From 6c66e23fe90ce5da279a80002abd585124b7cd2e Mon Sep 17 00:00:00 2001
From: Michael Herger <mherger@logitech.com>
Date: Mon, 3 May 2021 17:08:32 +0200
Subject: [PATCH] Move the balanced shuffle to the general Performance
 settings, and use it to shuffle the current playlist, too.

---
 Changelog8.html                               |  2 +-
 HTML/EN/settings/server/performance.html      |  7 ++
 Slim/Player/Playlist.pm                       | 64 ++++++++++++++++-
 .../HTML/EN/plugins/RandomPlay/list.html      |  8 ---
 Slim/Plugin/RandomPlay/Mixer.pm               | 45 +-----------
 Slim/Plugin/RandomPlay/Plugin.pm              | 72 -------------------
 Slim/Plugin/RandomPlay/strings.txt            | 12 ----
 Slim/Utils/Prefs.pm                           |  1 +
 Slim/Web/Settings/Server/Performance.pm       |  2 +-
 strings.txt                                   | 14 +++-
 10 files changed, 88 insertions(+), 139 deletions(-)

diff --git a/Changelog8.html b/Changelog8.html
index 71ad7342266..82c39bfe247 100644
--- a/Changelog8.html
+++ b/Changelog8.html
@@ -6,7 +6,7 @@ <h2><a name="v8.2.0" id="v8.2.0"></a>Version 8.2.0</h2>
 	<li>New Features:</li>
 	<ul>
 		<li>Try to group online artists with local artists by ignoring slightly different spelling (eg. "The Beatles" vs. "Beatles", "Amy Macdonald" vs. "Amy MacDonald").</li>
-		<li><a href="https://github.com/Logitech/slimserver/issues/510">#510</a> - Add (optional) "balanced" shuffling method to Random Play, which is less random, but hopefully more pleasing to the listener.</li>
+		<li><a href="https://github.com/Logitech/slimserver/issues/510">#510</a> - Add (optional) "balanced" track shuffling method, which is less random, but hopefully more pleasing to the listener.</li>
 		<li><a href="https://github.com/Logitech/slimserver/pull/537">#537</a> - Add audio option to combine channels to build a mono signal (whether player is synchronized or not).</li>
 		<li><a href="https://github.com/Logitech/slimserver/pull/538">#538</a> - Add Balance setting for players which support it (thanks philippe44!).</li>
 		<li>Enable basic track statistics (play count, last played, ratings) for online tracks imported into the library.</li>
diff --git a/HTML/EN/settings/server/performance.html b/HTML/EN/settings/server/performance.html
index d5921206ef9..91241a59abf 100644
--- a/HTML/EN/settings/server/performance.html
+++ b/HTML/EN/settings/server/performance.html
@@ -19,6 +19,13 @@
 		</select>
 	[% END %]
 
+	[% WRAPPER setting title="SETUP_SHUFFLE_METHOD" desc="" %]
+		<select class="stdedit" name="pref_useBalancedShuffle" id="useBalancedShuffle">
+			<option [% IF !prefs.pref_useBalancedShuffle %]selected[% END %] value="0">[% "SETUP_USE_FASTER_SHUFFLE" | string %]</option>
+			<option [% IF prefs.pref_useBalancedShuffle %]selected[% END %] value="1">[% "SETUP_USE_BALANCED_SHUFFLE" | string %]</option>
+		</select>
+	[% END %]
+
 	[% WRAPPER setting title="SETUP_DISABLESTATISTICS" desc="SETUP_DISABLESTATISTICS_DESC" %]
 		<select class="stdedit" name="pref_disableStatistics" id="disableStatistics">
 
diff --git a/Slim/Player/Playlist.pm b/Slim/Player/Playlist.pm
index d8dbea47a81..88e4a5aee0c 100644
--- a/Slim/Player/Playlist.pm
+++ b/Slim/Player/Playlist.pm
@@ -700,6 +700,50 @@ sub fischer_yates_shuffle {
 	}
 }
 
