Add feature flags that contains new image loader flag.

This allows to release new versions of the app with unfinished/
not fully implemented features.

Signed-off-by: Yahor Berdnikau <egorr.berd@gmail.com>

ultrasonic/src/main/java/org/moire/ultrasonic/activity/SubsonicTabActivity.java

@@ -44,6 +44,7 @@ import org.moire.ultrasonic.domain.MusicDirectory;
 import org.moire.ultrasonic.domain.MusicDirectory.Entry;
 import org.moire.ultrasonic.domain.PlayerState;
 import org.moire.ultrasonic.domain.Share;
+import org.moire.ultrasonic.featureflags.Feature;
 import org.moire.ultrasonic.service.*;
 import org.moire.ultrasonic.subsonic.SubsonicImageLoaderProxy;
 import org.moire.ultrasonic.util.*;
@@ -790,10 +791,14 @@ public class SubsonicTabActivity extends ResultActivity implements OnClickListen
 		}
 	}
 
-	public synchronized void clearImageLoader()
+    public synchronized void clearImageLoader() {
-	{
+        if (IMAGE_LOADER != null &&
-		if (IMAGE_LOADER != null && IMAGE_LOADER.isRunning()) IMAGE_LOADER.clear();
+                IMAGE_LOADER.isRunning()) {
-	}
+            IMAGE_LOADER.clear();
+        }
+
+        IMAGE_LOADER = null;
+    }
 
     public synchronized ImageLoader getImageLoader() {
         if (IMAGE_LOADER == null ||
@@ -802,10 +807,18 @@ public class SubsonicTabActivity extends ResultActivity implements OnClickListen
                     this,
                     Util.getImageLoaderConcurrency(this)
             );
-            IMAGE_LOADER = new SubsonicImageLoaderProxy(
+
-                    legacyImageLoader,
+            boolean isNewImageLoaderEnabled = ((UApp) getApplication()).getFeaturesStorage()
-                    ((UApp) getApplication()).getSubsonicImageLoader()
+                    .isFeatureEnabled(Feature.NEW_IMAGE_DOWNLOADER);
-            );
+            if (isNewImageLoaderEnabled) {
+                IMAGE_LOADER = new SubsonicImageLoaderProxy(
+                        legacyImageLoader,
+                        ((UApp) getApplication()).getSubsonicImageLoader()
+                );
+            } else {
+                IMAGE_LOADER = legacyImageLoader;
+            }
+
             IMAGE_LOADER.startImageLoader();
         }
 

ultrasonic/src/main/java/org/moire/ultrasonic/fragment/SettingsFragment.java

@@ -4,29 +4,21 @@ import android.content.Intent;
 import android.content.SharedPreferences;
 import android.os.Build;
 import android.os.Bundle;
-import android.preference.CheckBoxPreference;
+import android.preference.*;
-import android.preference.EditTextPreference;
-import android.preference.ListPreference;
-import android.preference.Preference;
-import android.preference.PreferenceCategory;
-import android.preference.PreferenceFragment;
-import android.preference.PreferenceManager;
 import android.provider.SearchRecentSuggestions;
 import android.support.annotation.Nullable;
 import android.util.Log;
 import android.view.View;
-
 import org.moire.ultrasonic.R;
 import org.moire.ultrasonic.activity.ServerSettingsActivity;
 import org.moire.ultrasonic.activity.SubsonicTabActivity;
+import org.moire.ultrasonic.app.UApp;
+import org.moire.ultrasonic.featureflags.Feature;
+import org.moire.ultrasonic.featureflags.FeatureStorage;
 import org.moire.ultrasonic.provider.SearchSuggestionProvider;
 import org.moire.ultrasonic.service.DownloadService;
 import org.moire.ultrasonic.service.DownloadServiceImpl;
-import org.moire.ultrasonic.util.Constants;
+import org.moire.ultrasonic.util.*;
-import org.moire.ultrasonic.util.FileUtil;
-import org.moire.ultrasonic.util.ImageLoader;
-import org.moire.ultrasonic.util.TimeSpanPreference;
-import org.moire.ultrasonic.util.Util;
 
 import java.io.File;
 
@@ -115,6 +107,7 @@ public class SettingsFragment extends PreferenceFragment
         sharingDefaultGreeting.setText(Util.getShareGreeting(getActivity()));
         setupClearSearchPreference();
         setupGaplessControlSettingsV14();
+        setupFeatureFlagsPreferences();
     }
 
     @Override
@@ -178,6 +171,24 @@ public class SettingsFragment extends PreferenceFragment
         }
     }
 
