Keep reminders off dateless tasks on every edit path (#159)

CHANGELOG.md

@@ -7,6 +7,11 @@ All notable changes to this project are documented here. The format follows
 
 ## [Unreleased]
 
+### Fixed
+- Removing a task's last date also removes its reminders, so the task can be
+  saved again. Reminders you picked yourself come back when you set a new date
+  (#159).
+
 ## [1.3.1] - 2026-11-09
 
 ### Changed

app/src/main/java/de/jeanlucmakiola/agendula/ui/edit/TaskEditViewModel.kt

@@ -149,6 +149,9 @@ class TaskEditViewModel @Inject constructor(
     private var loadedDue: Instant? = null
     private var loadedAllDay = false
 
+    /** The reminders the user picked before clearing the task's last date, and whether they were all-day ones. */
+    private var setAside: Pair<List<TaskReminder>, Boolean>? = null
+
     /** Start a fresh task, optionally pre-selecting a list / parent. */
     fun bindNew(
         presetListId: Long? = null,
@@ -255,7 +258,7 @@ class TaskEditViewModel @Inject constructor(
                     isOccurrence = task.isOccurrence,
                     lists = lists,
                     parentCandidates = loadParents(task.listId, selfId = taskId),
-                ),
+                ).let { if (it.start == null && it.due == null) it.withoutReminders() else it },
             ).also { baseline = it.toForm() }
             editingOccurrence = task.occurrenceStart
         }
@@ -309,15 +312,15 @@ class TaskEditViewModel @Inject constructor(
     /** Switching list invalidates the parent (it lived in the old list); reload candidates. */
     fun onListChange(listId: Long) {
         if (_state.value.listId == listId) return // re-picking the same list keeps the parent
-        update { it.copy(listId = listId, parentId = null, errors = emptySet()).withDefaultReminders() }
+        update { it.copy(listId = listId, parentId = null, errors = emptySet()).withDatedReminders() }
         viewModelScope.launch {
             val candidates = loadParents(listId, selfId = editingTaskId)
             update { it.copy(parentCandidates = candidates) }
         }
     }
 
-    fun onStartChange(value: Instant?) = update { it.copy(start = value).withDefaultReminders() }
-    fun onDueChange(value: Instant?) = update { it.copy(due = value).withDefaultReminders() }
+    fun onStartChange(value: Instant?) = update { it.copy(start = value).withDatedReminders() }
+    fun onDueChange(value: Instant?) = update { it.copy(due = value).withDatedReminders() }
     /**
      * All-day and timed values use different conventions (UTC midnight vs. a real
      * instant in the device zone), so the switch has to move the timestamps too —
@@ -335,7 +338,7 @@ class TaskEditViewModel @Inject constructor(
         )
         if (!it.remindersTouched) {
             loadedReminders = carried(loadedReminders, switched)
-            return@update switched.withDefaultReminders()
+            return@update switched.withDatedReminders()
         }
         switched.copy(reminders = carried(it.reminders, switched).sortedForDisplay(switched))
     }
@@ -352,6 +355,28 @@ class TaskEditViewModel @Inject constructor(
         return carried
     }
 
+    /**
+     * [withDefaultReminders] for a task that may have lost its dates: with none
+     * left its reminders have nothing to count from and go (#159). Those the user
+     * picked are set aside and come back with the next date; untouched ones come
+     * back from [loadedReminders] anyway.
+     */
+    private fun TaskEditUiState.withDatedReminders(): TaskEditUiState {
+        if (start == null && due == null) {
+            if (reminders.isEmpty()) return this
+            if (remindersTouched) setAside = reminders to isAllDay
+            return withoutReminders()
+        }
+        val aside = setAside ?: return withDefaultReminders()
+        setAside = null
+        val restored = if (aside.second == isAllDay) {
+            aside.first
+        } else {
+            StoredReminders.switched(aside.first, toForm(), settings, nowMillis(), ZoneId.systemDefault())
+        }
+        return copy(reminders = (reminders + restored).distinct().sortedForDisplay(this), remindersChosen = true)
+    }
+
     /**
      * The reminders the task will be saved with while the user has not
      * touched them: those it was loaded with, plus the defaults of the dates
@@ -474,6 +499,9 @@ private fun List<TaskReminder>.sortedForDisplay(state: TaskEditUiState): List<Ta
     sortedWith(taskReminderDisplayOrder(state.isAllDay, state.allDayMinuteOfDay))
 
 /** Snapshot the editable state as a validated [TaskForm]. */
+/** No reminders at all, stored as such. */
+private fun TaskEditUiState.withoutReminders(): TaskEditUiState = copy(reminders = emptyList(), remindersChosen = true)
+
 private fun TaskEditUiState.toForm(): TaskForm = TaskForm(
     title = title,
     listId = listId ?: 0L,

