From 375278d9985b35126dcd7b75f5e5a275d2a4e367 Mon Sep 17 00:00:00 2001
From: xynngh <xynngh@protonmail.com>
Date: Sat, 7 Sep 2019 14:39:12 +0400
Subject: [PATCH] Add support for external main DB

---
 .../yetanothercallblocker/MainActivity.java   |  54 ++++++++
 .../sia/DatabaseSingleton.java                |   6 +-
 .../sia/SiaConstants.java                     |   8 ++
 .../sia/model/database/AbstractDatabase.java  | 115 ++++++++++++++----
 .../database/AbstractDatabaseDataSlice.java   |  39 ------
 .../sia/model/database/CommunityDatabase.java |  83 +++++++++----
 .../database/CommunityDatabaseDataSlice.java  |   5 -
 .../sia/model/database/DbManager.java         |  48 ++++++++
 .../sia/model/database/FeaturedDatabase.java  |   6 +-
 .../database/FeaturedDatabaseDataSlice.java   |   5 -
 .../sia/network/DbDownloader.java             |  61 ++++++++++
 .../sia/utils/FileUtils.java                  |  68 +++++++++++
 app/src/main/res/layout/activity_main.xml     |  48 ++++++++
 app/src/main/res/values/strings.xml           |   4 +
 14 files changed, 448 insertions(+), 102 deletions(-)
 create mode 100644 app/src/main/java/dummydomain/yetanothercallblocker/sia/SiaConstants.java
 create mode 100644 app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/DbManager.java
 create mode 100644 app/src/main/java/dummydomain/yetanothercallblocker/sia/network/DbDownloader.java
 create mode 100644 app/src/main/java/dummydomain/yetanothercallblocker/sia/utils/FileUtils.java

diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java b/app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java
index d5edbb4..2237eec 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java
@@ -1,12 +1,19 @@
 package dummydomain.yetanothercallblocker;
 
+import android.annotation.SuppressLint;
 import android.content.Intent;
 import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.SwitchCompat;
+
+import android.os.AsyncTask;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuItem;
+import android.view.View;
+
+import dummydomain.yetanothercallblocker.sia.DatabaseSingleton;
+import dummydomain.yetanothercallblocker.sia.model.database.DbManager;
 
 public class MainActivity extends AppCompatActivity {
 
@@ -32,6 +39,20 @@ public class MainActivity extends AppCompatActivity {
             else Updater.cancelAutoUpdateWorker();
         });
 
+        @SuppressLint("StaticFieldLeak")
+        AsyncTask<Void, Void, Boolean> noDbTask = new AsyncTask<Void, Void, Boolean>() {
+            @Override
+            protected Boolean doInBackground(Void... voids) {
+                return DatabaseSingleton.getCommunityDatabase().isOperational();
+            }
+
+            @Override
+            protected void onPostExecute(Boolean result) {
+                updateNoDbUi(result ? UpdateUiState.HIDDEN : UpdateUiState.NO_DB);
+            }
+        };
+        noDbTask.execute();
+
         PermissionHelper.checkPermissions(this);
     }
 
@@ -49,8 +70,41 @@ public class MainActivity extends AppCompatActivity {
         // TODO: handle
     }
 
+    public void onDownloadDbClick(View view) {
+        // TODO: use service
+
+        updateNoDbUi(UpdateUiState.DOWNLOADING_DB);
+
+        @SuppressLint("StaticFieldLeak")
+        AsyncTask<Void, Void, Boolean> dlTask = new AsyncTask<Void, Void, Boolean>() {
+            @Override
+            protected Boolean doInBackground(Void... voids) {
+                return DbManager.downloadMainDb()
+                        && DatabaseSingleton.getCommunityDatabase().reload()
+                        && DatabaseSingleton.getFeaturedDatabase().reload();
+            }
+
+            @Override
+            protected void onPostExecute(Boolean result) {
+                updateNoDbUi(result ? UpdateUiState.HIDDEN : UpdateUiState.ERROR);
+            }
+        };
+        dlTask.execute();
+    }
+
     public void onOpenDebugActivity(MenuItem item) {
         startActivity(new Intent(this, DebugActivity.class));
     }
 
