fix(image-occlusion): support updating a note's deck

Once a note had been created, the deck couldn't be updated.

Fixed by:

* Enable editing the deck in NoteEditorFragment if in edit mode
* Disable editing the deck in ImageOcclusion if in edit mode

In future, we can handle this in ImageOcclusion, BUT:

There are 3 cases:
* A user wants to edit a card when studying
* A user wants to edit a selection of cards from the same note [Card Browser - CARDS]
* A user wants to edit a note [Card Browser - NOTES]
  * What does it mean to edit the deck of a note, is a user aware of this?

And a user can remove the cards they are editing (by removing masks).

Since we don't yet have full control over the process of adding an occlusion note,
 I decided it was a risk to take the time to implement this

Fixes 19605

Author: david-allison

AnkiDroid/src/main/java/com/ichi2/anki/NoteEditorFragment.kt

@@ -2423,10 +2423,11 @@ class NoteEditorFragment :
         populateEditFields(changeType, false)
         updateFieldsFromStickyText()
 
-        // Showing the deck selection parts is not needed for Image Occlusion notetypes
-        // as deck selection is handled by the backend page
-        requireView().findViewById<TextView>(R.id.CardEditorDeckText).isVisible = !currentNotetypeIsImageOcclusion()
-        requireView().findViewById<View>(R.id.note_deck_name).isVisible = !currentNotetypeIsImageOcclusion()
+        // When adding a note, ImageOcclusion handles the deck selection
+        // as a user can reach this screen directly from an intent
+        val disableDeckEditing = addNote && currentNotetypeIsImageOcclusion()
+        requireView().findViewById<TextView>(R.id.CardEditorDeckText).isVisible = !disableDeckEditing
+        requireView().findViewById<View>(R.id.note_deck_name).isVisible = !disableDeckEditing
     }
 
     private fun addClozeButton(
@@ -2764,12 +2765,11 @@ class NoteEditorFragment :
                 ImageOcclusionArgs.Add(
                     noteTypeId = noteTypeId,
                     imagePath = imagePath,
-                    deckId = deckId,
+                    originalDeckId = deckId,
                 )
             } else {
                 ImageOcclusionArgs.Edit(
                     noteId = editorNote!!.id,
-                    deckId = deckId,
                 )
             }
 

AnkiDroid/src/main/java/com/ichi2/anki/pages/ImageOcclusion.kt

@@ -24,6 +24,7 @@ import android.webkit.WebView
 import android.widget.TextView
 import androidx.activity.addCallback
 import androidx.core.os.bundleOf
+import androidx.core.view.isVisible
 import androidx.fragment.app.viewModels
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.lifecycleScope
@@ -53,6 +54,8 @@ import timber.log.Timber
  * ([docs](https://docs.ankiweb.net/editing.html#image-occlusion) and
  * [source](https://github.com/ankitects/anki/blob/main/proto/anki/image_occlusion.proto)).
  *
+ * When adding, a user may select the deck of the note
+ *
  * **Paths**
  * `/image-occlusion/$PATH`
  * `/image-occlusion/$NOTE_ID`
@@ -132,7 +135,9 @@ class ImageOcclusion :
             deckNameView.text = name
         }
 
-        viewModel.deckNameFlow.launchCollectionInLifecycleScope(::onDeckNameChanged)
+        viewModel.deckNameFlow?.launchCollectionInLifecycleScope(::onDeckNameChanged) ?: run {
+            deckNameView.isVisible = false
+        }
     }
 
     // TODO: Move this to an extension method once we have context parameters

AnkiDroid/src/main/java/com/ichi2/anki/pages/viewmodel/ImageOcclusionViewModel.kt

@@ -47,26 +47,18 @@ sealed class ImageOcclusionArgs : Parcelable {
     data class Add(
         val imagePath: String,
         val noteTypeId: NoteTypeId,
-        val deckId: DeckId,
+        /**
+         * The ID of the deck that was selected when the editor was opened.
+         * Used to restore the deck after saving a note to prevent unexpected deck changes.
+         */
+        val originalDeckId: DeckId,
     ) : ImageOcclusionArgs()
 
