Creating the Habitgroup model

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

@@ -79,6 +79,10 @@ class HabitsApplication : Application() {
         val habitList = component.habitList
         for (h in habitList) h.recompute()
 
+        val habitGroupList = component.habitGroupList
+        for (hgr in habitGroupList) hgr.recompute()
+        habitGroupList.populateGroupsWith(habitList)
+
         widgetUpdater = component.widgetUpdater.apply {
             startListening()
             scheduleStartDayWidgetUpdate()

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

@@ -24,6 +24,7 @@ import org.isoron.uhabits.core.AppScope
 import org.isoron.uhabits.core.commands.CommandRunner
 import org.isoron.uhabits.core.io.GenericImporter
 import org.isoron.uhabits.core.io.Logging
+import org.isoron.uhabits.core.models.HabitGroupList
 import org.isoron.uhabits.core.models.HabitList
 import org.isoron.uhabits.core.models.ModelFactory
 import org.isoron.uhabits.core.preferences.Preferences
@@ -50,6 +51,7 @@ interface HabitsApplicationComponent {
     val genericImporter: GenericImporter
     val habitCardListCache: HabitCardListCache
     val habitList: HabitList
+    val habitGroupList: HabitGroupList
     val intentFactory: IntentFactory
     val intentParser: IntentParser
     val logging: Logging

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

@@ -26,9 +26,11 @@ import org.isoron.uhabits.core.commands.CommandRunner
 import org.isoron.uhabits.core.database.Database
 import org.isoron.uhabits.core.database.DatabaseOpener
 import org.isoron.uhabits.core.io.Logging
+import org.isoron.uhabits.core.models.HabitGroupList
 import org.isoron.uhabits.core.models.HabitList
 import org.isoron.uhabits.core.models.ModelFactory
 import org.isoron.uhabits.core.models.sqlite.SQLModelFactory
+import org.isoron.uhabits.core.models.sqlite.SQLiteHabitGroupList
 import org.isoron.uhabits.core.models.sqlite.SQLiteHabitList
 import org.isoron.uhabits.core.preferences.Preferences
 import org.isoron.uhabits.core.preferences.WidgetPreferences
@@ -97,6 +99,12 @@ class HabitsModule(dbFile: File) {
         return list
     }
 
+    @Provides
+    @AppScope
+    fun getHabitGroupList(list: SQLiteHabitGroupList): HabitGroupList {
+        return list
+    }
+
     @Provides
     @AppScope
     fun getDatabaseOpener(opener: AndroidDatabaseOpener): DatabaseOpener {

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

@@ -40,12 +40,15 @@ data class Habit(
     val computedEntries: EntryList,
     val originalEntries: EntryList,
     val scores: ScoreList,
-    val streaks: StreakList
+    val streaks: StreakList,
+    var parentID: Long? = null,
+    var parentUUID: String? = null
 ) {
     init {
         if (uuid == null) this.uuid = UUID.randomUUID().toString().replace("-", "")
     }
 
+    var parent: HabitGroup? = null
     var observable = ModelObservable()
 
     val isNumerical: Boolean
@@ -111,6 +114,14 @@ data class Habit(
         return computedEntries.getKnown().lastOrNull()?.timestamp ?: DateUtils.getTodayWithOffset()
     }
 
+    fun hierarchyLevel(): Int {
+        return if (parentID == null) {
+            0
+        } else {
+            1 + parent!!.hierarchyLevel()
+        }
+    }
+
     fun copyFrom(other: Habit) {
         this.color = other.color
         this.description = other.description
@@ -127,6 +138,8 @@ data class Habit(
         this.type = other.type
         this.unit = other.unit
         this.uuid = other.uuid
+        this.parentID = other.parentID
+        this.parentUUID = other.parentUUID
     }
 
     override fun equals(other: Any?): Boolean {
@@ -148,6 +161,8 @@ data class Habit(
         if (type != other.type) return false
         if (unit != other.unit) return false
         if (uuid != other.uuid) return false
+        if (parentID != other.parentID) return false
+        if (parentUUID != other.parentUUID) return false
 
         return true
     }
@@ -168,6 +183,8 @@ data class Habit(
         result = 31 * result + type.value
         result = 31 * result + unit.hashCode()
         result = 31 * result + (uuid?.hashCode() ?: 0)
+        result = 31 * result + (parentID?.hashCode() ?: 0)
+        result = 31 * result + (parentUUID?.hashCode() ?: 0)
         return result
     }
 }