+    enum UpdateUiState {HIDDEN, NO_DB, DOWNLOADING_DB, ERROR}
+
+    private void updateNoDbUi(UpdateUiState state) {
+        findViewById(R.id.noDbText).setVisibility(state == UpdateUiState.NO_DB ? View.VISIBLE : View.GONE);
+        findViewById(R.id.downloadDbButton).setVisibility(state == UpdateUiState.NO_DB ? View.VISIBLE : View.GONE);
+
+        findViewById(R.id.downloadingDbText).setVisibility(state == UpdateUiState.DOWNLOADING_DB ? View.VISIBLE : View.GONE);
+
+        findViewById(R.id.dbCouldNotBeDownloaded).setVisibility(state == UpdateUiState.ERROR ? View.VISIBLE : View.GONE);
+    }
+
 }
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/DatabaseSingleton.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/DatabaseSingleton.java
index 10779d4..b9f8e5e 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/DatabaseSingleton.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/DatabaseSingleton.java
@@ -3,10 +3,12 @@ package dummydomain.yetanothercallblocker.sia;
 import dummydomain.yetanothercallblocker.sia.model.database.CommunityDatabase;
 import dummydomain.yetanothercallblocker.sia.model.database.FeaturedDatabase;
 
+import static dummydomain.yetanothercallblocker.sia.SiaConstants.*;
+
 public class DatabaseSingleton {
 
-    private static final CommunityDatabase COMMUNITY_DATABASE = new CommunityDatabase();
-    private static final FeaturedDatabase FEATURED_DATABASE = new FeaturedDatabase();
+    private static final CommunityDatabase COMMUNITY_DATABASE = new CommunityDatabase(SIA_PATH_PREFIX, SIA_SECONDARY_PATH_PREFIX);
+    private static final FeaturedDatabase FEATURED_DATABASE = new FeaturedDatabase(SIA_PATH_PREFIX);
 
     public static CommunityDatabase getCommunityDatabase() {
         return COMMUNITY_DATABASE;
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/SiaConstants.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/SiaConstants.java
new file mode 100644
index 0000000..312f46a
--- /dev/null
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/SiaConstants.java
@@ -0,0 +1,8 @@
+package dummydomain.yetanothercallblocker.sia;
+
+public interface SiaConstants {
+
+    String SIA_PATH_PREFIX = "sia/";
+    String SIA_SECONDARY_PATH_PREFIX = "sia-secondary/";
+
+}
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabase.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabase.java
index a26b84c..220d7ab 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabase.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabase.java
@@ -5,17 +5,22 @@ import android.util.SparseArray;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.io.BufferedInputStream;
 import java.io.BufferedReader;
 import java.io.FileNotFoundException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 
-import dummydomain.yetanothercallblocker.sia.utils.Utils;
+import static dummydomain.yetanothercallblocker.sia.utils.FileUtils.openFile;
 
 public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V> {
 
     private static final Logger LOG = LoggerFactory.getLogger(AbstractDatabase.class);
 
+    protected final String pathPrefix;
+
+    protected boolean useAssets;
+
     protected int baseDatabaseVersion;
     protected int numberOfItems;
 
@@ -26,39 +31,78 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
     protected boolean loaded;
     protected boolean failedToLoad;
 
+    public AbstractDatabase(String pathPrefix) {
+        this.pathPrefix = pathPrefix;
+    }
+
+    public boolean isOperational() {
+        checkLoaded();
+        return loaded;
+    }
+
+    public boolean reload() {
+        return load();
+    }
+
     protected void checkLoaded() {
-        if (loaded) return;
-        if (failedToLoad) throw new IllegalStateException("The DB has failed to load");
+        if (loaded || failedToLoad) return;
 
         LOG.debug("checkLoaded() loading DB");
-        loaded = load();
-        failedToLoad = !loaded;
+        load();
+    }
+
+    protected void reset() {
+        loaded = false;
+        failedToLoad = false;
+
+        baseDatabaseVersion = 0;
+        numberOfItems = 0;
+
+        dbRootNode = null;
+        sliceCache.clear();
     }
 
     protected boolean load() {
         LOG.debug("load() loading DB");
 