+    private void setupFeatureFlagsPreferences() {
+        CheckBoxPreference ffImageLoader = (CheckBoxPreference) findPreference(
+                Constants.PREFERENCES_KEY_FF_IMAGE_LOADER);
+
+        final FeatureStorage featureStorage = ((UApp) getActivity().getApplication()).getFeaturesStorage();
+        if (ffImageLoader != null) {
+            ffImageLoader.setChecked(featureStorage.isFeatureEnabled(Feature.NEW_IMAGE_DOWNLOADER));
+            ffImageLoader.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
+                @Override
+                public boolean onPreferenceChange(Preference preference, Object o) {
+                    featureStorage.changeFeatureFlag(Feature.NEW_IMAGE_DOWNLOADER, (Boolean) o);
+                    ((SubsonicTabActivity) getActivity()).clearImageLoader();
+                    return true;
+                }
+            });
+        }
+    }
+
     private void setupGaplessControlSettingsV14() {
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
             PreferenceCategory playbackControlSettings =

ultrasonic/src/main/java/org/moire/ultrasonic/util/Constants.java

@@ -130,6 +130,7 @@ public final class Constants
 	public static final String PREFERENCES_KEY_SHOW_ALL_SONGS_BY_ARTIST = "showAllSongsByArtist";
 	public static final String PREFERENCES_KEY_SCAN_MEDIA = "scanMedia";
 	public static final String PREFERENCES_KEY_IMAGE_LOADER_CONCURRENCY = "imageLoaderConcurrency";
+	public static final String PREFERENCES_KEY_FF_IMAGE_LOADER = "ff_new_image_loader";
 
 	// Number of free trial days for non-licensed servers.
 	public static final int FREE_TRIAL_DAYS = 30;

ultrasonic/src/main/kotlin/org/moire/ultrasonic/app/UApp.kt

@@ -5,7 +5,9 @@ import org.koin.android.ext.android.get
 import org.koin.android.ext.android.startKoin
 import org.moire.ultrasonic.di.baseNetworkModule
 import org.moire.ultrasonic.di.directoriesModule
+import org.moire.ultrasonic.di.featureFlagsModule
 import org.moire.ultrasonic.di.musicServiceModule
+import org.moire.ultrasonic.featureflags.FeatureStorage
 import org.moire.ultrasonic.subsonic.loader.image.SubsonicImageLoader
 import org.moire.ultrasonic.util.Util
 
@@ -17,6 +19,7 @@ class UApp : Application() {
         startKoin(this, listOf(
             directoriesModule,
             baseNetworkModule,
+            featureFlagsModule(this),
             musicServiceModule(sharedPreferences, this)
         ))
     }
@@ -27,4 +30,11 @@ class UApp : Application() {
     fun getSubsonicImageLoader(): SubsonicImageLoader {
         return get()
     }
+
+    /**
+     * Temporary method to get features storage.
+     */
+    fun getFeaturesStorage(): FeatureStorage {
+        return get()
+    }
 }

ultrasonic/src/main/kotlin/org/moire/ultrasonic/di/FeatureFlagsModule.kt

@@ -0,0 +1,11 @@
+package org.moire.ultrasonic.di
+
+import android.content.Context
+import org.koin.dsl.module.applicationContext
+import org.moire.ultrasonic.featureflags.FeatureStorage
+
+fun featureFlagsModule(
+    context: Context
+) = applicationContext {
+    factory { FeatureStorage(context) }
+}

ultrasonic/src/main/kotlin/org/moire/ultrasonic/featureflags/Feature.kt

@@ -0,0 +1,14 @@
+package org.moire.ultrasonic.featureflags
+
+/**
+ * Contains a list of new features/implementations that are not yet finished,
+ * but possible to try it out.
+ */
+enum class Feature(
+    val defaultValue: Boolean
+) {
+    /**
+     * Enables new image downloader implementation.
+     */
+    NEW_IMAGE_DOWNLOADER(false)
+}

ultrasonic/src/main/kotlin/org/moire/ultrasonic/featureflags/FeatureStorage.kt

@@ -0,0 +1,31 @@
+package org.moire.ultrasonic.featureflags
+
+import android.content.Context
+
+private const val SP_NAME = "feature_flags"
+
+/**
+ * Provides storage for current feature flag state.
+ */
+class FeatureStorage(
+    context: Context
+) {
+    private val sp = context.getSharedPreferences(SP_NAME, Context.MODE_PRIVATE)
+
+    /**
+     * Get [feature] current enabled state.
+     */
+    fun isFeatureEnabled(feature: Feature): Boolean {
+        return sp.getBoolean(feature.name, feature.defaultValue)
+    }
+
+    /**
+     * Update [feature] enabled state to [isEnabled].
+     */
+    fun changeFeatureFlag(
+        feature: Feature,
+        isEnabled: Boolean
+    ) {
+        sp.edit().putBoolean(feature.name, isEnabled).apply()
+    }
+}

ultrasonic/src/main/res/values-es/strings.xml

@@ -436,5 +436,10 @@
     <string name="api.subsonic.trial_period_is_over">El período de prueba ha terminado.</string>
     <string name="api.subsonic.upgrade_client">Versiones incompatibles. Por favor actualiza la aplicación de Android UltraSonic.</string>
     <string name="api.subsonic.upgrade_server">Versiones incompatibles. Por favor actualiza el servidor de Subsonic.</string>
+    <string name="feature_flags_category_title">Banderas de características</string>
+    <string name="feature_flags_image_loader_description">Permite la implementación de un nuevo cargador de imágenes.
+        Actualmente no guarda la imagen en el almacenamiento del dispositivo y sólo utiliza caché en la memoria.
+    </string>
+    <string name="feature_flags_image_loader_title">Habilitar nuevo cargador de imágenes</string>
 
