Add support for offline multi-level subtasks

app/src/androidTest/java/com/todoroo/astrid/dao/TaskDaoTests.java

@@ -6,12 +6,20 @@
 
 package com.todoroo.astrid.dao;
 
+import static com.natpryce.makeiteasy.MakeItEasy.with;
+import static java.util.Arrays.asList;
+import static java.util.Collections.singletonList;
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertNotSame;
 import static junit.framework.Assert.assertNull;
+import static org.tasks.makers.TaskMaker.ID;
+import static org.tasks.makers.TaskMaker.PARENT;
+import static org.tasks.makers.TaskMaker.newTask;
 
 import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.SdkSuppress;
 import com.google.common.collect.ImmutableList;
+import com.google.common.primitives.Longs;
 import com.todoroo.andlib.utility.DateUtilities;
 import com.todoroo.astrid.data.Task;
 import com.todoroo.astrid.service.TaskDeleter;
@@ -155,6 +163,34 @@ public class TaskDaoTests extends InjectingTestCase {
     assertEquals(0, taskDao.getAll().size());
   }
 
+  @Test
+  @SdkSuppress(minSdkVersion = 21)
+  public void findChildrenInList() {
+    taskDao.createNew(newTask(with(ID, 1L)));
+    taskDao.createNew(newTask(with(ID, 2L), with(PARENT, 1L)));
+
+    assertEquals(singletonList(2L), taskDao.findChildrenInList(Longs.asList(1, 2)));
+  }
+
+  @Test
+  @SdkSuppress(minSdkVersion = 21)
+  public void findRecursiveChildrenInList() {
+    taskDao.createNew(newTask(with(ID, 1L)));
+    taskDao.createNew(newTask(with(ID, 2L), with(PARENT, 1L)));
+    taskDao.createNew(newTask(with(ID, 3L), with(PARENT, 2L)));
+
+    assertEquals(asList(2L, 3L), taskDao.findChildrenInList(Longs.asList(1, 2, 3)));
+  }
+
+  @Test
+  @SdkSuppress(minSdkVersion = 21)
+  public void findRecursiveChildrenInListAfterSkippingParent() {
+    taskDao.createNew(newTask(with(ID, 1L)));
+    taskDao.createNew(newTask(with(ID, 2L), with(PARENT, 1L)));
+    taskDao.createNew(newTask(with(ID, 3L), with(PARENT, 2L)));
+
+    assertEquals(singletonList(3L), taskDao.findChildrenInList(Longs.asList(1, 3)));
+  }
   @Override
   protected void inject(TestComponent component) {
     component.inject(this);

app/src/androidTest/java/com/todoroo/astrid/service/TaskMoverTest.java

@@ -26,6 +26,7 @@ import com.google.common.primitives.Longs;
 import com.todoroo.astrid.api.CaldavFilter;
 import com.todoroo.astrid.api.GtasksFilter;
 import com.todoroo.astrid.dao.TaskDao;
+import com.todoroo.astrid.data.Task;
 import java.util.List;
 import javax.inject.Inject;
 import org.junit.Before;
@@ -41,6 +42,7 @@ import org.tasks.injection.TestComponent;
 import org.tasks.jobs.WorkManager;
 import org.tasks.makers.CaldavTaskMaker;
 import org.tasks.makers.GtaskListMaker;
+import org.tasks.makers.TaskMaker;
 
 @RunWith(AndroidJUnit4.class)
 public class TaskMoverTest extends InjectingTestCase {
@@ -125,7 +127,9 @@ public class TaskMoverTest extends InjectingTestCase {
   @Test
   @SdkSuppress(minSdkVersion = 21)
   public void moveRecursiveCaldavChildren() {
-    createTasks(1, 2, 3);
+    createTasks(1);
+    createSubtask(2, 1);
+    createSubtask(3, 2);
     caldavDao.insert(
         asList(
             newCaldavTask(
@@ -133,13 +137,11 @@ public class TaskMoverTest extends InjectingTestCase {
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 2L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
                 with(REMOTE_ID, "b"),
                 with(REMOTE_PARENT, "a")),
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 3L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 2L),
                 with(REMOTE_PARENT, "b"))));
 
     moveToCaldavList("2", 1);
@@ -148,7 +150,7 @@ public class TaskMoverTest extends InjectingTestCase {
     assertEquals(3, deleted.size());
     CaldavTask task = caldavDao.getTask(3);
     assertEquals("2", task.getCalendar());
-    assertEquals(2, task.getParent());
+    assertEquals(2, taskDao.fetch(3).getParent());
   }
 
   @Test
@@ -160,13 +162,49 @@ public class TaskMoverTest extends InjectingTestCase {
     moveToCaldavList("1", 1);
 
     CaldavTask task = caldavDao.getTask(2);
-    assertEquals(1L, task.getParent());
+    assertEquals("1", task.getCalendar());
+    assertEquals(1, taskDao.fetch(2).getParent());
+  }
+
+  @Test
+  @SdkSuppress(minSdkVersion = 21)
+  public void flattenLocalSubtasksWhenMovingToGoogleTasks() {
+    createTasks(1);
+    createSubtask(2, 1);
+    createSubtask(3, 2);
+
+    moveToGoogleTasks("1", 1);
+
+    assertEquals(1, googleTaskDao.getByTaskId(3).getParent());
+    assertEquals(0, taskDao.fetch(3).getParent());
+  }
+
+  @Test
+  public void moveLocalChildToGoogleTasks() {
+    createTasks(1);
+    createSubtask(2, 1);
+
+    moveToGoogleTasks("1", 2);
+
+    assertEquals(0, taskDao.fetch(2).getParent());
+  }
+
+  @Test
+  public void moveLocalChildToCaldav() {
+    createTasks(1);
+    createSubtask(2, 1);
+
+    moveToCaldavList("1", 2);
+
+    assertEquals(0, taskDao.fetch(2).getParent());
   }
 
   @Test
   @SdkSuppress(minSdkVersion = 21)
   public void flattenCaldavSubtasksWhenMovingToGoogleTasks() {
-    createTasks(1, 2, 3);
+    createTasks(1);
+    createSubtask(2, 1);
+    createSubtask(3, 2);
     caldavDao.insert(
         asList(
             newCaldavTask(
@@ -174,13 +212,11 @@ public class TaskMoverTest extends InjectingTestCase {
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 2L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
                 with(REMOTE_ID, "b"),
                 with(REMOTE_PARENT, "a")),
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 3L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 2L),
                 with(REMOTE_PARENT, "b"))));
 
     moveToGoogleTasks("1", 1);
@@ -204,7 +240,8 @@ public class TaskMoverTest extends InjectingTestCase {
 
   @Test
   public void moveCaldavChildWithoutParent() {
-    createTasks(1, 2);
+    createTasks(1);
+    createSubtask(2, 1);
     caldavDao.insert(
         asList(
             newCaldavTask(
@@ -212,13 +249,12 @@ public class TaskMoverTest extends InjectingTestCase {
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 2L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
                 with(REMOTE_PARENT, "a"))));
 
     moveToCaldavList("2", 2);
 
-    CaldavTask task = caldavDao.getTask(2);
+    assertEquals("2", caldavDao.getTask(2).getCalendar());
-    assertEquals(0, task.getParent());
+    assertEquals(0, taskDao.fetch(2).getParent());
   }
 
   @Test
@@ -241,6 +277,18 @@ public class TaskMoverTest extends InjectingTestCase {
     assertEquals("2", googleTaskDao.getByTaskId(1L).getListId());
   }
 
+  @Test
+  public void moveLocalToCaldav() {
+    createTasks(1);
+    createSubtask(2, 1);
+    createSubtask(3, 2);
+
+    moveToCaldavList("1", 1);
+
+    assertEquals("1", caldavDao.getTask(3).getCalendar());
+    assertEquals(2, taskDao.fetch(3).getParent());
+  }
+
   @Test
   public void dontSyncGoogleTask() {
     createTasks(1);
@@ -272,12 +320,17 @@ public class TaskMoverTest extends InjectingTestCase {
     dontSync(1);
 
     assertNull(googleTaskDao.getByTaskId(2));
-    assertFalse(taskDao.fetch(2).isDeleted());
+    Task task = taskDao.fetch(2);
+    assertFalse(task.isDeleted());
+    assertEquals(1, task.getParent());
+    assertEquals(taskDao.fetch(1).getUuid(), task.getParentUuid());
   }
 
