fixed the delete dictionary buttons not staying locked when navigating from and to the Languages screen, while deletion is in progress

app/src/main/java/io/github/sspanak/tt9/db/DataStore.java

@@ -11,7 +11,6 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicInteger;
 
 import io.github.sspanak.tt9.db.entities.AddWordResult;
 import io.github.sspanak.tt9.db.wordPairs.WordPairStore;
@@ -21,7 +20,6 @@ import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.preferences.settings.SettingsStore;
 import io.github.sspanak.tt9.util.ConsumerCompat;
 import io.github.sspanak.tt9.util.Logger;
-import io.github.sspanak.tt9.util.Timer;
 
 public class DataStore {
 	private final static String LOG_TAG = DataStore.class.getSimpleName();
@@ -80,27 +78,6 @@ public class DataStore {
 	}
 
 
-	public static void deleteLanguages(Runnable notification, @NonNull ArrayList<Language> languages) {
-		Timer.start(LOG_TAG);
-
-		AtomicInteger progress = new AtomicInteger(languages.size());
-		Runnable onDeleted = () -> {
-			if (progress.decrementAndGet() == 0) {
-				Logger.d(LOG_TAG, "Deleted " + languages.size() + " languages. Time: " + Timer.stop(LOG_TAG) + " ms");
-				notification.run();
-			}
-		};
-
-		for (Language language : languages) {
-			runInTransaction(
-				() -> { words.remove(language); pairs.remove(language); },
-				onDeleted,
-				"Failed deleting languages."
-			);
-		}
-	}
-
-
 	public static void put(ConsumerCompat<AddWordResult> statusHandler, Language language, String word) {
 		runInThread(() -> statusHandler.accept(words.put(language, word)));
 	}

app/src/main/java/io/github/sspanak/tt9/db/wordPairs/WordPairStore.java

@@ -165,17 +165,6 @@ public class WordPairStore extends BaseSyncStore {
 	}
 
 
-	public void remove(@NonNull Language language) {
-		if (!checkOrNotify()) {
-			return;
-		}
-
-		DeleteOps.deleteWordPairs(sqlite.getDb(), language.getId());
-		slowestLoadTime = 0;
-		slowestSaveTime = 0;
-	}
-
-
 	public void remove(@NonNull ArrayList<Language> languages) {
 		if (!checkOrNotify()) {
 			return;

app/src/main/java/io/github/sspanak/tt9/db/words/DictionaryDeleter.java

@@ -0,0 +1,106 @@
+package io.github.sspanak.tt9.db.words;
+
+import android.content.Context;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import java.util.ArrayList;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import io.github.sspanak.tt9.db.BaseSyncStore;
+import io.github.sspanak.tt9.db.sqlite.DeleteOps;
+import io.github.sspanak.tt9.languages.Language;
+import io.github.sspanak.tt9.languages.NaturalLanguage;
+import io.github.sspanak.tt9.util.Logger;
+import io.github.sspanak.tt9.util.Timer;
+
+public class DictionaryDeleter extends BaseSyncStore {
+	private static final String LOG_TAG = DictionaryDeleter.class.getSimpleName();
+	private static DictionaryDeleter self;
+
+	@NonNull private final ExecutorService executor = Executors.newSingleThreadExecutor();
+	@Nullable Future<?> deleteTask;
+	@Nullable private Runnable notification;
+
+
+	protected DictionaryDeleter(Context context) {
+		super(context);
+	}
+
+
+	public static DictionaryDeleter getInstance(Context context) {
+		if (self == null) {
+			self = new DictionaryDeleter(context);
+		}
+		return self;
+	}
+
+
+	public void deleteLanguages(@NonNull ArrayList<Language> languages) {
+		if (!checkOrNotify()) {
+			onFinish();
+			return;
+		}
+
+		Timer.start(LOG_TAG);
+		deleteTask = executor.submit(() -> deleteLanguagesSync(languages));
+	}
+
+
+	private void deleteLanguagesSync(@NonNull ArrayList<Language> languages) {
+		for (Language language : languages) {
+			if (!deleteLanguage(language)) {
+				break;
+			}
+		}
+
+		deleteTask = null;
+
+		if (notification != null) {
+			notification.run();
+		}
+
+		Logger.d(LOG_TAG, "Deleted " + languages.size() + " languages. Time: " + Timer.stop(LOG_TAG) + " ms");
+	}
+
+
+	private boolean deleteLanguage(Language language) {
+		if (!(language instanceof NaturalLanguage)) {
+			Logger.w(LOG_TAG, "Invalid language type to delete: " + language.getClass().getSimpleName() + ". Skipping.");
+			return true;
+		}
+
+		try {
+			sqlite.beginTransaction();
+			DeleteOps.delete(sqlite.getDb(), language.getId());
+			DeleteOps.deleteWordPairs(sqlite.getDb(), language.getId());
+			sqlite.finishTransaction();
+		} catch (Exception e) {
+			sqlite.failTransaction();
+			Logger.e(LOG_TAG, "Failed deleting language: " + language.getId() + ". " + e.getMessage());
+			return false;
+		}
+
+		return true;
+	}
+
+
+	private void onFinish() {
+		if (notification != null) {
+			notification.run();
+		}
+	}
+
+
+	public boolean isRunning() {
+		return deleteTask != null && !deleteTask.isDone();
+	}
+
+
+	public void setOnFinish(Runnable notification) {
+		this.notification = notification;
+	}
+}

