From 5f02dfeff1e92fb3cdb10a672a80e2f39ed824c2 Mon Sep 17 00:00:00 2001
From: emeric <itmfr@yahoo.fr>
Date: Thu, 23 May 2019 13:25:25 +0200
Subject: [PATCH] Added an option for the user to choice the type of the
 similarity engine to use

---
 approot/admin-database.xml            |  13 ++
 approot/messages.xml                  |   3 +
 approot/messages_fr.xml               |   3 +
 src/database/DatabaseHandler.cpp      |   2 +-
 src/database/SimilaritySettings.hpp   |  19 +--
 src/similarity/SimilaritySearcher.cpp |  39 +++---
 src/ui/SettingsView.cpp               | 151 ++++++----------------
 src/ui/admin/DatabaseSettingsView.cpp | 173 +++++++++-----------------
 src/ui/admin/UserView.cpp             | 105 ++++++----------
 src/ui/common/ValueStringModel.hpp    |  78 ++++++++++++
 10 files changed, 254 insertions(+), 332 deletions(-)
 create mode 100644 src/ui/common/ValueStringModel.hpp

diff --git a/approot/admin-database.xml b/approot/admin-database.xml
index 77bf80e6..435428e8 100644
--- a/approot/admin-database.xml
+++ b/approot/admin-database.xml
@@ -45,6 +45,19 @@
 	</div>
 	<legend>${tr:Lms.Admin.Database.scan-options}</legend>
 	<div class="form-horizontal">
+
+		<div class="form-group">
+			<label class="control-label col-sm-2"  for="${id:similarity-engine-type}">
+				${tr:Lms.Admin.Database.similarity-engine-type}
+			</label>
+			<div class="col-sm-5">
+				${similarity-engine-type}
+			</div>
+			<div class="help-block col-sm-5">
+				${similarity-engine-type-info}
+			</div>
+		</div>
+
 		<div class="form-group">
 			<label class="control-label col-sm-2"  for="${id:tags}">
 				${tr:Lms.Admin.Database.tags}
diff --git a/approot/messages.xml b/approot/messages.xml
index 887c6073..0c5446d9 100644
--- a/approot/messages.xml
+++ b/approot/messages.xml
@@ -26,6 +26,9 @@
 <message id="Lms.Admin.Database.monthly">Monthly</message>
 <message id="Lms.Admin.Database.never">Never</message>
 <message id="Lms.Admin.Database.path">Media root directory</message>
+<message id="Lms.Admin.Database.similarity-engine-type">Recommendation engine</message>
+<message id="Lms.Admin.Database.similarity-engine-type.clusters">Tags based</message>
+<message id="Lms.Admin.Database.similarity-engine-type.features">Audio analysis based</message>
 <message id="Lms.Admin.Database.scan-complete">Scan complete: {1} total files, {2} additions, {3} updates, {4} deletions, {5} duplicates, {6} errors</message>
 <message id="Lms.Admin.Database.scan-launched">Scan launched!</message>
 <message id="Lms.Admin.Database.scan-options">Scan options</message>
diff --git a/approot/messages_fr.xml b/approot/messages_fr.xml
index 6044714d..a084ac8b 100644
--- a/approot/messages_fr.xml
+++ b/approot/messages_fr.xml
@@ -26,6 +26,9 @@
 <message id="Lms.Admin.Database.monthly">Tous les mois</message>
 <message id="Lms.Admin.Database.never">Jamais</message>
 <message id="Lms.Admin.Database.path">Dossier racine des fichiers de musique</message>
+<message id="Lms.Admin.Database.similarity-engine-type">Moteur de recommandation</message>
+<message id="Lms.Admin.Database.similarity-engine-type.clusters">Basé sur les tags</message>
+<message id="Lms.Admin.Database.similarity-engine-type.features">Basé sur l'analyse audio</message>
 <message id="Lms.Admin.Database.scan-complete">Scan terminé : {1} fichiers, {2} ajouts, {3} mises à jour, {4} suppressions, {5} duplicatas, {6} erreurs</message>
 <message id="Lms.Admin.Database.scan-launched">Scan lancé !</message>
 <message id="Lms.Admin.Database.scan-options">Options </message>
diff --git a/src/database/DatabaseHandler.cpp b/src/database/DatabaseHandler.cpp
index ec6b828b..b9bf0a58 100644
--- a/src/database/DatabaseHandler.cpp
+++ b/src/database/DatabaseHandler.cpp
@@ -46,7 +46,7 @@
 
 namespace Database {
 
-#define LMS_DATABASE_VERSION	2
+#define LMS_DATABASE_VERSION	3
 
 namespace {
 	Wt::Auth::AuthService authService;
diff --git a/src/database/SimilaritySettings.hpp b/src/database/SimilaritySettings.hpp
index 350303ad..f7ee9056 100644
--- a/src/database/SimilaritySettings.hpp
+++ b/src/database/SimilaritySettings.hpp
@@ -61,11 +61,10 @@ class SimilaritySettings : public Wt::Dbo::Dbo<SimilaritySettings>
 {
 	public:
 
-		enum class PreferredMethod
+		enum class EngineType
 		{
-			Auto,
-			Features,
-			Clusters,
+			Features = 0,
+			Clusters = 1,
 		};
 
 		using pointer = Wt::Dbo::ptr<SimilaritySettings>;
@@ -75,23 +74,25 @@ class SimilaritySettings : public Wt::Dbo::Dbo<SimilaritySettings>
 