   @Test
   public void dontSyncCaldavWithSubtasks() {
-    createTasks(1, 2);
+    createTasks(1);
+    createSubtask(2, 1);
+    createSubtask(3, 2);
     caldavDao.insert(
         asList(
             newCaldavTask(
@@ -285,13 +338,20 @@ public class TaskMoverTest extends InjectingTestCase {
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 2L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
+                with(REMOTE_ID, "b"),
-                with(REMOTE_PARENT, "a"))));
+                with(REMOTE_PARENT, "a")),
+            newCaldavTask(
+                with(CaldavTaskMaker.TASK, 3L),
+                with(CALENDAR, "1"),
+                with(REMOTE_PARENT, "b"))));
 
-    dontSync(2);
+    dontSync(1);
 
-    assertNull(caldavDao.getTask(2));
+    assertNull(caldavDao.getTask(3));
-    assertFalse(taskDao.fetch(2).isDeleted());
+    Task task = taskDao.fetch(3);
+    assertFalse(task.isDeleted());
+    assertEquals(2, task.getParent());
+    assertEquals(taskDao.fetch(2).getUuid(), task.getParentUuid());
   }
 
   @Test
@@ -329,7 +389,8 @@ public class TaskMoverTest extends InjectingTestCase {
 
   @Test
   public void dontDuplicateWhenParentAndChildCaldavMoved() {
-    createTasks(1, 2);
+    createTasks(1);
+    createSubtask(2, 1);
     caldavDao.insert(
         asList(
             newCaldavTask(
@@ -337,7 +398,6 @@ public class TaskMoverTest extends InjectingTestCase {
             newCaldavTask(
                 with(CaldavTaskMaker.TASK, 2L),
                 with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
                 with(REMOTE_PARENT, "a"))));
 
     moveToCaldavList("2", 1, 2);
@@ -351,6 +411,10 @@ public class TaskMoverTest extends InjectingTestCase {
     }
   }
 
+  private void createSubtask(long id, long parent) {
+    taskDao.createNew(newTask(with(ID, id), with(TaskMaker.PARENT, parent)));
+  }
+
   private void moveToGoogleTasks(String list, long... tasks) {
     taskMover.move(
         Longs.asList(tasks), new GtasksFilter(newGtaskList(with(GtaskListMaker.REMOTE_ID, list))));

app/src/androidTest/java/org/tasks/data/CaldavDaoTests.java

@@ -1,14 +1,9 @@
 package org.tasks.data;
 
 import static com.natpryce.makeiteasy.MakeItEasy.with;
-import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
-import static org.tasks.makers.CaldavTaskMaker.CALENDAR;
-import static org.tasks.makers.CaldavTaskMaker.REMOTE_ID;
-import static org.tasks.makers.CaldavTaskMaker.REMOTE_PARENT;
-import static org.tasks.makers.CaldavTaskMaker.newCaldavTask;
 import static org.tasks.makers.TagDataMaker.newTagData;
 import static org.tasks.makers.TagMaker.TAGDATA;
 import static org.tasks.makers.TagMaker.TASK;
@@ -17,8 +12,6 @@ import static org.tasks.makers.TaskMaker.ID;
 import static org.tasks.makers.TaskMaker.newTask;
 
 import androidx.test.ext.junit.runners.AndroidJUnit4;
-import androidx.test.filters.SdkSuppress;
-import com.google.common.primitives.Longs;
 import com.todoroo.astrid.dao.TaskDao;
 import com.todoroo.astrid.data.Task;
 import javax.inject.Inject;
@@ -26,7 +19,6 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.tasks.injection.InjectingTestCase;
 import org.tasks.injection.TestComponent;
-import org.tasks.makers.CaldavTaskMaker;
 
 @RunWith(AndroidJUnit4.class)
 public class CaldavDaoTests extends InjectingTestCase {
@@ -71,74 +63,6 @@ public class CaldavDaoTests extends InjectingTestCase {
     assertTrue(caldavDao.getTasksWithTags().isEmpty());
   }
 
-  @Test
-  @SdkSuppress(minSdkVersion = 21)
-  public void findChildrenInList() {
-    taskDao.createNew(newTask(with(ID, 1L)));
-    taskDao.createNew(newTask(with(ID, 2L)));
-    caldavDao.insert(
-        asList(
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 1L), with(CALENDAR, "1"), with(REMOTE_ID, "a")),
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 2L),
-                with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
-                with(REMOTE_PARENT, "a"))));
-
-    assertEquals(singletonList(2L), caldavDao.findChildrenInList(Longs.asList(1, 2)));
-  }
-
-  @Test
-  @SdkSuppress(minSdkVersion = 21)
-  public void findRecursiveChildrenInList() {
-    taskDao.createNew(newTask(with(ID, 1L)));
-    taskDao.createNew(newTask(with(ID, 2L)));
-    taskDao.createNew(newTask(with(ID, 3L)));
-    caldavDao.insert(
-        asList(
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 1L), with(CALENDAR, "1"), with(REMOTE_ID, "a")),
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 2L),
-                with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
-                with(REMOTE_ID, "b"),
-                with(REMOTE_PARENT, "a")),
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 3L),
-                with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 2L),
-                with(REMOTE_PARENT, "b"))));
-
-    assertEquals(asList(2L, 3L), caldavDao.findChildrenInList(Longs.asList(1, 2, 3)));
-  }
-
-  @Test
-  @SdkSuppress(minSdkVersion = 21)
-  public void findRecursiveChildrenInListAfterSkippingParent() {
-    taskDao.createNew(newTask(with(ID, 1L)));
-    taskDao.createNew(newTask(with(ID, 2L)));
-    taskDao.createNew(newTask(with(ID, 3L)));
-    caldavDao.insert(
-        asList(
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 1L), with(CALENDAR, "1"), with(REMOTE_ID, "a")),
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 2L),
-                with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 1L),
-                with(REMOTE_ID, "b"),
-                with(REMOTE_PARENT, "a")),
-            newCaldavTask(
-                with(CaldavTaskMaker.TASK, 3L),
-                with(CALENDAR, "1"),
-                with(CaldavTaskMaker.PARENT, 2L),
-                with(REMOTE_PARENT, "b"))));
-
-    assertEquals(singletonList(3L), caldavDao.findChildrenInList(Longs.asList(1, 3)));
-  }
-
   @Override
   protected void inject(TestComponent component) {
     component.inject(this);

app/src/androidTest/java/org/tasks/makers/CaldavTaskMaker.java

@@ -3,7 +3,6 @@ package org.tasks.makers;
 import static com.natpryce.makeiteasy.Property.newProperty;
 import static org.tasks.makers.Maker.make;
 
-import com.google.common.base.Strings;
 import com.natpryce.makeiteasy.Instantiator;
 import com.natpryce.makeiteasy.Property;
 import com.natpryce.makeiteasy.PropertyValue;
@@ -13,7 +12,6 @@ public class CaldavTaskMaker {
 
   public static final Property<CaldavTask, String> CALENDAR = newProperty();
   public static final Property<CaldavTask, Long> TASK = newProperty();
-  public static final Property<CaldavTask, Long> PARENT = newProperty();
   public static final Property<CaldavTask, String> REMOTE_ID = newProperty();
   public static final Property<CaldavTask, String> REMOTE_PARENT = newProperty();
 
@@ -21,7 +19,6 @@ public class CaldavTaskMaker {
       lookup -> {
         CaldavTask task =
             new CaldavTask(lookup.valueOf(TASK, 1L), lookup.valueOf(CALENDAR, "calendar"));
-        task.setParent(lookup.valueOf(PARENT, 0L));
         task.setRemoteId(lookup.valueOf(REMOTE_ID, task.getRemoteId()));
         task.setRemoteParent(lookup.valueOf(REMOTE_PARENT, (String) null));
         return task;

app/src/androidTest/java/org/tasks/makers/TaskMaker.java

@@ -29,6 +29,8 @@ public class TaskMaker {
   public static final Property<Task, Boolean> AFTER_COMPLETE = newProperty();
   private static final Property<Task, String> TITLE = newProperty();
   private static final Property<Task, Integer> PRIORITY = newProperty();
+  public static final Property<Task, Long> PARENT = newProperty();
+
   private static final Instantiator<Task> instantiator =
       lookup -> {
         Task task = new Task();
@@ -101,6 +103,8 @@ public class TaskMaker {
         DateTime creationTime = lookup.valueOf(CREATION_TIME, newDateTime());
         task.setCreationDate(creationTime.getMillis());
 
