Minor update to show off the possiblities for the refactoring. This is just a short step, major improvements are still to come.

app/src/main/java/info/nightscout/androidaps/Services/DataService.java

@@ -20,6 +20,7 @@ import info.nightscout.androidaps.R;
 import info.nightscout.androidaps.data.ProfileStore;
 import info.nightscout.androidaps.db.BgReading;
 import info.nightscout.androidaps.db.CareportalEvent;
+import info.nightscout.androidaps.db.DataServiceManager;
 import info.nightscout.androidaps.events.EventNewBasalProfile;
 import info.nightscout.androidaps.plugins.ConfigBuilder.ConfigBuilderPlugin;
 import info.nightscout.androidaps.plugins.ConstraintsObjectives.ObjectivesPlugin;
@@ -522,14 +523,14 @@ public class DataService extends IntentService {
     private void handleRemovedFoodRecord(String _id) {
 
         try {
-            MainApp.getDbHelper().foodHelper.getDao().deleteByNSId(_id);
+            DataServiceManager.getInstance().getFoodService().deleteByNSId(_id);
         } catch (SQLException e) {
             log.error("Unhandled exception", e);
         }
     }
 
     public void handleAddChangeFoodRecord(JSONObject trJson) throws JSONException {
-        MainApp.getDbHelper().foodHelper.createFoodFromJsonIfNotExists(trJson);
+        DataServiceManager.getInstance().getFoodService().createFoodFromJsonIfNotExists(trJson);
     }
 
     private void handleRemovedRecordFromNS(String _id) {

app/src/main/java/info/nightscout/androidaps/db/DataServiceManager.java

@@ -0,0 +1,25 @@
+package info.nightscout.androidaps.db;
+
+/**
+ * This class should get registered in the MainApp.
+ */
+
+public class DataServiceManager {
+
+    private static final DataServiceManager INSTANCE = new DataServiceManager();
+
+    private FoodService foodService;
+
+    public static DataServiceManager getInstance() {
+        return INSTANCE;
+    }
+
+    public FoodService getFoodService() {
+        if (this.foodService == null) {
+            this.foodService = new FoodService();
+        }
+
+        return foodService;
+    }
+
+}

app/src/main/java/info/nightscout/androidaps/db/DatabaseHelper.java

@@ -35,7 +35,6 @@ import info.nightscout.androidaps.data.Profile;
 import info.nightscout.androidaps.data.ProfileStore;
 import info.nightscout.androidaps.events.EventCareportalEventChange;
 import info.nightscout.androidaps.events.EventExtendedBolusChange;
-import info.nightscout.androidaps.events.EventFoodDatabaseChanged;
 import info.nightscout.androidaps.events.EventNewBG;
 import info.nightscout.androidaps.events.EventProfileSwitchChange;
 import info.nightscout.androidaps.events.EventRefreshOverview;
@@ -55,6 +54,14 @@ import info.nightscout.utils.DateUtil;
 import info.nightscout.utils.NSUpload;
 import info.nightscout.utils.PercentageSplitter;
 
+/**
+ * This Helper contains all resource to provide a central DB management functionality. Only methods handling
+ * data-structure (and not the DB content) should be contained in here (meaning DDL and not SQL).
+ *
+ * This class can safely be called from Services, but should not call Services to avoid circular dependencies.
+ * One major issue with this (right now) are the scheduled events, which are put into the service. Therefor all
+ * direct calls to the corresponding methods (eg. resetDatabases) should be done by a central service.
+ */
 public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
     private static Logger log = LoggerFactory.getLogger(DatabaseHelper.class);
 
@@ -94,12 +101,9 @@ public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
     private static final ScheduledExecutorService profileSwitchEventWorker = Executors.newSingleThreadScheduledExecutor();
     private static ScheduledFuture<?> scheduledProfileSwitchEventPost = null;
 
-    public FoodHelper foodHelper;
-
     public DatabaseHelper(Context context) {
         super(context, DATABASE_NAME, null, DATABASE_VERSION);
         onCreate(getWritableDatabase(), getConnectionSource());
-        foodHelper = new FoodHelper(getConnectionSource());
         //onUpgrade(getWritableDatabase(), getConnectionSource(), 1,1);
     }
 
@@ -219,7 +223,7 @@ public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
             TableUtils.createTableIfNotExists(connectionSource, ExtendedBolus.class);
             TableUtils.createTableIfNotExists(connectionSource, CareportalEvent.class);
             TableUtils.createTableIfNotExists(connectionSource, ProfileSwitch.class);
-            foodHelper.resetFood();
+            resetFood();
             updateEarliestDataChange(0);
         } catch (SQLException e) {
             log.error("Unhandled exception", e);
@@ -232,7 +236,6 @@ public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
         scheduleTemporaryTargetChange();
         scheduleCareportalEventChange();
         scheduleProfileSwitchChange();
-        foodHelper.scheduleFoodChange();
         new java.util.Timer().schedule(
                 new java.util.TimerTask() {
                     @Override
@@ -308,6 +311,17 @@ public class DatabaseHelper extends OrmLiteSqliteOpenHelper {
         scheduleProfileSwitchChange();
     }
 