-        if (loadInfoData() && loadSliceListData()) {
-            LOG.info("load() loaded DB, baseDatabaseVersion={}, numberOfItems={}",
-                    this.baseDatabaseVersion, this.numberOfItems);
+        reset();
+
+        if (load(true)) {
+            useAssets = true;
+            loaded = true;
+            return true;
+        } else if (load(false)) {
+            useAssets = false;
+            loaded = true;
             return true;
         } else {
             LOG.warn("load() failed to load DB");
+            failedToLoad = true;
             return false;
         }
     }
 
-    protected String getAssetPathPrefix() {
-        return "sia/";
+    protected boolean load(boolean useAssets) {
+        if (loadInfoData(useAssets) && loadSliceListData(useAssets)) {
+            LOG.info("load() loaded DB useAssets={}, baseDatabaseVersion={}, numberOfItems={}",
+                    useAssets, this.baseDatabaseVersion, this.numberOfItems);
+            return true;
+        }
+        return false;
     }
 
-    protected abstract String getAssetNamePrefix();
+    protected String getPathPrefix() {
+        return pathPrefix;
+    }
 
-    protected boolean loadInfoData() {
-        LOG.debug("loadInfoData() started");
+    protected abstract String getNamePrefix();
 
-        String fileName = getAssetPathPrefix() + getAssetNamePrefix() + "info.dat";
-        try (InputStream is = Utils.getContext().getAssets().open(fileName);
+    protected boolean loadInfoData(boolean useAssets) {
+        LOG.debug("loadInfoData() started; useAssets: {}", useAssets);
+
+        String fileName = getPathPrefix() + getNamePrefix() + "info.dat";
+
+        try (InputStream is = openFile(fileName, useAssets);
              BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is))) {
 
             String headerString = bufferedReader.readLine();
@@ -81,11 +125,11 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
             LOG.debug("loadInfoData() loaded MDI, baseDatabaseVersion={}, numberOfItems={}",
                     this.baseDatabaseVersion, this.numberOfItems);
 
-            loadInfoDataAfterLoadedHook();
+            loadInfoDataAfterLoadedHook(useAssets);
 
             return true;
         } catch (FileNotFoundException e) {
-            LOG.error("loadInfoData() the info-file is not found! HAVE YOU COPIED THE ASSETS? (see `Building` in README)", e);
+            LOG.debug("loadInfoData() the info-file wasn't found");
         } catch (Exception e) {
             LOG.error("loadInfoData() error during info file loading", e);
         }
@@ -93,13 +137,13 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
         return false;
     }
 
-    protected void loadInfoDataAfterLoadedHook() {}
+    protected void loadInfoDataAfterLoadedHook(boolean useAssets) {}
 
-    protected boolean loadSliceListData() {
+    protected boolean loadSliceListData(boolean useAssets) {
         LOG.debug("loadSliceListData() started");
 
-        String fileName = getAssetPathPrefix() + getAssetNamePrefix() + "list.dat";
-        try (InputStream is = Utils.getContext().getAssets().open(fileName);
+        String fileName = getPathPrefix() + getNamePrefix() + "list.dat";
+        try (InputStream is = openFile(fileName, useAssets);
              BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is))) {
             String nodes = bufferedReader.readLine();
 
@@ -120,6 +164,11 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
     public V getDbItemByNumber(String numberString) {
         LOG.info("getDbItemByNumber({}) started", numberString);
 
+        if (!isOperational()) {
+            LOG.warn("getDbItemByNumber() request on a non-operational DB; returning null");
+            return null;
+        }
+
         if (numberString == null || numberString.isEmpty()) return null;
 
         if (numberString.startsWith("+")) {
@@ -134,8 +183,6 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
             return null;
         }
 
-        checkLoaded();
-
         LOG.debug("getDbItemByNumber() calling internal method for {}", number);
         return getDbItemByNumberInternal(number);
     }
@@ -156,7 +203,7 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
             LOG.trace("getDataSlice() loading slice with sliceId={}", sliceId);
 
             slice = createDbDataSlice();
-            slice.loadFromAsset(Utils.getContext(), sliceId);
+            loadSlice(slice, sliceId);
 
             sliceCache.put(sliceId, slice);
         } else {
@@ -165,4 +212,24 @@ public abstract class AbstractDatabase<T extends AbstractDatabaseDataSlice<V>, V
         return slice;
     }
 
