Fix moved or deleted task synchronization

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

@@ -103,7 +103,8 @@ public abstract class CaldavDao {
       "SELECT task.*, caldav_task.* FROM tasks AS task "
           + "INNER JOIN caldav_tasks AS caldav_task ON _id = cd_task "
           + "WHERE cd_calendar = :calendar "
-          + "AND modified > cd_last_sync")
+          + "AND modified > cd_last_sync "
+          + "AND cd_deleted = 0")
   public abstract List<CaldavTaskContainer> getCaldavTasksToPush(String calendar);
 
   @Query("SELECT * FROM caldav_lists ORDER BY cdl_name COLLATE NOCASE")

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

@@ -1,7 +1,6 @@
 package org.tasks.data;
 
 import androidx.room.Embedded;
-import com.google.common.base.Strings;
 import com.todoroo.astrid.data.Task;
 
 public class CaldavTaskContainer {
@@ -24,7 +23,12 @@ public class CaldavTaskContainer {
     return task.isDeleted();
   }
 
-  public boolean isNew() {
-    return Strings.isNullOrEmpty(caldavTask.getVtodo());
+  public String getVtodo() {
+    return caldavTask.getVtodo();
+  }
+
+  @Override
+  public String toString() {
+    return "CaldavTaskContainer{" + "task=" + task + ", caldavTask=" + caldavTask + '}';
   }
 }

app/src/main/java/org/tasks/etesync/EteSynchronizer.java

@@ -193,10 +193,23 @@ public class EteSynchronizer {
 
     List<SyncEntry> changes = new ArrayList<>();
     for (CaldavTask task : caldavDao.getDeleted(caldavCalendar.getUuid())) {
-      changes.add(new SyncEntry(task.getVtodo(), Actions.DELETE));
+      String vtodo = task.getVtodo();
+      if (!Strings.isNullOrEmpty(vtodo)) {
+        changes.add(new SyncEntry(vtodo, Actions.DELETE));
+      }
     }
+
     for (CaldavTaskContainer task : localChanges.values()) {
-      changes.add(new SyncEntry(getVtodo(task), task.isNew() ? Actions.ADD : Actions.CHANGE));
+      String vtodo = task.getVtodo();
+      boolean existingTask = !Strings.isNullOrEmpty(vtodo);
+
+      if (task.isDeleted()) {
+        if (existingTask) {
+          changes.add(new SyncEntry(vtodo, Actions.DELETE));
+        }
+      } else {
+        changes.add(new SyncEntry(getVtodo(task), existingTask ? Actions.CHANGE : Actions.ADD));
+      }
     }
 
     remoteCtag = caldavCalendar.getCtag();
@@ -211,10 +224,12 @@ public class EteSynchronizer {
       updates.add(Pair.create(entry, syncEntry));
       previous = entry;
     }
-    Timber.v("Pushing local changes");
-    client.pushEntries(journal, from(updates).transform(p -> p.first).toList(), remoteCtag);
-    Timber.v("Applying local changes");
-    applyEntries(caldavCalendar, updates, emptySet());
+    if (updates.size() > 0) {
+      Timber.v("Pushing local changes");
+      client.pushEntries(journal, from(updates).transform(p -> p.first).toList(), remoteCtag);
+      Timber.v("Applying local changes");
+      applyEntries(caldavCalendar, updates, emptySet());
+    }
 
     Timber.d("UPDATE %s", caldavCalendar);