app/src/main/java/io/github/sspanak/tt9/db/words/WordStore.java

@@ -118,13 +118,6 @@ public class WordStore extends BaseSyncStore {
 	}
 
 
-	public void remove(Language language) {
-		if (checkOrNotify() && readOps.exists(sqlite.getDb(), language.getId())) {
-			DeleteOps.delete(sqlite.getDb(), language.getId());
-		}
-	}
-
-
 	public void removeCustomWord(Language language, String word) {
 		if (language == null || language instanceof NullLanguage || !checkOrNotify()) {
 			return;

app/src/main/java/io/github/sspanak/tt9/preferences/screens/languages/ItemTruncateAll.java

@@ -3,7 +3,7 @@ package io.github.sspanak.tt9.preferences.screens.languages;
 import androidx.preference.Preference;
 
 import io.github.sspanak.tt9.R;
-import io.github.sspanak.tt9.db.DataStore;
+import io.github.sspanak.tt9.db.words.DictionaryDeleter;
 import io.github.sspanak.tt9.languages.LanguageCollection;
 import io.github.sspanak.tt9.preferences.PreferencesActivity;
 import io.github.sspanak.tt9.preferences.items.ItemClickable;
@@ -14,6 +14,7 @@ class ItemTruncateAll extends ItemClickable {
 	public static final String NAME = "dictionary_truncate";
 
 	protected final PreferencesActivity activity;
+	protected final DictionaryDeleter deleter;
 	private final Runnable onStart;
 	private final Runnable onFinish;
 
@@ -21,31 +22,49 @@ class ItemTruncateAll extends ItemClickable {
 	ItemTruncateAll(Preference item, PreferencesActivity activity, Runnable onStart, Runnable onFinish) {
 		super(item);
 		this.activity = activity;
+		this.deleter = DictionaryDeleter.getInstance(activity);
 		this.onStart = onStart;
 		this.onFinish = onFinish;
+
+		refreshStatus();
 	}
 
 
 	@Override
 	protected boolean onClick(Preference p) {
-		onStartDeleting();
+		onStart.run();
-		DataStore.deleteLanguages(this::onFinishDeleting, LanguageCollection.getAll(false));
+		setBusy();
+		deleter.deleteLanguages(LanguageCollection.getAll(false));
 
 		return true;
 	}
 
 
-	protected void onStartDeleting() {
+	void refreshStatus() {
-		onStart.run();
+		if (deleter.isRunning()) {
-		disable();
+			setBusy();
+		} else {
+			enable();
+		}
+	}
+
+
+	protected void setBusy() {
+		deleter.setOnFinish(this::onFinishDeleting);
 		item.setSummary(R.string.dictionary_truncating);
+		disable();
+	}
+
+
+	public void enable() {
+		super.enable();
+		item.setSummary("");
 	}
 
 
 	protected void onFinishDeleting() {
 		activity.runOnUiThread(() -> {
 			onFinish.run();
-			item.setSummary("");
 			enable();
 			UI.toastFromAsync(activity, R.string.dictionary_truncated);
 		});

app/src/main/java/io/github/sspanak/tt9/preferences/screens/languages/ItemTruncateUnselected.java