+# balancedShuffle is inspired by https://engineering.atspotify.com/2014/02/28/how-to-shuffle-songs/
+# It tries to not shuffle really randomly, which often is considered "unnatural". But it distributes
+# a group's items (eg. an artist's tracks) evenly along the full list.
+# $list must be a listref of tupels, where the first element of the tuple would be the item's key
+# (eg. track ID) and the second value would be the ID of the group (eg. the artist ID)
+# see also https://codegolf.stackexchange.com/questions/198094/spotify-shuffle-music-playlist-shuffle-algorithm
+sub balancedShuffle {
+	my ($list, $sortAlphabetically) = @_;
+
+	my %grouped;
+	foreach my $item (@$list) {
+		my $group = $grouped{$item->[1]} ||= [];
+		push @$group, $item->[0];
+	}
+
+	my $count = scalar @$list;
+	my %weighed;
+
+	while (my ($group, $items) = each %grouped) {
+		my $itemsCount = scalar @$items;
+
+		# shuffle items within the group
+		fischer_yates_shuffle($items);
+
+		# define initial offset - randomize to spread across range so not all start at 0
+		my $offset = rand(1/$itemsCount)*$count;
+		my $spacer = $count / $itemsCount;
+
+		my $i = 0;
+		foreach (@$items) {
+			my $jitter = -($itemsCount/10) + rand($itemsCount/10*2);
+			$weighed{$_} = $offset + $i * $spacer + $jitter;
+			$i++;
+		}
+	}
+
+
+	my $sorter = $sortAlphabetically
+		? sub { $weighed{$a} cmp $weighed{$b} }
+		: sub { $weighed{$a} <=> $weighed{$b} };
+
+	return [ sort $sorter keys %weighed ];
+}
+
 #reshuffle - every time the playlist is modified, the shufflelist should be updated
 #		We also invalidate the htmlplaylist at this point
 sub reshuffle {
@@ -747,8 +791,26 @@ sub reshuffle {
 	# 1 is shuffle by song
 	# 2 is shuffle by album
 	if (shuffle($client) == 1) {
+		if ($prefs->get('useBalancedShuffle')) {
+			main::DEBUGLOG && $log->is_debug && $log->debug("Using balanced shuffle");
+			$listRef = balancedShuffle([ map {
+				my $track = playList($client)->[$_];
+				my $artist = $track->artistName;
+
+				my $handler = Slim::Player::ProtocolHandlers->handlerForURL($track->url) if !$artist;
 
-		fischer_yates_shuffle($listRef);
+				if ( $handler && $handler->can('getMetadataFor') && (my $meta = $handler->getMetadataFor($client, $track->url)) ) {
+					$artist = $meta->{artist};
+				}
+
+				[$_, $artist || ''];
+			} @$listRef ], 'alpha');
+
+			@{$client->shufflelist} = @$listRef;
+		}
+		else {
+			fischer_yates_shuffle($listRef);
+		}
 
 		# If we're preserving the current song
 		# this places it at the top of the playlist
diff --git a/Slim/Plugin/RandomPlay/HTML/EN/plugins/RandomPlay/list.html b/Slim/Plugin/RandomPlay/HTML/EN/plugins/RandomPlay/list.html
index 49f1f4ea99b..c7702a5b85d 100644
--- a/Slim/Plugin/RandomPlay/HTML/EN/plugins/RandomPlay/list.html
+++ b/Slim/Plugin/RandomPlay/HTML/EN/plugins/RandomPlay/list.html
@@ -211,14 +211,6 @@
 			</p>
 		[% END %]
 