 </resources>

ultrasonic/src/main/res/values-fr/strings.xml

@@ -436,5 +436,11 @@
     <string name="api.subsonic.trial_period_is_over">La période d\'essai est terminée.</string>
     <string name="api.subsonic.upgrade_client">Versions incompatible. Veuillez mette à jour l\'application Android UltraSonic.</string>
     <string name="api.subsonic.upgrade_server">Versions incompatible. Veuillez mette à jour le serveur Subsonic.</string>
+    <string name="feature_flags_category_title">Drapeaux des fonctionnalités</string>
+    <string name="feature_flags_image_loader_description">Permet l\'implémentation d\'un nouveau chargeur d\'images.
+        Actuellement, il n\'enregistre pas l\'image dans le stockage de l\'appareil et n\'utilise que le cache en
+        mémoire.
+    </string>
+    <string name="feature_flags_image_loader_title">Activer le nouveau chargeur d\'images</string>
 
 </resources>

ultrasonic/src/main/res/values-hu/strings.xml

@@ -436,5 +436,10 @@
     <string name="api.subsonic.trial_period_is_over">A próbaidő vége.</string>
     <string name="api.subsonic.upgrade_client">Nem kompatibilis verzió. Kérjük, frissítse az UltraSonic Android alkalmazást!</string>
     <string name="api.subsonic.upgrade_server">Nem kompatibilis verzió. Kérjük, frissítse a Subsonic kiszolgálót!</string>
+    <string name="feature_flags_image_loader_description">Engedélyezi az új képbetöltő megvalósítását. Jelenleg nem
+        tárolja a képet az eszköz tárolójában, és csak a memóriában tárolja a gyorsítótárat.
+    </string>
+    <string name="feature_flags_category_title">Jellemzők Zászlók</string>
+    <string name="feature_flags_image_loader_title">Engedélyezzen új képbetöltőt</string>
 
 </resources>

ultrasonic/src/main/res/values-pt-rBR/strings.xml

@@ -436,5 +436,10 @@
     <string name="api.subsonic.trial_period_is_over">O período de avaliação acabou.</string>
     <string name="api.subsonic.upgrade_client">Versões incompativeis. Atualize o aplicativo UltraSonic para Android.</string>
     <string name="api.subsonic.upgrade_server">Versões incompativeis. Atualize o servidor UltraSonic.</string>
+    <string name="feature_flags_image_loader_description">Permite nova implementação do carregador de imagens.
+        Atualmente, ele não salva a imagem no armazenamento do dispositivo e usa apenas o cache na memória.
+    </string>
+    <string name="feature_flags_category_title">Bandeiras de recursos</string>
+    <string name="feature_flags_image_loader_title">Ativar novo carregador de imagens</string>
 
 </resources>

ultrasonic/src/main/res/values-pt/strings.xml

@@ -436,5 +436,10 @@
     <string name="api.subsonic.trial_period_is_over">O período de avaliação acabou.</string>
     <string name="api.subsonic.upgrade_client">Versões incompativeis. Atualize o aplicativo UltraSonic para Android.</string>
     <string name="api.subsonic.upgrade_server">Versões incompativeis. Atualize o servidor UltraSonic.</string>
+    <string name="feature_flags_image_loader_description">Permite nova implementação do carregador de imagens.
+        Atualmente, ele não salva a imagem no armazenamento do dispositivo e usa apenas o cache na memória.
+    </string>
+    <string name="feature_flags_category_title">Bandeiras de recursos</string>
+    <string name="feature_flags_image_loader_title">Ativar novo carregador de imagens</string>
 
 </resources>

ultrasonic/src/main/res/values/strings.xml

@@ -441,4 +441,10 @@
     <string name="api.subsonic.upgrade_client">Incompatible versions. Please upgrade UltraSonic Android app.</string>
     <string name="api.subsonic.upgrade_server">Incompatible versions. Please upgrade Subsonic server.</string>
 
+    <string name="feature_flags_image_loader_title">Enable new image loader</string>
+    <string name="feature_flags_image_loader_description">Enables new image loader implementation.
+        Currently it doesn\'t save image in device storage and uses only cache in memory.
+    </string>
+    <string name="feature_flags_category_title">Feature Flags</string>
+
 </resources>

ultrasonic/src/main/res/xml/settings.xml

@@ -284,5 +284,14 @@
             a:summary="@string/settings.screen_lit_summary"
             a:title="@string/settings.screen_lit_title"/>
     </PreferenceCategory>
+    <PreferenceCategory a:title="@string/feature_flags_category_title">
+        <CheckBoxPreference
+            a:key="ff_new_image_loader"
+            a:persistent="false"
+            a:title="@string/feature_flags_image_loader_title"
+            a:summary="@string/feature_flags_image_loader_description"
+        />
+
+    </PreferenceCategory>
 
 </PreferenceScreen>