fix: only ask for Notification permission once on first startup

This seems to be the only reliable way of making sure we only ever
bother the user once. If they accept, from then on the permission
check will be successful. If they deny or swipe away, we never ask
again at startup and the user has to manually change it in the
settings or go to our settings and re-do the prompt by activating
notifications.

Author: VougJo23

app/src/main/java/org/schabi/newpipe/MainActivity.java

@@ -179,12 +179,17 @@ protected void onCreate(final Bundle savedInstanceState) {
         }
         openMiniPlayerUponPlayerStarted();
 
-        if (PermissionHelper.checkPostNotificationsPermission(this,
-                PermissionHelper.POST_NOTIFICATIONS_REQUEST_CODE)) {
-            // Schedule worker for checking for new streams and creating corresponding notifications
-            // if this is enabled by the user.
-            NotificationWorker.initialize(this);
-        }
+        PermissionHelper.checkPostNotificationsPermissionOnStartup(
+                this,
+                notificationAllowed -> {
+                    // Schedule worker for checking for new streams and creating corresponding
+                    // notifications if this is enabled by the user.
+                    if (Boolean.TRUE.equals(notificationAllowed)) {
+                        NotificationWorker.initialize(this);
+                    }
+                }
+        );
+
         if (!UpdateSettingsFragment.wasUserAskedForConsent(this)
                 && !App.getApp().isFirstRun()
                 && ReleaseVersionUtil.INSTANCE.isReleaseApk()) {

app/src/main/java/org/schabi/newpipe/util/PermissionHelper.java

@@ -1,23 +1,32 @@
 package org.schabi.newpipe.util;
 
 import android.Manifest;
+import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.ActivityNotFoundException;
 import android.content.Context;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.net.Uri;
 import android.os.Build;
 import android.provider.Settings;
 import android.widget.Toast;
 
+import androidx.activity.ComponentActivity;
+import androidx.activity.result.ActivityResultCallback;
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts;
 import androidx.annotation.RequiresApi;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
+import androidx.preference.PreferenceManager;
 
 import org.schabi.newpipe.R;
 import org.schabi.newpipe.settings.NewPipeSettings;
 
+import java.util.function.Consumer;
+
 public final class PermissionHelper {
     public static final int POST_NOTIFICATIONS_REQUEST_CODE = 779;
     public static final int DOWNLOAD_DIALOG_REQUEST_CODE = 778;
@@ -81,17 +90,59 @@ public static boolean checkWriteStoragePermissions(final Activity activity,
         return true;
     }
 
-    public static boolean checkPostNotificationsPermission(final Activity activity,
-                                                           final int requestCode) {
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU
-                && ContextCompat.checkSelfPermission(activity,
-                Manifest.permission.POST_NOTIFICATIONS)
-                != PackageManager.PERMISSION_GRANTED) {
-            ActivityCompat.requestPermissions(activity,
-                    new String[] {Manifest.permission.POST_NOTIFICATIONS}, requestCode);
-            return false;
+
+    /**
+     * Check that we have the notification permission or ask the user for permission.
+     *
+     * @param activity main activity
+     * @param userChoice a callback that gets called with the user choice
+     */
+    public static void checkPostNotificationsPermissionOnStartup(
+            final ComponentActivity activity,
+            final Consumer<Boolean> userChoice) {
+
+        // On Android before TIRAMISU, notifications are always allowed to be sent
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU) {
+            userChoice.accept(true);
+            return;
         }
-        return true;
+
+        // if we have the permission already, continue
+        if (ContextCompat.checkSelfPermission(activity, Manifest.permission.POST_NOTIFICATIONS)
+                == PackageManager.PERMISSION_GRANTED) {
+            userChoice.accept(true);
+            return;
+        }
+
+        // if we already asked the user, don’t ask again
+        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
+        final String wasAskedKey = activity.getString(
+                R.string.user_was_asked_notification_permission_on_startup_key);
+        if (prefs.getBoolean(wasAskedKey, false)) {
+            userChoice.accept(false);
+            return;
+        }
+
+        // else let’s ask the user for permission
+        @SuppressLint("ApplySharedPref")
+        final ActivityResultCallback<Boolean> cb = isGranted -> {
+            // first make sure that we only ever ask the user once on startup
+            final SharedPreferences prefs2 =
+                    PreferenceManager.getDefaultSharedPreferences(activity);
+            // commit setting before doing anything else
+            prefs2.edit().putBoolean(wasAskedKey, true).commit();
+
+            // forward the user choice
+            userChoice.accept(isGranted);
+        };
+
+        final ActivityResultLauncher<String> notificationRequestReference =
+                activity.registerForActivityResult(
+                        new ActivityResultContracts.RequestPermission(),
+                        cb
+                );
+
+        notificationRequestReference.launch(Manifest.permission.POST_NOTIFICATIONS);
     }
 
     /**

app/src/main/res/values/settings_keys.xml

@@ -1405,6 +1405,7 @@
 
     <string name="recaptcha_cookies_key">recaptcha_cookies_key</string>
 
+    <string name="user_was_asked_notification_permission_on_startup_key">user_was_asked_notification_permission_on_startup</string>
     <string name="enable_streams_notifications">enable_streams_notifications</string>
     <string name="streams_notifications_interval_key">streams_notifications_interval</string>
     <string name="streams_notifications_interval_default">14400</string>