xW: add missing date change handling

xW/xW.cpp

@@ -100,6 +100,7 @@ struct {
 	HWND hwndInput;                     ///< edit: user input
 
 	HWND hwndLastFocused;               ///< For Alt+Tab, e.g.
+	HANDLE date_change_timer;           ///< Waitable timer for day changes
 
 	HICON hicon;                        ///< Normal program icon
 	HICON hiconHighlighted;             ///< Highlighted program icon
@@ -402,8 +403,7 @@ refresh_status()
 		status += L"🡇 ";
 
 	status += g.buffer_current;
-	auto b = buffer_by_name(g.buffer_current);
-	if (b) {
+	if (auto b = buffer_by_name(g.buffer_current)) {
 		if (!b->modes.empty())
 			status += L"(+" + b->modes + L")";
 		if (b->hide_unimportant)
@@ -542,39 +542,81 @@ convert_buffer_line(Relay::EventData_BufferLine &line)
 }
 
 static void
-buffer_print_line(std::vector<BufferLine>::const_iterator begin,
-	std::vector<BufferLine>::const_iterator line)
+buffer_print_date_change(bool &sameline, const tm &last, const tm &current)
 {
-	CHARRANGE cr = {};
-	cr.cpMin = cr.cpMax = GetWindowTextLength(g.hwndBuffer);
-	SendMessage(g.hwndBuffer, EM_EXSETSEL, 0, (LPARAM) &cr);
+	if (last.tm_year == current.tm_year &&
+		last.tm_mon == current.tm_mon &&
+		last.tm_mday == current.tm_mday)
+		return;
 
-	// The Rich Edit control makes the window cursor transparent
-	// each time you add an independent newline character. Avoid that.
-	// (Sadly, this also makes Windows 7 end lines with a bogus space that
-	// has the CHARFORMAT2 of what we flush that newline together with.)
-	bool sameline = !cr.cpMin;
-
-	time_t current_unix = line->when / 1000;
-	time_t last_unix = (line != begin)
-		? (line - 1)->when / 1000
-		: time(NULL);
-
-	tm current = {}, last = {};
-	(void) localtime_s(&current, &current_unix);
-	(void) localtime_s(&last, &last_unix);
-	if (last.tm_year != current.tm_year ||
-		last.tm_mon != current.tm_mon ||
-		last.tm_mday != current.tm_mday) {
 	wchar_t buffer[64] = {};
-		wcsftime(buffer, sizeof buffer, &L"\n%x\n"[sameline], &current);
-		sameline = true;
+	wcsftime(buffer, sizeof buffer, &L"\n%x"[sameline], &current);
+	sameline = false;
 
 	CHARFORMAT2 cf = default_charformat();
 	cf.dwEffects |= CFE_BOLD;
 	richedit_replacesel(g.hwndBuffer, &cf, buffer);
 }
+
+static LONG
+buffer_reset_selection()
 {
+	CHARRANGE cr = {};
+	cr.cpMin = cr.cpMax = GetWindowTextLength(g.hwndBuffer);
+	SendMessage(g.hwndBuffer, EM_EXSETSEL, 0, (LPARAM) &cr);
+	return cr.cpMin;
+}
+
+static struct tm
+buffer_localtime(time_t time)
+{
+	// This isn't critical, so let it fail quietly.
+	struct tm result = {};
+	(void) localtime_s(&result, &time);
+	return result;
+}
+
+static void
+buffer_print_and_watch_trailing_date_changes()
+{
+	time_t current_unix = time(NULL);
+	tm current = buffer_localtime(current_unix);
+	auto b = buffer_by_name(g.buffer_current);
+	if (b && !b->lines.empty()) {
+		tm last = buffer_localtime(b->lines.back().when / 1000);
+		bool sameline = !buffer_reset_selection();
+		buffer_print_date_change(sameline, last, current);
+	}
+
+	current.tm_sec = current.tm_min = current.tm_hour = 0;
+	current.tm_mday++;
+	current.tm_isdst = -1;
+	const time_t midnight = mktime(&current);
+	if (midnight == (time_t) -1 || midnight < current_unix)
+		return;
+
+	// Note that after printing the first trailing update,
+	// follow-up updates may be duplicated if timer events arrive too early.
+	LARGE_INTEGER li = {};
+	li.QuadPart = (midnight - current_unix + 1) * -10000000LL;
+	SetWaitableTimer(g.date_change_timer, &li, 0, NULL, NULL, FALSE);
+}
+
+static void
+buffer_print_line(std::vector<BufferLine>::const_iterator begin,
+	std::vector<BufferLine>::const_iterator line)
+{
+	tm current = buffer_localtime(line->when / 1000);
+	tm last = buffer_localtime(
+		line == begin ? time(NULL) : (line - 1)->when / 1000);
+
+	// The Rich Edit control makes the window cursor transparent
+	// each time you add an independent newline character. Avoid that.
+	// (Sadly, this also makes Windows 7 end lines with a bogus space that
+	// has the CHARFORMAT2 of what we flush that newline together with.)
+	bool sameline = !buffer_reset_selection();
+	buffer_print_date_change(sameline, last, current);
+
 	wchar_t buffer[64] = {};
 	wcsftime(buffer, sizeof buffer, &L"\n%H:%M:%S"[sameline], &current);
 
