend(list(orphan_ids))
            usf.folders = json.encode(folders)
            usf.save()
            

class MUserStory(mongo.Document):
    """
    Stories read by the user. These are deleted as the mark_read_date for the
    UserSubscription passes the UserStory date.
    """
    user_id = mongo.IntField(unique_with=('feed_id', 'story_id'))
    feed_id = mongo.IntField()
    read_date = mongo.DateTimeField()
    story_id = mongo.StringField(unique_with=('user_id', 'feed_id'))
    story_date = mongo.DateTimeField()
    story = mongo.ReferenceField(MStory)
    
    meta = {
        'collection': 'userstories',
        'indexes': [
            ('feed_id', 'story_id'),   # Updating stories with new guids
            ('feed_id', 'story_date'), # Trimming feeds
        ],
        'allow_inheritance': False,
        'index_drop_dups': True,
    }
    
    def save(self, *args, **kwargs):
        self.sync_redis()
        
        super(MUserStory, self).save(*args, **kwargs)
        
    def delete(self, *args, **kwargs):
        self.remove_from_redis()
        
        super(MUserStory, self).delete(*args, **kwargs)
        
    @property
    def guid_hash(self):
        return hashlib.sha1(self.story_id).hexdigest()
        
    @classmethod
    def delete_old_stories(cls, feed_id):
        UNREAD_CUTOFF = datetime.datetime.utcnow() - datetime.timedelta(days=settings.DAYS_OF_UNREAD)
        cls.objects(feed_id=feed_id, story_date__lte=UNREAD_CUTOFF).delete()
        
    @classmethod
    def delete_marked_as_read_stories(cls, user_id, feed_id, mark_read_date=None):
        if not mark_read_date:
            usersub = UserSubscription.objects.get(user__pk=user_id, feed__pk=feed_id)
            mark_read_date = usersub.mark_read_date
        
        # Next line forces only old read stories to be removed, just in case newer stories
        # come in as unread because they're being shared.
        mark_read_date = datetime.datetime.utcnow() - datetime.timedelta(days=settings.DAYS_OF_UNREAD)

        cls.objects(user_id=user_id, feed_id=feed_id, read_date__lte=mark_read_date).delete()
    
    @property
    def story_db_id(self):
        if self.story:
            return self.story.id

        try:
            story = MStory.objects.get(story_feed_id=self.feed_id, story_guid=self.story_id)
            return story.id
        except MStory.DoesNotExist:
            return
            
    def sync_redis(self, r=None):
        if not r:
            r = redis.Redis(connection_pool=settings.REDIS_STORY_POOL)

        if self.story_db_id:
            read_story_key = 'RS:%s:%s' % (self.user_id, self.feed_id)
            r.sadd(read_story_key, self.story_db_id)
            r.expire(read_story_key, settings.DAYS_OF_UNREAD*24*60*60)

    def remove_from_redis(self):
        r = redis.Redis(connection_pool=settings.REDIS_STORY_POOL)
        if self.story_db_id:
            r.srem('RS:%s:%s' % (self.user_id, self.feed_id), self.story_db_id)
        
    @classmethod
    def sync_all_redis(cls):
        read_stories = cls.objects.all()
        for read_story in read_stories:
            read_story.sync_redis()
        
class UserSubscriptionFolders(models.Model):
    """
    A JSON list of folders and feeds for while a user has subscribed. The list
    is a recursive descent of feeds and folders in folders. Used to layout
    the feeds and folders in the Reader's feed navigation pane.
    """
    user = models.ForeignKey(User, unique=True)
    folders = models.TextField(default="[]")
    
    def __unicode__(self):
        return "[%s]: %s" % (self.user, len(self.folders),)
        
    class Meta:
        verbose_name_plural = "folders"
        verbose_name = "folder"
    
    def compact(self):
        folders = json.decode(self.folders)
        
        def _compact(folder):
            new_folder = []
            for item in folder:
                if isinstance(item, int) and item not in new_folder:
                    new_folder.append(item)
                elif isinstance(item, dict):
                    for f_k, f_v in item.items():
                        new_folder.append({f_k: _compact(f_v)})
            return new_folder
        
        new_folders = _compact(folders)
        logging.info(" ---> Compacting from %s to %s" % (folders, new_folders))
        new_folders = json.encode(new_folders)
        logging.info(" ---> Compacting from %s to %s" % (len(self.folders), len(new_folders)))
        self.folders = new_folders
        self.save()
        
    def add_folder(self, parent_folder, folder):
        if self.folders:
            user_sub_folders = json.decode(self.folders)
        else:
            user_sub_folders = []
        obj = {folder: []}
        user_sub_folders = add_object_to_folder(obj, parent_folder, user_sub_folders)
        self.folders = json.encode(user_sub_folders)
        self.save()
        
    def delete_feed(self, feed_id, in_folder, commit_delete=True):
        def _find_feed_in_folders(old_folders, folder_name='', multiples_found=False, deleted=False):
            new_folders = []
            for k, folder in enumerate(old_folders):
                if isinstance(folder, int):
                    if (folder == feed_id and (
                        (folder_name != in_folder) or
                        (folder_name == in_folder and deleted))):
                        multiples_found = True
                        logging.user(self.user, "~FB~SBDeleting feed, and a multiple has been found in '%s'" % (folder_name))
                    if folder == feed_id and (folder_name == in_folder) and not deleted:
                        logging.user(self.user, "~FBDelete feed: %s'th item: %s folders/feeds" % (
                            k, len(old_folders)
                        ))
                        deleted = True
                    else:
                        new_folders.append(folder)
                elif isinstance(folder, dict):
                    for f_k, f_v in folder.items():
                        nf, multiples_found, deleted = _find_feed_in_folders(f_v, f_k, multiples_found, deleted)
                        new_folders.append({f_k: nf})
    