+        task.setParent(lookup.valueOf(PARENT, 0L));
+
         return task;
       };
 

app/src/main/java/com/todoroo/astrid/adapter/CaldavTaskAdapter.java

@@ -85,16 +85,17 @@ public final class CaldavTaskAdapter extends TaskAdapter {
 
     if (newParent == 0) {
       caldavTask.setRemoteParent("");
-      caldavTask.setParent(0);
+      task.setParent(0);
     } else {
       CaldavTask parentTask = caldavDao.getTask(newParent);
       if (parentTask == null) {
         return;
       }
       caldavTask.setRemoteParent(parentTask.getRemoteId());
-      caldavTask.setParent(newParent);
+      task.setParent(newParent);
     }
     caldavDao.update(caldavTask);
+    taskDao.save(task.getTask());
   }
 
   private boolean taskIsChild(TaskContainer source, int destinationIndex) {

app/src/main/java/com/todoroo/astrid/dao/Database.java

@@ -58,7 +58,7 @@ import org.tasks.notifications.NotificationDao;
       CaldavAccount.class,
       GoogleTaskAccount.class
     },
-    version = 69)
+    version = 70)
 public abstract class Database extends RoomDatabase {
 
   public static final String NAME = "database";

app/src/main/java/com/todoroo/astrid/dao/TaskDao.java

@@ -8,6 +8,7 @@ package com.todoroo.astrid.dao;
 
 import static com.google.common.collect.Iterables.filter;
 import static com.google.common.collect.Iterables.transform;
+import static com.google.common.collect.Lists.newArrayList;
 import static com.google.common.collect.Lists.transform;
 import static com.todoroo.andlib.sql.SqlConstants.COUNT;
 import static com.todoroo.andlib.utility.AndroidUtilities.atLeastLollipop;
@@ -32,6 +33,7 @@ import com.todoroo.astrid.api.Filter;
 import com.todoroo.astrid.api.PermaSql;
 import com.todoroo.astrid.data.Task;
 import com.todoroo.astrid.helper.UUIDHelper;
+import java.util.Collections;
 import java.util.List;
 import org.tasks.BuildConfig;
 import org.tasks.data.Place;
@@ -100,7 +102,7 @@ public abstract class TaskDao {
       "SELECT tasks.* FROM tasks "
           + "LEFT JOIN google_tasks ON tasks._id = google_tasks.gt_task "
           + "WHERE gt_list_id IN (SELECT gtl_remote_id FROM google_task_lists WHERE gtl_account = :account)"
-          + "AND (tasks.modified > google_tasks.gt_last_sync OR google_tasks.gt_remote_id = '') "
+          + "AND (tasks.modified > google_tasks.gt_last_sync OR google_tasks.gt_remote_id = '' OR google_tasks.gt_deleted > 0) "
           + "ORDER BY CASE WHEN gt_parent = 0 THEN 0 ELSE 1 END, gt_order ASC")
   public abstract List<Task> getGoogleTasksToPush(String account);
 
@@ -141,7 +143,7 @@ public abstract class TaskDao {
   public List<TaskContainer> fetchTasks(QueryCallback callback) {
     long start = BuildConfig.DEBUG ? now() : 0;
     boolean includeGoogleSubtasks = atLeastLollipop() && hasGoogleTaskSubtasks();
-    boolean includeCaldavSubtasks = atLeastLollipop() && hasCaldavSubtasks();
+    boolean includeCaldavSubtasks = atLeastLollipop() && hasSubtasks();
     List<String> queries = callback.getQueries(includeGoogleSubtasks, includeCaldavSubtasks);
     SupportSQLiteDatabase db = database.getOpenHelper().getWritableDatabase();
     int last = queries.size() - 1;
@@ -159,11 +161,8 @@ public abstract class TaskDao {
   @RawQuery
   abstract int count(SimpleSQLiteQuery query);
 
-  @Query(
+  @Query("SELECT EXISTS(SELECT 1 FROM tasks WHERE parent > 0 AND deleted = 0)")
-      "SELECT EXISTS(SELECT 1 FROM caldav_tasks "
+  abstract boolean hasSubtasks();
-          + "INNER JOIN tasks ON cd_task = _id "
-          + "WHERE deleted = 0 AND cd_parent > 0 AND cd_deleted = 0)")
-  abstract boolean hasCaldavSubtasks();
 
   @Query(
       "SELECT EXISTS(SELECT 1 FROM google_tasks "
@@ -187,6 +186,58 @@ public abstract class TaskDao {
   @Query("UPDATE tasks SET modified = strftime('%s','now')*1000 WHERE _id in (:ids)")
   abstract void touchInternal(List<Long> ids);
 
+  @Query(
+      "UPDATE tasks SET parent = IFNULL(("
+          + " SELECT parent._id FROM tasks AS parent"
+          + " WHERE parent.remoteId = tasks.parent_uuid AND parent.deleted = 0), 0)"
+          + "WHERE parent_uuid IS NOT NULL AND parent_uuid != ''")
+  public abstract void updateParents();
+
+  @Query(
+      "UPDATE tasks SET parent_uuid = "
+          + "  (SELECT parent.remoteId FROM tasks AS parent WHERE parent._id = tasks.parent)"
+          + "  WHERE parent > 0 AND _id IN (:tasks)")
+  public abstract void updateParentUids(List<Long> tasks);
+
+  @Query("UPDATE tasks SET parent = :parent, parent_uuid = :parentUuid WHERE _id IN (:children)")
+  public abstract void setParent(long parent, String parentUuid, List<Long> children);
+
+  @Transaction
+  public List<Task> fetchChildren(long id) {
+    return fetch(getChildren(id));
+  }
+
+  public List<Long> getChildren(long id) {
+    return getChildren(Collections.singletonList(id));
+  }
+
+  public List<Long> getChildren(List<Long> ids) {
+    return atLeastLollipop()
+        ? getChildrenRecursive(ids)
+        : Collections.emptyList();
+  }
+
+  @Query(
+      "WITH RECURSIVE "
+          + " recursive_tasks (task) AS ( "
+          + " SELECT _id "
+          + " FROM tasks "
+          + "WHERE parent IN (:ids)"
+          + "UNION ALL "
+          + " SELECT _id "
+          + " FROM tasks "
+          + " INNER JOIN recursive_tasks "
+          + "  ON recursive_tasks.task = tasks.parent"
+          + " WHERE tasks.deleted = 0)"
+          + "SELECT task FROM recursive_tasks")
+  abstract List<Long> getChildrenRecursive(List<Long> ids);
+
+  public List<Long> findChildrenInList(List<Long> ids) {
+    List<Long> result = newArrayList(ids);
+    result.retainAll(getChildren(ids));
+    return result;
+  }
+
   @Query("UPDATE tasks SET collapsed = :collapsed WHERE _id = :id")
   public abstract void setCollapsed(long id, boolean collapsed);
 

app/src/main/java/com/todoroo/astrid/data/Task.java

@@ -20,6 +20,7 @@ import androidx.room.Entity;
 import androidx.room.Ignore;
 import androidx.room.Index;
 import androidx.room.PrimaryKey;
+import com.google.common.base.Objects;
 import com.google.common.base.Strings;
 import com.google.ical.values.RRule;
 import com.todoroo.andlib.data.Property.IntegerProperty;
@@ -65,6 +66,7 @@ public class Task implements Parcelable {
   public static final LongProperty DELETION_DATE = new LongProperty(TABLE, "deleted");
   public static final StringProperty NOTES = new StringProperty(TABLE, "notes");
   public static final LongProperty TIMER_START = new LongProperty(TABLE, "timerStart");
+  public static final LongProperty PARENT = new LongProperty(TABLE, "parent");
   /** constant value for no uuid */
   public static final String NO_UUID = "0"; // $NON-NLS-1$
 
@@ -187,6 +189,12 @@ public class Task implements Parcelable {
   @ColumnInfo(name = "collapsed")
   public boolean collapsed;
 
+  @ColumnInfo(name = "parent")
+  public transient long parent;
+
+  @ColumnInfo(name = "parent_uuid")
+  public String parentUuid;
+
   // --- due and hide until date management
   @Ignore private transient HashMap<String, Object> transitoryData = null;
 
@@ -241,6 +249,8 @@ public class Task implements Parcelable {
     remoteId = parcel.readString();
     transitoryData = parcel.readHashMap(ContentValues.class.getClassLoader());
     collapsed = ParcelCompat.readBoolean(parcel);
+    parent = parcel.readLong();
+    parentUuid = parcel.readString();
   }
 
   /**
@@ -600,6 +610,22 @@ public class Task implements Parcelable {
     this.calendarUri = calendarUri;
   }
 
+  public long getParent() {
+    return parent;
+  }
+
+  public void setParent(long parent) {
+    this.parent = parent;
+  }
+
+  public String getParentUuid() {
+    return parentUuid;
+  }
+
+  public void setParentUuid(String parentUuid) {
+    this.parentUuid = parentUuid;
+  }
+
   public boolean isNotifyModeNonstop() {
     return isReminderFlagSet(Task.NOTIFY_MODE_NONSTOP);
   }
@@ -660,6 +686,8 @@ public class Task implements Parcelable {
     dest.writeString(remoteId);
     dest.writeMap(transitoryData);
     ParcelCompat.writeBoolean(dest, collapsed);
+    dest.writeLong(parent);
+    dest.writeString(parentUuid);
   }
 
