Option to auto check for extension updates (#2680)

* Option to auto check for extension updates

* Addressing comments

* Added foreground check for extensions

* Added Extension Preference widget

app/src/main/java/eu/kanade/tachiyomi/data/notification/NotificationReceiver.kt

@@ -437,5 +437,19 @@ class NotificationReceiver : BroadcastReceiver() {
             }
             return PendingIntent.getBroadcast(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
         }
+
+        /**
+         * Returns [PendingIntent] that opens the extensions controller.
+         *
+         * @param context context of application
+         */
+        internal fun openExtensionsPendingActivity(context: Context): PendingIntent {
+            val newIntent =
+                Intent(context, MainActivity::class.java).setAction(MainActivity.SHORTCUT_EXTENSIONS)
+                    .addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
+            return PendingIntent.getActivity(
+                context, 0, newIntent, PendingIntent.FLAG_UPDATE_CURRENT
+            )
+        }
     }
 }

app/src/main/java/eu/kanade/tachiyomi/data/notification/Notifications.kt

@@ -39,6 +39,12 @@ object Notifications {
     const val ID_NEW_CHAPTERS = -301
     const val GROUP_NEW_CHAPTERS = "eu.kanade.tachiyomi.NEW_CHAPTERS"
 
+    /**
+     * Notification channel and ids used by the library updater.
+     */
+    const val CHANNEL_UPDATES_TO_EXTS = "updates_ext_channel"
+    const val ID_UPDATES_TO_EXTS = -401
+
     /**
      * Creates the notification channels introduced in Android Oreo.
      *
@@ -59,7 +65,10 @@ object Notifications {
                     setShowBadge(false)
                 },
                 NotificationChannel(CHANNEL_NEW_CHAPTERS, context.getString(R.string.channel_new_chapters),
-                        NotificationManager.IMPORTANCE_DEFAULT)
+                        NotificationManager.IMPORTANCE_DEFAULT),
+                NotificationChannel(CHANNEL_UPDATES_TO_EXTS, context.getString(R.string.channel_ext_updates),
+                        NotificationManager.IMPORTANCE_DEFAULT
+        )
         )
         context.notificationManager.createNotificationChannels(channels)
     }