 		// Accessors Read
 		std::size_t		getVersion() const { return _settingsVersion; }
-		PreferredMethod		getPreferredMethod() const { return _preferredMethod; }
+		EngineType		getEngineType() const { return _engineType; }
 		std::vector<Wt::Dbo::ptr<SimilaritySettingsFeature>> getFeatures() const;
 
+		// Setters
+		void	setEngineType(EngineType type) { _engineType = type; }
 
 		template<class Action>
 		void persist(Action& a)
 		{
-			Wt::Dbo::field(a, _settingsVersion,		"settings_version");
-			Wt::Dbo::field(a, _preferredMethod,		"preferred_method");
+			Wt::Dbo::field(a, _settingsVersion,	"settings_version");
+			Wt::Dbo::field(a, _engineType,		"engine_type");
 
 			Wt::Dbo::hasMany(a, _features, Wt::Dbo::ManyToOne, "similarity_settings");
 		}
 
 	private:
 
-		int			_settingsVersion = 0;
-		PreferredMethod		_preferredMethod = PreferredMethod::Auto;
+		int		_settingsVersion {};
+		EngineType	_engineType {EngineType::Features};
 
 		Wt::Dbo::collection<Wt::Dbo::ptr<SimilaritySettingsFeature>> _features;
 };
diff --git a/src/similarity/SimilaritySearcher.cpp b/src/similarity/SimilaritySearcher.cpp
index 20e183f1..f7d3d920 100644
--- a/src/similarity/SimilaritySearcher.cpp
+++ b/src/similarity/SimilaritySearcher.cpp
@@ -31,23 +31,22 @@ Searcher::Searcher(FeaturesScannerAddon& somAddon)
 {}
 
 static
-Database::SimilaritySettings::PreferredMethod getPreferredMethod(Wt::Dbo::Session& session)
+Database::SimilaritySettings::EngineType getEngineType(Wt::Dbo::Session& session)
 {
-	Wt::Dbo::Transaction transaction(session);
-	return Database::SimilaritySettings::get(session)->getPreferredMethod();
+	Wt::Dbo::Transaction transaction{session};
+	return Database::SimilaritySettings::get(session)->getEngineType();
 }
 
 std::vector<Database::IdType>
 Searcher::getSimilarTracks(Wt::Dbo::Session& session, const std::set<Database::IdType>& trackIds, std::size_t maxCount)
 {
 
-	auto method = getPreferredMethod(session);
-	auto somSearcher = _somAddon.getSearcher();
+	auto engineType {getEngineType(session)};
+	auto somSearcher {_somAddon.getSearcher()};
 
-	if (method == Database::SimilaritySettings::PreferredMethod::Features
-		|| (method == Database::SimilaritySettings::PreferredMethod::Auto
-			&& somSearcher
-			&& std::any_of(std::cbegin(trackIds), std::cend(trackIds), [&](Database::IdType trackId) { return somSearcher->isTrackClassified(trackId); } )))
+	if (engineType == Database::SimilaritySettings::EngineType::Features
+		&& somSearcher
+		&& std::any_of(std::cbegin(trackIds), std::cend(trackIds), [&](Database::IdType trackId) { return somSearcher->isTrackClassified(trackId); } ))
 	{
 		return somSearcher->getSimilarTracks(trackIds, maxCount);
 	}
@@ -58,13 +57,12 @@ Searcher::getSimilarTracks(Wt::Dbo::Session& session, const std::set<Database::I
 std::vector<Database::IdType>
 Searcher::getSimilarReleases(Wt::Dbo::Session& session, Database::IdType releaseId, std::size_t maxCount)
 {
-	auto method = getPreferredMethod(session);
-	auto somSearcher = _somAddon.getSearcher();
+	auto engineType {getEngineType(session)};
+	auto somSearcher {_somAddon.getSearcher()};
 
-	if (method == Database::SimilaritySettings::PreferredMethod::Features
-		|| (method == Database::SimilaritySettings::PreferredMethod::Auto
-			&& somSearcher
-			&& somSearcher->isReleaseClassified(releaseId)))
+	if (engineType == Database::SimilaritySettings::EngineType::Features
+		&& somSearcher
+		&& somSearcher->isReleaseClassified(releaseId))
 	{
 		return somSearcher->getSimilarReleases(releaseId, maxCount);
 	}
@@ -75,13 +73,12 @@ Searcher::getSimilarReleases(Wt::Dbo::Session& session, Database::IdType release
 std::vector<Database::IdType>
 Searcher::getSimilarArtists(Wt::Dbo::Session& session, Database::IdType artistId, std::size_t maxCount)
 {
-	auto method = getPreferredMethod(session);
-	auto somSearcher = _somAddon.getSearcher();
+	auto engineType {getEngineType(session)};
+	auto somSearcher {_somAddon.getSearcher()};
 
-	if (method == Database::SimilaritySettings::PreferredMethod::Features
-		|| (method == Database::SimilaritySettings::PreferredMethod::Auto
-			&& somSearcher
-			&& somSearcher->isArtistClassified(artistId)))
+	if (engineType == Database::SimilaritySettings::EngineType::Features
+		&& somSearcher
+		&& somSearcher->isArtistClassified(artistId))
 	{
 		return somSearcher->getSimilarArtists(artistId, maxCount);
 	}
diff --git a/src/ui/SettingsView.cpp b/src/ui/SettingsView.cpp
index a23dc24b..90a03e1a 100644
--- a/src/ui/SettingsView.cpp
+++ b/src/ui/SettingsView.cpp
@@ -26,9 +26,9 @@
 #include <Wt/WLineEdit.h>
 
