Differential D55 Diff 187 src/it/reyboz/bustorino/data/FavoritesLiveData.java

Changeset View

Standalone View

src/it/reyboz/bustorino/data/FavoritesLiveData.java

This file was added.

				package it.reyboz.bustorino.data;

				import android.annotation.SuppressLint;
				import android.content.AsyncQueryHandler;
				import android.content.ContentResolver;
				import android.content.Context;
				import android.database.ContentObserver;
				import android.database.Cursor;
				import android.net.Uri;
				import android.os.AsyncTask;
				import android.os.Handler;
				import android.util.Log;

				import androidx.annotation.NonNull;
				import androidx.annotation.Nullable;
				import androidx.core.content.ContentResolverCompat;
				import androidx.core.os.CancellationSignal;
				import androidx.core.os.OperationCanceledException;
				import androidx.lifecycle.LiveData;

				import java.lang.ref.WeakReference;
				import java.util.ArrayList;
				import java.util.Arrays;
				import java.util.Collection;
				import java.util.Collections;
				import java.util.List;

				import it.reyboz.bustorino.backend.Route;
				import it.reyboz.bustorino.backend.Stop;

				import it.reyboz.bustorino.data.NextGenDB.Contract.*;

				public class FavoritesLiveData extends LiveData<List<Stop>> implements CustomAsyncQueryHandler.AsyncQueryListener {
				private static final String TAG = "FavoritesLiveData";
				private final boolean notifyChangesDescendants;


				@NonNull
				private final Context mContext;

				@NonNull
				private final FavoritesLiveData.ForceLoadContentObserver mObserver;
				private final CustomAsyncQueryHandler queryHandler;


				private final Uri FAVORITES_URI = AppDataProvider.getUriBuilderToComplete().appendPath(
				AppDataProvider.FAVORITES).build();


				private final int FAV_TOKEN = 23, STOPS_TOKEN_BASE=90;


				@Nullable
				private List<Stop> stopsFromFavorites, stopsDone;

				private boolean isQueryRunning = false;
				private int stopNeededCount = 0;

				public FavoritesLiveData(@NonNull Context context, boolean notifyDescendantsChanges) {
				super();
				mContext = context.getApplicationContext();
				mObserver = new FavoritesLiveData.ForceLoadContentObserver();
				notifyChangesDescendants = notifyDescendantsChanges;
				queryHandler = new CustomAsyncQueryHandler(mContext.getContentResolver(),this);

				}

				private void loadData() {
				loadData(false);
				}
				private static Uri.Builder getStopsBuilder(){
				return AppDataProvider.getUriBuilderToComplete().appendPath("stop");

				}

				private void loadData(boolean forceQuery) {
				Log.d(TAG, "loadData()");

				if (!forceQuery){
				if (getValue()!= null){
				//Data already loaded
				return;
				}
				}
				if (isQueryRunning){
				//we are waiting for data, we will get an update soon
				return;
				}

				isQueryRunning = true;
				queryHandler.startQuery(FAV_TOKEN,null, FAVORITES_URI, UserDB.getFavoritesColumnNamesAsArray, null, null, null);


				}

				@Override
				protected void onActive() {
				Log.d(TAG, "onActive()");
				loadData();
				}

				@Override
				protected void onInactive() {
				Log.d(TAG, "onInactive()");

				}

				/**
				* Clear the data for the cursor
				*/
				public void onClear(){

				ContentResolver resolver = mContext.getContentResolver();
				resolver.unregisterContentObserver(mObserver);

				}


				@Override
				protected void setValue(List<Stop> stops) {

				ContentResolver resolver = mContext.getContentResolver();
				resolver.registerContentObserver(FAVORITES_URI, notifyChangesDescendants,mObserver);

				super.setValue(stops);
				}

				@Override
				public void onQueryComplete(int token, Object cookie, Cursor cursor) {
				if (token == FAV_TOKEN) {
				stopsFromFavorites = UserDB.getFavoritesFromCursor(cursor, UserDB.getFavoritesColumnNamesAsArray);
				cursor.close();

				for (int i = 0; i < stopsFromFavorites.size(); i++) {
				Stop s = stopsFromFavorites.get(i);
				queryHandler.startQuery(STOPS_TOKEN_BASE + i, null, getStopsBuilder().appendPath(s.ID).build(),
				NextGenDB.QUERY_COLUMN_stops_all, null, null, null);
				}
				stopNeededCount = stopsFromFavorites.size();
				stopsDone = new ArrayList<>();


				} else if(token >= STOPS_TOKEN_BASE){
				final int index = token - STOPS_TOKEN_BASE;
				assert stopsFromFavorites != null;
				Stop stopUpdate = stopsFromFavorites.get(index);
				Stop finalStop;

				List<Stop> result = Arrays.asList(NextGenDB.getStopsFromCursorAllFields(cursor));
				cursor.close();
				if (result.size() < 1){
				// stop is not in the DB
				finalStop = stopUpdate;
				} else{
				finalStop = result.get(0);
				assert (finalStop.ID.equals(stopUpdate.ID));
				finalStop.setStopUserName(stopUpdate.getStopUserName());
				}
				if (stopsDone!=null)
				stopsDone.add(finalStop);

				stopNeededCount--;
				if (stopNeededCount == 0) {
				// we have finished the queries
				isQueryRunning = false;
				Collections.sort(stopsDone);

				setValue(stopsDone);
				}

				}
				}


				/**
				* Content Observer that forces reload of cursor when data changes
				* On different thread (new Handler)
				*/
				public final class ForceLoadContentObserver
				extends ContentObserver {

				public ForceLoadContentObserver() {
				super(new Handler());
				}

				@Override
				public boolean deliverSelfNotifications() {
				return true;
				}

				@Override
				public void onChange(boolean selfChange) {
				Log.d(TAG, "ForceLoadContentObserver.onChange()");
				loadData(true);
				}

				}


				}