+    public void resetFood() {
+        try {
+            TableUtils.dropTable(this.getConnectionSource(), Food.class, true);
+            TableUtils.createTableIfNotExists(this.getConnectionSource(), Food.class);
+        } catch (SQLException e) {
+            log.error("Unhandled exception", e);
+        }
+    }
+
+
+
     // ------------------ getDao -------------------------------------------
 
     private Dao<TempTarget, Long> getDaoTempTargets() throws SQLException {

app/src/main/java/info/nightscout/androidaps/db/FoodDao.java

@@ -86,7 +86,6 @@ public class FoodDao extends BaseDaoImpl<Food, Long> {
                         old.copyFrom(food);
                         this.create(old);
                         log.debug("FOOD: Updating record by _id: " + old.toString());
-                        FoodHelper.scheduleFoodChange();
                         return true;
                     } else {
                         return false;
@@ -95,7 +94,6 @@ public class FoodDao extends BaseDaoImpl<Food, Long> {
             }
             this.createOrUpdate(food);
             log.debug("FOOD: New record: " + food.toString());
-            FoodHelper.scheduleFoodChange();
             return true;
         } catch (SQLException e) {
             log.error("Unhandled exception", e);
@@ -103,39 +101,6 @@ public class FoodDao extends BaseDaoImpl<Food, Long> {
         return false;
     }
 
-    /**
-     * deletes an entry by its NS Id.
-     *
-     * Basically a convenience method for findByNSId and deleteFood.
-     *
-     * should be moved to a Service
-     *
-     * @param _id
-     */
-    public void deleteByNSId(String _id) throws SQLException {
-        Food stored = findByNSId(_id);
-        if (stored != null) {
-            log.debug("FOOD: Removing Food record from database: " + stored.toString());
-            this.deleteFood(stored);
-        }
-    }
-
-    /**
-     * deletes the food and sends the foodChange Event
-     *
-     * should be moved ot a Service
-     *
-     * @param food
-     */
-    public void deleteFood(Food food) {
-        try {
-            this.delete(food);
-            FoodHelper.scheduleFoodChange();
-        } catch (SQLException e) {
-            log.error("Unhandled exception", e);
-        }
-    }
-
     /**
      * finds food by its NS Id.
      *

