From d0fd159efe9ceafba25322aa65e6de1d1dcf5ae2 Mon Sep 17 00:00:00 2001
From: Marten Gajda <marten@dmfs.org>
Date: Sat, 14 Sep 2019 06:12:24 +0200
Subject: [PATCH] Ignore recurrence if start and due are absent, fixes #841
 (#844)

Apparently there are tasks which have a recurrence rule but neither a dtstart nor a due date. This caused an NPE. By treating such tasks as non-recurring this should be fixed.
---
 .../dmfs/provider/tasks/TaskProviderTest.java | 38 +++++++++++++++++++
 .../tasks/model/AbstractTaskAdapter.java      |  3 +-
 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/opentasks-provider/src/androidTest/java/org/dmfs/provider/tasks/TaskProviderTest.java b/opentasks-provider/src/androidTest/java/org/dmfs/provider/tasks/TaskProviderTest.java
index 911f43d53..47a8d9d3e 100644
--- a/opentasks-provider/src/androidTest/java/org/dmfs/provider/tasks/TaskProviderTest.java
+++ b/opentasks-provider/src/androidTest/java/org/dmfs/provider/tasks/TaskProviderTest.java
@@ -53,6 +53,7 @@
 import org.dmfs.opentaskspal.tasklists.NameData;
 import org.dmfs.opentaskspal.tasks.OriginalInstanceData;
 import org.dmfs.opentaskspal.tasks.OriginalInstanceSyncIdData;
+import org.dmfs.opentaskspal.tasks.RRuleTaskData;
 import org.dmfs.opentaskspal.tasks.StatusData;
 import org.dmfs.opentaskspal.tasks.SyncIdData;
 import org.dmfs.opentaskspal.tasks.TimeData;
@@ -61,6 +62,8 @@
 import org.dmfs.opentaskstestpal.InstanceTestData;
 import org.dmfs.rfc5545.DateTime;
 import org.dmfs.rfc5545.Duration;
+import org.dmfs.rfc5545.recur.InvalidRecurrenceRuleException;
+import org.dmfs.rfc5545.recur.RecurrenceRule;
 import org.dmfs.tasks.contract.TaskContract.Instances;
 import org.dmfs.tasks.contract.TaskContract.TaskLists;
 import org.dmfs.tasks.contract.TaskContract.Tasks;
@@ -904,4 +907,39 @@ public void testMoveTaskInstanceAsSyncAdapter() throws Exception
         ));
     }
 
+
+    /**
+     * Create task with start and due, check datetime values including generated duration.
+     */
+    @Test
+    public void testInsertTaskWithoutStartAndDueButRRULE() throws InvalidRecurrenceRuleException
+    {
+        RowSnapshot<TaskLists> taskList = new VirtualRowSnapshot<>(new LocalTaskListsTable(mAuthority));
+        RowSnapshot<Tasks> task = new VirtualRowSnapshot<>(new TaskListScoped(taskList, new TasksTable(mAuthority)));
+
+        DateTime start = DateTime.now();
+        DateTime due = start.addDuration(new Duration(1, 1, 0));
+
+        assertThat(new Seq<>(
+                        new Put<>(taskList, new EmptyRowData<>()),
+                        new Put<>(task, new Composite<>(
+                                new TitleData("test"),
+                                new RRuleTaskData(new RecurrenceRule("FREQ=DAILY;COUNT=5", RecurrenceRule.RfcMode.RFC2445_LAX))))),
+                resultsIn(mClient,
+                        new Assert<>(task, new Composite<>(
+                                new TitleData("test"),
+                                new VersionData(0))),
+                        new AssertRelated<>(
+                                new InstanceTable(mAuthority), Instances.TASK_ID, task,
+                                new Composite<>(
+                                        new CharSequenceRowData<>(Tasks.TITLE, "test"),
+                                        new InstanceTestData(
+                                                absent(),
+                                                absent(),
+                                                absent(),
+                                                0),
+                                        new CharSequenceRowData<>(Tasks.TZ, null))
+                        )));
+    }
+
 }
diff --git a/opentasks-provider/src/main/java/org/dmfs/provider/tasks/model/AbstractTaskAdapter.java b/opentasks-provider/src/main/java/org/dmfs/provider/tasks/model/AbstractTaskAdapter.java
index 5ca586e56..1f23f7735 100644
--- a/opentasks-provider/src/main/java/org/dmfs/provider/tasks/model/AbstractTaskAdapter.java
+++ b/opentasks-provider/src/main/java/org/dmfs/provider/tasks/model/AbstractTaskAdapter.java
@@ -44,7 +44,8 @@ public Uri uri(String authority)
     @Override
     public boolean isRecurring()
     {
-        return valueOf(RRULE) != null || valueOf(RDATE).iterator().hasNext();
+        // recurring tasks must have an RRULE or RDATEs and at least one of DTSTART and DUE date
+        return (valueOf(RRULE) != null || valueOf(RDATE).iterator().hasNext()) && (valueOf(DTSTART) != null || valueOf(DUE) != null);
     }