fix(pickers): keep non-syncing calendars out of the event targets (#78)

The new row states were documented as the reasons a calendar is missing from the
event and import pickers, but only three of the four were: a calendar whose
account keeps its events off the device is dimmed, switchless and marked "Not
synced" in the manager, and was still offered as a place to save a new or
imported event. Nothing there ever reaches the account, and CalendarProvider2
wipes the calendar's rows outright when the subscription is switched back on —
so the event is a dead end, saved into a calendar that also can't show it.

Both pickers now filter on one predicate, isEventTarget, which is the label set
restated: what the manager marks is what the picker leaves out, which is what
its "Missing a calendar?" footer promises. The manager's restore-from-backup row
uses it too, so the entry point and the picker behind it agree on whether there
is anywhere to import to.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -14,8 +14,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Calendars your device isn't syncing are marked **Not synced**, moved to the
   bottom of their account and left without a switch. None of their events are on
   the device, so the switch they used to have could not have shown you anything
-  — the calendar simply looked broken. Whether an account syncs a calendar stays
-  that account's own app's decision ([#78]).
+  — the calendar simply looked broken. They are no longer offered when you pick
+  a calendar for a new or an imported event either: an event saved there would
+  never reach the account. Whether an account syncs a calendar stays that
+  account's own app's decision ([#78]).
 - The birthday and anniversary calendars Calendula fills from your contacts are
   marked **Filled from your contacts**, which is why they can't be picked for a
   new event: anything you put there would be removed again on the next sync.

app/src/main/java/de/jeanlucmakiola/calendula/domain/CalendarRowState.kt

@@ -41,6 +41,25 @@ val CalendarSource.isNotSynced: Boolean
 val CalendarSource.hasVisibilitySwitch: Boolean
     get() = !isNotSynced
 
+/**
+ * Whether this calendar can be offered as a target for a new or imported event.
+ * The one predicate behind both pickers, so the states [CalendarStateLabel]
+ * names on a manager row are exactly the states that keep a calendar out of
+ * them (#76):
+ *
+ * - read-only has nowhere to write;
+ * - switched off would hide the event the moment it was saved;
+ * - a managed mirror has the next contact sync delete it;
+ * - a non-syncing one never carries the event up to the account, and
+ *   `CalendarProvider2` wipes the calendar's rows outright when the
+ *   subscription is switched back on — a saved event is a dead end either way.
+ *
+ * This is the test for *targets*. An event already living in an excluded
+ * calendar keeps it; the editor adds that calendar back to its picker.
+ */
+val CalendarSource.isEventTarget: Boolean
+    get() = canModifyContents && isVisibleInSystem && !isManaged && !isNotSynced
+
 /** Every state worth naming on this calendar's row, in reading order. */
 fun CalendarSource.stateLabels(): List<CalendarStateLabel> = buildList {
     if (isManaged) add(CalendarStateLabel.MANAGED)

app/src/main/java/de/jeanlucmakiola/calendula/ui/calendars/CalendarsScreen.kt

@@ -94,6 +94,7 @@ import de.jeanlucmakiola.calendula.data.prefs.SettingsPrefs
 import de.jeanlucmakiola.calendula.domain.CalendarSource
 import de.jeanlucmakiola.calendula.domain.CalendarStateLabel
 import de.jeanlucmakiola.calendula.domain.hasVisibilitySwitch
+import de.jeanlucmakiola.calendula.domain.isEventTarget
 import de.jeanlucmakiola.calendula.domain.isNotSynced
 import de.jeanlucmakiola.calendula.domain.orderedForManager
 import de.jeanlucmakiola.calendula.domain.stateLabels
@@ -335,9 +336,9 @@ private fun CalendarsList(
         // safety net. Offered only when there is something exportable: the user's
         // own local calendars (managed special-dates mirrors don't count).
         val exportable = local.filter { it.canModifyContents && !it.isManaged }
-        // Restore/import can target any writable, non-managed calendar (local or
-        // synced), so its availability is broader than export's.
-        val canImport = (local + synced).any { it.canModifyContents && !it.isManaged }
+        // Restore/import can target any calendar the import picker would offer
+        // (local or synced), so its availability is broader than export's.
+        val canImport = (local + synced).any { it.isEventTarget }
         if (exportable.isNotEmpty()) {
             Spacer(Modifier.height(16.dp))
             SectionHeader(stringResource(R.string.calendars_backup_header))

app/src/main/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModel.kt

@@ -19,6 +19,7 @@ import de.jeanlucmakiola.calendula.domain.EventColorOption
 import de.jeanlucmakiola.calendula.domain.EventForm
 import de.jeanlucmakiola.calendula.domain.EventFormField
 import de.jeanlucmakiola.calendula.domain.RecurringWriteScope
+import de.jeanlucmakiola.calendula.domain.isEventTarget
 import de.jeanlucmakiola.calendula.domain.populatedFields
 import de.jeanlucmakiola.calendula.domain.problems
 import de.jeanlucmakiola.calendula.domain.toEditSnapshot
@@ -177,19 +178,16 @@ class EventEditViewModel @Inject constructor(
         repository.calendars().catch { emit(emptyList()) }
 
