Add WidgetAlarm for managing recurring widget updates

- Introduced `WidgetAlarm` object to handle the setting and cancellation of recurring alarms for widget updates.
- Added methods to create or retrieve `PendingIntent` instances associated with widgets.
- Ensured that alarms are set to trigger widget updates every minute, avoiding multiple alarms for the same widget.
- Integrated logging with Timber for tracking alarm creation and cancellation.

AnkiDroid/src/main/java/com/ichi2/widget/DeckPickerWidget.kt

@@ -174,6 +174,7 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
                 Timber.d("Selected deck IDs: ${selectedDeckIds.joinToString(", ")} for widget ID: $widgetId")
                 updateWidget(context, appWidgetManager, widgetId, selectedDeckIds)
             }
+            WidgetAlarm.setRecurringAlarm(context, widgetId)
         }
 
         Timber.d("Widget update process completed for appWidgetIds: ${appWidgetIds.joinToString(", ")}")
@@ -236,7 +237,7 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
                 )
                 if (appWidgetId != AppWidgetManager.INVALID_APPWIDGET_ID) {
                     Timber.d("Deleting widget with ID: $appWidgetId")
-
+                    WidgetAlarm.cancelRecurringAlarm(context, appWidgetId)
                     widgetPreferences.deleteDeckPickerWidgetData(appWidgetId)
                 } else {
                     Timber.e("Invalid widget ID received in ACTION_APPWIDGET_DELETED")
@@ -269,7 +270,7 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
         val widgetPreferences = WidgetPreferences(context)
 
         appWidgetIds?.forEach { widgetId ->
-
+            WidgetAlarm.cancelRecurringAlarm(context, widgetId)
             widgetPreferences.deleteDeckPickerWidgetData(widgetId)
         }
     }

AnkiDroid/src/main/java/com/ichi2/widget/WidgetAlarm.kt

@@ -0,0 +1,118 @@
+/*
+ *  Copyright (c) 2024 Anoop <[email protected]>
+ *
+ *  This program is free software; you can redistribute it and/or modify it under
+ *  the terms of the GNU General Public License as published by the Free Software
+ *  Foundation; either version 3 of the License, or (at your option) any later
+ *  version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ *  PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.ichi2.widget
+
+import android.app.AlarmManager
+import android.app.PendingIntent
+import android.appwidget.AppWidgetManager
+import android.content.Context
+import android.content.Intent
+import android.os.SystemClock
+import timber.log.Timber
+import kotlin.time.Duration.Companion.seconds
+
+object WidgetAlarm {
+
+    /**
+     * Provides the AlarmManager instance.
+     *
+     * @param context the context of the application
+     * @return the AlarmManager instance
+     */
+    private fun alarmManager(context: Context): AlarmManager {
+        return context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
+    }
+
+    /**
+     * Retrieves or creates a PendingIntent for the widget.
+     *
+     * @param context the context of the application
+     * @param appWidgetId the ID of the widget
+     * @param create whether to create a new PendingIntent or just retrieve it
+     * @return the PendingIntent for the widget
+     */
+    private fun getPendingIntent(
+        context: Context,
+        appWidgetId: AppWidgetId,
+        create: Boolean
+    ): PendingIntent? {
+        val intent = Intent(context, DeckPickerWidget::class.java).apply {
+            action = DeckPickerWidget.ACTION_UPDATE_WIDGET
+            putExtra(AppWidgetManager.EXTRA_APPWIDGET_ID, appWidgetId)
+        }
+        return PendingIntent.getBroadcast(
+            context,
+            appWidgetId,
+            intent,
+            if (create) {
+                PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
+            } else {
+                PendingIntent.FLAG_NO_CREATE or PendingIntent.FLAG_IMMUTABLE
+            }
+        )
+    }
+
+    /**
+     * Ensure a recurring alarm is set to update the widget every minute.
+     *
+     * If the alarm is already set for the widget, this method does nothing.
+     * This ensures that multiple alarms are not created for the same widget,
+     * preventing potential performance issues or unexpected behavior.
+     *
+     * @param context the context of the application
+     * @param appWidgetId the ID of the widget
+     */
+    fun setRecurringAlarm(context: Context, appWidgetId: AppWidgetId) {
+        val pendingIntent = getPendingIntent(context, appWidgetId, create = false)
+
+        if (pendingIntent != null) {
+            Timber.v("Recurring alarm PendingIntent already exists for widget ID: $appWidgetId")
+            return
+        }
+
+        Timber.v("Creating a new recurring alarm PendingIntent for widget ID: $appWidgetId")
+
+        val alarmManager = alarmManager(context)
+        val newPendingIntent = getPendingIntent(context, appWidgetId, create = true)
+
+        // Set alarm to trigger every minute
+        val ONE_MINUTE_MILLIS = 60.seconds.inWholeMilliseconds
+        if (newPendingIntent != null) {
+            alarmManager.setRepeating(
+                AlarmManager.ELAPSED_REALTIME,
+                SystemClock.elapsedRealtime() + ONE_MINUTE_MILLIS,
+                ONE_MINUTE_MILLIS,
+                newPendingIntent
+            )
+        }
+    }
+
+    /**
+     * Cancels the recurring alarm for the widget.
+     *
+     * @param context the context of the application
+     * @param appWidgetId the ID of the widget
+     */
+    fun cancelRecurringAlarm(context: Context, appWidgetId: AppWidgetId) {
+        val pendingIntent = getPendingIntent(context, appWidgetId, create = true)
+        val alarmManager = alarmManager(context)
+        Timber.d("Canceling recurring alarm for widget ID: $appWidgetId")
+        if (pendingIntent != null) {
+            alarmManager.cancel(pendingIntent)
+        }
+    }
+}