   @Override
@@ -714,6 +742,11 @@ public class Task implements Parcelable {
         + '\''
         + ", collapsed="
         + collapsed
+        + ", parent="
+        + parent
+        + ", parentUuid='"
+        + parentUuid
+        + '\''
         + ", transitoryData="
         + transitoryData
         + '}';
@@ -786,6 +819,12 @@ public class Task implements Parcelable {
     if (calendarUri != null ? !calendarUri.equals(task.calendarUri) : task.calendarUri != null) {
       return false;
     }
+    if (parent != task.parent) {
+      return false;
+    }
+    if (!Objects.equal(parentUuid, task.parentUuid)) {
+      return false;
+    }
     return remoteId != null ? remoteId.equals(task.remoteId) : task.remoteId == null;
   }
 
@@ -809,6 +848,9 @@ public class Task implements Parcelable {
     if (deleted != null ? !deleted.equals(original.deleted) : original.deleted != null) {
       return false;
     }
+    if (parent != original.parent) {
+      return false;
+    }
     return notes != null ? notes.equals(original.notes) : original.notes == null;
   }
 
@@ -843,6 +885,9 @@ public class Task implements Parcelable {
         : original.recurrence != null) {
       return false;
     }
+    if (parent != original.parent) {
+      return false;
+    }
     return repeatUntil != null
         ? repeatUntil.equals(original.repeatUntil)
         : original.repeatUntil == null;
@@ -902,6 +947,9 @@ public class Task implements Parcelable {
     if (collapsed != task.collapsed) {
       return false;
     }
+    if (parent != task.parent) {
+      return false;
+    }
     if (id != null ? !id.equals(task.id) : task.id != null) {
       return false;
     }
@@ -932,31 +980,26 @@ public class Task implements Parcelable {
     if (notes != null ? !notes.equals(task.notes) : task.notes != null) {
       return false;
     }
-    if (estimatedSeconds != null
+    if (estimatedSeconds != null ? !estimatedSeconds.equals(task.estimatedSeconds)
-        ? !estimatedSeconds.equals(task.estimatedSeconds)
         : task.estimatedSeconds != null) {
       return false;
     }
-    if (elapsedSeconds != null
+    if (elapsedSeconds != null ? !elapsedSeconds.equals(task.elapsedSeconds)
-        ? !elapsedSeconds.equals(task.elapsedSeconds)
         : task.elapsedSeconds != null) {
       return false;
     }
     if (timerStart != null ? !timerStart.equals(task.timerStart) : task.timerStart != null) {
       return false;
     }
-    if (notificationFlags != null
+    if (notificationFlags != null ? !notificationFlags.equals(task.notificationFlags)
-        ? !notificationFlags.equals(task.notificationFlags)
         : task.notificationFlags != null) {
       return false;
     }
-    if (notifications != null
+    if (notifications != null ? !notifications.equals(task.notifications)
-        ? !notifications.equals(task.notifications)
         : task.notifications != null) {
       return false;
     }
-    if (lastNotified != null
+    if (lastNotified != null ? !lastNotified.equals(task.lastNotified)
-        ? !lastNotified.equals(task.lastNotified)
         : task.lastNotified != null) {
       return false;
     }
@@ -975,8 +1018,10 @@ public class Task implements Parcelable {
     if (remoteId != null ? !remoteId.equals(task.remoteId) : task.remoteId != null) {
       return false;
     }
-    return transitoryData != null
+    if (parentUuid != null ? !parentUuid.equals(task.parentUuid) : task.parentUuid != null) {
-        ? transitoryData.equals(task.transitoryData)
+      return false;
+    }
+    return transitoryData != null ? transitoryData.equals(task.transitoryData)
         : task.transitoryData == null;
   }
 
@@ -1004,6 +1049,8 @@ public class Task implements Parcelable {
     result = 31 * result + (calendarUri != null ? calendarUri.hashCode() : 0);
     result = 31 * result + (remoteId != null ? remoteId.hashCode() : 0);
     result = 31 * result + (collapsed ? 1 : 0);
+    result = 31 * result + (int) (parent ^ (parent >>> 32));
+    result = 31 * result + (parentUuid != null ? parentUuid.hashCode() : 0);
     result = 31 * result + (transitoryData != null ? transitoryData.hashCode() : 0);
     return result;
   }

app/src/main/java/com/todoroo/astrid/service/TaskCompleter.java

@@ -17,13 +17,11 @@ public class TaskCompleter {
 
   private final TaskDao taskDao;
   private final GoogleTaskDao googleTaskDao;
-  private final CaldavDao caldavDao;
 
   @Inject
-  TaskCompleter(TaskDao taskDao, GoogleTaskDao googleTaskDao, CaldavDao caldavDao) {
+  TaskCompleter(TaskDao taskDao, GoogleTaskDao googleTaskDao) {
     this.taskDao = taskDao;
     this.googleTaskDao = googleTaskDao;
-    this.caldavDao = caldavDao;
   }
 
   public void setComplete(long taskId) {
@@ -39,7 +37,7 @@ public class TaskCompleter {
     long completionDate = completed ? now() : 0L;
     setComplete(Collections.singletonList(item), completionDate);
     List<Task> tasks = newArrayList(googleTaskDao.getChildTasks(item.getId()));
-    List<Long> caldavChildren = caldavDao.getChildren(item.getId());
+    List<Long> caldavChildren = taskDao.getChildren(item.getId());
     if (!caldavChildren.isEmpty()) {
       tasks.addAll(taskDao.fetch(caldavChildren));
     }

app/src/main/java/com/todoroo/astrid/service/TaskDeleter.java

@@ -15,7 +15,6 @@ import javax.inject.Inject;
 import org.tasks.LocalBroadcastManager;
 import org.tasks.data.CaldavAccount;
 import org.tasks.data.CaldavCalendar;
-import org.tasks.data.CaldavDao;
 import org.tasks.data.DeletionDao;
 import org.tasks.data.GoogleTaskAccount;
 import org.tasks.data.GoogleTaskDao;
@@ -31,7 +30,6 @@ public class TaskDeleter {
   private final TaskDao taskDao;
   private final LocalBroadcastManager localBroadcastManager;
   private final GoogleTaskDao googleTaskDao;
-  private final CaldavDao caldavDao;
   private final Preferences preferences;
   private final DeletionDao deletionDao;
 
@@ -42,14 +40,12 @@ public class TaskDeleter {
       TaskDao taskDao,
       LocalBroadcastManager localBroadcastManager,
       GoogleTaskDao googleTaskDao,
-      CaldavDao caldavDao,
       Preferences preferences) {
     this.deletionDao = deletionDao;
     this.workManager = workManager;
     this.taskDao = taskDao;
     this.localBroadcastManager = localBroadcastManager;
     this.googleTaskDao = googleTaskDao;
-    this.caldavDao = caldavDao;
     this.preferences = preferences;
   }
 
@@ -66,7 +62,7 @@ public class TaskDeleter {
   public List<Task> markDeleted(List<Long> taskIds) {
     Set<Long> ids = new HashSet<>(taskIds);
     ids.addAll(collect(taskIds, googleTaskDao::getChildren));
-    ids.addAll(collect(taskIds, caldavDao::getChildren));
+    ids.addAll(collect(taskIds, taskDao::getChildren));
     deletionDao.markDeleted(ids);
     workManager.cleanup(ids);
     workManager.sync(false);

app/src/main/java/com/todoroo/astrid/service/TaskMover.java

@@ -1,17 +1,22 @@
 package com.todoroo.astrid.service;
 
+import static com.google.common.collect.FluentIterable.from;
 import static com.google.common.collect.Lists.newArrayList;
 import static com.google.common.collect.Lists.transform;
+import static com.google.common.collect.Maps.newHashMap;
 import static com.todoroo.andlib.utility.DateUtilities.now;
 import static java.util.Collections.emptyList;
 
+import androidx.annotation.Nullable;
+import com.google.common.collect.Lists;
 import com.todoroo.astrid.api.CaldavFilter;
 import com.todoroo.astrid.api.Filter;
 import com.todoroo.astrid.api.GtasksFilter;
 import com.todoroo.astrid.dao.TaskDao;
-import com.todoroo.astrid.data.SyncFlags;
 import com.todoroo.astrid.data.Task;
+import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 import javax.inject.Inject;
 import org.tasks.LocalBroadcastManager;
 import org.tasks.data.CaldavDao;
@@ -45,20 +50,6 @@ public class TaskMover {
     this.localBroadcastManager = localBroadcastManager;
   }
 
