Function CalendarEnginesMonthlyLoop

src/engine.cpp:1139–1184

Monthly update of the availability, reliability, and preview offers of the engines. */

/** Monthly update of the availability, reliability, and preview offers of the engines. */
void CalendarEnginesMonthlyLoop()
{
	if (TimerGameCalendar::year < _year_engine_aging_stops) {
		bool refresh = false;
		for (Engine *e : Engine::Iterate()) {
			/* Age the vehicle */
			if (e->flags.Test(EngineFlag::Available) && e->age != INT32_MAX) {
				e->age++;
				CalcEngineReliability(e, true);
				refresh = true;
			}

			/* Do not introduce invalid engines */
			if (!e->IsEnabled()) continue;

			if (!e->flags.Test(EngineFlag::Available) && TimerGameCalendar::date >= (e->intro_date + CalendarTime::DAYS_IN_YEAR)) {
				/* Introduce it to all companies */
				NewVehicleAvailable(e);
			} else if (!e->flags.Any({EngineFlag::Available, EngineFlag::ExclusivePreview}) && TimerGameCalendar::date >= e->intro_date) {
				/* Introduction date has passed...
				 * Check if it is allowed to build this vehicle type at all
				 * based on the current game settings. If not, it does not
				 * make sense to show the preview dialog to any company. */
				if (IsVehicleTypeDisabled(e->type, false)) continue;

				/* Do not introduce new rail wagons */
				if (IsWagon(e->index)) continue;

				/* Engine has no preview */
				if (e->info.extra_flags.Test(ExtraEngineFlag::NoPreview)) continue;

				/* Show preview dialog to one of the companies. */
				e->flags.Set(EngineFlag::ExclusivePreview);
				e->preview_company = CompanyID::Invalid();
				e->preview_asked = CompanyMask{};
			}
		}

		InvalidateWindowClassesData(WC_BUILD_VEHICLE); // rebuild the purchase list (esp. when sorted by reliability)

		if (refresh) {
			SetWindowClassesDirty(WC_BUILD_VEHICLE);
			SetWindowClassesDirty(WC_REPLACE_VEHICLE);
		}
	}
}

static const IntervalTimer<TimerGameCalendar> _calendar_engines_monthly({TimerGameCalendar::MONTH, TimerGameCalendar::Priority::ENGINE}, [](auto)
{