+    protected void loadSlice(T slice, int sliceId) {
+        LOG.debug("loadSlice() started with sliceId={}", sliceId);
+
+        String fileName = getPathPrefix() + getNamePrefix() + sliceId + ".dat";
+        loadSlice(slice, fileName, useAssets);
+    }
+
+    protected void loadSlice(T slice, String fileName, boolean useAssets) {
+        LOG.debug("loadSlice() started with fileName={}, useAssets={}", fileName, useAssets);
+
+        try (InputStream is = openFile(fileName, useAssets);
+             BufferedInputStream stream = new BufferedInputStream(is)) {
+
+            slice.loadFromStream(stream);
+        } catch (Exception e) {
+            LOG.error("loadSlice()", e);
+        }
+        LOG.trace("loadSlice() finished");
+    }
+
 }
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabaseDataSlice.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabaseDataSlice.java
index d4f91f2..c18d8aa 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabaseDataSlice.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/AbstractDatabaseDataSlice.java
@@ -1,14 +1,10 @@
 package dummydomain.yetanothercallblocker.sia.model.database;
 
-import android.content.Context;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.BufferedInputStream;
-import java.io.FileInputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.Arrays;
 
 import dummydomain.yetanothercallblocker.sia.utils.LittleEndianDataInputStream;
@@ -139,41 +135,6 @@ public abstract class AbstractDatabaseDataSlice<T> {
         return true;
     }
 
-    protected String getAssetPathPrefix() {
-        return "sia/";
-    }
-
-    protected abstract String getAssetNamePrefix();
-
-    public void loadFromAsset(Context context, int sliceId) {
-        LOG.debug("loadFromAsset() started with sliceId={}", sliceId);
-
-        String assetName = getAssetPathPrefix() + getAssetNamePrefix() + String.valueOf(sliceId) + ".dat";
-        LOG.trace("loadFromAsset() assetName={}", assetName);
-
-        try (InputStream is = context.getAssets().open(assetName);
-             BufferedInputStream stream = new BufferedInputStream(is)) {
-
-            loadFromStream(stream);
-        } catch (Exception e) {
-            LOG.error("loadFromAsset()", e);
-        }
-        LOG.trace("loadFromAsset() finished");
-    }
-
-    public void loadFromFile(String fileName) {
-        LOG.debug("loadFromFile({}) started", fileName);
-
-        try (FileInputStream fis = new FileInputStream(fileName);
-             BufferedInputStream stream = new BufferedInputStream(fis)) {
-
-            loadFromStream(stream);
-        } catch (Exception e) {
-            LOG.error("loadFromFile()", e);
-        }
-        LOG.trace("loadFromFile() finished");
-    }
-
     @Override
     public String toString() {
         return "AbstractDatabaseDataSlice{" +
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabase.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabase.java
index 23f428e..9cfccfc 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabase.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabase.java
@@ -11,7 +11,6 @@ import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.BufferedReader;
 import java.io.File;
-import java.io.FileFilter;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
@@ -24,11 +23,16 @@ import java.util.List;
 import java.util.zip.GZIPInputStream;
 
 import dummydomain.yetanothercallblocker.sia.network.WebService;
+import dummydomain.yetanothercallblocker.sia.utils.FileUtils;
 import dummydomain.yetanothercallblocker.sia.utils.Utils;
 import okhttp3.MediaType;
 import okhttp3.Response;
 import okhttp3.ResponseBody;
 
+import static dummydomain.yetanothercallblocker.sia.utils.FileUtils.getDataDir;
+import static dummydomain.yetanothercallblocker.sia.utils.FileUtils.getDataDirPath;
+import static dummydomain.yetanothercallblocker.sia.utils.FileUtils.openFile;
+
 public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSlice, CommunityDatabaseItem> {
 
     private enum UpdateResult {
@@ -37,13 +41,22 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
 
     private static final Logger LOG = LoggerFactory.getLogger(CommunityDatabase.class);
 
-    private int siaAppVersion = 114;
+    private static final int FALLBACK_APP_VERSION = 114;
+
+    private int siaAppVersion = FALLBACK_APP_VERSION;
+
+    protected final String secondaryPathPrefix;
 
     private SparseArray<CommunityDatabaseDataSlice> secondarySliceCache = new SparseArray<>();
 
