Allow creation of empty filtered decks (#2788)

* Add new button to UI

* Add bool to allow creating empty filtered in back end

* Implement logic into front end for passing on bool

* Hide option on old decks

* Show option again if any settings are changed

* Revert "Show option again if any settings are changed"

This reverts commit 094acd9c65936823fa206594da5c1f3e4eb09248.

* Revert "Hide option on old decks"

This reverts commit d20a9a240b4fd85d080e8cc52d94318416ca753f.

* Update string

* Update ftl/core/decks.ftl

---------

Co-authored-by: Damien Elmes <dae@users.noreply.github.com>

ftl/core/decks.ftl

@@ -2,6 +2,7 @@ decks-add-new-deck-ctrlandn = Add New Deck (Ctrl+N)
 decks-build = Build
 decks-cards-selected-by = cards selected by
 decks-create-deck = Create Deck
+decks_create_even_if_empty = Create/update this deck even if empty
 decks-custom-steps-in-minutes = Custom steps (in minutes)
 decks-deck = Deck
 decks-decreasing-intervals = Decreasing intervals

proto/anki/decks.proto

@@ -212,4 +212,5 @@ message FilteredDeckForUpdate {
   int64 id = 1;
   string name = 2;
   Deck.Filtered config = 3;
+  bool allow_empty = 4;
 }

qt/aqt/filtered_deck.py

@@ -79,6 +79,8 @@ class FilteredDeckConfigDialog(QDialog):
         self.form.order.addItems(order_labels)
         self.form.order_2.addItems(order_labels)
 
+        qconnect(self.form.allow_empty.stateChanged, self._on_allow_empty_toggled)
+
         qconnect(self.form.resched.stateChanged, self._onReschedToggled)
 
         qconnect(self.form.search_button.clicked, self.on_search_button)
@@ -233,6 +235,9 @@ class FilteredDeckConfigDialog(QDialog):
     def _onReschedToggled(self, _state: int) -> None:
         self.form.previewDelayWidget.setVisible(not self.form.resched.isChecked())
 
+    def _on_allow_empty_toggled(self) -> None:
+        self.deck.allow_empty = self.form.allow_empty.isChecked()
+
     def _update_deck(self) -> bool:
         """Update our stored deck with the details from the GUI.
         If false, abort adding."""

qt/aqt/forms/filtered_deck.ui

@@ -255,6 +255,13 @@
         </property>
        </widget>
       </item>
+      <item row="5" column="0" alignment="Qt::AlignLeft">
+       <widget class="QCheckBox" name="allow_empty">
+        <property name="text">
+         <string>decks_create_even_if_empty</string>
+        </property>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>

rslib/src/decks/service.rs

@@ -251,6 +251,7 @@ impl From<FilteredDeckForUpdate> for anki_proto::decks::FilteredDeckForUpdate {
             id: deck.id.into(),
             name: deck.human_name,
             config: Some(deck.config),
+            allow_empty: deck.allow_empty,
         }
     }
 }
@@ -261,6 +262,7 @@ impl From<anki_proto::decks::FilteredDeckForUpdate> for FilteredDeckForUpdate {
             id: deck.id.into(),
             human_name: deck.name,
             config: deck.config.unwrap_or_default(),
+            allow_empty: deck.allow_empty,
         }
     }
 }

rslib/src/scheduler/filtered/custom_study.rs

@@ -184,6 +184,7 @@ impl Collection {
             id,
             human_name,
             config,
+            allow_empty: false,
         };
 
         self.add_or_update_filtered_deck_inner(deck)

rslib/src/scheduler/filtered/mod.rs

@@ -21,6 +21,7 @@ pub struct FilteredDeckForUpdate {
     pub id: DeckId,
     pub human_name: String,
     pub config: FilteredDeck,
+    pub allow_empty: bool,
 }
 
 pub(crate) struct DeckFilterContext<'a> {
@@ -144,6 +145,7 @@ impl Collection {
         mut update: FilteredDeckForUpdate,
     ) -> Result<DeckId> {
         let usn = self.usn()?;
+        let allow_empty = update.allow_empty;
 
         // check the searches are valid, and normalize them
         for term in &mut update.config.search_terms {
@@ -167,7 +169,7 @@ impl Collection {
         let count = self.rebuild_filtered_deck_inner(&deck, usn)?;
 
         // if it failed to match any cards, we revert the changes
-        if count == 0 {
+        if count == 0 && !allow_empty {
             Err(FilteredDeckError::SearchReturnedNoCards.into())
         } else {
             // update current deck and return id
@@ -233,6 +235,7 @@ impl TryFrom<Deck> for FilteredDeckForUpdate {
                 id: value.id,
                 human_name,
                 config: filtered,
+                allow_empty: false,
             }),
             _ => invalid_input!("not filtered"),
         }