-  public void move(List<Long> tasks, Filter selectedList) {
-    tasks = newArrayList(tasks);
-    tasks.removeAll(googleTaskDao.findChildrenInList(tasks));
-    tasks.removeAll(caldavDao.findChildrenInList(tasks));
-    for (Task task : taskDao.fetch(tasks)) {
-      performMove(task, selectedList);
-    }
-    if (selectedList instanceof CaldavFilter) {
-      caldavDao.updateParents((((CaldavFilter) selectedList).getUuid()));
-    }
-    taskDao.touch(tasks);
-    localBroadcastManager.broadcastRefresh();
-  }
-
   public Filter getSingleFilter(List<Long> tasks) {
     List<String> caldavCalendars = caldavDao.getCalendars(tasks);
     List<String> googleTaskLists = googleTaskDao.getLists(tasks);
@@ -74,44 +65,57 @@ public class TaskMover {
     return null;
   }
 
-  private void performMove(Task task, Filter selectedList) {
+  public void move(List<Long> tasks, Filter selectedList) {
+    tasks = newArrayList(tasks);
+    tasks.removeAll(googleTaskDao.findChildrenInList(tasks));
+    tasks.removeAll(taskDao.findChildrenInList(tasks));
+    taskDao.setParent(0, null, tasks);
+    for (Task task : taskDao.fetch(tasks)) {
+      performMove(task, selectedList);
+    }
+    if (selectedList instanceof CaldavFilter) {
+      caldavDao.updateParents((((CaldavFilter) selectedList).getUuid()));
+    }
+    taskDao.touch(tasks);
+    localBroadcastManager.broadcastRefresh();
+  }
+
+  private void performMove(Task task, @Nullable Filter selectedList) {
     long id = task.getId();
+
     GoogleTask googleTask = googleTaskDao.getByTaskId(id);
-    List<GoogleTask> googleTaskChildren = emptyList();
+    if (googleTask != null) {
-    List<CaldavTask> caldavChildren = emptyList();
+      moveGoogleTask(task, googleTask, selectedList);
-    if (googleTask != null
-        && selectedList instanceof GtasksFilter
-        && googleTask.getListId().equals(((GtasksFilter) selectedList).getRemoteId())) {
       return;
     }
+
     CaldavTask caldavTask = caldavDao.getTask(id);
-    if (caldavTask != null
+    if (caldavTask != null) {
-        && selectedList instanceof CaldavFilter
+      moveCaldavTask(task, caldavTask, selectedList);
-        && caldavTask.getCalendar().equals(((CaldavFilter) selectedList).getUuid())) {
       return;
     }
-    if (googleTask != null) {
-      googleTaskChildren = googleTaskDao.getChildren(id);
-      googleTaskDao.markDeleted(now(), id);
-    }
 
-    if (caldavTask != null) {
+    moveLocalTask(task, selectedList);
-      List<Long> toDelete = newArrayList(caldavTask.getTask());
+  }
-      List<Long> childIds = caldavDao.getChildren(caldavTask.getTask());
+
-      if (!childIds.isEmpty()) {
+  private void moveGoogleTask(Task task, GoogleTask googleTask, Filter selected) {
-        caldavChildren = caldavDao.getTasks(childIds);
+    if (selected instanceof GtasksFilter
-        toDelete.addAll(childIds);
+        && googleTask.getListId().equals(((GtasksFilter) selected).getRemoteId())) {
-      }
+      return;
-      caldavDao.markDeleted(now(), toDelete);
     }
 
-    if (selectedList instanceof GtasksFilter) {
+    long id = googleTask.getTask();
-      String listId = ((GtasksFilter) selectedList).getRemoteId();
+    List<GoogleTask> children = googleTaskDao.getChildren(id);
+    List<Long> childIds = from(children).transform(GoogleTask::getTask).toList();
+    googleTaskDao.markDeleted(now(), id);
+
+    if (selected instanceof GtasksFilter) {
+      String listId = ((GtasksFilter) selected).getRemoteId();
       googleTaskDao.insertAndShift(new GoogleTask(id, listId), preferences.addGoogleTasksToTop());
-      if (!googleTaskChildren.isEmpty()) {
+      if (!children.isEmpty()) {
         googleTaskDao.insert(
             transform(
-                googleTaskChildren,
+                children,
                 child -> {
                   GoogleTask newChild = new GoogleTask(child.getTask(), listId);
                   newChild.setOrder(child.getOrder());
@@ -119,37 +123,91 @@ public class TaskMover {
                   return newChild;
                 }));
       }
-      if (!caldavChildren.isEmpty()) {
+    } else if (selected instanceof CaldavFilter) {
-        List<GoogleTask> children = newArrayList();
+      String listId = ((CaldavFilter) selected).getUuid();
-        for (int i = 0 ; i < caldavChildren.size() ; i++) {
+      CaldavTask newParent = new CaldavTask(id, listId);
-          CaldavTask child = caldavChildren.get(i);
+      caldavDao.insert(newParent);
-          GoogleTask newChild = new GoogleTask(child.getTask(), listId);
+      caldavDao.insert(
-          newChild.setOrder(i);
+          transform(
-          newChild.setParent(id);
+              childIds,
-          children.add(newChild);
+              child -> {
-        }
+                CaldavTask newChild = new CaldavTask(child, listId);
-        googleTaskDao.insert(children);
+                newChild.setRemoteParent(newParent.getRemoteId());
-      }
+                return newChild;
-    } else if (selectedList instanceof CaldavFilter) {
+              }));
-      String listId = ((CaldavFilter) selectedList).getUuid();
+    } else {
-      CaldavTask newParent = caldavTask == null
+      taskDao.setParent(task.getId(), task.getUuid(), childIds);
-          ? new CaldavTask(id, listId)
+    }
-          : new CaldavTask(id, listId, caldavTask.getRemoteId(), caldavTask.getObject());
+  }
-      if (caldavTask != null) {
+
-        newParent.setVtodo(caldavTask.getVtodo());
+  private void moveCaldavTask(Task task, CaldavTask caldavTask, Filter selected) {
-      }
+    if (selected instanceof CaldavFilter
+        && caldavTask.getCalendar().equals(((CaldavFilter) selected).getUuid())) {
+      return;
+    }
+
+    long id = task.getId();
+    List<Long> childIds = taskDao.getChildren(id);
+    List<Long> toDelete = newArrayList(id);
+    List<CaldavTask> children = emptyList();
+    if (!childIds.isEmpty()) {
+      children = caldavDao.getTasks(childIds);
+      toDelete.addAll(childIds);
+    }
+    caldavDao.markDeleted(now(), toDelete);
+
+    if (selected instanceof CaldavFilter) {
+      long id1 = caldavTask.getTask();
+      String listId = ((CaldavFilter) selected).getUuid();
+      CaldavTask newParent =
+          new CaldavTask(id1, listId, caldavTask.getRemoteId(), caldavTask.getObject());
+      newParent.setVtodo(caldavTask.getVtodo());
       caldavDao.insert(newParent);
-      caldavDao.insert(transform(googleTaskChildren, child -> {
+      caldavDao.insert(
-        CaldavTask newChild = new CaldavTask(child.getTask(), listId);
+          transform(
-        newChild.setRemoteParent(newParent.getRemoteId());
+              children,
-        return newChild;
+              child -> {
-      }));
+                CaldavTask newChild =
-      caldavDao.insert(transform(caldavChildren, child -> {
+                    new CaldavTask(child.getTask(), listId, child.getRemoteId(), child.getObject());
-        CaldavTask newChild = new CaldavTask(child.getTask(), listId, child.getRemoteId(), child.getObject());
+                newChild.setVtodo(child.getVtodo());
-        newChild.setVtodo(child.getVtodo());
+                newChild.setRemoteParent(child.getRemoteParent());
-        newChild.setRemoteParent(child.getRemoteParent());
+                return newChild;
-        return newChild;
+              }));
-      }));
+    } else if (selected instanceof GtasksFilter) {
+      moveToGoogleTasks(id, childIds, (GtasksFilter) selected);
+    } else {
+      taskDao.updateParentUids(from(children).transform(CaldavTask::getTask).toList());
+    }
+  }
+
+  private void moveLocalTask(Task task, @Nullable Filter selected) {
+    if (selected instanceof GtasksFilter) {
+      moveToGoogleTasks(task.getId(), taskDao.getChildren(task.getId()), (GtasksFilter) selected);
+    } else if (selected instanceof CaldavFilter) {
+      long id = task.getId();
+      String listId = ((CaldavFilter) selected).getUuid();
+      Map<Long, CaldavTask> tasks = newHashMap();
+      tasks.put(id, new CaldavTask(id, listId));
+      for (Task child : taskDao.fetchChildren(task.getId())) {
+        CaldavTask newTask = new CaldavTask(child.getId(), listId);
+        newTask.setRemoteParent(tasks.get(child.parent).getRemoteId());
+        tasks.put(child.getId(), newTask);
+      }
+      caldavDao.insert(tasks.values());
+    }
+  }
+
+  private void moveToGoogleTasks(long id, List<Long> children, GtasksFilter filter) {
+    taskDao.setParent(0, null, children);
+    String listId = filter.getRemoteId();
+    googleTaskDao.insertAndShift(new GoogleTask(id, listId), preferences.addGoogleTasksToTop());
+    List<GoogleTask> newChildren = new ArrayList<>();
+    for (int i = 0; i < children.size(); i++) {
+      GoogleTask newChild = new GoogleTask(children.get(i), listId);
+      newChild.setOrder(i);
+      newChild.setParent(id);
+      newChildren.add(newChild);
     }
+    googleTaskDao.insert(newChildren);
   }
 }