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

@@ -12,17 +12,19 @@ data class HabitGroup(
     var position: Int = 0,
     var question: String = "",
     var reminder: Reminder? = null,
-    var unit: String = "",
     var uuid: String? = null,
     var habitList: HabitList,
     var habitGroupList: HabitGroupList,
     val scores: ScoreList,
-    val streaks: StreakList
+    val streaks: StreakList,
+    var parentID: Long? = null,
+    var parentUUID: String? = null
 ) {
     init {
         if (uuid == null) this.uuid = UUID.randomUUID().toString().replace("-", "")
     }
 
+    var parent: HabitGroup? = null
     var observable = ModelObservable()
 
     val uriString: String
@@ -76,7 +78,7 @@ data class HabitGroup(
         )
     }
 
-    fun copyFrom(other: Habit) {
+    fun copyFrom(other: HabitGroup) {
         this.color = other.color
         this.description = other.description
         // this.id should not be copied
@@ -85,8 +87,9 @@ data class HabitGroup(
         this.position = other.position
         this.question = other.question
         this.reminder = other.reminder
-        this.unit = other.unit
         this.uuid = other.uuid
+        this.parentID = other.parentID
+        this.parentUUID = other.parentUUID
     }
 
     override fun equals(other: Any?): Boolean {
@@ -101,8 +104,9 @@ data class HabitGroup(
         if (position != other.position) return false
         if (question != other.question) return false
         if (reminder != other.reminder) return false
-        if (unit != other.unit) return false
         if (uuid != other.uuid) return false
+        if (parentID != other.parentID) return false
+        if (parentUUID != other.parentUUID) return false
 
         return true
     }
@@ -116,8 +120,37 @@ data class HabitGroup(
         result = 31 * result + position
         result = 31 * result + question.hashCode()
         result = 31 * result + (reminder?.hashCode() ?: 0)
-        result = 31 * result + unit.hashCode()
         result = 31 * result + (uuid?.hashCode() ?: 0)
+        result = 31 * result + (parentID?.hashCode() ?: 0)
+        result = 31 * result + (parentUUID?.hashCode() ?: 0)
         return result
     }
+
+    fun hierarchyLevel(): Int {
+        return if (parentID == null) {
+            0
+        } else {
+            1 + parent!!.hierarchyLevel()
+        }
+    }
+
+    fun getHabitByUUIDDeep(uuid: String?): Habit? {
+        val habit = habitList.getByUUID(uuid)
+        if (habit != null) return habit
+        for (hgr in habitGroupList) {
+            val found = hgr.getHabitByUUIDDeep(uuid)
+            if (found != null) return found
+        }
+        return null
+    }
+
+    fun getHabitGroupByUUIDDeep(uuid: String?): HabitGroup? {
+        val habitGroup = habitGroupList.getByUUID(uuid)
+        if (habitGroup != null) return habitGroup
+        for (hgr in habitGroupList) {
+            val found = hgr.getHabitGroupByUUIDDeep(uuid)
+            if (found != null) return found
+        }
+        return null
+    }
 }

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

@@ -1,6 +1,7 @@
 package org.isoron.uhabits.core.models
 
 import com.opencsv.CSVWriter
+import org.isoron.uhabits.core.models.HabitList.Order
 import java.io.IOException
 import java.io.Writer
 import java.util.LinkedList
@@ -63,6 +64,30 @@ abstract class HabitGroupList : Iterable<HabitGroup> {
      */
     abstract fun getByUUID(uuid: String?): HabitGroup?
 
