engine.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <https://www.gnu.org/licenses/old-licenses/gpl-2.0>.
 */

 
#include "stdafx.h"
#include "core/container_func.hpp"
#include "company_func.h"
#include "command_func.h"
#include "news_func.h"
#include "aircraft.h"
#include "newgrf.h"
#include "newgrf_engine.h"
#include "strings_func.h"
#include "core/random_func.hpp"
#include "window_func.h"
#include "autoreplace_gui.h"
#include "string_func.h"
#include "ai/ai.hpp"
#include "core/pool_func.hpp"
#include "engine_gui.h"
#include "engine_func.h"
#include "engine_base.h"
#include "company_base.h"
#include "vehicle_func.h"
#include "articulated_vehicles.h"
#include "error.h"
#include "engine_base.h"
#include "timer/timer.h"
#include "timer/timer_game_tick.h"
#include "timer/timer_game_calendar.h"
 
#include "table/strings.h"
#include "table/engines.h"
 
#include "safeguards.h"
 
EnginePool _engine_pool("Engine");
INSTANTIATE_POOL_METHODS(Engine)
 
EngineOverrideManager _engine_mngr;

static TimerGameCalendar::Year _year_engine_aging_stops;

const uint8_t _engine_counts[4] = {
  lengthof(_orig_rail_vehicle_info),
  lengthof(_orig_road_vehicle_info),
  lengthof(_orig_ship_vehicle_info),
  lengthof(_orig_aircraft_vehicle_info),
};

const uint8_t _engine_offsets[4] = {
  0,
  lengthof(_orig_rail_vehicle_info),
  lengthof(_orig_rail_vehicle_info) + lengthof(_orig_road_vehicle_info),
  lengthof(_orig_rail_vehicle_info) + lengthof(_orig_road_vehicle_info) + lengthof(_orig_ship_vehicle_info),
};
 
static_assert(lengthof(_orig_rail_vehicle_info) + lengthof(_orig_road_vehicle_info) + lengthof(_orig_ship_vehicle_info) + lengthof(_orig_aircraft_vehicle_info) == lengthof(_orig_engine_info));
 
Engine::Engine(EngineID index, VehicleType type, uint16_t local_id) : EnginePool::PoolItem<&_engine_pool>(index)
{
  this->type = type;
 
  /* Called in the context of loading a savegame. The rest comes from the loader. */
  if (type == VEH_INVALID) return;
 
  this->grf_prop.local_id = local_id;
  this->list_position = local_id;
  this->preview_company = CompanyID::Invalid();
  this->display_last_variant = EngineID::Invalid();
 
  /* Check if this base engine is within the original engine data range */
  if (local_id >= _engine_counts[type]) {
    /* Initialise default type-specific information. */
    switch (type) {
      case VEH_TRAIN: this->vehicle_info.emplace<RailVehicleInfo>(); break;
      case VEH_ROAD: this->vehicle_info.emplace<RoadVehicleInfo>(); break;
      case VEH_SHIP: this->vehicle_info.emplace<ShipVehicleInfo>(); break;
      case VEH_AIRCRAFT: this->vehicle_info.emplace<AircraftVehicleInfo>(); break;
      default: break;
    }
    /* Set model life to maximum to make wagons available */
    this->info.base_life = TimerGameCalendar::Year{0xFF};
    /* Aircraft must have CT_INVALID as default, as there is no property */
    this->info.cargo_type = INVALID_CARGO;
    this->info.cargo_label = (type == VEH_AIRCRAFT) ? CT_INVALID : CT_PASSENGERS;
    /* Set cargo aging period to the default value. */
    this->info.cargo_age_period = Ticks::CARGO_AGING_TICKS;
    /* Not a variant */
    this->info.variant_id = EngineID::Invalid();
    return;
  }
 
  /* Copy the original engine info for this slot */
  this->info = _orig_engine_info[_engine_offsets[type] + local_id];
 
  /* Copy the original engine data for this slot */
  switch (type) {
    default: NOT_REACHED();
 
    case VEH_TRAIN: {
      RailVehicleInfo &rvi = this->vehicle_info.emplace<RailVehicleInfo>(_orig_rail_vehicle_info[local_id]);
      this->original_image_index = rvi.image_index;
      this->info.string_id = STR_VEHICLE_NAME_TRAIN_ENGINE_RAIL_KIRBY_PAUL_TANK_STEAM + local_id;
 