app/src/main/java/org/tasks/backup/TasksJsonImporter.java

@@ -243,6 +243,7 @@ public class TasksJsonImporter {
 
       googleTaskDao.updateParents();
       caldavDao.updateParents();
+      taskDao.updateParents();
 
       for (Entry<String, Integer> entry : backupContainer.getIntPrefs().entrySet()) {
         preferences.setInt(entry.getKey(), entry.getValue());

app/src/main/java/org/tasks/caldav/CaldavConverter.java

@@ -157,7 +157,7 @@ public class CaldavConverter {
     }
     remote.setLastModified(newDateTime(task.getModificationDate()).toUTC().getMillis());
     remote.setPriority(toRemote(remote.getPriority(), task.getPriority()));
-    setParent(remote, caldavTask.getParent() == 0 ? null : caldavTask.getRemoteParent());
+    setParent(remote, task.getParent() == 0 ? null : caldavTask.getRemoteParent());
 
     return remote;
   }

app/src/main/java/org/tasks/data/CaldavDao.java

@@ -1,7 +1,5 @@
 package org.tasks.data;
 
-import static com.google.common.collect.Lists.newArrayList;
-import static com.todoroo.andlib.utility.AndroidUtilities.atLeastLollipop;
 import static org.tasks.db.DbUtils.collect;
 
 import androidx.lifecycle.LiveData;
@@ -11,7 +9,6 @@ import androidx.room.Insert;
 import androidx.room.Query;
 import androidx.room.Update;
 import io.reactivex.Single;
-import java.util.Collections;
 import java.util.List;
 import org.tasks.filters.CaldavFilters;
 
@@ -59,12 +56,12 @@ public abstract class CaldavDao {
   public abstract void update(CaldavTask caldavTask);
 
   public void update(SubsetCaldav caldavTask) {
-    update(caldavTask.getId(), caldavTask.getParent(), caldavTask.getRemoteParent());
+    update(caldavTask.getId(), caldavTask.getRemoteParent());
   }
 
   @Query(
-      "UPDATE caldav_tasks SET cd_parent = :parent, cd_remote_parent = :remoteParent WHERE cd_id = :id")
+      "UPDATE caldav_tasks SET cd_remote_parent = :remoteParent WHERE cd_id = :id")
-  abstract void update(long id, long parent, String remoteParent);
+  abstract void update(long id,String remoteParent);
 
   @Update
   public abstract void update(Iterable<CaldavTask> tasks);
@@ -152,51 +149,24 @@ public abstract class CaldavDao {
   public abstract List<Long> getTasksWithTags();
 
   @Query(
-      "UPDATE caldav_tasks"
+      "UPDATE tasks SET parent = IFNULL(("
-          + " SET cd_parent = IFNULL(("
+          + " SELECT p.cd_task FROM caldav_tasks AS p"
-          + "   SELECT cd_task FROM caldav_tasks AS p "
+          + "  INNER JOIN caldav_tasks ON caldav_tasks.cd_task = tasks._id"
-          + "   WHERE p.cd_remote_id = caldav_tasks.cd_remote_parent"
+          + "  WHERE p.cd_remote_id = caldav_tasks.cd_remote_parent"
-          + "     AND p.cd_calendar = caldav_tasks.cd_calendar"
+          + "    AND p.cd_calendar = caldav_tasks.cd_calendar"
-          + "     AND p.cd_deleted = 0),"
+          + "    AND p.cd_deleted = 0), 0)"
-          + " 0)")
+          + "WHERE _id IN (SELECT _id FROM tasks INNER JOIN caldav_tasks ON _id = cd_task WHERE cd_deleted = 0)")
   public abstract void updateParents();
 
-  @Query("UPDATE caldav_tasks SET cd_parent = IFNULL((SELECT cd_task FROM caldav_tasks AS p WHERE p.cd_remote_id = caldav_tasks.cd_remote_parent), 0) WHERE cd_calendar = :calendar")
+  @Query(
+      "UPDATE tasks SET parent = IFNULL(("
+          + " SELECT p.cd_task FROM caldav_tasks AS p"
+          + "  INNER JOIN caldav_tasks "
+          + "    ON caldav_tasks.cd_task = tasks._id"
+          + "    AND caldav_tasks.cd_calendar = :calendar"
+          + "  WHERE p.cd_remote_id = caldav_tasks.cd_remote_parent"
+          + "    AND p.cd_calendar = caldav_tasks.cd_calendar"
+          + "    AND caldav_tasks.cd_deleted = 0), 0)"
+          + "WHERE _id IN (SELECT _id FROM tasks INNER JOIN caldav_tasks ON _id = cd_task WHERE cd_deleted = 0 AND cd_calendar = :calendar)")
   public abstract void updateParents(String calendar);
-
-  public List<Long> getChildren(long id) {
-    return getChildren(Collections.singletonList(id));
-  }
-
-  public List<Long> getChildren(List<Long> ids) {
-    return atLeastLollipop()
-        ? getChildrenRecursive(ids)
-        : Collections.emptyList();
-  }
-
-  @Query("WITH RECURSIVE "
-          + " recursive_caldav (cd_task) AS ( "
-          + " SELECT cd_task "
-          + " FROM tasks "
-          + " INNER JOIN caldav_tasks "
-          + "  ON _id = cd_task "
-          + " WHERE cd_parent IN (:ids) "
-          + " AND tasks.deleted = 0 AND caldav_tasks.cd_deleted = 0 "
-          + "UNION ALL "
-          + " SELECT caldav_tasks.cd_task "
-          + " FROM tasks "
-          + " INNER JOIN caldav_tasks "
-          + "  ON _id = caldav_tasks.cd_task "
-          + " INNER JOIN recursive_caldav "
-          + "  ON recursive_caldav.cd_task = caldav_tasks.cd_parent "
-          + " WHERE tasks.deleted = 0 AND caldav_tasks.cd_deleted = 0 "
-          + " ) "
-          + "SELECT cd_task FROM recursive_caldav")
-  abstract List<Long> getChildrenRecursive(List<Long> ids);
-
-  public List<Long> findChildrenInList(List<Long> ids) {
-    List<Long> result = newArrayList(ids);
-    result.retainAll(getChildren(ids));
-    return result;
-  }
 }

app/src/main/java/org/tasks/data/CaldavTask.java

@@ -10,23 +10,13 @@ import androidx.room.PrimaryKey;
 import com.todoroo.andlib.data.Property;
 import com.todoroo.andlib.data.Table;
 
-@Entity(
+@Entity(tableName = "caldav_tasks", indices = @Index(name = "cd_task", value = "cd_task"))
-    tableName = "caldav_tasks",
-    indices = {
-      @Index(name = "cd_task", value = "cd_task"),
-      @Index(
-          name = "cd_calendar_parent",
-          value = {"cd_calendar", "cd_parent"})
-    })
 public class CaldavTask {
 
   public static final String KEY = "caldav";
 
   public static final Table TABLE = new Table("caldav_tasks");
 
-  public static final Property.IntegerProperty PARENT =
-      new Property.IntegerProperty(TABLE, "cd_parent");
-
   public static final Property.IntegerProperty TASK =
       new Property.IntegerProperty(TABLE, "cd_task");
 
@@ -64,9 +54,6 @@ public class CaldavTask {
   @ColumnInfo(name = "cd_vtodo")
   private String vtodo;
 
-  @ColumnInfo(name = "cd_parent")
-  private transient long parent;
-
   @ColumnInfo(name = "cd_remote_parent")
   private String remoteParent;
 