app/src/main/java/info/nightscout/androidaps/db/FoodService.java

@@ -0,0 +1,175 @@
+package info.nightscout.androidaps.db;
+
+import android.content.Intent;
+import android.os.IBinder;
+import android.support.annotation.Nullable;
+
+import com.j256.ormlite.android.apptools.OrmLiteBaseService;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.sql.SQLException;
+import java.util.List;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+import info.nightscout.androidaps.MainApp;
+import info.nightscout.androidaps.events.Event;
+import info.nightscout.androidaps.events.EventFoodDatabaseChanged;
+
+/**
+ * Created by mike on 24.09.2017.
+ */
+
+public class FoodService extends OrmLiteBaseService<DatabaseHelper> {
+    private static Logger log = LoggerFactory.getLogger(FoodService.class);
+
+    private static final ScheduledExecutorService foodEventWorker = Executors.newSingleThreadScheduledExecutor();
+    private static ScheduledFuture<?> scheduledFoodEventPost = null;
+
+    public FoodDao getDao() {
+        return FoodDao.with(this.getConnectionSource());
+    }
+
+    /**
+     * This service method is just taking care about the Food-Table,
+     * a central dataService should be use for throwing events for all
+     * tables.
+     */
+    public void resetFood() {
+        this.getHelper().resetFood();
+        scheduleFoodChange();
+    }
+
+    /**
+     * A place to centrally register events to be posted, if any data changed.
+     * This should be implemented in an abstract service-class.
+     *
+     * We do need to make sure, that ICallback is extended to be able to handle multiple
+     * events, or handle a list of events.
+     *
+     * on some methods the earliestDataChange event is handled separatly, in that it is checked if it is
+     * set to null by another event already (eg. scheduleExtendedBolusChange).
+     *
+     * @param event
+     * @param eventWorker
+     * @param callback
+     */
+    private void scheduleEvent(final Event event, ScheduledExecutorService eventWorker,
+                               final ICallback callback) {
+
+        class PostRunnable implements Runnable {
+            public void run() {
+                log.debug("Firing EventFoodChange");
+                MainApp.bus().post(event);
+                callback.setPost(null);
+            }
+        }
+        // prepare task for execution in 1 sec
+        // cancel waiting task to prevent sending multiple posts
+        if (callback.getPost() != null)
+            callback.getPost().cancel(false);
+        Runnable task = new PostRunnable();
+        final int sec = 1;
+        callback.setPost(eventWorker.schedule(task, sec, TimeUnit.SECONDS));
+    }
+
+    /**
+     * Schedule a foodChange Event.
+     */
+    public void scheduleFoodChange() {
+        this.scheduleEvent(new EventFoodDatabaseChanged(), foodEventWorker, new ICallback() {
+            @Override
+            public void setPost(ScheduledFuture<?> post) {
+                scheduledFoodEventPost = post;
+            }
+
+            @Override
+            public ScheduledFuture<?> getPost() {
+                return scheduledFoodEventPost;
+            }
+        });
+    }
+
+    public List<Food> getFoodData() {
+        return this.getDao().getFoodData();
+    }
+
+    /*
+    {
+        "_id": "551ee3ad368e06e80856e6a9",
+        "type": "food",
+        "category": "Zakladni",
+        "subcategory": "Napoje",
+        "name": "Mleko",
+        "portion": 250,
+        "carbs": 12,
+        "gi": 1,
+        "created_at": "2015-04-14T06:59:16.500Z",
+        "unit": "ml"
+    }
+     */
+    public void createFoodFromJsonIfNotExists(JSONObject trJson) {
+        try {
+            Food food = Food.createFromJson(trJson);
+            this.getDao().createOrUpdate(food);
+        } catch (JSONException | SQLException e) {
+            log.error("Unhandled exception", e);
+        }
+    }
+
+    /**
+     * Create of update a food record by the NS (Nightscout) Id.
+     *
+     * @param food
+     * @return
+     */
+    public boolean createOrUpdateByNS(Food food) {
+        boolean result = this.getDao().createOrUpdateByNS(food);
+        if (result) this.scheduleFoodChange();
+
+        return result;
+    }
+
+    /**
+     * deletes an entry by its NS Id.
+     *
+     * Basically a convenience method for findByNSId and delete.
+     *
+     * @param _id
+     */
+    public void deleteByNSId(String _id) throws SQLException {
+        Food stored = this.getDao().findByNSId(_id);
+        if (stored != null) {
+            log.debug("FOOD: Removing Food record from database: " + stored.toString());
+            this.delete(stored);
+        }
+    }
+
+    /**
+     * deletes the food and sends the foodChange Event
+     *
+     * should be moved ot a Service
+     *
+     * @param food
+     */
+    public void delete(Food food) {
+        try {
+            this.getDao().delete(food);
+            this.scheduleFoodChange();
+        } catch (SQLException e) {
+            log.error("Unhandled exception", e);
+        }
+    }
+
+    @Nullable
+    @Override
+    public IBinder onBind(Intent intent) {
+        return null;
+    }
+}

app/src/main/java/info/nightscout/androidaps/db/ICallback.java

@@ -0,0 +1,15 @@
+package info.nightscout.androidaps.db;
+
+import java.util.concurrent.ScheduledFuture;
+
+/**
+ * Created by triplem on 05.01.18.
+ */
+
+public interface ICallback {
+
+    void setPost(ScheduledFuture<?> post);
+
+    ScheduledFuture<?> getPost();
+
+}

app/src/main/java/info/nightscout/androidaps/plugins/Food/FoodFragment.java

@@ -30,6 +30,7 @@ import java.util.List;
 
 import info.nightscout.androidaps.MainApp;
 import info.nightscout.androidaps.R;
+import info.nightscout.androidaps.db.DataServiceManager;
 import info.nightscout.androidaps.db.Food;
 import info.nightscout.androidaps.events.EventFoodDatabaseChanged;
 import info.nightscout.androidaps.plugins.Common.SubscriberFragment;
@@ -121,7 +122,7 @@ public class FoodFragment extends SubscriberFragment {
                 }
             });
 
-            RecyclerViewAdapter adapter = new RecyclerViewAdapter(MainApp.getDbHelper().foodHelper.getDao().getFoodData());
+            RecyclerViewAdapter adapter = new RecyclerViewAdapter(DataServiceManager.getInstance().getFoodService().getFoodData());
             recyclerView.setAdapter(adapter);
 
             loadData();
@@ -144,7 +145,7 @@ public class FoodFragment extends SubscriberFragment {
     }
 
     void loadData() {
-        unfiltered = MainApp.getDbHelper().foodHelper.getDao().getFoodData();
+        unfiltered = DataServiceManager.getInstance().getFoodService().getFoodData();
     }
 
     void fillCategories() {
@@ -299,7 +300,7 @@ public class FoodFragment extends SubscriberFragment {
                                 if (_id != null && !_id.equals("")) {
                                     NSUpload.removeFoodFromNS(_id);
                                 }
-                                MainApp.getDbHelper().foodHelper.getDao().deleteFood(food);
+                                DataServiceManager.getInstance().getFoodService().delete(food);
                             }
                         });
                         builder.setNegativeButton(MainApp.sResources.getString(R.string.cancel), null);