      /* Set the default model life of original wagons to "infinite" */
      if (rvi.railveh_type == RAILVEH_WAGON) this->info.base_life = TimerGameCalendar::Year{0xFF};
 
      break;
    }
 
    case VEH_ROAD: {
      RoadVehicleInfo &rvi = this->vehicle_info.emplace<RoadVehicleInfo>(_orig_road_vehicle_info[local_id]);
      this->original_image_index = rvi.image_index;
      this->info.string_id = STR_VEHICLE_NAME_ROAD_VEHICLE_MPS_REGAL_BUS + local_id;
      break;
    }
 
    case VEH_SHIP: {
      ShipVehicleInfo &svi = this->vehicle_info.emplace<ShipVehicleInfo>(_orig_ship_vehicle_info[local_id]);
      this->original_image_index = svi.image_index;
      this->info.string_id = STR_VEHICLE_NAME_SHIP_MPS_OIL_TANKER + local_id;
      break;
    }
 
    case VEH_AIRCRAFT: {
      AircraftVehicleInfo &avi = this->vehicle_info.emplace<AircraftVehicleInfo>(_orig_aircraft_vehicle_info[local_id]);
      this->original_image_index = avi.image_index;
      this->info.string_id = STR_VEHICLE_NAME_AIRCRAFT_SAMPSON_U52 + local_id;
      break;
    }
  }
}

bool Engine::IsEnabled() const
{
  return this->info.string_id != STR_NEWGRF_INVALID_ENGINE && this->info.climates.Test(_settings_game.game_creation.landscape);
}

uint32_t Engine::GetGRFID() const
{
  const GRFFile *file = this->GetGRF();
  return file == nullptr ? 0 : file->grfid;
}

bool Engine::CanCarryCargo() const
{
  /* For engines that can appear in a consist (i.e. rail vehicles and (articulated) road vehicles), a capacity
   * of zero is a special case, to define the vehicle to not carry anything. The default cargotype is still used
   * for livery selection etc.
   * Note: Only the property is tested. A capacity callback returning 0 does not have the same effect.
   */
  switch (this->type) {
    case VEH_TRAIN:
      if (this->VehInfo<RailVehicleInfo>().capacity == 0) return false;
      break;
 
    case VEH_ROAD:
      if (this->VehInfo<RoadVehicleInfo>().capacity == 0) return false;
      break;
 
    case VEH_SHIP:
    case VEH_AIRCRAFT:
      break;
 
    default: NOT_REACHED();
  }
  return IsValidCargoType(this->GetDefaultCargoType());
}
 

uint Engine::DetermineCapacity(const Vehicle *v, uint16_t *mail_capacity) const
{
  assert(v == nullptr || this->index == v->engine_type);
  if (mail_capacity != nullptr) *mail_capacity = 0;
 
  if (!this->CanCarryCargo()) return 0;
 
  bool new_multipliers = this->info.misc_flags.Test(EngineMiscFlag::NoDefaultCargoMultiplier);
  CargoType default_cargo = this->GetDefaultCargoType();
  CargoType cargo_type = (v != nullptr) ? v->cargo_type : default_cargo;
 
  if (mail_capacity != nullptr && this->type == VEH_AIRCRAFT && IsCargoInClass(cargo_type, CargoClass::Passengers)) {
    *mail_capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->VehInfo<AircraftVehicleInfo>().mail_capacity, v);
  }
 
  /* Check the refit capacity callback if we are not in the default configuration, or if we are using the new multiplier algorithm. */
  if (this->info.callback_mask.Test(VehicleCallbackMask::RefitCapacity) &&
      (new_multipliers || default_cargo != cargo_type || (v != nullptr && v->cargo_subtype != 0))) {
    uint16_t callback = GetVehicleCallback(CBID_VEHICLE_REFIT_CAPACITY, 0, 0, this->index, v);
    if (callback != CALLBACK_FAILED) return callback;
  }
 