 #include <Wt/WFormModel.h>
-#include <Wt/WStringListModel.h>
 
 #include "common/Validators.hpp"
+#include "common/ValueStringModel.hpp"
 
 #include "utils/Logger.hpp"
 #include "LmsApplication.hpp"
@@ -67,6 +67,24 @@ class SettingsModel : public Wt::WFormModel
 		std::shared_ptr<Wt::WAbstractItemModel> transcodeBitrateModel() { return _transcodeBitrateModel; }
 		std::shared_ptr<Wt::WAbstractItemModel> transcodeFormatModel() { return _transcodeFormatModel; }
 
+		void saveData()
+		{
+			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
+
+			LmsApp->getUser().modify()->setAudioTranscodeEnable(Wt::asNumber(value(TranscodeEnableField)));
+
+			auto transcodeBitrateRow {_transcodeBitrateModel->getRowFromString(valueText(TranscodeBitrateField))};
+			if (transcodeBitrateRow)
+				LmsApp->getUser().modify()->setAudioTranscodeBitrate(_transcodeBitrateModel->getValue(*transcodeBitrateRow));
+
+			auto transcodeFormatRow {_transcodeFormatModel->getRowFromString(valueText(TranscodeFormatField))};
+			if (transcodeFormatRow)
+				LmsApp->getUser().modify()->setAudioTranscodeFormat(_transcodeFormatModel->getValue(*transcodeFormatRow));
+
+			if (!valueText(PasswordField).empty())
+				Handler::getPasswordService().updatePassword(LmsApp->getAuthUser(), valueText(PasswordField));
+		}
+
 		void loadData()
 		{
 			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
@@ -78,32 +96,16 @@ class SettingsModel : public Wt::WFormModel
 				setReadOnly(TranscodeBitrateField, true);
 			}
 
-			auto transcodeBitrateRow {getTranscodeBitrateRow(LmsApp->getUser()->getAudioTranscodeBitrate())};
+			auto transcodeBitrateRow {_transcodeBitrateModel->getRowFromValue(LmsApp->getUser()->getAudioTranscodeBitrate())};
 			if (transcodeBitrateRow)
-				setValue(TranscodeBitrateField, transcodeBitrateString(*transcodeBitrateRow));
+				setValue(TranscodeBitrateField, _transcodeBitrateModel->getString(*transcodeBitrateRow));
 
-			auto transcodeFormatRow {getTranscodeFormatRow(LmsApp->getUser()->getAudioTranscodeFormat())};
+			auto transcodeFormatRow {_transcodeFormatModel->getRowFromValue(LmsApp->getUser()->getAudioTranscodeFormat())};
 			if (transcodeFormatRow)
-				setValue(TranscodeFormatField, transcodeFormatString(*transcodeFormatRow));
+				setValue(TranscodeFormatField, _transcodeFormatModel->getString(*transcodeFormatRow));
 		}
 
-		void saveData()
-		{
-			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
-
-			LmsApp->getUser().modify()->setAudioTranscodeEnable(Wt::asNumber(value(TranscodeEnableField)));
-
-			auto transcodeBitrateRow {getTranscodeBitrateRow(Wt::asString(value(TranscodeBitrateField)))};
-			if (transcodeBitrateRow)
-				LmsApp->getUser().modify()->setAudioTranscodeBitrate(transcodeBitrate(*transcodeBitrateRow));
-
-			auto transcodeFormatRow {getTranscodeFormatRow(Wt::asString(value(TranscodeFormatField)))};
-			if (transcodeFormatRow)
-				LmsApp->getUser().modify()->setAudioTranscodeFormat(transcodeFormat(*transcodeFormatRow));
-
-			if (!valueText(PasswordField).empty())
-				Database::Handler::getPasswordService().updatePassword(LmsApp->getAuthUser(), valueText(PasswordField));
-		}
+	private:
 
 		bool validateField(Field field)
 		{
@@ -114,7 +116,7 @@ class SettingsModel : public Wt::WFormModel
 				if (!valueText(PasswordField).empty())
 				{
 					// Evaluate the strength of the password
-					auto res = Database::Handler::getPasswordService().strengthValidator()->evaluateStrength(valueText(PasswordField), LmsApp->getUserIdentity(), "");
+					auto res = Handler::getPasswordService().strengthValidator()->evaluateStrength(valueText(PasswordField), LmsApp->getUserIdentity(), "");
 
 					if (!res.isValid())
 						error = res.message();
@@ -140,115 +142,34 @@ class SettingsModel : public Wt::WFormModel
 			return (validation(field).state() == Wt::ValidationState::Valid);
 		}
 
-		boost::optional<int> getTranscodeBitrateRow(Wt::WString value)
-		{
-			for (int i = 0; i < _transcodeBitrateModel->rowCount(); ++i)
-			{
-				if (transcodeBitrateString(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		boost::optional<int> getTranscodeBitrateRow(std::size_t value)
-		{
-			for (int i = 0; i < _transcodeBitrateModel->rowCount(); ++i)
-			{
-				if (transcodeBitrate(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		std::size_t transcodeBitrate(int row)
-		{
-			return Wt::cpp17::any_cast<std::size_t>
-				(_transcodeBitrateModel->data(_transcodeBitrateModel->index(row, 0), Wt::ItemDataRole::User));
-		}
-
-		Wt::WString transcodeBitrateString(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WString>
-				(_transcodeBitrateModel->data(_transcodeBitrateModel->index(row, 0), Wt::ItemDataRole::Display));
-		}
-
-		boost::optional<int> getTranscodeFormatRow(Wt::WString value)
-		{
-			for (int i = 0; i < _transcodeFormatModel->rowCount(); ++i)
-			{
-				if (transcodeFormatString(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		boost::optional<int> getTranscodeFormatRow(Database::AudioFormat format)
-		{
-			for (int i = 0; i < _transcodeFormatModel->rowCount(); ++i)
-			{
-				if (transcodeFormat(i) == format)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		Database::AudioFormat transcodeFormat(int row)
-		{
-			return Wt::cpp17::any_cast<Database::AudioFormat>
-				(_transcodeFormatModel->data(_transcodeFormatModel->index(row, 0), Wt::ItemDataRole::User));
-		}
-
-		Wt::WString transcodeFormatString(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WString>
-				(_transcodeFormatModel->data(_transcodeFormatModel->index(row, 0), Wt::ItemDataRole::Display));
-		}
-
-
 	private:
 
