From 5a078800e4abad08532b397a5fd4d8f70fb19002 Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Fri, 26 May 2023 22:42:06 -0500
Subject: [PATCH] QDate::toStdSysDays is needlessly behind __cpp_lib_chrono >=
 201907L

---
 scwx-qt/scwx-qt.cmake                         |  6 +++--
 .../scwx/qt/ui/animation_dock_widget.cpp      |  5 ++--
 scwx-qt/source/scwx/qt/util/time.cpp          | 24 ++++++++++++++++++
 scwx-qt/source/scwx/qt/util/time.hpp          | 25 +++++++++++++++++++
 4 files changed, 56 insertions(+), 4 deletions(-)
 create mode 100644 scwx-qt/source/scwx/qt/util/time.cpp
 create mode 100644 scwx-qt/source/scwx/qt/util/time.hpp

diff --git a/scwx-qt/scwx-qt.cmake b/scwx-qt/scwx-qt.cmake
index 5aaa1f2a..1cee1716 100644
--- a/scwx-qt/scwx-qt.cmake
+++ b/scwx-qt/scwx-qt.cmake
@@ -186,7 +186,8 @@ set(HDR_UTIL source/scwx/qt/util/color.hpp
              source/scwx/qt/util/streams.hpp
              source/scwx/qt/util/texture_atlas.hpp
              source/scwx/qt/util/q_file_buffer.hpp
-             source/scwx/qt/util/q_file_input_stream.hpp)
+             source/scwx/qt/util/q_file_input_stream.hpp
+             source/scwx/qt/util/time.hpp)
 set(SRC_UTIL source/scwx/qt/util/color.cpp
              source/scwx/qt/util/file.cpp
              source/scwx/qt/util/font.cpp
@@ -195,7 +196,8 @@ set(SRC_UTIL source/scwx/qt/util/color.cpp
              source/scwx/qt/util/json.cpp
              source/scwx/qt/util/texture_atlas.cpp
              source/scwx/qt/util/q_file_buffer.cpp
-             source/scwx/qt/util/q_file_input_stream.cpp)
+             source/scwx/qt/util/q_file_input_stream.cpp
+             source/scwx/qt/util/time.cpp)
 set(HDR_VIEW source/scwx/qt/view/level2_product_view.hpp
              source/scwx/qt/view/level3_product_view.hpp
              source/scwx/qt/view/level3_radial_view.hpp
diff --git a/scwx-qt/source/scwx/qt/ui/animation_dock_widget.cpp b/scwx-qt/source/scwx/qt/ui/animation_dock_widget.cpp
index a147cef3..f9bcbd58 100644
--- a/scwx-qt/source/scwx/qt/ui/animation_dock_widget.cpp
+++ b/scwx-qt/source/scwx/qt/ui/animation_dock_widget.cpp
@@ -1,6 +1,7 @@
 #include "animation_dock_widget.hpp"
 #include "ui_animation_dock_widget.h"
 
+#include <scwx/qt/util/time.hpp>
 #include <scwx/util/logger.hpp>
 
 #include <QTimer>
@@ -65,7 +66,7 @@ AnimationDockWidget::AnimationDockWidget(QWidget* parent) :
    ui->dateEdit->setDate(currentDate);
    ui->timeEdit->setTime(currentTime);
    ui->dateEdit->setMaximumDate(currentDateTime.date());
-   p->selectedDate_ = currentDate.toStdSysDays();
+   p->selectedDate_ = util::SysDays(currentDate);
    p->selectedTime_ =
       std::chrono::seconds(currentTime.msecsSinceStartOfDay() / 1000);
 
@@ -129,7 +130,7 @@ void AnimationDockWidgetImpl::ConnectSignals()
       {
          if (date.isValid())
          {
-            selectedDate_ = date.toStdSysDays();
+            selectedDate_ = util::SysDays(date);
             emit self_->DateTimeChanged(selectedDate_ + selectedTime_);
          }
       });
diff --git a/scwx-qt/source/scwx/qt/util/time.cpp b/scwx-qt/source/scwx/qt/util/time.cpp
new file mode 100644
index 00000000..f34c6ea5
--- /dev/null
+++ b/scwx-qt/source/scwx/qt/util/time.cpp
@@ -0,0 +1,24 @@
+#include <scwx/qt/util/time.hpp>
+
+namespace scwx
+{
+namespace qt
+{
+namespace util
+{
+
+std::chrono::sys_days SysDays(const QDate& date)
+{
+   using namespace std::chrono;
+   using sys_days             = time_point<system_clock, days>;
+   constexpr auto julianEpoch = sys_days {-4713y / November / 24d};
+   constexpr auto unixEpoch   = sys_days {1970y / January / 1d};
+   constexpr auto offset      = std::chrono::days(julianEpoch - unixEpoch);
+
+   return std::chrono::sys_days(std::chrono::days(date.toJulianDay()) +
+                                julianEpoch);
+}
+
+} // namespace util
+} // namespace qt
+} // namespace scwx
diff --git a/scwx-qt/source/scwx/qt/util/time.hpp b/scwx-qt/source/scwx/qt/util/time.hpp
new file mode 100644
index 00000000..8f3e7a53
--- /dev/null
+++ b/scwx-qt/source/scwx/qt/util/time.hpp
@@ -0,0 +1,25 @@
+#pragma once
+
+#include <chrono>
+
+#include <QDateTime>
+
+namespace scwx
+{
+namespace qt
+{
+namespace util
+{
+
+/**
+ * @brief Convert QDate to std::chrono::sys_days.
+ *
+ * @param [in] date Date to convert
+ *
+ * @return Days
+ */
+std::chrono::sys_days SysDays(const QDate& date);
+
+} // namespace util
+} // namespace qt
+} // namespace scwx