  /* Get capacity according to property resp. CB */
  uint capacity;
  uint extra_mail_cap = 0;
  switch (this->type) {
    case VEH_TRAIN:
      capacity = GetEngineProperty(this->index, PROP_TRAIN_CARGO_CAPACITY,        this->VehInfo<RailVehicleInfo>().capacity, v);
 
      /* In purchase list add the capacity of the second head. Always use the plain property for this. */
      if (v == nullptr && this->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_MULTIHEAD) capacity += this->VehInfo<RailVehicleInfo>().capacity;
      break;
 
    case VEH_ROAD:
      capacity = GetEngineProperty(this->index, PROP_ROADVEH_CARGO_CAPACITY,      this->VehInfo<RoadVehicleInfo>().capacity, v);
      break;
 
    case VEH_SHIP:
      capacity = GetEngineProperty(this->index, PROP_SHIP_CARGO_CAPACITY,         this->VehInfo<ShipVehicleInfo>().capacity, v);
      break;
 
    case VEH_AIRCRAFT:
      capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_PASSENGER_CAPACITY, this->VehInfo<AircraftVehicleInfo>().passenger_capacity, v);
      if (!IsCargoInClass(cargo_type, CargoClass::Passengers)) {
        extra_mail_cap = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->VehInfo<AircraftVehicleInfo>().mail_capacity, v);
      }
      if (IsValidCargoType(GetCargoTypeByLabel(CT_MAIL))) {
        if (!new_multipliers && cargo_type == GetCargoTypeByLabel(CT_MAIL)) return capacity + extra_mail_cap;
      }
      default_cargo = GetCargoTypeByLabel(CT_PASSENGERS); // Always use 'passengers' wrt. cargo multipliers
      break;
 
    default: NOT_REACHED();
  }
 
  if (!new_multipliers) {
    /* Use the passenger multiplier for mail as well */
    capacity += extra_mail_cap;
    extra_mail_cap = 0;
  }
 
  /* Apply multipliers depending on cargo- and vehicletype. */
  if (new_multipliers || (this->type != VEH_SHIP && default_cargo != cargo_type)) {
    uint16_t default_multiplier = new_multipliers ? 0x100 : CargoSpec::Get(default_cargo)->multiplier;
    uint16_t cargo_multiplier = CargoSpec::Get(cargo_type)->multiplier;
    capacity *= cargo_multiplier;
    if (extra_mail_cap > 0 && IsValidCargoType(GetCargoTypeByLabel(CT_MAIL))) {
      uint mail_multiplier = CargoSpec::Get(GetCargoTypeByLabel(CT_MAIL))->multiplier;
      capacity += (default_multiplier * extra_mail_cap * cargo_multiplier + mail_multiplier / 2) / mail_multiplier;
    }
    capacity = (capacity + default_multiplier / 2) / default_multiplier;
  }
 
  return capacity;
}

Money Engine::GetRunningCost() const
{
  Price base_price;
  uint cost_factor;
  switch (this->type) {
    case VEH_ROAD:
      base_price = this->VehInfo<RoadVehicleInfo>().running_cost_class;
      if (base_price == Price::Invalid) return 0;
      cost_factor = GetEngineProperty(this->index, PROP_ROADVEH_RUNNING_COST_FACTOR, this->VehInfo<RoadVehicleInfo>().running_cost);
      break;
 
    case VEH_TRAIN:
      base_price = this->VehInfo<RailVehicleInfo>().running_cost_class;
      if (base_price == Price::Invalid) return 0;
      cost_factor = GetEngineProperty(this->index, PROP_TRAIN_RUNNING_COST_FACTOR, this->VehInfo<RailVehicleInfo>().running_cost);
      break;
 
    case VEH_SHIP:
      base_price = Price::RunningShip;
      cost_factor = GetEngineProperty(this->index, PROP_SHIP_RUNNING_COST_FACTOR, this->VehInfo<ShipVehicleInfo>().running_cost);
      break;
 
    case VEH_AIRCRAFT:
      base_price = Price::RunningAircraft;
      cost_factor = GetEngineProperty(this->index, PROP_AIRCRAFT_RUNNING_COST_FACTOR, this->VehInfo<AircraftVehicleInfo>().running_cost);
      break;
 