 		void initializeModels()
 		{
-			_transcodeBitrateModel = std::make_shared<Wt::WStringListModel>();
-
-			Database::Bitrate maxAudioBitrate;
+			Bitrate maxAudioBitrate;
 			{
 				Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
 				maxAudioBitrate = LmsApp->getUser()->getMaxAudioTranscodeBitrate();
 			}
 
-			std::size_t id = 0;
-			for (Database::Bitrate bitrate : Database::User::audioTranscodeAllowedBitrates)
+			_transcodeBitrateModel = std::make_shared<ValueStringModel<Bitrate>>();
+			for (Bitrate bitrate : User::audioTranscodeAllowedBitrates)
 			{
 				if (bitrate > maxAudioBitrate)
 					break;
 
-				_transcodeBitrateModel->addString( Wt::WString::fromUTF8(std::to_string(bitrate / 1000)) );
-				_transcodeBitrateModel->setData( id, 0, bitrate, Wt::ItemDataRole::User);
-				id++;
+				_transcodeBitrateModel->add(Wt::WString::fromUTF8(std::to_string(bitrate / 1000)), bitrate);
 			}
 
-			_transcodeFormatModel = std::make_shared<Wt::WStringListModel>();
-
-			_transcodeFormatModel->addString(Wt::WString::tr("Lms.Settings.transcoding.mp3"));
-			_transcodeFormatModel->setData(0, 0, Database::AudioFormat::MP3, Wt::ItemDataRole::User);
-
-			_transcodeFormatModel->addString(Wt::WString::tr("Lms.Settings.transcoding.ogg_opus"));
-			_transcodeFormatModel->setData(1, 0, Database::AudioFormat::OGG_OPUS, Wt::ItemDataRole::User);
-
-			_transcodeFormatModel->addString(Wt::WString::tr("Lms.Settings.transcoding.ogg_vorbis"));
-			_transcodeFormatModel->setData(2, 0, Database::AudioFormat::OGG_VORBIS, Wt::ItemDataRole::User);
-
-			_transcodeFormatModel->addString(Wt::WString::tr("Lms.Settings.transcoding.webm_vorbis"));
-			_transcodeFormatModel->setData(3, 0, Database::AudioFormat::WEBM_VORBIS, Wt::ItemDataRole::User);
+			_transcodeFormatModel = std::make_shared<ValueStringModel<AudioFormat>>();
+			_transcodeFormatModel->add(Wt::WString::tr("Lms.Settings.transcoding.mp3"), AudioFormat::MP3);
+			_transcodeFormatModel->add(Wt::WString::tr("Lms.Settings.transcoding.ogg_opus"), AudioFormat::OGG_OPUS);
+			_transcodeFormatModel->add(Wt::WString::tr("Lms.Settings.transcoding.ogg_vorbis"), AudioFormat::OGG_VORBIS);
+			_transcodeFormatModel->add(Wt::WString::tr("Lms.Settings.transcoding.webm_vorbis"), AudioFormat::WEBM_VORBIS);
 		}
 
-		std::shared_ptr<Wt::WStringListModel>	_transcodeBitrateModel;
-		std::shared_ptr<Wt::WStringListModel>	_transcodeFormatModel;
+		std::shared_ptr<ValueStringModel<Bitrate>>	_transcodeBitrateModel;
+		std::shared_ptr<ValueStringModel<AudioFormat>>	_transcodeFormatModel;
 
 };
 
diff --git a/src/ui/admin/DatabaseSettingsView.cpp b/src/ui/admin/DatabaseSettingsView.cpp
index 59ae5fd1..63f704a3 100644
--- a/src/ui/admin/DatabaseSettingsView.cpp
+++ b/src/ui/admin/DatabaseSettingsView.cpp
@@ -24,21 +24,23 @@
 #include <Wt/WLineEdit.h>
 #include <Wt/WPushButton.h>
 #include <Wt/WString.h>
-#include <Wt/WStringListModel.h>
 #include <Wt/WTemplateFormView.h>
 
 #include "database/Cluster.hpp"
+#include "database/SimilaritySettings.hpp"
 #include "main/Service.hpp"
 #include "utils/Logger.hpp"
 #include "utils/Utils.hpp"
 
 #include "common/Validators.hpp"
+#include "common/ValueStringModel.hpp"
 #include "LmsApplication.hpp"
 
 namespace UserInterface {
 
 using namespace Database;
 
+
 class DatabaseSettingsModel : public Wt::WFormModel
 {
 	public:
@@ -46,6 +48,7 @@ class DatabaseSettingsModel : public Wt::WFormModel
 		static const Field MediaDirectoryField;
 		static const Field UpdatePeriodField;
 		static const Field UpdateStartTimeField;
+		static const Field SimilarityEngineTypeField;
 		static const Field TagsField;
 