+    /**
+     *  Returns the habit with the specified UUID which is
+     *  present at any hierarchy within this list.
+     */
+    fun getHabitByUUIDDeep(uuid: String?): Habit? {
+        for (hgr in this) {
+            val habit = hgr.getHabitByUUIDDeep(uuid)
+            if (habit != null) {
+                return habit
+            }
+        }
+        return null
+    }
+
+    fun getHabitGroupByUUIDDeep(uuid: String?): HabitGroup? {
+        for (hgr in this) {
+            val habit = hgr.getHabitGroupByUUIDDeep(uuid)
+            if (habit != null) {
+                return habit
+            }
+        }
+        return null
+    }
+
     /**
      * Returns the habit that occupies a certain position.
      *
@@ -150,6 +175,42 @@ abstract class HabitGroupList : Iterable<HabitGroup> {
         update(listOf(habitGroup))
     }
 
+    fun populateGroupsWith(habitList: HabitList) {
+        val toRemove = mutableListOf<String?>()
+        for (habit in habitList) {
+            val hgr = getByUUID(habit.parentUUID)
+            if (hgr != null) {
+                hgr.habitList.add(habit)
+                habit.parent = hgr
+                toRemove.add(habit.uuid)
+            }
+        }
+        for (uuid in toRemove) {
+            val h = habitList.getByUUID(uuid)
+            if (h != null) {
+                habitList.remove(h)
+            }
+        }
+        toRemove.clear()
+        for (hgr1 in this) {
+            val hgr2 = getByUUID(hgr1.parentUUID)
+            if (hgr2 != null) {
+                hgr2.habitGroupList.add(hgr1)
+                toRemove.add(hgr1.uuid)
+                hgr1.parent = hgr2
+            }
+        }
+        for (uuid in toRemove) {
+            val h = getByUUID(uuid)
+            if (h != null) {
+                remove(h)
+            }
+        }
+        for (hgr in this) {
+            hgr.recompute()
+        }
+    }
+
     /**
      * Writes the list of habits to the given writer, in CSV format. There is
      * one line for each habit, containing the fields name, description,
@@ -186,15 +247,4 @@ abstract class HabitGroupList : Iterable<HabitGroup> {
     }
 
     abstract fun resort()
-    enum class Order {
-        BY_NAME_ASC,
-        BY_NAME_DESC,
-        BY_COLOR_ASC,
-        BY_COLOR_DESC,
-        BY_SCORE_ASC,
-        BY_SCORE_DESC,
-        BY_STATUS_ASC,
-        BY_STATUS_DESC,
-        BY_POSITION
-    }
 }

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

@@ -32,6 +32,14 @@ data class HabitMatcher(
         return true
     }
 
+    fun matches(habitGroup: HabitGroup): Boolean {
+        if (!isArchivedAllowed && habitGroup.isArchived) return false
+        if (isReminderRequired && !habitGroup.hasReminder()) return false
+        if (!isCompletedAllowed && habitGroup.isCompletedToday()) return false
+        if (!isEnteredAllowed && habitGroup.isEnteredToday()) return false
+        return true
+    }
+
     companion object {
         @JvmField
         val WITH_ALARM = HabitMatcher(

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

@@ -20,6 +20,7 @@ package org.isoron.uhabits.core.models
 
 import org.isoron.uhabits.core.database.Repository
 import org.isoron.uhabits.core.models.sqlite.records.EntryRecord
+import org.isoron.uhabits.core.models.sqlite.records.HabitGroupRecord
 import org.isoron.uhabits.core.models.sqlite.records.HabitRecord
 
 /**
@@ -38,11 +39,25 @@ interface ModelFactory {
             computedEntries = buildComputedEntries()
         )
     }
+    fun buildHabitGroup(): HabitGroup {
+        val habits = buildHabitList()
+        val groups = buildHabitGroupList()
+        val scores = buildScoreList()
+        val streaks = buildStreakList()
+        return HabitGroup(
+            habitList = habits,
+            habitGroupList = groups,
+            scores = scores,
+            streaks = streaks
+        )
+    }
     fun buildComputedEntries(): EntryList
     fun buildOriginalEntries(): EntryList
     fun buildHabitList(): HabitList
+    fun buildHabitGroupList(): HabitGroupList
     fun buildScoreList(): ScoreList
     fun buildStreakList(): StreakList
     fun buildHabitListRepository(): Repository<HabitRecord>
     fun buildRepetitionListRepository(): Repository<EntryRecord>
+    fun buildHabitGroupListRepository(): Repository<HabitGroupRecord>
 }