-		<p>
-			[% "PLUGIN_RANDOM_SHUFFLE_METHOD" | string %][% "COLON" | string %]
-			<select class="stdedit" name="useBalancedShuffle" id="useBalancedShuffle">
-				<option [% IF !useBalancedShuffle %]selected[% END %] value="0">[% "PLUGIN_RANDOM_USE_FASTER_SHUFFLE" | string %]</option>
-				<option [% IF useBalancedShuffle %]selected[% END %] value="1">[% "PLUGIN_RANDOM_USE_BALANCED_SHUFFLE" | string %]</option>
-			</select>
-		</p>
-
 		<p>
 			[% "PLUGIN_RANDOM_BEFORE_NUM_TRACKS" | string %]
 			<input class="stdedit" type="text" size="2" name="numTracks" value="[% pluginRandomNumTracks %]">
diff --git a/Slim/Plugin/RandomPlay/Mixer.pm b/Slim/Plugin/RandomPlay/Mixer.pm
index 934488fa963..f9259dbdd02 100644
--- a/Slim/Plugin/RandomPlay/Mixer.pm
+++ b/Slim/Plugin/RandomPlay/Mixer.pm
@@ -112,9 +112,9 @@ sub getIdList {
 			libraryId => $queryLibrary,
 		} );
 
-		if ($prefs->get('useBalancedShuffle')) {
+		if (preferences('server')->get('useBalancedShuffle')) {
 			main::DEBUGLOG && $log->is_debug && $log->debug("Using balanced shuffle");
-			$idList = balancedShuffle([ map { [$_, $results->{$_}->{'tracks.primary_artist'}] } keys %$results ]);
+			$idList = Slim::Player::Playlist::balancedShuffle([ map { [$_, $results->{$_}->{'tracks.primary_artist'}] } keys %$results ]);
 		}
 		else {
 			# shuffle ID list
@@ -151,47 +151,6 @@ sub getIdList {
 	return $idList;
 }
 
-# balancedShuffle is inspired by https://engineering.atspotify.com/2014/02/28/how-to-shuffle-songs/
-# It tries to not shuffle really randomly, which often is considered "unnatural". But it distributes
-# a group's items (eg. an artist's tracks) evenly along the full list.
-# $list must be a listref of tupels, where the first element of the tuple would be the item's key
-# (eg. track ID) and the second value would be the ID of the group (eg. the artist ID)
-# see also https://codegolf.stackexchange.com/questions/198094/spotify-shuffle-music-playlist-shuffle-algorithm
-sub balancedShuffle {
-	my ($list) = @_;
-
-	my %grouped;
-	foreach my $item (@$list) {
-		my $group = $grouped{$item->[1]} ||= [];
-		push @$group, $item->[0];
-	}
-
-	my $count = scalar @$list;
-	my %weighed;
-
-	while (my ($group, $items) = each %grouped) {
-		my $itemsCount = scalar @$items;
-
-		# shuffle items within the group
-		Slim::Player::Playlist::fischer_yates_shuffle($items);
-
-		# define initial offset - randomize to spread across range so not all start at 0
-		my $offset = rand(1/$itemsCount)*$count;
-		my $spacer = $count / $itemsCount;
-
-		my $i = 0;
-		foreach (@$items) {
-			my $jitter = -($itemsCount/10) + rand($itemsCount/10*2);
-			$weighed{$_} = $offset + $i * $spacer + $jitter;
-			$i++;
-		}
-	}
-
-	return [ sort {
-		$weighed{$a} <=> $weighed{$b}
-	} keys %weighed ];
-}
-
 sub getRandomYear {
 	my $client = shift;
 	my $filteredGenres = shift;
diff --git a/Slim/Plugin/RandomPlay/Plugin.pm b/Slim/Plugin/RandomPlay/Plugin.pm
index 73620aac1e8..f164b2a7faf 100644
--- a/Slim/Plugin/RandomPlay/Plugin.pm
+++ b/Slim/Plugin/RandomPlay/Plugin.pm
@@ -183,10 +183,6 @@ sub initPlugin {
         [1, 1, 0, \&chooseLibrariesMenu]);
 	Slim::Control::Request::addDispatch(['randomplaychooselibrary', '_library'],
         [1, 0, 0, \&chooseLibrary]);
-	Slim::Control::Request::addDispatch(['randomplayshufflemethodlist', '_index', '_quantity'],
-        [1, 0, 0, \&chooseShuffleMethod]);
-	Slim::Control::Request::addDispatch(['randomplayshufflemethod', '_value'],
-        [1, 0, 0, \&shuffleMethod]);
 	Slim::Control::Request::addDispatch(['randomplaygenreselectall', '_value'],
         [1, 0, 0, \&genreSelectAllOrNone]);
 	Slim::Control::Request::addDispatch(['randomplayisactive'],
@@ -298,19 +294,6 @@ sub initPlugin {
 				},
 			},
 		},
-		{
-			stringToken    => 'PLUGIN_RANDOM_SHUFFLE_METHOD',
-			id      => 'randomshufflemethod',
-			weight  => 65,
-			window  => { titleStyle => 'random' },
-			node    => 'randomplay',
-			actions => {
-				go => {
-					player => 0,
-					cmd    => [ 'randomplayshufflemethodlist' ],
-				},
-			},
-		},
 		{
 			stringToken    => 'PLUGIN_RANDOM_DISABLE',
 			id      => 'randomdisable',
@@ -355,10 +338,6 @@ sub initPlugin {
 			{ title => '{PLUGIN_RANDOM_YEAR}', url => 'randomplay://year' },
 		]
 	);
-
-	$prefs->init({
-		useBalancedShuffle => sub { Slim::Utils::OSDetect->getOS()->canDBHighMem() ? 1 : 0 },
-	});
 }
 