 		DatabaseSettingsModel()
@@ -56,6 +59,7 @@ class DatabaseSettingsModel : public Wt::WFormModel
 			addField(MediaDirectoryField);
 			addField(UpdatePeriodField);
 			addField(UpdateStartTimeField);
+			addField(SimilarityEngineTypeField);
 			addField(TagsField);
 
 			auto dirValidator = std::make_shared<DirectoryValidator>();
@@ -64,6 +68,7 @@ class DatabaseSettingsModel : public Wt::WFormModel
 
 			setValidator(UpdatePeriodField, createMandatoryValidator());
 			setValidator(UpdateStartTimeField, createMandatoryValidator());
+			setValidator(SimilarityEngineTypeField, createMandatoryValidator());
 			setValidator(TagsField, createTagsValidator());
 
 			// populate the model with initial data
@@ -72,26 +77,30 @@ class DatabaseSettingsModel : public Wt::WFormModel
 
 		std::shared_ptr<Wt::WAbstractItemModel> updatePeriodModel() { return _updatePeriodModel; }
 		std::shared_ptr<Wt::WAbstractItemModel> updateStartTimeModel() { return _updateStartTimeModel; }
+		std::shared_ptr<Wt::WAbstractItemModel> similarityEngineTypeModel() { return _similarityEngineTypeModel; }
 
 		void loadData()
 		{
-			using namespace Database;
+			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
 
-			Wt::Dbo::Transaction transaction(LmsApp->getDboSession());
-
-			auto scanSettings = ScanSettings::get(LmsApp->getDboSession());
+			auto scanSettings {ScanSettings::get(LmsApp->getDboSession())};
+			auto similaritySettings {SimilaritySettings::get(LmsApp->getDboSession())};
 
 			setValue(MediaDirectoryField, scanSettings->getMediaDirectory().string());
 
-			auto periodRow = getUpdatePeriodModelRow( scanSettings->getUpdatePeriod() );
+			auto periodRow {_updatePeriodModel->getRowFromValue(scanSettings->getUpdatePeriod())};
 			if (periodRow)
-				setValue(UpdatePeriodField, updatePeriodString(*periodRow));
+				setValue(UpdatePeriodField, _updatePeriodModel->getString(*periodRow));
 
-			auto startTimeRow = getUpdateStartTimeModelRow( scanSettings->getUpdateStartTime() );
+			auto startTimeRow {_updateStartTimeModel->getRowFromValue(scanSettings->getUpdateStartTime())};
 			if (startTimeRow)
-				setValue(UpdateStartTimeField, updateStartTimeString(*startTimeRow) );
+				setValue(UpdateStartTimeField, _updateStartTimeModel->getString(*startTimeRow));
 
-			auto clusterTypes = scanSettings->getClusterTypes();
+			auto similarityEngineTypeRow {_similarityEngineTypeModel->getRowFromValue(similaritySettings->getEngineType())};
+			if (similarityEngineTypeRow)
+				setValue(SimilarityEngineTypeField, _similarityEngineTypeModel->getString(*similarityEngineTypeRow));
+
+			auto clusterTypes {scanSettings->getClusterTypes()};
 			if (!clusterTypes.empty())
 			{
 				std::vector<std::string> names;
@@ -102,94 +111,29 @@ class DatabaseSettingsModel : public Wt::WFormModel
 
 		void saveData()
 		{
-			Wt::Dbo::Transaction transaction(LmsApp->getDboSession());
+			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
 
-			auto scanSettings = ScanSettings::get(LmsApp->getDboSession());
+			auto scanSettings {ScanSettings::get(LmsApp->getDboSession())};
+			auto similaritySettings {SimilaritySettings::get(LmsApp->getDboSession())};
 
 			scanSettings.modify()->setMediaDirectory(valueText(MediaDirectoryField).toUTF8());
 
-			auto updatePeriodRow = getUpdatePeriodModelRow( valueText(UpdatePeriodField));
-			assert(updatePeriodRow);
-			scanSettings.modify()->setUpdatePeriod(updatePeriod(*updatePeriodRow));
+			auto updatePeriodRow {_updatePeriodModel->getRowFromString(valueText(UpdatePeriodField))};
+			if (updatePeriodRow)
+				scanSettings.modify()->setUpdatePeriod(_updatePeriodModel->getValue(*updatePeriodRow));
 
-			auto startTimeRow = getUpdateStartTimeModelRow( valueText(UpdateStartTimeField));
-			assert(startTimeRow);
-			scanSettings.modify()->setUpdateStartTime(updateStartTime(*startTimeRow));
+			auto startTimeRow {_updateStartTimeModel->getRowFromString(valueText(UpdateStartTimeField))};
+			if (startTimeRow)
+				scanSettings.modify()->setUpdateStartTime(_updateStartTimeModel->getValue(*startTimeRow));
 
-			auto clusterTypes = splitString(valueText(TagsField).toUTF8(), " ");
+			auto similarityEngineTypeRow {_similarityEngineTypeModel->getRowFromString(valueText(SimilarityEngineTypeField))};
+			if (similarityEngineTypeRow)
+				similaritySettings.modify()->setEngineType(_similarityEngineTypeModel->getValue(*similarityEngineTypeRow));
+
+			auto clusterTypes {splitString(valueText(TagsField).toUTF8(), " ")};
 			scanSettings.modify()->setClusterTypes(std::set<std::string>(clusterTypes.begin(), clusterTypes.end()));
 		}
 