    default: NOT_REACHED();
  }
 
  return GetPrice(base_price, cost_factor, this->GetGRF(), -8);
}

Money Engine::GetCost() const
{
  Price base_price;
  uint cost_factor;
  switch (this->type) {
    case VEH_ROAD:
      base_price = Price::BuildVehicleRoad;
      cost_factor = GetEngineProperty(this->index, PROP_ROADVEH_COST_FACTOR, this->VehInfo<RoadVehicleInfo>().cost_factor);
      break;
 
    case VEH_TRAIN:
      if (this->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_WAGON) {
        base_price = Price::BuildVehicleWagon;
        cost_factor = GetEngineProperty(this->index, PROP_TRAIN_COST_FACTOR, this->VehInfo<RailVehicleInfo>().cost_factor);
      } else {
        base_price = Price::BuildVehicleTrain;
        cost_factor = GetEngineProperty(this->index, PROP_TRAIN_COST_FACTOR, this->VehInfo<RailVehicleInfo>().cost_factor);
      }
      break;
 
    case VEH_SHIP:
      base_price = Price::BuildVehicleShip;
      cost_factor = GetEngineProperty(this->index, PROP_SHIP_COST_FACTOR, this->VehInfo<ShipVehicleInfo>().cost_factor);
      break;
 
    case VEH_AIRCRAFT:
      base_price = Price::BuildVehicleAircraft;
      cost_factor = GetEngineProperty(this->index, PROP_AIRCRAFT_COST_FACTOR, this->VehInfo<AircraftVehicleInfo>().cost_factor);
      break;
 
    default: NOT_REACHED();
  }
 
  return GetPrice(base_price, cost_factor, this->GetGRF(), -8);
}

uint Engine::GetDisplayMaxSpeed() const
{
  switch (this->type) {
    case VEH_TRAIN:
      return GetEngineProperty(this->index, PROP_TRAIN_SPEED, this->VehInfo<RailVehicleInfo>().max_speed);
 
    case VEH_ROAD: {
      uint max_speed = GetEngineProperty(this->index, PROP_ROADVEH_SPEED, 0);
      return (max_speed != 0) ? max_speed * 2 : this->VehInfo<RoadVehicleInfo>().max_speed / 2;
    }
 
    case VEH_SHIP:
      return GetEngineProperty(this->index, PROP_SHIP_SPEED, this->VehInfo<ShipVehicleInfo>().max_speed) / 2;
 
    case VEH_AIRCRAFT: {
      uint max_speed = GetEngineProperty(this->index, PROP_AIRCRAFT_SPEED, 0);
      if (max_speed != 0) {
        return (max_speed * 128) / 10;
      }
      return this->VehInfo<AircraftVehicleInfo>().max_speed;
    }
 
    default: NOT_REACHED();
  }
}

uint Engine::GetPower() const
{
  /* Only trains and road vehicles have 'power'. */
  switch (this->type) {
    case VEH_TRAIN:
      return GetEngineProperty(this->index, PROP_TRAIN_POWER, this->VehInfo<RailVehicleInfo>().power);
    case VEH_ROAD:
      return GetEngineProperty(this->index, PROP_ROADVEH_POWER, this->VehInfo<RoadVehicleInfo>().power) * 10;
 
    default: NOT_REACHED();
  }
}

uint Engine::GetDisplayWeight() const
{
  /* Only trains and road vehicles have 'weight'. */
  switch (this->type) {
    case VEH_TRAIN:
      return GetEngineProperty(this->index, PROP_TRAIN_WEIGHT, this->VehInfo<RailVehicleInfo>().weight) << (this->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_MULTIHEAD ? 1 : 0);
    case VEH_ROAD:
      return GetEngineProperty(this->index, PROP_ROADVEH_WEIGHT, this->VehInfo<RoadVehicleInfo>().weight) / 4;
 
    default: NOT_REACHED();
  }
}

uint Engine::GetDisplayMaxTractiveEffort() const
{
  /* Only trains and road vehicles have 'tractive effort'. */
  switch (this->type) {
    case VEH_TRAIN:
      return (GROUND_ACCELERATION * this->GetDisplayWeight() * GetEngineProperty(this->index, PROP_TRAIN_TRACTIVE_EFFORT, this->VehInfo<RailVehicleInfo>().tractive_effort)) / 256;
    case VEH_ROAD:
      return (GROUND_ACCELERATION * this->GetDisplayWeight() * GetEngineProperty(this->index, PROP_ROADVEH_TRACTIVE_EFFORT, this->VehInfo<RoadVehicleInfo>().tractive_effort)) / 256;
 