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

@@ -0,0 +1,216 @@
+package org.isoron.uhabits.core.models.memory
+
+import org.isoron.uhabits.core.models.HabitGroup
+import org.isoron.uhabits.core.models.HabitGroupList
+import org.isoron.uhabits.core.models.HabitList.Order
+import org.isoron.uhabits.core.models.HabitMatcher
+import org.isoron.uhabits.core.utils.DateUtils.Companion.getTodayWithOffset
+import java.util.LinkedList
+import java.util.Objects
+
+/**
+ * In-memory implementation of [HabitGroupList].
+ */
+class MemoryHabitGroupList : HabitGroupList {
+    private val list = LinkedList<HabitGroup>()
+
+    @get:Synchronized
+    override var primaryOrder = Order.BY_POSITION
+        set(value) {
+            field = value
+            comparator = getComposedComparatorByOrder(primaryOrder, secondaryOrder)
+            resort()
+        }
+
+    @get:Synchronized
+    override var secondaryOrder = Order.BY_NAME_ASC
+        set(value) {
+            field = value
+            comparator = getComposedComparatorByOrder(primaryOrder, secondaryOrder)
+            resort()
+        }
+
+    private var comparator: Comparator<HabitGroup>? =
+        getComposedComparatorByOrder(primaryOrder, secondaryOrder)
+    private var parent: MemoryHabitGroupList? = null
+
+    constructor() : super()
+    constructor(
+        matcher: HabitMatcher,
+        comparator: Comparator<HabitGroup>?,
+        parent: MemoryHabitGroupList
+    ) : super(matcher) {
+        this.parent = parent
+        this.comparator = comparator
+        primaryOrder = parent.primaryOrder
+        secondaryOrder = parent.secondaryOrder
+        parent.observable.addListener { loadFromParent() }
+        loadFromParent()
+    }
+
+    @Synchronized
+    @Throws(IllegalArgumentException::class)
+    override fun add(habitGroup: HabitGroup) {
+        throwIfHasParent()
+        require(!list.contains(habitGroup)) { "habit already added" }
+        val id = habitGroup.id
+        if (id != null && getById(id) != null) throw RuntimeException("duplicate id")
+        if (id == null) habitGroup.id = list.size.toLong()
+        list.addLast(habitGroup)
+        resort()
+    }
+
+    @Synchronized
+    override fun getById(id: Long): HabitGroup? {
+        for (h in list) {
+            checkNotNull(h.id)
+            if (h.id == id) return h
+        }
+        return null
+    }
+
+    @Synchronized
+    override fun getByUUID(uuid: String?): HabitGroup? {
+        for (h in list) if (Objects.requireNonNull(h.uuid) == uuid) return h
+        return null
+    }
+
+    @Synchronized
+    override fun getByPosition(position: Int): HabitGroup {
+        return list[position]
+    }
+
+    @Synchronized
+    override fun getFiltered(matcher: HabitMatcher?): HabitGroupList {
+        return MemoryHabitGroupList(matcher!!, comparator, this)
+    }
+
+    private fun getComposedComparatorByOrder(
+        firstOrder: Order,
+        secondOrder: Order?
+    ): Comparator<HabitGroup> {
+        return Comparator { h1: HabitGroup, h2: HabitGroup ->
+            val firstResult = getComparatorByOrder(firstOrder).compare(h1, h2)
+            if (firstResult != 0 || secondOrder == null) {
+                return@Comparator firstResult
+            }
+            getComparatorByOrder(secondOrder).compare(h1, h2)
+        }
+    }
+
+    private fun getComparatorByOrder(order: Order): Comparator<HabitGroup> {
+        val nameComparatorAsc = Comparator<HabitGroup> { habit1, habit2 ->
+            habit1.name.compareTo(habit2.name)
+        }
+        val nameComparatorDesc =
+            Comparator { h1: HabitGroup, h2: HabitGroup -> nameComparatorAsc.compare(h2, h1) }
+        val colorComparatorAsc = Comparator<HabitGroup> { (color1), (color2) ->
+            color1.compareTo(color2)
+        }
+        val colorComparatorDesc =