@@ -6,7 +6,6 @@ import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.Set;
 
-import io.github.sspanak.tt9.db.DataStore;
 import io.github.sspanak.tt9.languages.Language;
 import io.github.sspanak.tt9.languages.LanguageCollection;
 import io.github.sspanak.tt9.preferences.PreferencesActivity;
@@ -31,8 +30,9 @@ class ItemTruncateUnselected extends ItemTruncateAll {
 			}
 		}
 
-		onStartDeleting();
+		setBusy();
-		DataStore.deleteLanguages(this::onFinishDeleting, unselectedLanguages);
+		deleter.setOnFinish(this::onFinishDeleting);
+		deleter.deleteLanguages(unselectedLanguages);
 
 		return true;
 	}

app/src/main/java/io/github/sspanak/tt9/preferences/screens/languages/LanguagesScreen.java

@@ -11,6 +11,7 @@ import io.github.sspanak.tt9.R;
 import io.github.sspanak.tt9.db.customWords.CustomWordsExporter;
 import io.github.sspanak.tt9.db.customWords.CustomWordsImporter;
 import io.github.sspanak.tt9.db.customWords.DictionaryExporter;
+import io.github.sspanak.tt9.db.words.DictionaryDeleter;
 import io.github.sspanak.tt9.db.words.DictionaryLoader;
 import io.github.sspanak.tt9.preferences.PreferencesActivity;
 import io.github.sspanak.tt9.preferences.items.ItemClickable;
@@ -19,12 +20,14 @@ import io.github.sspanak.tt9.preferences.screens.BaseScreenFragment;
 public class LanguagesScreen extends BaseScreenFragment {
 	public static final String NAME = "Languages";
 
-	private final ArrayList<ItemClickable> clickables = new ArrayList<>();
+	private static final ArrayList<ItemClickable> clickables = new ArrayList<>();
 
 	private ItemLoadDictionary loadItem;
 	private ItemImportCustomWords importCustomWordsItem;
 	private ItemExportDictionary exportDictionaryItem;
 	private ItemExportCustomWords exportCustomWordsItem;
+	private ItemTruncateAll truncateAllItem;
+	private ItemTruncateUnselected truncateUnselectedItem;
 
 	public LanguagesScreen() { init(); }
 	public LanguagesScreen(PreferencesActivity activity) { init(activity); }
@@ -56,22 +59,25 @@ public class LanguagesScreen extends BaseScreenFragment {
 			this::onActionFinish
 		);
 
-		clickables.add(loadItem);
+		truncateUnselectedItem = new ItemTruncateUnselected(
-		clickables.add(exportDictionaryItem);
-
-		clickables.add(new ItemTruncateUnselected(
 			findPreference(ItemTruncateUnselected.NAME),
 			activity,
 			this::onActionStart,
 			this::onActionFinish
-		));
+		);
 
-		clickables.add(new ItemTruncateAll(
+		truncateAllItem = new ItemTruncateAll(
 			findPreference(ItemTruncateAll.NAME),
 			activity,
 			this::onActionStart,
 			this::onActionFinish
-		));
+		);
+
+		clickables.clear();
+		clickables.add(loadItem);
+		clickables.add(exportDictionaryItem);
+		clickables.add(truncateUnselectedItem);
+		clickables.add(truncateAllItem);
 
 		clickables.add(new ItemDeleteCustomWords(findPreference(ItemDeleteCustomWords.NAME)));
 
@@ -112,6 +118,8 @@ public class LanguagesScreen extends BaseScreenFragment {
 		exportDictionaryItem.refreshStatus();
 		exportCustomWordsItem.refreshStatus();
 		importCustomWordsItem.refreshStatus();
+		truncateUnselectedItem.refreshStatus();
+		truncateAllItem.refreshStatus();
 
 		if (DictionaryLoader.getInstance(activity).isRunning()) {
 			loadItem.refreshStatus();
@@ -120,6 +128,7 @@ public class LanguagesScreen extends BaseScreenFragment {
 			CustomWordsExporter.getInstance().isRunning()
 			|| DictionaryExporter.getInstance().isRunning()
 			|| CustomWordsImporter.getInstance(activity).isRunning()
+			|| DictionaryDeleter.getInstance(activity).isRunning()
 		) {
 			onActionStart();
 		} else {