-		boost::optional<int> getUpdatePeriodModelRow(Wt::WString value)
-		{
-			for (int i = 0; i < _updatePeriodModel->rowCount(); ++i)
-			{
-				if (updatePeriodString(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		boost::optional<int> getUpdatePeriodModelRow(ScanSettings::UpdatePeriod period)
-		{
-			for (int i = 0; i < _updatePeriodModel->rowCount(); ++i)
-			{
-				if (updatePeriod(i) == period)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		ScanSettings::UpdatePeriod updatePeriod(int row)
-		{
-			return Wt::cpp17::any_cast<ScanSettings::UpdatePeriod>
-				(_updatePeriodModel->data(_updatePeriodModel->index(row, 0), Wt::ItemDataRole::User));
-		}
-
-		Wt::WString updatePeriodString(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WString>
-				(_updatePeriodModel->data(_updatePeriodModel->index(row, 0), Wt::ItemDataRole::Display));
-		}
-
-
-		boost::optional<int> getUpdateStartTimeModelRow(Wt::WString value)
-		{
-			for (int i = 0; i < _updateStartTimeModel->rowCount(); ++i)
-			{
-				if (updateStartTimeString(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		boost::optional<int> getUpdateStartTimeModelRow(Wt::WTime startTime)
-		{
-			for (int i = 0; i < _updateStartTimeModel->rowCount(); ++i)
-			{
-				if (updateStartTime(i) == startTime)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		Wt::WTime updateStartTime(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WTime>
-				(_updateStartTimeModel->data(_updateStartTimeModel->index(row, 0), Wt::ItemDataRole::User));
-		}
-
-		Wt::WString updateStartTimeString(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WString>
-				(_updateStartTimeModel->data(_updateStartTimeModel->index(row, 0), Wt::ItemDataRole::Display));
-		}
-
-
 	private:
 
 		static std::shared_ptr<Wt::WValidator> createTagsValidator()
@@ -200,42 +144,34 @@ class DatabaseSettingsModel : public Wt::WFormModel
 
 		void initializeModels()
 		{
+			_updatePeriodModel = std::make_shared<ValueStringModel<ScanSettings::UpdatePeriod>>();
+			_updatePeriodModel->add(Wt::WString::tr("Lms.Admin.Database.never"), ScanSettings::UpdatePeriod::Never);
+			_updatePeriodModel->add(Wt::WString::tr("Lms.Admin.Database.daily"), ScanSettings::UpdatePeriod::Daily);
+			_updatePeriodModel->add(Wt::WString::tr("Lms.Admin.Database.weekly"), ScanSettings::UpdatePeriod::Weekly);
+			_updatePeriodModel->add(Wt::WString::tr("Lms.Admin.Database.monthly"), ScanSettings::UpdatePeriod::Monthly);
 
-			_updatePeriodModel = std::make_shared<Wt::WStringListModel>();
-
-			_updatePeriodModel->addString(Wt::WString::tr("Lms.Admin.Database.never"));
-			_updatePeriodModel->setData(0, 0, ScanSettings::UpdatePeriod::Never, Wt::ItemDataRole::User);
-
-			_updatePeriodModel->addString(Wt::WString::tr("Lms.Admin.Database.daily"));
-			_updatePeriodModel->setData(1, 0, ScanSettings::UpdatePeriod::Daily, Wt::ItemDataRole::User);
-
-			_updatePeriodModel->addString(Wt::WString::tr("Lms.Admin.Database.weekly"));
-			_updatePeriodModel->setData(2, 0, ScanSettings::UpdatePeriod::Weekly, Wt::ItemDataRole::User);
-
-			_updatePeriodModel->addString(Wt::WString::tr("Lms.Admin.Database.monthly"));
-			_updatePeriodModel->setData(3, 0, ScanSettings::UpdatePeriod::Monthly, Wt::ItemDataRole::User);
-
-			_updateStartTimeModel = std::make_shared<Wt::WStringListModel>();
-
+			_updateStartTimeModel = std::make_shared<ValueStringModel<Wt::WTime>>();
 			for (std::size_t i = 0; i < 24; ++i)
 			{
-				Wt::WTime time(i, 0);
-
-				_updateStartTimeModel->addString( time.toString() );
-				_updateStartTimeModel->setData(i, 0, time, Wt::ItemDataRole::User);
+				Wt::WTime time {static_cast<int>(i), 0};
+				_updateStartTimeModel->add(time.toString(), time);
 			}
 
+			_similarityEngineTypeModel = std::make_shared<ValueStringModel<SimilaritySettings::EngineType>>();
+			_similarityEngineTypeModel->add(Wt::WString::tr("Lms.Admin.Database.similarity-engine-type.clusters"), SimilaritySettings::EngineType::Clusters);
+			_similarityEngineTypeModel->add(Wt::WString::tr("Lms.Admin.Database.similarity-engine-type.features"), SimilaritySettings::EngineType::Features);
 		}
 
-
-		std::shared_ptr<Wt::WStringListModel>	_updatePeriodModel;
-		std::shared_ptr<Wt::WStringListModel>	_updateStartTimeModel;
+		std::shared_ptr<ValueStringModel<ScanSettings::UpdatePeriod>>		_updatePeriodModel;
+		std::shared_ptr<ValueStringModel<Wt::WTime>>				_updateStartTimeModel;
+		std::shared_ptr<ValueStringModel<SimilaritySettings::EngineType>>	_similarityEngineTypeModel;
 
