refactor

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

@@ -23,12 +23,14 @@ import android.content.Context
 import android.content.Intent
 import android.os.SystemClock
 import android.widget.RemoteViews
+import anki.collection.OpChanges
 import com.ichi2.anki.AnkiDroidApp
 import com.ichi2.anki.CollectionManager.withCol
 import com.ichi2.anki.CrashReportService
 import com.ichi2.anki.R
 import com.ichi2.anki.Reviewer
 import com.ichi2.anki.analytics.UsageAnalytics
+import com.ichi2.libanki.ChangeManager
 import kotlinx.coroutines.launch
 import timber.log.Timber
 import kotlin.time.Duration.Companion.seconds
@@ -60,7 +62,7 @@ data class DeckPickerWidgetData(
  * No user actions can be performed from this widget as of now; it is for display purposes only.
  * There is only one way to configure the widget i.e. while adding it on home screen,
  */
-class DeckPickerWidget : AnalyticsWidgetProvider() {
+class DeckPickerWidget : AnalyticsWidgetProvider(), ChangeManager.Subscriber {
 
     companion object {
         /**
@@ -98,7 +100,7 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
             val remoteViews = RemoteViews(context.packageName, R.layout.widget_deck_picker_large)
 
             AnkiDroidApp.applicationScope.launch {
-                val deckData = getDeckNameAndStats(deckIds.toList().map { it })
+                val deckData = getDeckNameAndStats(deckIds.toList())
 
                 remoteViews.removeAllViews(R.id.deckCollection)
 
@@ -213,6 +215,9 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
             }
             setRecurringAlarm(context, widgetId)
         }
+
+        // Subscribe to changes
+        ChangeManager.subscribe(this)
     }
 
     override fun onReceive(context: Context?, intent: Intent?) {
@@ -258,25 +263,46 @@ class DeckPickerWidget : AnalyticsWidgetProvider() {
     }
 
     /**
-     * Cancels the recurring alarm for the deleted widgets, and the preference values associated to those widgets.
+     * Updates the `DeckPickerWidget` when changes in the Anki collection affect deck data.
+     *
+     * This method is triggered by the `ChangeManager` when operations impact study queues, such as adding or
+     * removing cards from decks. It updates all relevant widgets with the latest deck information.
      *
-     * @param context the context of the application
-     * @param appWidgetIds the array of widget IDs being deleted
+     * @param changes The `OpChanges` object containing details of the operations performed.
+     * @param handler The object that executed the operation. Updates are ignored if the handler is the current instance.
      */
+    override fun opExecuted(changes: OpChanges, handler: Any?) {
+        if (changes.studyQueues && handler !== this) {
+            val context = AnkiDroidApp.instance.applicationContext
+            val appWidgetManager = AppWidgetManager.getInstance(context)
+            val widgetPreferences = WidgetPreferences(context)
+
+            val widgetIds = widgetPreferences.getAllWidgetIds()
+
+            for (widgetId in widgetIds) {
+                val selectedDeckIds = widgetPreferences.getSelectedDeckIdsFromPreferencesDeckPickerWidget(widgetId)
+                if (selectedDeckIds.isNotEmpty()) {
+                    updateWidget(context, appWidgetManager, widgetId, selectedDeckIds)
+                }
+            }
+        }
+    }
+
     override fun onDeleted(context: Context?, appWidgetIds: IntArray?) {
-        // Ensure context is not null
         if (context == null) {
             Timber.e("Context is null in onDeleted")
             return
         }
 
         val widgetPreferences = WidgetPreferences(context)
 
-        // Proceed with deleting widget preferences and canceling alarms
         appWidgetIds?.forEach { widgetId ->
             cancelRecurringAlarm(context, widgetId)
             widgetPreferences.deleteDeckPickerWidgetData(widgetId)
         }
+
+        // Unsubscribe from changes
+        ChangeManager.clearSubscribers()
     }
 }
 