     @SuppressLint("UseSparseArrays") // uses null as a special value
     private SparseArray<Boolean> existingSecondarySliceFiles = new SparseArray<>();
 
+    public CommunityDatabase(String pathPrefix, String secondaryPathPrefix) {
+        super(pathPrefix);
+        this.secondaryPathPrefix = secondaryPathPrefix;
+    }
+
     public int getEffectiveDbVersion() {
         checkLoaded();
 
@@ -56,18 +69,27 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
     }
 
     @Override
-    protected String getAssetNamePrefix() {
+    protected String getNamePrefix() {
         return "data_slice_";
     }
 
     @Override
-    protected boolean load() {
-        if (!super.load()) return false;
+    protected void reset() {
+        super.reset();
 
-        LOG.debug("load() started");
+        siaAppVersion = FALLBACK_APP_VERSION;
+        secondarySliceCache.clear();
+        existingSecondarySliceFiles.clear();
+    }
 
-        String fileName = getAssetPathPrefix() + "sia_info.dat";
-        try (InputStream is = Utils.getContext().getAssets().open(fileName);
+    @Override
+    protected boolean load(boolean useAssets) {
+        if (!super.load(useAssets)) return false;
+
+        LOG.debug("load() started; useAssets={}", useAssets);
+
+        String fileName = getPathPrefix() + "sia_info.dat";
+        try (InputStream is = openFile(fileName, useAssets);
              BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(is))) {
 
             if (!"SIA".equals(bufferedReader.readLine())) {
@@ -87,7 +109,7 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
     }
 
     @Override
-    protected void loadInfoDataAfterLoadedHook() {
+    protected void loadInfoDataAfterLoadedHook(boolean useAssets) {
         int oldDbVersion = Utils.getSettings().getBaseDbVersion();
         if (baseDatabaseVersion != oldDbVersion) {
             LOG.info("loadInfoDataAfterLoadedHook() base version changed; resetting secondary DB;" +
@@ -145,7 +167,7 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
             String path = getCachedSecondarySliceFilePath(sliceId);
             if (path != null) {
                 LOG.trace("getSecondaryDataSlice() slice file exists, loading from: {}", path);
-                communityDatabaseDataSlice.loadFromFile(path);
+                loadSlice(communityDatabaseDataSlice, path, false);
             } else {
                 LOG.trace("getSecondaryDataSlice() slice file doesn't exist");
             }
@@ -160,30 +182,25 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
         String path = getSecondarySliceFilePath(id);
         Boolean exists = existingSecondarySliceFiles.get(id, null);
         if (exists == null) {
-            exists = new File(path).exists();
+            exists = new File(getDataDirPath() + path).exists();
             existingSecondarySliceFiles.put(id, exists);
         }
         return exists ? path : null;
     }
 
     private String getSecondarySliceFilePath(int id) {
-        File dir = Utils.getContext().getFilesDir();
-        return dir.getAbsolutePath() + "/sia_updates_" + id + ".sia";
+        return getSecondaryDbPathPrefix() + id + ".sia";
     }
 
     public void resetSecondaryDatabase() {
         LOG.debug("resetSecondaryDatabase() started");
 
-        FileFilter fileFilter = new FileFilter() {
-            @Override
-            public boolean accept(File pathname) {
-                return pathname.getName().endsWith(".sia");
-            }
-        };
-
-        for (File file : Utils.getContext().getFilesDir().listFiles(fileFilter)) {
-            if (!file.delete()) {
-                LOG.warn("resetSecondaryDatabase() failed to delete secondary DB file: {}", file.getAbsolutePath());
+        File dir = new File(getDataDir(), getSecondaryDbPathPrefix());
+        if (dir.exists()) {
+            for (File file : dir.listFiles()) {
+                if (!file.delete()) {
+                    LOG.warn("resetSecondaryDatabase() failed to delete secondary DB file: {}", file.getAbsolutePath());
+                }
             }
         }
 
@@ -194,9 +211,22 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
         LOG.info("resetSecondaryDatabase() secondary DB was reset");
     }
 