            return new_folders, multiples_found, deleted

        user_sub_folders = json.decode(self.folders)
        user_sub_folders, multiples_found, deleted = _find_feed_in_folders(user_sub_folders)
        self.folders = json.encode(user_sub_folders)
        self.save()

        if not multiples_found and deleted and commit_delete:
            try:
                user_sub = UserSubscription.objects.get(user=self.user, feed=feed_id)
            except Feed.DoesNotExist:
                duplicate_feed = DuplicateFeed.objects.filter(duplicate_feed_id=feed_id)
                if duplicate_feed:
                    try:
                        user_sub = UserSubscription.objects.get(user=self.user, 
                                                                feed=duplicate_feed[0].feed)
                    except Feed.DoesNotExist:
                        return
            if user_sub:
                user_sub.delete()
            MUserStory.objects(user_id=self.user_id, feed_id=feed_id).delete()

    def delete_folder(self, folder_to_delete, in_folder, feed_ids_in_folder, commit_delete=True):
        def _find_folder_in_folders(old_folders, folder_name, feeds_to_delete, deleted_folder=None):
            new_folders = []
            for k, folder in enumerate(old_folders):
                if isinstance(folder, int):
                    new_folders.append(folder)
                    if folder in feeds_to_delete:
                        feeds_to_delete.remove(folder)
                elif isinstance(folder, dict):
                    for f_k, f_v in folder.items():
                        if f_k == folder_to_delete and folder_name == in_folder:
                            logging.user(self.user, "~FBDeleting folder '~SB%s~SN' in '%s': %s" % (f_k, folder_name, folder))
                            deleted_folder = folder
                        else:
                            nf, feeds_to_delete, deleted_folder = _find_folder_in_folders(f_v, f_k, feeds_to_delete, deleted_folder)
                            new_folders.append({f_k: nf})
    
            return new_folders, feeds_to_delete, deleted_folder
            
        user_sub_folders = json.decode(self.folders)
        user_sub_folders, feeds_to_delete, deleted_folder = _find_folder_in_folders(user_sub_folders, '', feed_ids_in_folder)
        self.folders = json.encode(user_sub_folders)
        self.save()

        if commit_delete:
            UserSubscription.objects.filter(user=self.user, feed__in=feeds_to_delete).delete()
          
        return deleted_folder
        
    def rename_folder(self, folder_to_rename, new_folder_name, in_folder):
        def _find_folder_in_folders(old_folders, folder_name):
            new_folders = []
            for k, folder in enumerate(old_folders):
                if isinstance(folder, int):
                    new_folders.append(folder)
                elif isinstance(folder, dict):
                    for f_k, f_v in folder.items():
                        nf = _find_folder_in_folders(f_v, f_k)
                        if f_k == folder_to_rename and folder_name == in_folder:
                            logging.user(self.user, "~FBRenaming folder '~SB%s~SN' in '%s' to: ~SB%s" % (
                                         f_k, folder_name, new_folder_name))
                            f_k = new_folder_name
                        new_folders.append({f_k: nf})
    
            return new_folders
            
        user_sub_folders = json.decode(self.folders)
        user_sub_folders = _find_folder_in_folders(user_sub_folders, '')
        self.folders = json.encode(user_sub_folders)
        self.save()
        
    def move_feed_to_folder(self, feed_id, in_folder=None, to_folder=None):
        logging.user(self.user, "~FBMoving feed '~SB%s~SN' in '%s' to: ~SB%s" % (
                     feed_id, in_folder, to_folder))
        user_sub_folders = json.decode(self.folders)
        self.delete_feed(feed_id, in_folder, commit_delete=False)
        user_sub_folders = json.decode(self.folders)
        user_sub_folders = add_object_to_folder(int(feed_id), to_folder, user_sub_folders)
        self.folders = json.encode(user_sub_folders)
        self.save()
        
        return self

    def move_folder_to_folder(self, folder_name, in_folder=None, to_folder=None):
        logging.user(self.user, "~FBMoving folder '~SB%s~SN' in '%s' to: ~SB%s" % (
                     folder_name, in_folder, to_folder))
        user_sub_folders = json.decode(self.folders)
        deleted_folder = self.delete_folder(folder_name, in_folder, [], commit_delete=False)
        user_sub_folders = json.decode(self.folders)
        user_sub_folders = add_object_to_folder(deleted_folder, to_folder, user_sub_folders)
        self.folders = json.encode(user_sub_folders)
        self.save()
        
        return self
    
    def rewrite_feed(self, original_feed, duplicate_feed):
        def rewrite_folders(folders, original_feed, duplicate_feed):
            new_folders = []
    
            for k, folder in enumerate(folders):
                if isinstance(folder, int):
                    if folder == duplicate_feed.pk:
                        # logging.info("              ===> Rewrote %s'th item: %s" % (k+1, folders))
                        new_folders.append(original_feed.pk)
                    else:
                        new_folders.append(folder)
                elif isinstance(folder, dict):
                    for f_k, f_v in folder.items():
                        new_folders.append({f_k: rewrite_folders(f_v, original_feed, duplicate_feed)})

            return new_folders
            
        folders = json.decode(self.folders)
        folders = rewrite_folders(folders, original_feed, duplicate_feed)
        self.folders = json.encode(folders)
        self.save()


class Feature(models.Model):
    """
    Simple blog-like feature board shown to all users on the home page.
    """
    description = models.TextField(default="")
    date = models.DateTimeField(default=datetime.datetime.now)
    
    def __unicode__(self):
        return "[%s] %s" % (self.date, self.description[:50])
    
    class Meta:
        ordering = ["-date"]