@@ -585,7 +627,6 @@ buffer_print_line(std::vector<BufferLine>::const_iterator begin,
 	richedit_replacesel(g.hwndBuffer, &cf, buffer);
 	cf = default_charformat();
 	richedit_replacesel(g.hwndBuffer, &cf, L" ");
-	}
 
 	// Tabstops won't quite help us here, since we need it centred.
 	std::wstring prefix;
@@ -673,6 +714,7 @@ refresh_buffer(const Buffer &b)
 		i++;
 	}
 
+	buffer_print_and_watch_trailing_date_changes();
 	buffer_scroll_to_bottom();
 
 	SendMessage(g.hwndBuffer, WM_SETREDRAW, (WPARAM) TRUE, 0);
@@ -1580,6 +1622,11 @@ window_proc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 	case WM_SIZE:
 		process_resize(LOWORD(lParam), HIWORD(lParam));
 		return 0;
+	case WM_TIMECHANGE:
+		_tzset();
+		if (auto b = buffer_by_name(g.buffer_current))
+			refresh_buffer(*b);
+		return 0;
 	case WM_ACTIVATE:
 		if (LOWORD(wParam) == WA_INACTIVE)
 			g.hwndLastFocused = GetFocus();
@@ -1847,20 +1894,38 @@ wWinMain(HINSTANCE hInstance, [[maybe_unused]] HINSTANCE hPrevInstance,
 		return 1;
 	}
 
+	g.date_change_timer = CreateWaitableTimer(NULL, FALSE, NULL);
+	if (!g.date_change_timer) {
+		show_error_message(format_error_message(GetLastError()).c_str());
+		return 1;
+	}
+
 	while (process_messages(accelerators)) {
+		HANDLE handles[] = {g.date_change_timer, g.event};
+		DWORD count = 2 - !handles[1];
 		DWORD result = MsgWaitForMultipleObjects(
-			g.event != NULL, &g.event, FALSE, INFINITE, QS_ALLINPUT);
+			count, handles, FALSE, INFINITE, QS_ALLINPUT);
 		if (result == WAIT_FAILED) {
 			show_error_message(format_error_message(GetLastError()).c_str());
 			return 1;
 		}
-		if (g.event != NULL && result == WAIT_OBJECT_0 &&
-			!relay_process_socket_events(error)) {
+		if (result >= WAIT_OBJECT_0 + count)
+			continue;
+
+		auto signalled = handles[result];
+		if (signalled == g.date_change_timer) {
+			bool to_bottom = buffer_at_bottom();
+			buffer_print_and_watch_trailing_date_changes();
+			if (to_bottom)
+				buffer_scroll_to_bottom();
+		}
+		if (signalled == g.event && !relay_process_socket_events(error)) {
 			show_error_message(error.c_str());
 			return 1;
 		}
 	}
 	FreeAddrInfo(g.addresses);
 	WSACleanup();
+	CloseHandle(g.date_change_timer);
 	return 0;
 }