+    protected String getSecondaryDbPathPrefix() {
+        return secondaryPathPrefix;
+    }
+
+    protected void createSecondaryDbDirectory() {
+        FileUtils.createDirectory(getDataDir(), getSecondaryDbPathPrefix());
+    }
+
     public void updateSecondaryDb() {
         LOG.info("updateSecondaryDb() started");
 
+        if (!isOperational()) {
+            LOG.warn("updateSecondaryDb() DB is not operational, update aborted");
+            return;
+        }
+
         long startTimestamp = System.currentTimeMillis();
 
         boolean updated = false;
@@ -267,6 +297,7 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
                             LOG.trace("updateSecondaryDbInternal() loading slice from received data");
                             CommunityDatabaseDataSlice slice = new CommunityDatabaseDataSlice();
                             if (slice.loadFromStream(bis)) {
+                                createSecondaryDbDirectory();
                                 LOG.trace("updateSecondaryDbInternal() distributing slice");
                                 updateSecondaryWithSlice(slice);
                             }
@@ -331,11 +362,11 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
                 if (newSlice.partialClone(dataSlice, sliceId, shortSliceIdToIndexMap, shortSliceIdToIndexToDeleteMap)) {
                     CommunityDatabaseDataSlice sliceFromExistingFile = new CommunityDatabaseDataSlice();
                     if (getCachedSecondarySliceFilePath(sliceId) != null) {
-                        sliceFromExistingFile.loadFromFile(filePath);
+                        loadSlice(sliceFromExistingFile, filePath, false);
                     }
 
                     try (BufferedOutputStream stream = new BufferedOutputStream(
-                            new FileOutputStream(filePath + ".update", false))) {
+                            new FileOutputStream(getDataDirPath() + filePath + ".update", false))) {
                         sliceFromExistingFile.writeMerged(newSlice, stream);
                     }
 
@@ -348,7 +379,7 @@ public class CommunityDatabase extends AbstractDatabase<CommunityDatabaseDataSli
             LOG.debug("updateSecondaryWithSlice() update files created, renaming files");
 
             for (int sliceId : updatedIndexes) {
-                String filePath = getSecondarySliceFilePath(sliceId);
+                String filePath = getDataDirPath() + getSecondarySliceFilePath(sliceId);
 
                 File updatedFile = new File(filePath + ".update");
                 File oldFile = new File(filePath);
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabaseDataSlice.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabaseDataSlice.java
index 520023f..608d5e0 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabaseDataSlice.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/CommunityDatabaseDataSlice.java
@@ -141,11 +141,6 @@ public class CommunityDatabaseDataSlice extends AbstractDatabaseDataSlice<Commun
         }
     }
 
-    @Override
-    protected String getAssetNamePrefix() {
-        return "data_slice_";
-    }
-
     public boolean writeMerged(CommunityDatabaseDataSlice newSlice, BufferedOutputStream outputStream) {
         LOG.debug("writeMerged() started with newSlice={}", newSlice);
 
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/DbManager.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/DbManager.java
new file mode 100644
index 0000000..cc0d7fb
--- /dev/null
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/DbManager.java
@@ -0,0 +1,48 @@
+package dummydomain.yetanothercallblocker.sia.model.database;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+
+import dummydomain.yetanothercallblocker.sia.SiaConstants;
+import dummydomain.yetanothercallblocker.sia.network.DbDownloader;
+import dummydomain.yetanothercallblocker.sia.utils.FileUtils;
+
+public class DbManager {
+
+    private static final Logger LOG = LoggerFactory.getLogger(DbManager.class);
+
+    public static boolean downloadMainDb() {
+        String url = "https://gitlab.com/xynngh/YetAnotherCallBlocker_data/raw/zip_v1/archives/sia.zip";
+        return downloadMainDb(url);
+    }
+
+    public static boolean downloadMainDb(String url) {
+        LOG.debug("downloadMainDb() started");
+
+        File dataDir = FileUtils.getDataDir();
+
+        String siaDir = SiaConstants.SIA_PATH_PREFIX;
+        String tmpUpdateDir = siaDir.substring(0, siaDir.indexOf('/')) + "-tmp/";
+        String oldDir = siaDir.substring(0, siaDir.indexOf('/')) + "-old/";
+
+        FileUtils.delete(dataDir, tmpUpdateDir);
+        FileUtils.createDirectory(dataDir, tmpUpdateDir);
+        LOG.debug("downloadMainDb() prepared dirs");
+
+        if (DbDownloader.download(url, FileUtils.getDataDirPath() + tmpUpdateDir)) {
+            LOG.debug("downloadMainDb() downloaded and unpacked");
+            new File(dataDir, siaDir).renameTo(new File(dataDir, oldDir));
+            new File(dataDir, tmpUpdateDir).renameTo(new File(dataDir, siaDir));
+            FileUtils.delete(dataDir, oldDir);
+            LOG.debug("downloadMainDb() folders moved");
+            return true;
+        } else {
+            LOG.warn("downloadMainDb() failed downloading");
+        }
+
+        return false;
+    }
+
+}
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabase.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabase.java
index 04ead18..0d816f3 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabase.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabase.java
@@ -2,8 +2,12 @@ package dummydomain.yetanothercallblocker.sia.model.database;
 