 sub postinitPlugin {
@@ -631,55 +610,6 @@ sub chooseLibrariesMenu {
 	Slim::Control::Jive::sliceAndShip($request, $client, \@menu);
 }
 
-sub shuffleMethod {
-	my $request = shift;
-
-	if (!$initialized) {
-		$request->setStatusBadConfig();
-		return;
-	}
-
-	$prefs->set('useBalancedShuffle', $request->getParam('_value') ? 1 : 0);
-
-	$request->setStatusDone();
-}
-
-sub chooseShuffleMethod {
-	my $request = shift;
-
-	if (!$initialized) {
-		$request->setStatusBadConfig();
-		return;
-	}
-
-	my $client = $request->client();
-
-	my $useBalancedShuffle = $prefs->get('useBalancedShuffle');
-
-	my @menu = ({
-		text     => cstring($client, 'PLUGIN_RANDOM_USE_FASTER_SHUFFLE'),
-		radio    => ($useBalancedShuffle ? 0 : 1),
-		actions  => {
-			'do' => {
-				player => 0,
-				cmd	=> ['randomplayshufflemethod', 0],
-			},
-		},
-	},{
-		text     => cstring($client, 'PLUGIN_RANDOM_USE_BALANCED_SHUFFLE'),
-		radio    => ($useBalancedShuffle ? 1 : 0),
-		actions  => {
-			'do' => {
-				player => 0,
-				cmd	=> ['randomplayshufflemethod', 1],
-			},
-		},
-	});
-
-	Slim::Control::Jive::sliceAndShip($request, $client, \@menu);
-}
-
-
 # Returns a hash whose keys are the genres in the db
 sub getGenres {
 	my ($client, $useIncludeGenres) = @_;
@@ -1209,7 +1139,6 @@ sub handleWebList {
 		$params->{'pluginRandomContinuousMode'}= $prefs->get('continuous');
 		$params->{'pluginRandomNowPlaying'}    = $client->master->pluginData('type');
 		$params->{'pluginRandomUseLibrary'}    = $prefs->get('library');
-		$params->{'useBalancedShuffle'}        = $prefs->get('useBalancedShuffle');
 
 		$params->{'mixTypes'}                  = \@mixTypes;
 		$params->{'favorites'}                 = {};
@@ -1258,7 +1187,6 @@ sub handleWebSettings {
 	$prefs->set('oldtracks', $params->{'numOldTracks'});
 	$prefs->set('continuous', $params->{'continuousMode'} ? 1 : 0);
 	$prefs->set('library', $params->{'useLibrary'});
-	$prefs->set('useBalancedShuffle', $params->{'useBalancedShuffle'} ? 1 : 0);
 
