shell/rb-play-order-random-by-age-and-rating.c

   1 /*
   2  *  arch-tag: Implementation of random play order weighted by the time since last play and the rating
   3  *
   4  *  Copyright (C) 2003 Jeffrey Yasskin <jyasskin@mail.utexas.edu>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA.
  19  *
  20  */
  21
  22 #include "rb-play-order-random-by-age-and-rating.h"
  23
  24 #include "rhythmdb.h"
  25 #include <time.h>
  26 #include <math.h>
  27
  28 static void rb_random_play_order_by_age_and_rating_class_init (RBRandomPlayOrderByAgeAndRatingClass *klass);
  29
  30 static double rb_random_by_age_and_rating_get_entry_weight (RBRandomPlayOrder *rorder,
  31                                                  RhythmDB *db, RhythmDBEntry *entry);
  32
  33 G_DEFINE_TYPE (RBRandomPlayOrderByAgeAndRating,
  34                rb_random_play_order_by_age_and_rating,
  35                RB_TYPE_RANDOM_PLAY_ORDER)
  36
  37 static void
  38 rb_random_play_order_by_age_and_rating_class_init (RBRandomPlayOrderByAgeAndRatingClass *klass)
  39 {
  40         RBRandomPlayOrderClass *rorder;
  41
  42         rorder = RB_RANDOM_PLAY_ORDER_CLASS (klass);
  43         rorder->get_entry_weight = rb_random_by_age_and_rating_get_entry_weight;
  44 }
  45
  46 RBPlayOrder *
  47 rb_random_play_order_by_age_and_rating_new (RBShellPlayer *player)
  48 {
  49         RBRandomPlayOrderByAgeAndRating *rorder;
  50
  51         rorder = g_object_new (RB_TYPE_RANDOM_PLAY_ORDER_BY_AGE_AND_RATING,
  52                         "player", player,
  53                         NULL);
  54
  55         return RB_PLAY_ORDER (rorder);
  56 }
  57
  58 static void
  59 rb_random_play_order_by_age_and_rating_init (RBRandomPlayOrderByAgeAndRating *porder)
  60 {
  61 }
  62
  63 static double
  64 rb_random_by_age_and_rating_get_entry_weight (RBRandomPlayOrder *rorder, RhythmDB *db, RhythmDBEntry *entry)
  65 {
  66         time_t now;
  67         gulong last_play;
  68         gulong seconds_since_last_play;
  69         gdouble rating;
  70
  71         /* This finds the log of the number of seconds since the last play.
  72          * It handles never played automatically, since now-0 is a valid
  73          * argument to log(). */
  74         time (&now);
  75         last_play = rhythmdb_entry_get_ulong (entry, RHYTHMDB_PROP_LAST_PLAYED);
  76         seconds_since_last_play = now - last_play;
  77         /* The lowest weight should be 0. */
  78         if (seconds_since_last_play < 1)
  79                 seconds_since_last_play = 1;
  80
  81         rating = rhythmdb_entry_get_double (entry, RHYTHMDB_PROP_RATING);
  82
  83         /* treat unrated as 2.5 for the purposes of probabilities */
  84         if (rating < 0.01)
  85                 rating = 2.5;
  86
  87         return log (seconds_since_last_play) * (rating + 1.0);
  88 }