     @Parcelize
     data class Edit(
         val noteId: NoteId,
-        val deckId: DeckId,
     ) : ImageOcclusionArgs()
 
-    /**
-     * The ID of the deck that was selected when the editor was opened.
-     * Used to restore the deck after saving a note to prevent unexpected deck changes.
-     */
-    val originalDeckId: DeckId
-        get() =
-            when (this) {
-                is Add -> this.deckId
-                is Edit -> this.deckId
-            }
-
     /**
      * A [JSONObject] containing options for loading the [image occlusion page][ImageOcclusion].
      * This includes the type of operation ("add" or "edit"), and relevant IDs and paths.
@@ -98,18 +90,30 @@ class ImageOcclusionViewModel(
     val args: ImageOcclusionArgs =
         checkNotNull(savedStateHandle[IO_ARGS_KEY]) { "$IO_ARGS_KEY required" }
 
-    var selectedDeckIdFlow = MutableStateFlow(args.originalDeckId)
+    private val originalDeckId: DeckId? = (args as? ImageOcclusionArgs.Add)?.originalDeckId
+
+    /**
+     * The currently selected deck ID
+     *
+     * Only valid in 'ADD' mode
+     */
+    val selectedDeckIdFlow: MutableStateFlow<DeckId>? =
+        originalDeckId?.let { MutableStateFlow(it) }
 
+    /**
+     * The currently selected deck name
+     *
+     * Only valid in 'ADD' mode
+     */
     val deckNameFlow =
-        selectedDeckIdFlow
-            .map { did -> withCol { decks.name(did) } }
+        selectedDeckIdFlow?.map { did -> withCol { decks.name(did) } }
 
     init {
-        // if we are in 'add' mode, thr current deck is used to add the note.
-        // This is reverted in 'onSaveOperationCompleted'
+        // if we are in 'add' mode, the current deck is used to add the note.
+        // This is reverted in 'resetTemporaryDeckOverride'
         selectedDeckIdFlow
-            .onEach { withCol { decks.select(it) } }
-            .launchIn(viewModelScope)
+            ?.onEach { withCol { decks.select(it) } }
+            ?.launchIn(viewModelScope)
     }
 
     /**
@@ -118,21 +122,37 @@ class ImageOcclusionViewModel(
      * @param deckId The [DeckId] object representing the selected deck. Can be null if no deck is selected.
      */
     fun handleDeckSelection(deckId: DeckId) {
-        selectedDeckIdFlow.value = deckId
+        selectedDeckIdFlow?.let { it.value = deckId } ?: run {
+            Timber.w("deck selection is unavailable")
+        }
     }
 
     /**
      * Executed when the 'save' operation is completed, before the UI receives the response
      */
     fun onSaveOperationCompleted() {
         Timber.i("save operation completed")
-        if (args.originalDeckId == selectedDeckIdFlow.value) return
+        if (originalDeckId != null) {
+            resetTemporaryDeckOverride(originalDeckId)
+        }
+    }
+
+    /**
+     * Resets the current deck to the deck the screen was opened with
+     *
+     * Only for [ImageOcclusionArgs.Add] mode
+     */
+    private fun resetTemporaryDeckOverride(originalDeckId: DeckId) {
+        // no need to reset if the DeckId was unchanged
+        if (originalDeckId == selectedDeckIdFlow?.value) return
+
         // reset to the previous deck that the backend "saw" as selected, this
-        // avoids other screens unexpectedly having their working decks modified(
-        // most important being the Reviewer where the user would find itself
-        // studying another deck after editing a note with changing the deck)
+        // avoids other screens unexpectedly having their working decks modified
+        // For example, the study screen: if a user backgrounds the screen, then
+        // adds an occluded image via 'Share'
         viewModelScope.launch {
-            withCol { backend.setCurrentDeck(args.originalDeckId) }
+            Timber.i("resetting temporary deck override")
+            withCol { backend.setCurrentDeck(originalDeckId) }
         }
     }