Persist notifications

- Persist the map of active notifications on every change and reload it on
application startup.
- Reshow all active notifications on application startup using the original
reminder due time.

uhabits-android/src/main/java/org/isoron/uhabits/HabitsApplication.kt

@@ -94,6 +94,7 @@ class HabitsApplication : Application() {
         taskRunner.execute {
             reminderScheduler.scheduleAll()
             widgetUpdater.updateWidgets()
+            notificationTray.reshowAll()
         }
     }
 

uhabits-android/src/main/java/org/isoron/uhabits/inject/HabitsModule.kt

@@ -72,9 +72,10 @@ class HabitsModule(dbFile: File) {
         taskRunner: TaskRunner,
         commandRunner: CommandRunner,
         preferences: Preferences,
-        screen: AndroidNotificationTray
+        screen: AndroidNotificationTray,
+        habitList: HabitList
     ): NotificationTray {
-        return NotificationTray(taskRunner, commandRunner, preferences, screen)
+        return NotificationTray(taskRunner, commandRunner, preferences, screen, habitList)
     }
 
     @Provides

uhabits-core/src/jvmMain/java/org/isoron/uhabits/core/models/Timestamp.kt

@@ -18,6 +18,7 @@
  */
 package org.isoron.uhabits.core.models
 
+import kotlinx.serialization.Serializable
 import org.isoron.platform.time.LocalDate
 import org.isoron.uhabits.core.utils.DateFormats.Companion.getCSVDateFormat
 import org.isoron.uhabits.core.utils.DateFormats.Companion.getDialogDateFormat
@@ -29,6 +30,7 @@ import java.util.Date
 import java.util.GregorianCalendar
 import java.util.TimeZone
 
+@Serializable
 data class Timestamp(var unixTime: Long) : Comparable<Timestamp> {
 
     constructor(cal: GregorianCalendar) : this(cal.timeInMillis)

uhabits-core/src/jvmMain/java/org/isoron/uhabits/core/preferences/Preferences.kt

@@ -18,11 +18,17 @@
  */
 package org.isoron.uhabits.core.preferences
 
+import kotlinx.serialization.builtins.MapSerializer
+import kotlinx.serialization.builtins.serializer
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
 import org.isoron.platform.time.DayOfWeek
 import org.isoron.platform.utils.StringUtils.Companion.joinLongs
 import org.isoron.platform.utils.StringUtils.Companion.splitLongs
+import org.isoron.uhabits.core.models.Habit
 import org.isoron.uhabits.core.models.HabitList
 import org.isoron.uhabits.core.models.Timestamp
+import org.isoron.uhabits.core.ui.NotificationTray
 import org.isoron.uhabits.core.ui.ThemeSwitcher
 import org.isoron.uhabits.core.utils.DateUtils.Companion.getFirstWeekdayNumberAccordingToLocale
 import java.util.LinkedList
@@ -135,6 +141,23 @@ open class Preferences(private val storage: Storage) {
             storage.putBoolean("pref_short_toggle", enabled)
         }
 
+    internal fun setActiveNotifications(activeNotifications: Map<Habit, NotificationTray.NotificationData>) {
+        val activeById = activeNotifications.mapKeys { it.key.id }
+        val serialized = Json.encodeToString(activeById)
+        storage.putString("pref_active_notifications", serialized)
+    }
+
+    internal fun getActiveNotifications(habitList: HabitList): HashMap<Habit, NotificationTray.NotificationData> {
+        val serialized = storage.getString("pref_active_notifications", "")
+        return if (serialized == "") {
+            HashMap()
+        } else {
+            val activeById = Json.decodeFromString(MapSerializer(Long.serializer(), NotificationTray.NotificationData.serializer()), serialized)
+            val activeByHabit = activeById.mapNotNull { (id, v) -> habitList.getById(id)?.let { it to v } }
+            activeByHabit.toMap(HashMap())
+        }
+    }
+
     fun removeListener(listener: Listener) {
         listeners.remove(listener)
     }

uhabits-core/src/jvmMain/java/org/isoron/uhabits/core/ui/NotificationTray.kt

@@ -18,17 +18,18 @@
  */
 package org.isoron.uhabits.core.ui
 
+import kotlinx.serialization.Serializable
 import org.isoron.uhabits.core.AppScope
 import org.isoron.uhabits.core.commands.Command
 import org.isoron.uhabits.core.commands.CommandRunner
 import org.isoron.uhabits.core.commands.CreateRepetitionCommand
 import org.isoron.uhabits.core.commands.DeleteHabitsCommand
 import org.isoron.uhabits.core.models.Habit
+import org.isoron.uhabits.core.models.HabitList
 import org.isoron.uhabits.core.models.Timestamp
 import org.isoron.uhabits.core.preferences.Preferences
 import org.isoron.uhabits.core.tasks.Task
 import org.isoron.uhabits.core.tasks.TaskRunner
-import java.util.HashMap
 import java.util.Locale
 import java.util.Objects
 import javax.inject.Inject
@@ -38,9 +39,31 @@ class NotificationTray @Inject constructor(
     private val taskRunner: TaskRunner,
     private val commandRunner: CommandRunner,
     private val preferences: Preferences,
-    private val systemTray: SystemTray
+    private val systemTray: SystemTray,
+    private val habitList: HabitList
 ) : CommandRunner.Listener, Preferences.Listener {
-    private val active: HashMap<Habit, NotificationData> = HashMap()
+
+    /**
+     * A mapping from habits to active notifications, automatically persisting on removal.
+     */
+    private val active = object {
+        private val m: HashMap<Habit, NotificationData> =
+            preferences.getActiveNotifications(habitList)
+
+        val entries get() = m.entries
+
+        operator fun set(habit: Habit, notificationData: NotificationData) {
+            m[habit] = notificationData
+            persist()
+        }
+
+        fun remove(habit: Habit) {
+            m.remove(habit)?.let { persist() } // persist if changed
+        }
+
+        fun persist() = preferences.setActiveNotifications(m)
+    }
+
     fun cancel(habit: Habit) {
         val notificationId = getNotificationId(habit)
         systemTray.removeNotification(notificationId)
@@ -64,7 +87,6 @@ class NotificationTray @Inject constructor(
 
     fun show(habit: Habit, timestamp: Timestamp, reminderTime: Long) {
         val data = NotificationData(timestamp, reminderTime)
-        active[habit] = data
         taskRunner.execute(ShowNotificationTask(habit, data))
     }
 
@@ -83,7 +105,7 @@ class NotificationTray @Inject constructor(
         return (id % Int.MAX_VALUE).toInt()
     }
 
-    private fun reshowAll() {
+    fun reshowAll() {
         for ((habit, data) in active.entries) {
             taskRunner.execute(ShowNotificationTask(habit, data))
         }
@@ -101,6 +123,7 @@ class NotificationTray @Inject constructor(
         fun log(msg: String)
     }
 
+    @Serializable
     internal class NotificationData(val timestamp: Timestamp, val reminderTime: Long)
     private inner class ShowNotificationTask(private val habit: Habit, data: NotificationData) :
         Task {
@@ -164,6 +187,17 @@ class NotificationTray @Inject constructor(
                 timestamp,
                 reminderTime
             )
+            if (data.shown) {
+                systemTray.log(
+                    String.format(
+                        Locale.US,
+                        "Showing notification for habit %d silently because it has been shown before.",
+                        habit.id
+                    )
+                )
+            }
+            data.shown = true
+            active[habit] = data
         }
 
         private fun shouldShowReminderToday(): Boolean {