 public class FeaturedDatabase extends AbstractDatabase<FeaturedDatabaseDataSlice, FeaturedDatabaseItem> {
 
+    public FeaturedDatabase(String pathPrefix) {
+        super(pathPrefix);
+    }
+
     @Override
-    protected String getAssetNamePrefix() {
+    protected String getNamePrefix() {
         return "featured_slice_";
     }
 
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabaseDataSlice.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabaseDataSlice.java
index eb18874..27c3fd9 100644
--- a/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabaseDataSlice.java
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/model/database/FeaturedDatabaseDataSlice.java
@@ -31,9 +31,4 @@ public class FeaturedDatabaseDataSlice extends AbstractDatabaseDataSlice<Feature
         names[index] = stream.readUtf8StringChars(nameLength);
     }
 
-    @Override
-    protected String getAssetNamePrefix() {
-        return "featured_slice_";
-    }
-
 }
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/network/DbDownloader.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/network/DbDownloader.java
new file mode 100644
index 0000000..a59768e
--- /dev/null
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/network/DbDownloader.java
@@ -0,0 +1,61 @@
+package dummydomain.yetanothercallblocker.sia.network;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
+
+import dummydomain.yetanothercallblocker.sia.utils.FileUtils;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+import okhttp3.ResponseBody;
+import okio.Okio;
+import okio.Sink;
+
+public class DbDownloader {
+
+    private static final Logger LOG = LoggerFactory.getLogger(DbDownloader.class);
+
+    public static boolean download(String url, String path) {
+        LOG.info("download() started; path: {}", path);
+
+        LOG.debug("download() making a request");
+        Request request = new Request.Builder().url(url).build();
+        try (Response response = new OkHttpClient().newCall(request).execute()) {
+            LOG.debug("download() got response; successful: {}", response.isSuccessful());
+            if (response.isSuccessful()) {
+                ResponseBody body = response.body();
+
+                try (ZipInputStream zipInputStream = new ZipInputStream(body.byteStream())) {
+                    for (ZipEntry zipEntry; (zipEntry = zipInputStream.getNextEntry()) != null; ) {
+                        String name = zipEntry.getName();
+
+                        if (zipEntry.isDirectory()) {
+                            FileUtils.createDirectory(path + name);
+                            continue;
+                        }
+
+                        try (Sink out = Okio.sink(new File(path + name))) {
+                            Okio.buffer(Okio.source(zipInputStream)).readAll(out);
+                        }
+                    }
+
+                    LOG.debug("download() finished successfully");
+                    return true;
+                }
+            } else {
+                LOG.warn("download() unsuccessful response {}", response.message());
+            }
+        } catch (IOException e) {
+            LOG.warn("download()", e);
+        }
+
+        LOG.debug("download() finished unsuccessfully");
+        return false;
+    }
+
+}
diff --git a/app/src/main/java/dummydomain/yetanothercallblocker/sia/utils/FileUtils.java b/app/src/main/java/dummydomain/yetanothercallblocker/sia/utils/FileUtils.java
new file mode 100644
index 0000000..7a710c1
--- /dev/null
+++ b/app/src/main/java/dummydomain/yetanothercallblocker/sia/utils/FileUtils.java
@@ -0,0 +1,68 @@
+package dummydomain.yetanothercallblocker.sia.utils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+public class FileUtils {
+
+    private static final Logger LOG = LoggerFactory.getLogger(FileUtils.class);
+
+    public static File getDataDir() {
+        return Utils.getContext().getFilesDir();
+    }
+
+    public static String getDataDirPath() {
+        return getDataDir().getAbsolutePath() + "/";
+    }
+
+    public static InputStream openFile(String fileName, boolean asset) throws IOException {
+        if (asset) {
+            return Utils.getContext().getAssets().open(fileName);
+        } else {
+            return new FileInputStream(getDataDirPath() + fileName);
+        }
+    }
+
+    public static File createDirectory(String path) {
+        return createDirectory(new File(path));
+    }
+
+    public static File createDirectory(File base, String dir) {
+        return createDirectory(new File(base, dir));
+    }
+
+    public static File createDirectory(File d) {
+        if (!d.exists()) {
+            LOG.debug("createDirectory() creating: {}, result: {}", d.getAbsolutePath(), d.mkdir());
+        }
+        if (!d.isDirectory()) {
+            LOG.error("createDirectory() is not a directory: {}", d.getAbsolutePath());
+        }
+        return d;
+    }
+
+    public static void delete(File base, String name) {
+        delete(new File(base, name));
+    }
+
+    public static void delete(File file) {
+        if (file.exists()) {
+            if (file.isDirectory()) {
+                File[] list = file.listFiles();
+                if (list != null) {
+                    for (File f : list) {
+                        delete(f);
+                    }
+                }
+            } else {
+                file.delete();
+            }
+        }
+    }
+
+}
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index ce6ff85..4adb9ec 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -25,6 +25,54 @@
         android:paddingRight="@dimen/item_padding"
         android:showDividers="middle">
 