+            Comparator { h1: HabitGroup, h2: HabitGroup -> colorComparatorAsc.compare(h2, h1) }
+        val scoreComparatorDesc =
+            Comparator<HabitGroup> { habit1, habit2 ->
+                val today = getTodayWithOffset()
+                habit1.scores[today].value.compareTo(habit2.scores[today].value)
+            }
+        val scoreComparatorAsc =
+            Comparator { h1: HabitGroup, h2: HabitGroup -> scoreComparatorDesc.compare(h2, h1) }
+        val positionComparator =
+            Comparator<HabitGroup> { habit1, habit2 -> habit1.position.compareTo(habit2.position) }
+        val statusComparatorDesc = Comparator { h1: HabitGroup, h2: HabitGroup ->
+            if (h1.isCompletedToday() != h2.isCompletedToday()) {
+                return@Comparator if (h1.isCompletedToday()) -1 else 1
+            }
+            val today = getTodayWithOffset()
+            val v1 = h1.scores[today].value
+            val v2 = h2.scores[today].value
+            v2.compareTo(v1)
+        }
+        val statusComparatorAsc =
+            Comparator { h1: HabitGroup, h2: HabitGroup -> statusComparatorDesc.compare(h2, h1) }
+        return when {
+            order === Order.BY_POSITION -> positionComparator
+            order === Order.BY_NAME_ASC -> nameComparatorAsc
+            order === Order.BY_NAME_DESC -> nameComparatorDesc
+            order === Order.BY_COLOR_ASC -> colorComparatorAsc
+            order === Order.BY_COLOR_DESC -> colorComparatorDesc
+            order === Order.BY_SCORE_DESC -> scoreComparatorDesc
+            order === Order.BY_SCORE_ASC -> scoreComparatorAsc
+            order === Order.BY_STATUS_DESC -> statusComparatorDesc
+            order === Order.BY_STATUS_ASC -> statusComparatorAsc
+            else -> throw IllegalStateException()
+        }
+    }
+
+    @Synchronized
+    override fun indexOf(h: HabitGroup): Int {
+        return list.indexOf(h)
+    }
+
+    @Synchronized
+    override fun iterator(): Iterator<HabitGroup> {
+        return ArrayList(list).iterator()
+    }
+
+    @Synchronized
+    override fun remove(h: HabitGroup) {
+        throwIfHasParent()
+        list.remove(h)
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun reorder(from: HabitGroup, to: HabitGroup) {
+        throwIfHasParent()
+        check(!(primaryOrder !== Order.BY_POSITION)) { "cannot reorder automatically sorted list" }
+        require(indexOf(from) >= 0) { "list does not contain (from) habit" }
+        val toPos = indexOf(to)
+        require(toPos >= 0) { "list does not contain (to) habit" }
+        list.remove(from)
+        list.add(toPos, from)
+        var position = 0
+        for (h in list) h.position = position++
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun size(): Int {
+        return list.size
+    }
+
+    @Synchronized
+    override fun update(habitGroups: List<HabitGroup>) {
+        resort()
+    }
+
+    private fun throwIfHasParent() {
+        check(parent == null) {
+            "Filtered lists cannot be modified directly. " +
+                "You should modify the parent list instead."
+        }
+    }
+
+    @Synchronized
+    private fun loadFromParent() {
+        checkNotNull(parent)
+        list.clear()
+        for (h in parent!!) if (filter.matches(h)) list.add(h)
+        resort()
+    }
+
+    @Synchronized
+    override fun resort() {
+        for (hgr in list) {
+            hgr.habitList.primaryOrder = primaryOrder
+            hgr.habitList.secondaryOrder = secondaryOrder
+            hgr.habitList.resort()
+
+            hgr.habitGroupList.primaryOrder = primaryOrder
+            hgr.habitGroupList.secondaryOrder = secondaryOrder
+            hgr.habitGroupList.resort()
+        }
+        if (comparator != null) list.sortWith(comparator!!)
+        observable.notifyListeners()
+    }
+}