@@ -160,14 +147,6 @@ public class CaldavTask {
     this.vtodo = vtodo;
   }
 
-  public long getParent() {
-    return parent;
-  }
-
-  public void setParent(long parent) {
-    this.parent = parent;
-  }
-
   public String getRemoteParent() {
     return remoteParent;
   }
@@ -202,9 +181,6 @@ public class CaldavTask {
         + ", vtodo='"
         + vtodo
         + '\''
-        + ", parent='"
-        + parent
-        + '\''
         + ", remoteParent='"
         + remoteParent
         + '\''

app/src/main/java/org/tasks/data/TaskContainer.java

@@ -1,5 +1,6 @@
 package org.tasks.data;
 
+import androidx.annotation.Nullable;
 import androidx.room.Embedded;
 import com.todoroo.astrid.data.Task;
 
@@ -189,19 +190,19 @@ public class TaskContainer {
   public long getParent() {
     if (googletask != null) {
       return googletask.getParent();
-    } else if (caldavTask != null) {
-      return caldavTask.getParent();
     } else {
-      return 0;
+      return task.getParent();
     }
   }
 
   public void setParent(long parent) {
     if (googletask != null) {
+      task.setParent(0);
       googletask.setParent(parent);
-    } else if (caldavTask != null) {
+    } else {
-      caldavTask.setParent(parent);
+      task.setParent(parent);
     }
+    task.setParentUuid(null);
   }
 
   public boolean hasParent() {

app/src/main/java/org/tasks/db/Migrations.java

@@ -356,6 +356,31 @@ public class Migrations {
         }
       };
 
+  private static final Migration MIGRATION_69_70 =
+      new Migration(69, 70) {
+        @Override
+        public void migrate(@NonNull SupportSQLiteDatabase database) {
+          database.execSQL("ALTER TABLE `tasks` ADD COLUMN `parent` INTEGER NOT NULL DEFAULT 0");
+          database.execSQL("ALTER TABLE `tasks` ADD COLUMN `parent_uuid` TEXT");
+          database.execSQL(
+              "UPDATE `tasks` SET `parent` = IFNULL(("
+                  + " SELECT p.cd_task FROM caldav_tasks"
+                  + "  INNER JOIN caldav_tasks AS p ON p.cd_remote_id = caldav_tasks.cd_remote_parent"
+                  + "  WHERE caldav_tasks.cd_task = tasks._id"
+                  + "    AND caldav_tasks.cd_deleted = 0"
+                  + "    AND p.cd_calendar = caldav_tasks.cd_calendar"
+                  + "    AND p.cd_deleted = 0), 0)");
+          database.execSQL("ALTER TABLE `caldav_tasks` RENAME TO `caldav_tasks-temp`");
+          database.execSQL(
+              "CREATE TABLE IF NOT EXISTS `caldav_tasks` (`cd_id` INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, `cd_task` INTEGER NOT NULL, `cd_calendar` TEXT, `cd_object` TEXT, `cd_remote_id` TEXT, `cd_etag` TEXT, `cd_last_sync` INTEGER NOT NULL, `cd_deleted` INTEGER NOT NULL, `cd_vtodo` TEXT, `cd_remote_parent` TEXT)");
+          database.execSQL(
+              "INSERT INTO `caldav_tasks` (`cd_id`, `cd_task`, `cd_calendar`, `cd_object`, `cd_remote_id`, `cd_etag`, `cd_last_sync`, `cd_deleted`, `cd_vtodo`, `cd_remote_parent`) "
+                  + "SELECT `cd_id`, `cd_task`, `cd_calendar`, `cd_object`, `cd_remote_id`, `cd_etag`, `cd_last_sync`, `cd_deleted`, `cd_vtodo`, `cd_remote_parent` FROM `caldav_tasks-temp`");
+          database.execSQL("DROP TABLE `caldav_tasks-temp`");
+          database.execSQL("CREATE INDEX `cd_task` ON `caldav_tasks` (`cd_task`)");
+        }
+      };
+
   public static final Migration[] MIGRATIONS =
       new Migration[] {
         MIGRATION_35_36,
@@ -382,7 +407,8 @@ public class Migrations {
         MIGRATION_65_66,
         MIGRATION_66_67,
         MIGRATION_67_68,
-        MIGRATION_68_69
+        MIGRATION_68_69,
+        MIGRATION_69_70
       };
 
   private static Migration NOOP(int from, int to) {

app/src/main/java/org/tasks/tasklist/SubtaskViewHolder.java

@@ -72,9 +72,9 @@ public class SubtaskViewHolder extends RecyclerView.ViewHolder {
     return Math.round(indent * getShiftSize());
   }
 
-  void bindView(TaskContainer task, boolean multiLevelSubtasks) {
+  void bindView(TaskContainer task) {
     this.task = task;
-    setIndent(multiLevelSubtasks ? task.indent : 0);
+    setIndent(task.indent);
     if (task.hasChildren()) {
       chip.setText(locale.formatNumber(task.children));
       chip.setVisibility(View.VISIBLE);

app/src/main/java/org/tasks/tasklist/SubtasksRecyclerAdapter.java

@@ -50,7 +50,8 @@ public class SubtasksRecyclerAdapter extends RecyclerView.Adapter<SubtaskViewHol
   public void onBindViewHolder(@NonNull SubtaskViewHolder holder, int position) {
     TaskContainer task = getItem(position);
     if (task != null) {
-      holder.bindView(task, multiLevelSubtasks);
+      task.setIndent(multiLevelSubtasks ? task.indent : 0);
+      holder.bindView(task);
     }
   }
 
@@ -88,6 +89,9 @@ public class SubtasksRecyclerAdapter extends RecyclerView.Adapter<SubtaskViewHol
   }
 
   public void setMultiLevelSubtasksEnabled(boolean enabled) {
-    multiLevelSubtasks = enabled;
+    if (multiLevelSubtasks != enabled) {
+      multiLevelSubtasks = enabled;
+      notifyItemRangeChanged(0, differ.getCurrentList().size());
+    }
   }
 }

app/src/main/java/org/tasks/ui/SubtaskControlSet.java

@@ -127,16 +127,10 @@ public class SubtaskControlSet extends TaskEditControlFragment implements Callba
                     GoogleTask.PARENT.eq(task.getId()),
                     GoogleTask.TASK.eq(Task.ID),
                     GoogleTask.DELETED.eq(0))))
-        .join(
+        .where(
-            Join.left(
+            Criterion.and(
-                CaldavTask.TABLE,
+                TaskCriteria.activeAndVisible(),
-                Criterion.and(
+                Criterion.or(Task.PARENT.eq(task.getId()), GoogleTask.TASK.gt(0))));
-                    CaldavTask.PARENT.eq(task.getId()),
-                    CaldavTask.TASK.eq(Task.ID),
-                    CaldavTask.DELETED.eq(0))))
-        .where(Criterion.and(TaskCriteria.activeAndVisible(),
-            Criterion.or(CaldavTask.TASK.gt(0), GoogleTask.TASK.gt(0))));
-
   }
 
   @Override
@@ -176,16 +170,21 @@ public class SubtaskControlSet extends TaskEditControlFragment implements Callba
       } else if (remoteList instanceof CaldavFilter) {
         CaldavTask caldavTask =
             new CaldavTask(subtask.getId(), ((CaldavFilter) remoteList).getUuid());
-        caldavTask.setParent(task.getId());
+        subtask.setParent(task.getId());
         caldavTask.setRemoteParent(caldavDao.getRemoteIdForTask(task.getId()));
+        taskDao.save(subtask);
         caldavDao.insert(caldavTask);
+      } else {
+        subtask.setParent(task.getId());
+        subtask.setParentUuid(task.getUuid());
+        taskDao.save(subtask);
       }
     }
   }
 
   @Override
   public boolean hasChanges(Task original) {
-    return remoteList != null && !getNewSubtasks().isEmpty();
+    return !getNewSubtasks().isEmpty();
   }
 
   private ArrayList<Task> getNewSubtasks() {
@@ -224,10 +223,6 @@ public class SubtaskControlSet extends TaskEditControlFragment implements Callba
 
