From dc282b6ab5cc234ab9ba7c1605ac7e292842dacd Mon Sep 17 00:00:00 2001
From: BlackMark <me@blackmark.me>
Date: Sun, 5 Jul 2020 17:38:15 +0200
Subject: [PATCH] Implemented windows error formatting

---
 AdaptiveBrightness/monitor_control_win.cpp | 38 +++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/AdaptiveBrightness/monitor_control_win.cpp b/AdaptiveBrightness/monitor_control_win.cpp
index 9db8da7..b3c4950 100644
--- a/AdaptiveBrightness/monitor_control_win.cpp
+++ b/AdaptiveBrightness/monitor_control_win.cpp
@@ -2,19 +2,55 @@
 
 #ifdef _MSC_VER
 
+    #include <type_traits>
+
     #include <QString>
     #include <QtDebug>
     #include <QtGlobal>
 
+    #include <tchar.h>
+
     #include "log_tr.hpp"
 
 namespace detail {
 
+template<typename...>
+struct always_false : std::false_type {
+};
+
+template<typename... Ts>
+inline constexpr auto always_false_v = always_false<Ts...>::value;
+
+template<typename T>
+static QString fromTchar(T* tString)
+{
+    if constexpr(std::is_same_v<T, char>) {
+        return QString().fromLocal8Bit(tString).trimmed();
+    }
+    else if constexpr(std::is_same_v<T, wchar_t>) {
+        return QString().fromWCharArray(tString).trimmed();
+    }
+    else {
+        static_assert(always_false_v<T>, "Unknown TCHAR type");
+    }
+}
+
 static QString getLastErrorString()
 {
     DWORD lastErrorId = GetLastError();
 
-    return {};
+    TCHAR* msgBuf;
+    const auto formatFlags = FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS;
+
+    if(FormatMessage(formatFlags, nullptr, lastErrorId, 0, reinterpret_cast<LPTSTR>(&msgBuf), 0, nullptr) == 0) {
+        return "FormatMessage failed";
+    }
+
+    const auto lastErrorString = fromTchar(msgBuf);
+
+    LocalFree(msgBuf);
+
+    return lastErrorString;
 }
 
 static BOOL enumMonitorsCallback(HMONITOR hMonitor, [[maybe_unused]] HDC hDC, [[maybe_unused]] LPRECT lpRect, LPARAM lParam)