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

@@ -27,8 +27,10 @@ class MemoryModelFactory : ModelFactory {
     override fun buildComputedEntries() = EntryList()
     override fun buildOriginalEntries() = EntryList()
     override fun buildHabitList() = MemoryHabitList()
+    override fun buildHabitGroupList() = MemoryHabitGroupList()
     override fun buildScoreList() = ScoreList()
     override fun buildStreakList() = StreakList()
     override fun buildHabitListRepository() = throw NotImplementedError()
     override fun buildRepetitionListRepository() = throw NotImplementedError()
+    override fun buildHabitGroupListRepository() = throw NotImplementedError()
 }

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

@@ -25,6 +25,7 @@ import org.isoron.uhabits.core.models.ModelFactory
 import org.isoron.uhabits.core.models.ScoreList
 import org.isoron.uhabits.core.models.StreakList
 import org.isoron.uhabits.core.models.sqlite.records.EntryRecord
+import org.isoron.uhabits.core.models.sqlite.records.HabitGroupRecord
 import org.isoron.uhabits.core.models.sqlite.records.HabitRecord
 import javax.inject.Inject
 
@@ -38,6 +39,8 @@ class SQLModelFactory
     override fun buildOriginalEntries() = SQLiteEntryList(database)
     override fun buildComputedEntries() = EntryList()
     override fun buildHabitList() = SQLiteHabitList(this)
+    override fun buildHabitGroupList() = SQLiteHabitGroupList(this)
+
     override fun buildScoreList() = ScoreList()
     override fun buildStreakList() = StreakList()
 
@@ -46,4 +49,7 @@ class SQLModelFactory
 
     override fun buildRepetitionListRepository() =
         Repository(EntryRecord::class.java, database)
+
+    override fun buildHabitGroupListRepository() =
+        Repository(HabitGroupRecord::class.java, database)
 }

