From 4eecd088e80cd3858a61f1c4044853fd50af03eb Mon Sep 17 00:00:00 2001
From: James Turner <james@flightgear.org>
Date: Fri, 12 Mar 2021 14:45:25 +0000
Subject: [PATCH] TimeManager: handle reposition better

Extend the timeManager unit-tests to check for some movements, all
seems to work correctly now.
---
 src/Main/fg_init.cxx                            |  8 +++++---
 src/Time/TimeManager.cxx                        |  6 ++++++
 src/Time/TimeManager.hxx                        |  2 ++
 test_suite/unit_tests/Main/test_timeManager.cxx | 17 ++++++++++++++++-
 4 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/Main/fg_init.cxx b/src/Main/fg_init.cxx
index cd6a0d55a..325832405 100644
--- a/src/Main/fg_init.cxx
+++ b/src/Main/fg_init.cxx
@@ -1241,9 +1241,11 @@ void fgStartReposition()
   globals->get_subsystem("xml-autopilot")->reinit();
 
   // need to update the timezone
-  SGTime *t = globals->get_time_params();
-  t->updateLocal(globals->get_aircraft_position(), globals->get_fg_root() / "Timezone");
-    
+  auto timeManager = globals->get_subsystem<TimeManager>();
+  if (timeManager) {
+      timeManager->reposition();
+  }
+
   // setup state to end re-init
   fgSetBool("/sim/signals/reinit", false);
   if ( !freeze ) {
diff --git a/src/Time/TimeManager.cxx b/src/Time/TimeManager.cxx
index ad1b19d46..279fe9340 100644
--- a/src/Time/TimeManager.cxx
+++ b/src/Time/TimeManager.cxx
@@ -404,6 +404,12 @@ void TimeManager::throttleUpdateRate()
     _frameWait->setDoubleValue(frameWaitStart.elapsedMSec());
 }
 
+void TimeManager::reposition()
+{
+    // force a zone check, next update()
+    _lastTimeZoneCheckPosition = SGVec3d::zeros();
+}
+
 // periodic time updater wrapper
 void TimeManager::updateLocalTime() 
 {
diff --git a/src/Time/TimeManager.hxx b/src/Time/TimeManager.hxx
index d29b503c5..2cb292313 100644
--- a/src/Time/TimeManager.hxx
+++ b/src/Time/TimeManager.hxx
@@ -43,6 +43,8 @@ public:
     void unbind() override;
     void update(double dt) override;
 
+    void reposition();
+
     // Subsystem identification.
     static const char* staticSubsystemClassId() { return "time"; }
 
diff --git a/test_suite/unit_tests/Main/test_timeManager.cxx b/test_suite/unit_tests/Main/test_timeManager.cxx
index 86c38af5e..3798607dd 100644
--- a/test_suite/unit_tests/Main/test_timeManager.cxx
+++ b/test_suite/unit_tests/Main/test_timeManager.cxx
@@ -143,7 +143,7 @@ void TimeManagerTests::testTimeZones()
 
     timeManager->update(0.0);
 
-    CPPUNIT_ASSERT_EQUAL((time_t) 18000, globals->get_time_params()->get_local_offset());
+    CPPUNIT_ASSERT_EQUAL((time_t)19800, globals->get_time_params()->get_local_offset());
 
     auto gmt = globals->get_time_params()->getGmt();
     CPPUNIT_ASSERT_EQUAL(79, gmt->tm_year);
@@ -152,6 +152,21 @@ void TimeManagerTests::testTimeZones()
 
 
     // relocate to somewhere, check the time values update
+
+    auto eddf = FGAirport::getByIdent("EDDF");
+    FGTestApi::setPositionAndStabilise(eddf->geod());
+    timeManager->reposition();
+    timeManager->update(0.0);
+
+    CPPUNIT_ASSERT_EQUAL((time_t)3600, globals->get_time_params()->get_local_offset());
+
+
+    auto zbaa = FGAirport::getByIdent("ZBAA");
+    FGTestApi::setPositionAndStabilise(zbaa->geod());
+    timeManager->reposition();
+    timeManager->update(0.0);
+
+    CPPUNIT_ASSERT_EQUAL((time_t)28800, globals->get_time_params()->get_local_offset());
 }
 
 void TimeManagerTests::testSpecifyTimeOffset()