+        <TextView
+            android:id="@+id/noDbText"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="start"
+            android:layout_marginStart="@dimen/text_margin"
+            android:layout_marginLeft="@dimen/text_margin"
+            android:paddingTop="@dimen/item_padding"
+            android:text="@string/no_main_db"
+            android:textAlignment="textStart"
+            android:textColor="@color/rateNegative"
+            android:visibility="gone" />
+
+        <androidx.appcompat.widget.AppCompatButton
+            android:id="@+id/downloadDbButton"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="@dimen/text_margin"
+            android:layout_marginBottom="@dimen/text_margin"
+            android:onClick="onDownloadDbClick"
+            android:text="@string/download_main_db"
+            android:visibility="gone" />
+
+        <TextView
+            android:id="@+id/downloadingDbText"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="start"
+            android:layout_marginStart="@dimen/text_margin"
+            android:layout_marginLeft="@dimen/text_margin"
+            android:paddingTop="@dimen/item_padding"
+            android:text="@string/downloading_db"
+            android:textAlignment="textStart"
+            android:visibility="gone" />
+
+        <TextView
+            android:id="@+id/dbCouldNotBeDownloaded"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="start"
+            android:layout_marginStart="@dimen/text_margin"
+            android:layout_marginLeft="@dimen/text_margin"
+            android:paddingTop="@dimen/item_padding"
+            android:text="@string/db_could_not_be_downloaded"
+            android:textAlignment="textStart"
+            android:textColor="@color/rateNegative"
+            android:visibility="gone" />
+
         <androidx.appcompat.widget.SwitchCompat
             android:id="@+id/notificationsEnabledSwitch"
             android:layout_width="match_parent"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 093e97b..289b0dc 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -47,10 +47,14 @@
     <string name="reviews_loading">Loading reviews…</string>
 
     <string name="general_settings">General settings</string>
+    <string name="no_main_db">Database is not present! For the app to function offline you need to download DB. Press the button below to do it.</string>
+    <string name="downloading_db">Downloading DB…</string>
+    <string name="db_could_not_be_downloaded">Database couldn\'t be downloaded</string>
 
     <string name="incoming_call_notifications_enabled">Incoming call notifications enabled</string>
     <string name="block_calls">Block unwanted calls</string>
     <string name="auto_update_enabled">Auto-update enabled</string>
+    <string name="download_main_db">Download database</string>
 
     <string name="open_debug_activity">Open debug screen</string>
     <string name="debug_activity_label">Debug</string>