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

@@ -0,0 +1,200 @@
+package org.isoron.uhabits.core.models.sqlite
+
+import org.isoron.uhabits.core.database.Repository
+import org.isoron.uhabits.core.models.HabitGroup
+import org.isoron.uhabits.core.models.HabitGroupList
+import org.isoron.uhabits.core.models.HabitList.Order
+import org.isoron.uhabits.core.models.HabitMatcher
+import org.isoron.uhabits.core.models.ModelFactory
+import org.isoron.uhabits.core.models.memory.MemoryHabitGroupList
+import org.isoron.uhabits.core.models.sqlite.records.HabitGroupRecord
+import javax.inject.Inject
+
+/**
+ * Implementation of a [HabitGroupList] that is backed by SQLite.
+ */
+class SQLiteHabitGroupList @Inject constructor(private val modelFactory: ModelFactory) : HabitGroupList() {
+    private val repository: Repository<HabitGroupRecord> = modelFactory.buildHabitGroupListRepository()
+    private val list: MemoryHabitGroupList = MemoryHabitGroupList()
+    private var loaded = false
+    private fun loadRecords() {
+        if (loaded) return
+        loaded = true
+        list.removeAll()
+        val records = repository.findAll("order by position")
+        var shouldRebuildOrder = false
+        for ((expectedPosition, rec) in records.withIndex()) {
+            if (rec.position != expectedPosition) shouldRebuildOrder = true
+            val h = modelFactory.buildHabitGroup()
+            rec.copyTo(h)
+            list.add(h)
+        }
+        if (shouldRebuildOrder) rebuildOrder()
+    }
+
+    @Synchronized
+    override fun add(habitGroup: HabitGroup) {
+        loadRecords()
+        habitGroup.position = size()
+        val record = HabitGroupRecord()
+        record.copyFrom(habitGroup)
+        repository.save(record)
+        habitGroup.id = record.id
+        list.add(habitGroup)
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun getById(id: Long): HabitGroup? {
+        loadRecords()
+        return list.getById(id)
+    }
+
+    @Synchronized
+    override fun getByUUID(uuid: String?): HabitGroup? {
+        loadRecords()
+        return list.getByUUID(uuid)
+    }
+
+    @Synchronized
+    override fun getByPosition(position: Int): HabitGroup {
+        loadRecords()
+        return list.getByPosition(position)
+    }
+
+    @Synchronized
+    override fun getFiltered(matcher: HabitMatcher?): HabitGroupList {
+        loadRecords()
+        return list.getFiltered(matcher)
+    }
+
+    @set:Synchronized
+    override var primaryOrder: Order
+        get() = list.primaryOrder
+        set(order) {
+            list.primaryOrder = order
+            observable.notifyListeners()
+        }
+
+    @set:Synchronized
+    override var secondaryOrder: Order
+        get() = list.secondaryOrder
+        set(order) {
+            list.secondaryOrder = order
+            observable.notifyListeners()
+        }
+
+    @Synchronized
+    override fun indexOf(h: HabitGroup): Int {
+        loadRecords()
+        return list.indexOf(h)
+    }
+
+    @Synchronized
+    override fun iterator(): Iterator<HabitGroup> {
+        loadRecords()
+        return list.iterator()
+    }
+
+    @Synchronized
+    private fun rebuildOrder() {
+        val records = repository.findAll("order by position")
+        repository.executeAsTransaction {
+            for ((pos, r) in records.withIndex()) {
+                if (r.position != pos) {
+                    r.position = pos
+                    repository.save(r)
+                }
+            }
+        }
+    }
+
+    @Synchronized
+    override fun remove(h: HabitGroup) {
+        loadRecords()
+        list.remove(h)
+        val record = repository.find(
+            h.id!!
+        ) ?: throw RuntimeException("habit not in database")
+        repository.executeAsTransaction {
+            repository.remove(record)
+        }
+        rebuildOrder()
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun removeAll() {
+        list.removeAll()
+        repository.execSQL("delete from habits")
+        repository.execSQL("delete from repetitions")
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun reorder(from: HabitGroup, to: HabitGroup) {
+        loadRecords()
+        list.reorder(from, to)
+        val fromRecord = repository.find(
+            from.id!!
+        )
+        val toRecord = repository.find(
+            to.id!!
+        )
+        if (fromRecord == null) throw RuntimeException("habit not in database")
+        if (toRecord == null) throw RuntimeException("habit not in database")
+        if (toRecord.position!! < fromRecord.position!!) {
+            repository.execSQL(
+                "update habits set position = position + 1 " +
+                    "where position >= ? and position < ?",
+                toRecord.position!!,
+                fromRecord.position!!
+            )
+        } else {
+            repository.execSQL(
+                "update habits set position = position - 1 " +
+                    "where position > ? and position <= ?",
+                fromRecord.position!!,
+                toRecord.position!!
+            )
+        }
+        fromRecord.position = toRecord.position
+        repository.save(fromRecord)
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun repair() {
+        loadRecords()
+        rebuildOrder()
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    override fun size(): Int {
+        loadRecords()
+        return list.size()
+    }
+
+    @Synchronized
+    override fun update(habitGroups: List<HabitGroup>) {
+        loadRecords()
+        list.update(habitGroups)
+        for (h in habitGroups) {
+            val record = repository.find(h.id!!) ?: continue
+            record.copyFrom(h)
+            repository.save(record)
+        }
+        observable.notifyListeners()
+    }
+
+    override fun resort() {
+        list.resort()
+        observable.notifyListeners()
+    }
+
+    @Synchronized
+    fun reload() {
+        loaded = false
+    }
+}

uhabits-core/src/jvmMain/java/org/isoron/uhabits/core/models/sqlite/records/HabitGroupRecord.kt