   @OnClick(R.id.add_subtask)
   void addSubtask() {
-    if (remoteList == null) {
-      toaster.longToast(R.string.subtasks_enable_synchronization);
-      return;
-    }
     if (isGoogleTaskChild()) {
       toaster.longToast(R.string.subtasks_multilevel_google_task);
       return;
@@ -290,7 +285,7 @@ public class SubtaskControlSet extends TaskEditControlFragment implements Callba
   }
 
   private void updateUI() {
-    if (remoteList == null || isGoogleTaskChild()) {
+    if (isGoogleTaskChild()) {
       recyclerView.setVisibility(View.GONE);
       newSubtaskContainer.setVisibility(View.GONE);
     } else {

app/src/main/java/org/tasks/ui/TaskListViewModel.java

@@ -157,19 +157,12 @@ public class TaskListViewModel extends ViewModel implements Observer<PagedList<T
                         CaldavTask.TABLE,
                         Criterion.and(
                             CaldavTask.CALENDAR.eq(calendar.getUuid()),
-                            CaldavTask.PARENT.eq(0),
                             CaldavTask.TASK.eq(Task.ID),
                             CaldavTask.DELETED.eq(0))))
-                .where(TaskCriteria.activeAndVisible())
+                .where(Criterion.and(TaskCriteria.activeAndVisible(), Task.PARENT.eq(0)))
                 .toString();
         subtaskQuery
-            .join(Join.inner(RECURSIVE, CaldavTask.PARENT.eq(RECURSIVE_TASK)))
+            .join(Join.inner(RECURSIVE, Task.PARENT.eq(RECURSIVE_TASK)))
-            .join(
-                Join.inner(
-                    CaldavTask.TABLE,
-                    Criterion.and(
-                        CaldavTask.TASK.eq(Task.ID),
-                        CaldavTask.DELETED.eq(0))))
             .where(TaskCriteria.activeAndVisible());
       } else if (filter instanceof GtasksFilter) {
         GoogleTaskList list = ((GtasksFilter) filter).getList();
@@ -212,7 +205,7 @@ public class TaskListViewModel extends ViewModel implements Observer<PagedList<T
       String sortSelect = SortHelper.orderSelectForSortTypeRecursive(preferences.getSortMode());
       String withClause = "CREATE TEMPORARY TABLE `recursive_tasks` AS\n"
               + "WITH RECURSIVE recursive_tasks (task, parent, collapsed, hidden, indent, title, sortField) AS (\n"
-              + " SELECT tasks._id, 0 as parent, tasks.collapsed as collapsed, 0 as hidden, 0 AS sort_indent, UPPER(title) AS sort_title, "
+              + " SELECT tasks._id, 0 as parent, tasks.collapsed as collapsed, 0 as hidden, 0 AS sort_indent, UPPER(tasks.title) AS sort_title, "
               + sortSelect
               + " FROM tasks\n"
               + parentQuery
@@ -282,13 +275,7 @@ public class TaskListViewModel extends ViewModel implements Observer<PagedList<T
 
   private static void addCaldavSubtasks(QueryTemplate subtaskQuery) {
     subtaskQuery
-        .join(Join.inner(RECURSIVE, CaldavTask.PARENT.eq(RECURSIVE_TASK)))
+        .join(Join.inner(RECURSIVE, Task.PARENT.eq(RECURSIVE_TASK)));
-        .join(
-            Join.inner(
-                CaldavTask.TABLE,
-                Criterion.and(
-                    CaldavTask.TASK.eq(Task.ID),
-                    CaldavTask.DELETED.eq(0))));
   }
 
   private static void addGoogleAndCaldavSubtasks(QueryTemplate subtaskQuery) {
@@ -298,7 +285,7 @@ public class TaskListViewModel extends ViewModel implements Observer<PagedList<T
                 RECURSIVE,
                 Criterion.or(
                     GoogleTask.PARENT.eq(RECURSIVE_TASK),
-                    CaldavTask.PARENT.eq(RECURSIVE_TASK))))
+                    Task.PARENT.eq(RECURSIVE_TASK))))
         .join(
             Join.left(
                 GoogleTask.TABLE,

app/src/main/res/values-de/strings.xml

@@ -550,7 +550,6 @@
     <string name="collapse_subtasks">Unteraufgaben einklappen</string>
     <string name="TEA_add_subtask">Unteraufgabe hinzufügen</string>
     <string name="subtasks">Unteraufgaben</string>
-    <string name="subtasks_enable_synchronization">Synchronisation aktivieren, um Unteraufgaben hinzuzufügen</string>
+  <string name="subtasks_multilevel_google_task">Mehrere Unteraufgaben-Ebenen werden von Google Tasks nicht unterstützt</string>
-    <string name="subtasks_multilevel_google_task">Mehrere Unteraufgaben-Ebenen werden von Google Tasks nicht unterstützt</string>
     <string name="enter_title_hint">Titel eingeben</string>
 </resources>

app/src/main/res/values-es/strings.xml

@@ -550,8 +550,7 @@
     <string name="collapse_subtasks">Contraer subtareas</string>
     <string name="TEA_add_subtask">Añadir subtarea</string>
     <string name="subtasks">Subtareas</string>
-    <string name="subtasks_enable_synchronization">Habilitar la sincronización para añadir subtareas</string>
+  <string name="subtasks_multilevel_google_task">Subtareas multinivel no compatibles con Google Tasks</string>
-    <string name="subtasks_multilevel_google_task">Subtareas multinivel no compatibles con Google Tasks</string>
     <string name="enter_title_hint">Introducir título</string>
     <string name="show_subtasks">Mostrar subtareas</string>
     <string name="show_subtasks_summary">La visualización de subtareas degradará el rendimiento de la aplicación</string>

app/src/main/res/values-eu/strings.xml

@@ -557,7 +557,6 @@
     <string name="collapse_subtasks">Tolestu azpi-zereginak</string>
     <string name="TEA_add_subtask">Gehitu azpi-zeregina</string>
     <string name="subtasks">Azpi-zereginak</string>
-    <string name="subtasks_enable_synchronization">Gaitu sinkronizazioa azpi-zereginak gehitzeko</string>
     <string name="subtasks_multilevel_google_task">Google Tasks-ek ez ditu hainbat mailako azpi-zereginak onartzen</string>
     <string name="enter_title_hint">Sartu izenburua</string>
     <string name="show_subtasks">Erakutsi azpi-zereginak</string>

app/src/main/res/values-fr/strings.xml

@@ -551,8 +551,7 @@ est configuré correctement</string>
     <string name="collapse_subtasks">Réduire les sous-tâches</string>
     <string name="TEA_add_subtask">Ajouter sous-tâche</string>
     <string name="subtasks">Sous-tâches</string>
-    <string name="subtasks_enable_synchronization">Activer la synchronisation pour ajouter des sous-tâches</string>
+  <string name="subtasks_multilevel_google_task">Les sous-tâches multi-niveaux ne sont pas prises en charge par Google Tasks</string>
-    <string name="subtasks_multilevel_google_task">Les sous-tâches multi-niveaux ne sont pas prises en charge par Google Tasks</string>
     <string name="enter_title_hint">Entrer le titre</string>
     <string name="show_subtasks">Afficher les sous-tâches</string>
     <string name="show_subtasks_summary">L\'affichage des sous-tâches dégradera les performances de l\'application</string>

app/src/main/res/values-nl/strings.xml

@@ -550,8 +550,7 @@
     <string name="collapse_subtasks">Deeltaken inklappen</string>
     <string name="TEA_add_subtask">Deeltaak toevoegen</string>
     <string name="subtasks">Deeltaken</string>
-    <string name="subtasks_enable_synchronization">Zet synchronisatie aan om deeltaken toe te voegen</string>
+  <string name="subtasks_multilevel_google_task">Deeltaken met meerdere niveau\'s worden niet ondersteund door Google Taken</string>
-    <string name="subtasks_multilevel_google_task">Deeltaken met meerdere niveau\'s worden niet ondersteund door Google Taken</string>
     <string name="enter_title_hint">Voer titel in</string>
     <string name="show_subtasks">Deeltaken tonen</string>
     <string name="show_subtasks_summary">Deeltaken tonen vermindert prestaties van de app</string>

app/src/main/res/values-zh-rCN/strings.xml

@@ -546,8 +546,7 @@
     <string name="collapse_subtasks">缩回子任务列表</string>
     <string name="TEA_add_subtask">添加子任务</string>
     <string name="subtasks">子任务</string>
-    <string name="subtasks_enable_synchronization">启用同步来添加子任务</string>
+  <string name="subtasks_multilevel_google_task">Google Tasks不支持多层子任务</string>
-    <string name="subtasks_multilevel_google_task">Google Tasks不支持多层子任务</string>
     <string name="enter_title_hint">输入标题</string>
     <string name="show_subtasks">显示子任务</string>
     <string name="show_subtasks_summary">显示子任务将降级应用性能</string>

app/src/main/res/values/strings.xml

@@ -558,7 +558,6 @@ File %1$s contained %2$s.\n\n
   <string name="caldav_account_repeating_tasks">Let server schedule recurring tasks</string>
   <string name="expand_subtasks">Expand subtasks</string>
   <string name="collapse_subtasks">Collapse subtasks</string>
-  <string name="subtasks_enable_synchronization">Enable synchronization to add subtasks</string>
   <string name="subtasks_multilevel_google_task">Multi-level subtasks not supported by Google Tasks</string>
   <string name="enter_title_hint">Enter title</string>
   <string name="show_subtasks">Show subtasks</string>