 	# Pass on to check if the user requested a new mix as well
 	handleWebMix($client, $params);
diff --git a/Slim/Plugin/RandomPlay/strings.txt b/Slim/Plugin/RandomPlay/strings.txt
index 09b29802612..ef6158f7e1c 100644
--- a/Slim/Plugin/RandomPlay/strings.txt
+++ b/Slim/Plugin/RandomPlay/strings.txt
@@ -344,18 +344,6 @@ PLUGIN_RANDOM_LIBRARY_FILTER
 	NL	Gebruik deelcollectie
 	NO	Bruk delbiblioteker
 
-PLUGIN_RANDOM_SHUFFLE_METHOD
-	DE	Mischmethode
-	EN	Shuffle method
-
-PLUGIN_RANDOM_USE_BALANCED_SHUFFLE
-	DE	Ausbalancierter, aber langsamer mischen
-	EN	Use more balanced, but slower shuffle
-
-PLUGIN_RANDOM_USE_FASTER_SHUFFLE
-	DE	Schneller, aber weniger ausbalanciert mischen
-	EN	Use faster, but less balanced shuffle
-
 PLUGIN_RANDOM_CHOOSE_BELOW
 	CS	Vybrat náhodně zvolený mix hudby z vaší knihovny:
 	DA	Vælg en tilfældig blanding af musik fra dit bibliotek:
diff --git a/Slim/Utils/Prefs.pm b/Slim/Utils/Prefs.pm
index a8dd92fdd54..3cdfd0786e1 100644
--- a/Slim/Utils/Prefs.pm
+++ b/Slim/Utils/Prefs.pm
@@ -214,6 +214,7 @@ sub init {
 		'precacheArtwork'       => 1,
 		'customArtSpecs'        => {},
 		'maxPlaylistLength'     => sub { $os->canDBHighMem() ? 2500 : 500 },
+		'useBalancedShuffle'    => sub { $os->canDBHighMem() ? 1 : 0 },
 		# Server Settings - Security
 		'filterHosts'           => 0,
 		'allowedHosts'          => sub {
diff --git a/Slim/Web/Settings/Server/Performance.pm b/Slim/Web/Settings/Server/Performance.pm
index bdba3b69253..f7729ec3b57 100644
--- a/Slim/Web/Settings/Server/Performance.pm
+++ b/Slim/Web/Settings/Server/Performance.pm
@@ -22,7 +22,7 @@ sub page {
 }
 
 sub prefs {
-	my @prefs = ( $prefs, qw(dbhighmem disableStatistics serverPriority scannerPriority
+	my @prefs = ( $prefs, qw(dbhighmem disableStatistics serverPriority scannerPriority useBalancedShuffle
  				precacheArtwork maxPlaylistLength useLocalImageproxy dontTriggerScanOnPrefChange) );
  	push @prefs, qw(autorescan autorescan_stat_interval) if Slim::Utils::OSDetect::getOS->canAutoRescan;
  	return @prefs;
diff --git a/strings.txt b/strings.txt
index cde1a00a8aa..565e7c3dca4 100644
--- a/strings.txt
+++ b/strings.txt
@@ -8426,7 +8426,7 @@ SETUP_ENHANCEDHTTP_DESC
 SETUP_ENABLE_PERSISTENTHTTP
 	EN	Persistent mode
 	FR	Mode persistent
-	
+
 SETUP_ENABLE_BUFFEREDHTTP
 	DE	HTTP(S) Datenströme zwischenspeichern
 	EN	Cache HTTP(S) streams on disk
@@ -19334,6 +19334,18 @@ SETUP_SERVERPRIORITY
 	SV	Serverprioritet
 	ZH_CN	Logitech Media Server服务器流程优先值
 
+SETUP_SHUFFLE_METHOD
+	DE	Mischmethode
+	EN	Shuffle method
+
+SETUP_USE_BALANCED_SHUFFLE
+	DE	Ausbalancierter, aber langsamer mischen
+	EN	Use more balanced, but slower shuffle
+
+SETUP_USE_FASTER_SHUFFLE
+	DE	Schneller, aber weniger ausbalanciert mischen
+	EN	Use faster, but less balanced shuffle
+
 SETUP_SERVERPRIORITY_DESC
 	CS	Můžete zadat prioritu pro Logitech Media Server.
 	DA	Du kan specificere hvilken prioritet Logitech Media Server skal have.