Add message about denied permissions

app/src/main/java/dummydomain/yetanothercallblocker/MainActivity.java

@@ -75,7 +75,7 @@ public class MainActivity extends AppCompatActivity {
                                            @NonNull int[] grantResults) {
         super.onRequestPermissionsResult(requestCode, permissions, grantResults);
 
-        // TODO: handle
+        PermissionHelper.onRequestPermissionsResult(this, requestCode, permissions, grantResults);
 
         loadCallLog();
     }

app/src/main/java/dummydomain/yetanothercallblocker/PermissionHelper.java

@@ -4,7 +4,9 @@ import android.Manifest;
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.os.Build;
+import android.widget.Toast;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.app.ActivityCompat;
 import androidx.core.content.ContextCompat;
@@ -41,6 +43,27 @@ public class PermissionHelper {
         }
     }
 
+    public static void onRequestPermissionsResult(@NonNull Context context, int requestCode,
+                                                  @NonNull String[] permissions,
+                                                  @NonNull int[] grantResults) {
+        boolean denied = false;
+
+        if (permissions.length == 0) {
+            denied = true;
+        } else {
+            for (int grantResult : grantResults) {
+                if (grantResult != PackageManager.PERMISSION_GRANTED) {
+                    denied = true;
+                    break;
+                }
+            }
+        }
+
+        if (denied) {
+            Toast.makeText(context, R.string.denied_permissions_message, Toast.LENGTH_SHORT).show();
+        }
+    }
+
     public static boolean havePermission(Context context, String permission) {
         return ContextCompat.checkSelfPermission(context, permission)
                 == PackageManager.PERMISSION_GRANTED;

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

@@ -50,6 +50,8 @@
     <string name="title_activity_reviews">Reviews</string>
     <string name="reviews_loading">Loading reviews…</string>
 
+    <string name="denied_permissions_message">Some functionality may not work due to denied permissions</string>
+
     <string name="general_settings">General settings</string>
 
     <string name="no_main_db_title">Download main database</string>