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

@@ -32,12 +32,14 @@ import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
 import com.google.android.material.floatingactionbutton.FloatingActionButton
 import com.ichi2.anki.AnkiActivity
+import com.ichi2.anki.CollectionManager.withCol
 import com.ichi2.anki.R
 import com.ichi2.anki.dialogs.DeckSelectionDialog
 import com.ichi2.anki.dialogs.DeckSelectionDialog.DeckSelectionListener
 import com.ichi2.anki.dialogs.DeckSelectionDialog.SelectableDeck
 import com.ichi2.anki.dialogs.DiscardChangesDialog
 import com.ichi2.anki.snackbar.showSnackbar
+import com.ichi2.libanki.sched.DeckNode
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -56,6 +58,7 @@ class DeckPickerWidgetConfig : AnkiActivity(), DeckSelectionListener {
     private lateinit var deckPickerWidgetPreferences: WidgetPreferences
     private val MAX_DECKS_ALLOWED = 5 // Maximum number of decks allowed in the widget
     private var hasUnsavedChanges = false // Flag to track unsaved changes
+    private var dueTree: DeckNode? = null
 
     override fun onCreate(savedInstanceState: Bundle?) {
         if (showedActivityFailedScreen(savedInstanceState)) {
@@ -114,13 +117,28 @@ class DeckPickerWidgetConfig : AnkiActivity(), DeckSelectionListener {
             finish()
         }
 
+        // Load the due tree
+        loadDueTree()
+
         findViewById<FloatingActionButton>(R.id.fabWidgetDeckPicker).setOnClickListener {
-            showDeckSelectionDialog()
+            lifecycleScope.launch {
+                val tree = dueTree
+                if (tree != null) {
+                    // Check if the default deck is the only available deck and there are no cards
+                    val isEmpty = isCollectionEmpty(tree, collectionIsEmpty = true)
+                    if (isEmpty) {
+                        showSnackbar(R.string.no_decks_available_message)
+                    } else {
+                        showDeckSelectionDialog()
+                    }
+                }
+            }
         }
 
         // Load and display saved preferences
         loadSavedPreferences()
 
+        // Update the visibility of the "no decks" placeholder and the widget configuration container
         updateViewVisibility()
 
         // Register broadcast receiver to handle widget deletion
@@ -288,6 +306,36 @@ class DeckPickerWidgetConfig : AnkiActivity(), DeckSelectionListener {
             context?.let { deleteWidgetDataDeckPickerWidget(appWidgetId) }
         }
     }
+
+    /**
+     * Checks whether the collection is empty based on the structure of the provided deck tree and
+     * an external flag indicating whether the collection is empty.
+     *
+     * This function is specifically implemented to address an issue where the default deck
+     * (with `did` equal to `1L`) isn't handled correctly when a second deck is added to the
+     * collection. In this case, the deck tree may incorrectly appear as non-empty when it contains
+     * only the default deck and no other cards.
+     *
+     * @param tree The root node of the deck tree, representing the hierarchy of decks.
+     * @param collectionIsEmpty A flag indicating whether the collection is externally considered empty.
+     * @return `true` if the collection is empty based on the deck tree and the external flag;
+     *         `false` otherwise.
+     */
+    private fun isCollectionEmpty(tree: DeckNode, collectionIsEmpty: Boolean): Boolean {
+        val isEmpty = tree.children.size == 1 && tree.children[0].did == 1L && collectionIsEmpty
+        Timber.d("isEmpty: $isEmpty")
+
+        return isEmpty
+    }
+
+    /**
+     * Loads the due tree asynchronously.
+     */
+    private fun loadDueTree() {
+        lifecycleScope.launch {
+            dueTree = withCol { sched.deckDueTree() }
+        }
+    }
 }
 
 /**

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

@@ -51,4 +51,13 @@ class WidgetPreferences(context: Context) {
             putString("deck_picker_widget_selected_decks_$appWidgetId", selectedDecks.joinToString(","))
         }
     }
+
+    fun getAllWidgetIds(): IntArray {
+        val widgetIdsString = deckPickerSharedPreferences.getString("all_widget_ids", "")
+        return if (!widgetIdsString.isNullOrEmpty()) {
+            widgetIdsString.split(",").map { it.toInt() }.toIntArray()
+        } else {
+            intArrayOf()
+        }
+    }
 }

AnkiDroid/src/main/res/values/08-widget.xml

@@ -45,6 +45,7 @@
     <string name="no_selected_deck_placeholder_title" comment="Placeholder title when no decks are selected ">Select decks to display in the widgets</string>
     <string name="no_selected_deck_placeholder_description" comment="Description for starting to mark decks ">Select decks with the + icon.</string>
     <string name="deck_removed_from_widget" comment="Snackbar when deck is removed from widget " >Deck Removed</string>
+    <string name="no_decks_available_message" comment="Snackbar when the collection is empty ">No decks available to select</string>"
     <string name="keep_editing">Keep Editing</string>
     <string name="discard_changes_message">Discard current input?</string>
     <plurals name="deck_limit_reached">