app/src/test/java/de/jeanlucmakiola/agendula/ui/edit/TaskEditViewModelTest.kt

@@ -0,0 +1,176 @@
+package de.jeanlucmakiola.agendula.ui.edit
+
+import androidx.datastore.core.DataStore
+import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.emptyPreferences
+import com.google.common.truth.Truth.assertThat
+import de.jeanlucmakiola.agendula.data.prefs.SettingsPrefs
+import de.jeanlucmakiola.agendula.data.tasks.ProviderEnvironment
+import de.jeanlucmakiola.agendula.data.tasks.ProviderResolver
+import de.jeanlucmakiola.agendula.data.tasks.TasksRepository
+import de.jeanlucmakiola.agendula.domain.Priority
+import de.jeanlucmakiola.agendula.domain.Task
+import de.jeanlucmakiola.agendula.domain.TaskDetail
+import de.jeanlucmakiola.agendula.domain.TaskFilter
+import de.jeanlucmakiola.agendula.domain.TaskForm
+import de.jeanlucmakiola.agendula.domain.TaskList
+import de.jeanlucmakiola.agendula.domain.TaskReminder
+import de.jeanlucmakiola.agendula.domain.TaskStatus
+import de.jeanlucmakiola.agendula.domain.recurrence.RecurringScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.flowOf
+import kotlinx.coroutines.test.UnconfinedTestDispatcher
+import kotlinx.coroutines.test.resetMain
+import kotlinx.coroutines.test.setMain
+import org.junit.jupiter.api.AfterEach
+import org.junit.jupiter.api.BeforeEach
+import org.junit.jupiter.api.Test
+import java.lang.reflect.Proxy
+import kotlin.time.Clock
+import kotlin.time.Duration.Companion.days
+import kotlin.time.Instant
+
+/** Reminders on a task that loses or regains its dates in the editor (#159). */
+@OptIn(ExperimentalCoroutinesApi::class)
+class TaskEditViewModelTest {
+
+    private val due = Clock.System.now() + 3.days
+    private val reminder = TaskReminder(30)
+    private val repository = FakeRepository()
+
+    @BeforeEach fun setUp() = Dispatchers.setMain(UnconfinedTestDispatcher())
+
+    @AfterEach fun tearDown() = Dispatchers.resetMain()
+
+    private fun editing(start: Instant? = null, due: Instant? = this.due): TaskEditViewModel {
+        repository.task = task(start, due)
+        repository.reminders = listOf(reminder)
+        return TaskEditViewModel(repository, settingsPrefs()).apply { bindEdit(TASK_ID) }
+    }
+
+    @Test
+    fun `clearing the last date drops the reminders and the task saves`() {
+        val vm = editing()
+        vm.onDueChange(null)
+        vm.save()
+
+        assertThat(vm.state.value.errors).isEmpty()
+        assertThat(repository.saved?.reminders).isEmpty()
+        assertThat(repository.saved?.remindersChosen).isTrue()
+    }
+
+    @Test
+    fun `an all-day switch or another list does not bring them back`() {
+        val vm = editing()
+        vm.onDueChange(null)
+        vm.onAllDayChange(true)
+        vm.onListChange(LIST_ID + 1)
+
+        assertThat(vm.state.value.reminders).isEmpty()
+    }
+
+    @Test
+    fun `untouched reminders come back with a new date`() {
+        val vm = editing()
+        vm.onDueChange(null)
+        vm.onDueChange(due + 1.days)
+
+        assertThat(vm.state.value.reminders).contains(reminder)
+    }
+
+    @Test
+    fun `picked reminders come back with a new date`() {
+        val vm = editing()
+        val picked = TaskReminder(120)
+        vm.addReminder(picked)
+        vm.onDueChange(null)
+        vm.onDueChange(due + 1.days)
+
+        assertThat(vm.state.value.reminders).containsExactly(reminder, picked)
+    }
+
+    @Test
+    fun `clearing one of two dates keeps the reminders`() {
+        val vm = editing(start = due - 1.days)
+        vm.onDueChange(null)
+
+        assertThat(vm.state.value.reminders).containsExactly(reminder)
+    }
+
+    @Test
+    fun `a task stored without dates opens without its reminders`() {
+        val vm = editing(due = null)
+
+        assertThat(vm.state.value.reminders).isEmpty()
+        assertThat(vm.state.value.isDirty).isFalse()
+    }
+
+    private fun task(start: Instant?, due: Instant?) = Task(
+        taskId = TASK_ID,
+        listId = LIST_ID,
+        title = "Task",
+        description = null,
+        location = null,
+        url = null,
+        priority = Priority.NONE,
+        status = TaskStatus.NEEDS_ACTION,
+        percentComplete = null,
+        start = start,
+        due = due,
+        isAllDay = false,
+        timeZone = null,
+        completedAt = null,
+        listColor = 0,
+        taskColor = null,
+        listName = null,
+        accountName = null,
+        parentId = null,
+        isRecurring = false,
+        distanceFromCurrent = null,
+        created = null,
+        lastModified = null,
+    )
+
+    private class FakeRepository : TasksRepository by unsupported() {
+        var task: Task? = null
+        var reminders: List<TaskReminder> = emptyList()
+        var saved: TaskForm? = null
+
+        override fun taskLists() = flowOf(emptyList<TaskList>())
+        override fun tasks(filter: TaskFilter): Flow<List<Task>> = flowOf(emptyList())
+        override fun taskDetail(taskId: Long, occurrenceStart: Instant?) =
+            flowOf(task?.let { TaskDetail(it, emptyList()) })
+        override suspend fun remindersFor(taskId: Long) = reminders
+        override suspend fun updateTask(
+            taskId: Long,
+            form: TaskForm,
+            expectedLastModified: Instant?,
+            occurrenceStart: Instant?,
+            scope: RecurringScope,
+        ) {
+            saved = form
+        }
+    }
+
+    private class MemoryDataStore : DataStore<Preferences> {
+        override val data = MutableStateFlow(emptyPreferences())
+        override suspend fun updateData(transform: suspend (t: Preferences) -> Preferences) =
+            transform(data.value).also { data.value = it }
+    }
+
+    private fun settingsPrefs() = SettingsPrefs(MemoryDataStore(), ProviderResolver(unsupported<ProviderEnvironment>()))
+
+    private companion object {
+        const val TASK_ID = 1L
+        const val LIST_ID = 7L
+
+        /** Calls the test does not expect answer false or null. */
+        inline fun <reified T> unsupported(): T =
+            Proxy.newProxyInstance(T::class.java.classLoader, arrayOf(T::class.java)) { _, method, _ ->
+                if (method.returnType == Boolean::class.javaPrimitiveType) false else null
+            } as T
+    }
+}