     /**
-     * Writable calendars — the only valid event targets. Calendars switched off
-     * in Settings → Calendars are excluded, so you can't create into one you've
-     * turned off; a last-used preselect landing on a now-off calendar falls back
-     * to the first remaining writable one (handled by [resolvedCalendarId] and
-     * [state]). Managed special-dates calendars are excluded too: their events
-     * are owned by the contact sync, which would delete any user event created
-     * there.
+     * The calendars a new event can be saved to ([isEventTarget]): writable,
+     * switched on, not a contact-filled mirror, not a non-syncing subscription.
+     * A last-used preselect landing on an excluded calendar falls back to the
+     * first remaining one (handled by [resolvedCalendarId] and [state]).
      *
      * This is the list of *targets*. An event already living in an excluded
      * calendar keeps it — [state] adds it back to the picker.
      */
     private val writableCalendars: Flow<List<CalendarSource>> = allCalendars.map { calendars ->
-        calendars.filter { it.canModifyContents && it.isVisibleInSystem && !it.isManaged }
+        calendars.filter { it.isEventTarget }
     }
 
     /** The target calendar id, resolved exactly as the form shows it. */

app/src/main/java/de/jeanlucmakiola/calendula/ui/imports/ImportViewModel.kt

@@ -14,6 +14,7 @@ import de.jeanlucmakiola.calendula.domain.ics.IcsParseWarning
 import de.jeanlucmakiola.calendula.domain.ics.IcsParser
 import de.jeanlucmakiola.calendula.domain.ics.ParsedIcsEvent
 import de.jeanlucmakiola.calendula.domain.ics.toEventForm
+import de.jeanlucmakiola.calendula.domain.isEventTarget
 import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
@@ -85,18 +86,14 @@ class ImportViewModel @Inject constructor(
                     warnings = parsed.warnings,
                 )
                 else -> {
-                    // A calendar switched off in Settings → Calendars is off
-                    // everywhere, so it can't be an import target — exclude it
-                    // alongside the read-only ones. Managed special-dates
-                    // calendars are contact-derived and editor-locked, so
-                    // they're not a valid destination either.
+                    // The same targets the event form offers ([isEventTarget]):
+                    // an import is a bulk create, so a calendar that can't hold
+                    // one event can't hold thirty.
                     ImportUiState.Many(
                         events = parsed.events,
                         warnings = parsed.warnings,
                         calendars = repository.calendars().first()
-                            .filter {
-                                it.canModifyContents && !it.isManaged && it.isVisibleInSystem
-                            },
+                            .filter { it.isEventTarget },
                     )
                 }
             }

app/src/test/java/de/jeanlucmakiola/calendula/domain/CalendarRowStateTest.kt

@@ -70,6 +70,30 @@ class CalendarRowStateTest {
         assertThat(calendar.hasVisibilitySwitch).isTrue()
     }
 
+    @Test
+    fun `every named state keeps a calendar out of the pickers`() {
+        // The labels and the picker exclusion are the same set, stated twice —
+        // a labelled row the pickers still offered would make the footer's
+        // "manage your calendars to see why" a lie (#76).
+        assertThat(cal().isEventTarget).isTrue()
+        listOf(
+            cal(writable = false),
+            cal(syncsEvents = false),
+            cal(local = true, managed = true),
+        ).forEach { calendar ->
+            assertThat(calendar.stateLabels()).isNotEmpty()
+            assertThat(calendar.isEventTarget).isFalse()
+        }
+    }
+
+    @Test
+    fun `a switched-off calendar is no target although it carries no label`() {
+        // The switch is right there on the row, so the state speaks for itself.
+        val calendar = cal().copy(isVisibleInSystem = false)
+        assertThat(calendar.stateLabels()).isEmpty()
+        assertThat(calendar.isEventTarget).isFalse()
+    }
+
     @Test
     fun `manager order puts non-syncing calendars last and is otherwise stable`() {
         val ordered = listOf(

app/src/test/java/de/jeanlucmakiola/calendula/ui/edit/EventEditViewModelTest.kt

@@ -45,9 +45,14 @@ class EventEditViewModelTest {
     private val beginMillis = 1_781_164_800_000L
     private val endMillis = beginMillis + 3_600_000L
 
-    private fun cal(id: Long, visible: Boolean = true): CalendarSource = CalendarSource(
+    private fun cal(
+        id: Long,
+        visible: Boolean = true,
+        syncsEvents: Boolean = true,
+    ): CalendarSource = CalendarSource(
         id = id, displayName = "Cal $id", accountName = "acc@local", accountType = "LOCAL",
         color = 0xFF112233.toInt(), isVisibleInSystem = visible, canModifyContents = true,
+        syncsEvents = syncsEvents,
     )
 
     private fun detail(calendarId: Long, rrule: String? = null): EventDetail = EventDetail(
@@ -108,6 +113,27 @@ class EventEditViewModelTest {
         job.cancel()
     }
 
+    @Test
+    fun `a calendar whose account is not synced to this device is not a target`(
+        @TempDir tempDir: Path,
+    ) = runTest(dispatcher) {
+        // Writable and switched on, but the account keeps its events off the
+        // device: nothing saved here ever reaches it, and the provider drops the
+        // rows when the subscription comes back (#76).
+        val fake = FakeCalendarDataSource().apply {
+            calendarsResult = listOf(cal(1L), cal(2L, syncsEvents = false))
+            eventDetailResult = { detail(calendarId = 1L) }
+        }
+        val vm = viewModel(tempDir, fake)
+        val job = activate(vm)
+
+        vm.openForEdit(eventId = 42L, beginMillis = beginMillis, endMillis = endMillis)
+        advanceUntilIdle()
+
+        assertThat(vm.state.value?.calendars?.map { it.id }).containsExactly(1L)
+        job.cancel()
+    }
+
     @Test
     fun `editing an event in a switched-off calendar keeps it in the picker`(
         @TempDir tempDir: Path,