 };
 
 const Wt::WFormModel::Field DatabaseSettingsModel::MediaDirectoryField		= "media-directory";
 const Wt::WFormModel::Field DatabaseSettingsModel::UpdatePeriodField		= "update-period";
 const Wt::WFormModel::Field DatabaseSettingsModel::UpdateStartTimeField		= "update-start-time";
+const Wt::WFormModel::Field DatabaseSettingsModel::SimilarityEngineTypeField	= "similarity-engine-type";
 const Wt::WFormModel::Field DatabaseSettingsModel::TagsField			= "tags";
 
 DatabaseSettingsView::DatabaseSettingsView()
@@ -256,22 +192,27 @@ DatabaseSettingsView::refreshView()
 
 	clear();
 
-	auto t = addNew<Wt::WTemplateFormView>(Wt::WString::tr("Lms.Admin.Database.template"));
-	auto model = std::make_shared<DatabaseSettingsModel>();
+	auto t {addNew<Wt::WTemplateFormView>(Wt::WString::tr("Lms.Admin.Database.template"))};
+	auto model {std::make_shared<DatabaseSettingsModel>()};
 
 	// Media Directory
 	t->setFormWidget(DatabaseSettingsModel::MediaDirectoryField, std::make_unique<Wt::WLineEdit>());
 
 	// Update Period
-	auto updatePeriod = std::make_unique<Wt::WComboBox>();
+	auto updatePeriod {std::make_unique<Wt::WComboBox>()};
 	updatePeriod->setModel(model->updatePeriodModel());
 	t->setFormWidget(DatabaseSettingsModel::UpdatePeriodField, std::move(updatePeriod));
 
 	// Update Start Time
-	auto updateStartTime = std::make_unique<Wt::WComboBox>();
+	auto updateStartTime {std::make_unique<Wt::WComboBox>()};
 	updateStartTime->setModel(model->updateStartTimeModel());
 	t->setFormWidget(DatabaseSettingsModel::UpdateStartTimeField, std::move(updateStartTime));
 
+	// Similarity engine type
+	auto similarityEngineType {std::make_unique<Wt::WComboBox>()};
+	similarityEngineType->setModel(model->similarityEngineTypeModel());
+	t->setFormWidget(DatabaseSettingsModel::SimilarityEngineTypeField, std::move(similarityEngineType));
+
 	// Tags
 	t->setFormWidget(DatabaseSettingsModel::TagsField, std::make_unique<Wt::WLineEdit>());
 
diff --git a/src/ui/admin/UserView.cpp b/src/ui/admin/UserView.cpp
index fc73d1af..becfc877 100644
--- a/src/ui/admin/UserView.cpp
+++ b/src/ui/admin/UserView.cpp
@@ -27,21 +27,24 @@
 #include <Wt/WTemplateFormView.h>
 
 #include <Wt/WFormModel.h>
-#include <Wt/WStringListModel.h>
 
-#include "common/Validators.hpp"
+#include "database/User.hpp"
 #include "utils/Config.hpp"
 #include "utils/Exception.hpp"
 #include "utils/Logger.hpp"
 #include "utils/Utils.hpp"
 
+#include "common/Validators.hpp"
+#include "common/ValueStringModel.hpp"
 #include "LmsApplication.hpp"
 
 namespace UserInterface {
 
+using namespace Database;
 
 class UserModel : public Wt::WFormModel
 {
+
 	public:
 		static const Field LoginField;
 		static const Field PasswordField;
@@ -71,23 +74,7 @@ class UserModel : public Wt::WFormModel
 			loadData();
 		}
 
-		void loadData()
-		{
-			if (!_userId)
-				return;
-
-			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
-
-			auto authUser = LmsApp->getDb().getUserDatabase().findWithId( std::to_string(*_userId) );
-			auto user = LmsApp->getDb().getUser(authUser);
-
-			if (user == LmsApp->getUser())
-				throw LmsException("Cannot edit ourselves");
-
-			auto bitrate {getTranscodeBitrateLimitRow(user->getMaxAudioTranscodeBitrate())};
-			if (bitrate)
-				setValue(AudioTranscodeBitrateLimitField, transcodeBitrateLimitString(*bitrate));
-		}
+		std::shared_ptr<Wt::WAbstractItemModel> bitrateModel() { return _bitrateModel; }
 
 		void saveData()
 		{
@@ -103,9 +90,9 @@ class UserModel : public Wt::WFormModel
 				if (!valueText(PasswordField).empty())
 					Database::Handler::getPasswordService().updatePassword(authUser, valueText(PasswordField));
 
-				auto transcodeBitrateLimitRow = getTranscodeBitrateLimitRow(Wt::asString(value(AudioTranscodeBitrateLimitField)));
-				user.modify()->setMaxAudioTranscodeBitrate(transcodeBitrateLimit(*transcodeBitrateLimitRow));
-				LMS_LOG(UI, DEBUG) << "Max audio bitrate set to " << transcodeBitrateLimit(*transcodeBitrateLimitRow);
+				auto transcodeBitrateLimitRow {_bitrateModel->getRowFromString(valueText(AudioTranscodeBitrateLimitField))};
+				if (transcodeBitrateLimitRow)
+					user.modify()->setMaxAudioTranscodeBitrate(_bitrateModel->getValue(*transcodeBitrateLimitRow));
 			}
 			else
 			{
@@ -117,14 +104,35 @@ class UserModel : public Wt::WFormModel
 				authUser.setIdentity(Wt::Auth::Identity::LoginName, valueText(LoginField));
 				Database::Handler::getPasswordService().updatePassword(authUser, valueText(PasswordField));
 