@@ -0,0 +1,100 @@
+package org.isoron.uhabits.core.models.sqlite.records
+
+import org.isoron.uhabits.core.database.Column
+import org.isoron.uhabits.core.database.Table
+import org.isoron.uhabits.core.models.HabitGroup
+import org.isoron.uhabits.core.models.PaletteColor
+import org.isoron.uhabits.core.models.Reminder
+import org.isoron.uhabits.core.models.WeekdayList
+import java.util.Objects.requireNonNull
+
+/**
+ * The SQLite database record corresponding to a [HabitGroup].
+ */
+@Table(name = "habitgroups")
+class HabitGroupRecord {
+    @field:Column
+    var description: String? = null
+
+    @field:Column
+    var question: String? = null
+
+    @field:Column
+    var name: String? = null
+
+    @field:Column
+    var color: Int? = null
+
+    @field:Column
+    var position: Int? = null
+
+    @field:Column(name = "reminder_hour")
+    var reminderHour: Int? = null
+
+    @field:Column(name = "reminder_min")
+    var reminderMin: Int? = null
+
+    @field:Column(name = "reminder_days")
+    var reminderDays: Int? = null
+
+    @field:Column
+    var highlight: Int? = null
+
+    @field:Column
+    var archived: Int? = null
+
+    @field:Column
+    var id: Long? = null
+
+    @field:Column
+    var uuid: String? = null
+
+    @field:Column(name = "parent_id")
+    var parentID: Long? = null
+
+    @field:Column(name = "parent_uuid")
+    var parentUUID: String? = null
+
+    fun copyFrom(model: HabitGroup) {
+        id = model.id
+        name = model.name
+        description = model.description
+        highlight = 0
+        color = model.color.paletteIndex
+        archived = if (model.isArchived) 1 else 0
+        position = model.position
+        question = model.question
+        uuid = model.uuid
+        reminderDays = 0
+        reminderMin = null
+        reminderHour = null
+        parentID = model.parentID
+        parentUUID = model.parentUUID
+        if (model.hasReminder()) {
+            val reminder = model.reminder
+            reminderHour = requireNonNull(reminder)!!.hour
+            reminderMin = reminder!!.minute
+            reminderDays = reminder.days.toInteger()
+        }
+    }
+
+    fun copyTo(habitGroup: HabitGroup) {
+        habitGroup.id = id
+        habitGroup.name = name!!
+        habitGroup.description = description!!
+        habitGroup.question = question!!
+        habitGroup.color = PaletteColor(color!!)
+        habitGroup.isArchived = archived != 0
+        habitGroup.position = position!!
+        habitGroup.uuid = uuid
+        habitGroup.parentID = parentID
+        habitGroup.parentUUID = parentUUID
+        if (reminderHour != null && reminderMin != null) {
+            habitGroup.reminder = Reminder(
+                reminderHour!!,
+                reminderMin!!,
+                WeekdayList(reminderDays!!)
+            )
+        }
+    }
+}

uhabits-core/src/jvmMain/java/org/isoron/uhabits/core/models/sqlite/records/HabitRecord.kt

@@ -95,6 +95,12 @@ class HabitRecord {
     @field:Column
     var uuid: String? = null
 
+    @field:Column(name = "parent_id")
+    var parentID: Long? = null
+
+    @field:Column(name = "parent_uuid")
+    var parentUUID: String? = null
+
     fun copyFrom(model: Habit) {
         id = model.id
         name = model.name
@@ -109,6 +115,8 @@ class HabitRecord {
         position = model.position
         question = model.question
         uuid = model.uuid
+        parentID = model.parentID
+        parentUUID = model.parentUUID
         val (numerator, denominator) = model.frequency
         freqNum = numerator
         freqDen = denominator
@@ -140,6 +148,8 @@ class HabitRecord {
         habit.unit = unit!!
         habit.position = position!!
         habit.uuid = uuid
+        habit.parentID = parentID
+        habit.parentUUID = parentUUID
         if (reminderHour != null && reminderMin != null) {
             habit.reminder = Reminder(
                 reminderHour!!,

uhabits-core/src/jvmMain/resources/migrations/26.sql

@@ -1,2 +1,21 @@
 alter table Habits add column skip_days integer not null default 0;
-alter table Habits add column skip_days_list integer not null default 0;
+alter table Habits add column skip_days_list integer not null default 0;
+alter table Habits add column parent_id integer;
+alter table Habits add column parent_uuid text;
+
+create table HabitGroups (
+    id integer primary key autoincrement,
+    archived integer,
+    color integer,
+    description text not null default "",
+    highlight integer,
+    name text,
+    position integer,
+    reminder_days integer not null default 127,
+    reminder_hour integer,
+    reminder_min integer,
+    question text not null default "",
+    uuid text,
+    parent_id integer,
+    parent_uuid integer
+);