File indexing completed on 2024-05-19 04:49:50

 /****************************************************************************************
  * Copyright (c) 2008 Seb Ruiz <ruiz@kde.org>                                           *
  * Copyright (c) 2008 Soren Harward <stharward@gmail.com>                               *
  * Copyright (c) 2008 Nikolaj Hald Nielsen <nhn@kde.org>                                *
  * Copyright (c) 2009 Téo Mrnjavac <teo@kde.org>                                        *
  * Copyright (c) 2010 Nanno Langstraat <langstr@gmail.com>                              *
  * Copyright (c) 2013 Daniel Schmitz <daniel.schmitz@gmx.info>                          *
  *                                                                                      *
  * This program is free software; you can redistribute it and/or modify it under        *
  * the terms of the GNU General Public License as published by the Free Software        *
  * Foundation; either version 2 of the License, or (at your option) version 3 or        *
  * any later version accepted by the membership of KDE e.V. (or its successor approved  *
  * by the membership of KDE e.V.), which shall act as a proxy defined in Section 14 of  *
  * version 3 of the license.                                                            *
  *                                                                                      *
  * This program is distributed in the hope that it will be useful, but WITHOUT ANY      *
  * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A      *
  * PARTICULAR PURPOSE. See the GNU General Public License for more details.             *
  *                                                                                      *
  * You should have received a copy of the GNU General Public License along with         *
  * this program.  If not, see <http://www.gnu.org/licenses/>.                           *
  ****************************************************************************************/
 
 #define DEBUG_PREFIX "Playlist::RandomTrackNavigator"
 
 #include "RandomTrackNavigator.h"
 
 #include "core/support/Debug.h"
 
 #include <QDateTime>
 #include <QRandomGenerator> // For 'QRandomGenerator::global()->generate()'
 
 #include <cmath> // For 'round()'
 
 Playlist::RandomTrackNavigator::RandomTrackNavigator()
 {
     loadFromSourceModel();
 }
 
 void
 Playlist::RandomTrackNavigator::planOne()
 {
     DEBUG_BLOCK
 
     if ( m_plannedItems.isEmpty() )
     {
         if ( !allItemsList().isEmpty() )
         {
             quint64 chosenItem;
 
             int avoidRecentlyPlayedSize = AVOID_RECENTLY_PLAYED_MAX;    // Start with being very picky.
 
             // Don't over-constrain ourself:
             //   - Keep enough headroom to be unpredictable.
             //   - Make sure that 'chooseRandomItem()' doesn't need to find a needle in a haystack.
             avoidRecentlyPlayedSize = qMin( avoidRecentlyPlayedSize, allItemsList().size() / 2 );
 
             QSet<quint64> avoidSet = getRecentHistory( avoidRecentlyPlayedSize );
             chosenItem = chooseRandomItem( avoidSet );
 
             m_plannedItems.append( chosenItem );
         }
     }
 }
 
 QSet<quint64>
 Playlist::RandomTrackNavigator::getRecentHistory( int size )
 {
     QList<quint64> allHistory = historyItems();
     QSet<quint64> recentHistory;
 
     if ( size > 0 ) {    // If '== 0', we even need to consider playing the same item again.
         recentHistory.insert( currentItem() );    // Might be '0'
         size--;
     }
 
     for ( int i = allHistory.size() - 1; ( i >= 0 ) && ( i >= allHistory.size() - size ); i-- )
         recentHistory.insert( allHistory.at( i ) );
 
     return recentHistory;
 }
 
 quint64
 Playlist::RandomTrackNavigator::chooseRandomItem( const QSet<quint64> &avoidSet )
 {
     quint64 chosenItem;
 
     do
     {
         int maxPosition = allItemsList().size() - 1;
         int randomPosition = round( ( QRandomGenerator::global()->generate() / (float)RAND_MAX ) * maxPosition );
         chosenItem = allItemsList().at( randomPosition );
     } while ( avoidSet.contains( chosenItem ) );
 
     return chosenItem;
 }