mygpo/web/heatmap.py

   1 #
   2 # This file is part of my.gpodder.org.
   3 #
   4 # my.gpodder.org is free software: you can redistribute it and/or modify it
   5 # under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or (at your
   7 # option) any later version.
   8 #
   9 # my.gpodder.org is distributed in the hope that it will be useful, but
  10 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11 # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
  12 # License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with my.gpodder.org. If not, see <http://www.gnu.org/licenses/>.
  16 #
  17
  18 from functools import wraps
  19
  20 from mygpo.users.models import EpisodeUserState
  21
  22
  23 class EpisodeHeatmap(object):
  24     """ Information about how often certain parts of Episodes are played """
  25
  26     def __init__(self, podcast_id, episode_id=None, user_id=None,
  27                  duration=None):
  28         """ Initialize a new Episode heatmap
  29
  30         EpisodeHeatmap(podcast_id, [episode_id, [user_id]]) """
  31
  32         self.podcast_id = podcast_id
  33
  34         if episode_id is not None and podcast_id is None:
  35             raise ValueError('episode_id can only be used '
  36                     'if podcast_id is not None')
  37
  38         self.episode_id = episode_id
  39
  40         if user_id is not None and episode_id is None:
  41             raise ValueError('user_id can only be used '
  42                     'if episode_id is not None')
  43
  44         self.user_id = user_id
  45         self.duration = duration
  46         self.heatmap = None
  47         self.borders = None
  48
  49
  50     def _query(self):
  51         """ Queries the database and stores the heatmap and its borders """
  52
  53         db = EpisodeUserState.get_db()
  54
  55         group_level = len(filter(None, [self.podcast_id,
  56                     self.episode_id, self.user_id]))
  57
  58         r = db.view('users/episode_heatmap',
  59                 startkey    = [self.podcast_id, self.episode_id,
  60                                 self.user_id],
  61                 endkey      = [self.podcast_id, self.episode_id or {},
  62                                 self.user_id or {}],
  63                 reduce      = True,
  64                 group       = True,
  65                 group_level = group_level,
  66                 stale       = 'update_after',
  67             )
  68
  69         if not r:
  70             self.heatmap = []
  71             self.borders = []
  72         else:
  73             res = r.first()['value']
  74             self.heatmap = res['heatmap']
  75             self.borders = res['borders']
  76
  77             # heatmap info doesn't reach until the end of the episode
  78             # so we extend it with 0 listeners
  79             if self.duration > self.borders[-1]:
  80                 self.heatmap.append(0)
  81                 self.borders.append(self.duration)
  82
  83
  84     def query_if_required():
  85         """ If required, queries the database before calling the function """
  86
  87         def decorator(f):
  88             @wraps(f)
  89             def tmp(self, *args, **kwargs):
  90                 if None in (self.heatmap, self.borders):
  91                     self._query()
  92
  93                 return f(self, *args, **kwargs)
  94             return tmp
  95         return decorator
  96
  97
  98     @property
  99     @query_if_required()
 100     def max_plays(self):
 101         """ Returns the highest number of plays of all sections """
 102
 103         return max(self.heatmap)
 104
 105
 106     @property
 107     @query_if_required()
 108     def sections(self):
 109         """ Returns an iterator that emits (from, to, play-counts) tuples
 110
 111         Each tuple represents one part in the heatmap with a distinct
 112         play-count. from and to indicate the range of section in seconds."""
 113
 114         for i in range(len(self.heatmap)):
 115             yield (self.borders[i], self.borders[i+1], self.heatmap[i])
 116
 117
 118     @query_if_required()
 119     def __nonzero__(self):
 120         return any(self.heatmap)