-				auto transcodeBitrateLimitRow = getTranscodeBitrateLimitRow(Wt::asString(value(AudioTranscodeBitrateLimitField)));
-				user.modify()->setMaxAudioTranscodeBitrate(transcodeBitrateLimit(*transcodeBitrateLimitRow));
+				auto transcodeBitrateLimitRow {_bitrateModel->getRowFromString(valueText(AudioTranscodeBitrateLimitField))};
+				if (transcodeBitrateLimitRow )
+					user.modify()->setMaxAudioTranscodeBitrate(_bitrateModel->getValue(*transcodeBitrateLimitRow));
 
 				if (Wt::asNumber(value(DemoField)))
 					user.modify()->setType(Database::User::Type::DEMO);
 			}
 		}
 
+	private:
+
+		void loadData()
+		{
+			if (!_userId)
+				return;
+
+			Wt::Dbo::Transaction transaction {LmsApp->getDboSession()};
+
+			auto authUser {LmsApp->getDb().getUserDatabase().findWithId( std::to_string(*_userId) )};
+			auto user {LmsApp->getDb().getUser(authUser)};
+
+			if (user == LmsApp->getUser())
+				throw LmsException("Cannot edit ourselves");
+
+			auto transcodeBitrateLimitRow {_bitrateModel->getRowFromValue(user->getMaxAudioTranscodeBitrate())};
+			if (transcodeBitrateLimitRow)
+				setValue(AudioTranscodeBitrateLimitField, _bitrateModel->getString(*transcodeBitrateLimitRow));
+		}
+
 		Wt::WString getLogin() const
 		{
 			if (_userId)
@@ -182,59 +190,16 @@ class UserModel : public Wt::WFormModel
 			return false;
 		}
 
-		boost::optional<int> getTranscodeBitrateLimitRow(Wt::WString value)
-		{
-			for (int i = 0; i < _bitrateModel->rowCount(); ++i)
-			{
-				if (transcodeBitrateLimitString(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		boost::optional<int> getTranscodeBitrateLimitRow(std::size_t value)
-		{
-			for (int i = 0; i < _bitrateModel->rowCount(); ++i)
-			{
-				if (transcodeBitrateLimit(i) == value)
-					return i;
-			}
-
-			return boost::none;
-		}
-
-		std::size_t transcodeBitrateLimit(int row)
-		{
-			return Wt::cpp17::any_cast<std::size_t>
-				(_bitrateModel->data(_bitrateModel->index(row, 0), Wt::ItemDataRole::User));
-		}
-
-		Wt::WString transcodeBitrateLimitString(int row)
-		{
-			return Wt::cpp17::any_cast<Wt::WString>
-				(_bitrateModel->data(_bitrateModel->index(row, 0), Wt::ItemDataRole::Display));
-		}
-
-		std::shared_ptr<Wt::WAbstractItemModel> bitrateModel() { return _bitrateModel; }
-
-	private:
 
 		void initializeModels()
 		{
-			_bitrateModel = std::make_shared<Wt::WStringListModel>();
+			_bitrateModel = std::make_shared<ValueStringModel<Bitrate>>();
 
-			std::size_t id = 0;
 			for (auto bitrate : Database::User::audioTranscodeAllowedBitrates)
-			{
-				_bitrateModel->addString( Wt::WString::fromUTF8(std::to_string(bitrate / 1000)) );
-				_bitrateModel->setData( id++, 0, bitrate, Wt::ItemDataRole::User);
-			}
-
-
+				_bitrateModel->add( Wt::WString::fromUTF8(std::to_string(bitrate / 1000)), bitrate );
 		}
 
-		std::shared_ptr<Wt::WStringListModel>	_bitrateModel;
+		std::shared_ptr<ValueStringModel<Bitrate>>	_bitrateModel;
 		boost::optional<Database::IdType> _userId;
 };
 
diff --git a/src/ui/common/ValueStringModel.hpp b/src/ui/common/ValueStringModel.hpp
new file mode 100644
index 00000000..728b1857
--- /dev/null
+++ b/src/ui/common/ValueStringModel.hpp
@@ -0,0 +1,78 @@
+
+/*
+ * Copyright (C) 2019 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS 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 LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <boost/optional.hpp>
+#include <Wt/WStringListModel.h>
+
+namespace UserInterface {
+
+// Helper class
+template <typename T>
+class ValueStringModel : public Wt::WStringListModel
+{
+	public:
+
+		T getValue(std::size_t row)
+		{
+			return Wt::cpp17::any_cast<T>(data(index(static_cast<int>(row), 0), Wt::ItemDataRole::User));
+		}
+
+		Wt::WString getString(std::size_t row)
+		{
+			return Wt::cpp17::any_cast<Wt::WString>(data(index(static_cast<int>(row), 0), Wt::ItemDataRole::Display));
+		}
+
+		boost::optional<std::size_t>
+		getRowFromString(const Wt::WString& value)
+		{
+			for (std::size_t i{}; i < static_cast<std::size_t>(rowCount()); ++i)
+			{
+				if (getString(i) == value)
+					return i;
+			}
+
+			return boost::none;
+		}
+
+		boost::optional<std::size_t>
+		getRowFromValue(const T& value)
+		{
+			for (std::size_t i{}; i < static_cast<std::size_t>(rowCount()); ++i)
+			{
+				if (getValue(i) == value)
+					return i;
+			}
+
+			return boost::none;
+		}
+
+		void
+		add(const Wt::WString& str, const T& value)
+		{
+			insertRows(rowCount(), 1);
+			setData(rowCount() - 1, 0, value, Wt::ItemDataRole::User);
+			setData(rowCount() - 1, 0, str, Wt::ItemDataRole::Display);
+		}
+
+};
+
+} // namespace UserInterface