    default: NOT_REACHED();
  }
}

TimerGameCalendar::Date Engine::GetLifeLengthInDays() const
{
  /* Assume leap years; this gives the player a bit more than the given amount of years, but never less. */
  return TimerGameCalendar::Date{(this->info.lifelength + _settings_game.vehicle.extend_vehicle_life).base() * CalendarTime::DAYS_IN_LEAP_YEAR};
}

uint16_t Engine::GetRange() const
{
  switch (this->type) {
    case VEH_AIRCRAFT:
      return GetEngineProperty(this->index, PROP_AIRCRAFT_RANGE, this->VehInfo<AircraftVehicleInfo>().max_range);
 
    default: NOT_REACHED();
  }
}

StringID Engine::GetAircraftTypeText() const
{
  switch (this->type) {
    case VEH_AIRCRAFT:
      switch (this->VehInfo<AircraftVehicleInfo>().subtype) {
        case AIR_HELI: return STR_LIVERY_HELICOPTER;
        case AIR_CTOL: return STR_LIVERY_SMALL_PLANE;
        case AIR_CTOL | AIR_FAST: return STR_LIVERY_LARGE_PLANE;
        default: NOT_REACHED();
      }
 
    default: NOT_REACHED();
  }
}

bool Engine::IsVariantHidden(CompanyID c) const
{
  /* In case company is spectator. */
  if (c >= MAX_COMPANIES) return false;
 
  /* Shortcut if this engine is explicitly hidden. */
  if (this->IsHidden(c)) return true;
 
  /* Check for hidden parent variants. This is a bit convoluted as we must check hidden status of
   * the last display variant rather than the actual parent variant. */
  const Engine *re = this;
  const Engine *ve = re->GetDisplayVariant();
  while (!(ve->IsHidden(c)) && re->info.variant_id != EngineID::Invalid()) {
    re = Engine::Get(re->info.variant_id);
    ve = re->GetDisplayVariant();
  }
  return ve->IsHidden(c);
}

void EngineOverrideManager::ResetToDefaultMapping()
{
  EngineID id = EngineID::Begin();
  for (VehicleType type = VEH_TRAIN; type <= VEH_AIRCRAFT; type++) {
    auto &map = this->mappings[type];
    map.clear();
    for (uint internal_id = 0; internal_id < _engine_counts[type]; internal_id++, ++id) {
      map.emplace_back(INVALID_GRFID, internal_id, type, internal_id, id);
    }
  }
}

EngineID EngineOverrideManager::GetID(VehicleType type, uint16_t grf_local_id, uint32_t grfid)
{
  const auto &map = this->mappings[type];
  const auto key = EngineIDMapping::Key(grfid, grf_local_id);
  auto it = std::ranges::lower_bound(map, key, std::less{}, EngineIDMappingKeyProjection{});
  if (it == std::end(map) || it->Key() != key) return EngineID::Invalid();
  return it->engine;
}

EngineID EngineOverrideManager::UseUnreservedID(VehicleType type, uint16_t grf_local_id, uint32_t grfid, bool static_access)
{
  auto &map = _engine_mngr.mappings[type];
  const auto key = EngineIDMapping::Key(INVALID_GRFID, grf_local_id);
  auto it = std::ranges::lower_bound(map, key, std::less{}, EngineIDMappingKeyProjection{});
  if (it == std::end(map) || it->Key() != key) return EngineID::Invalid();
 
  if (!static_access && grfid != INVALID_GRFID) {
    /* Reserve the engine slot for the new grfid. */
    it->grfid = grfid;
 
    /* Relocate entry to its new position in the mapping list to keep it sorted. */
    auto p = std::ranges::lower_bound(map, EngineIDMapping::Key(grfid, grf_local_id), std::less{}, EngineIDMappingKeyProjection{});
    it = Slide(it, std::next(it), p).first;
  }
 
  return it->engine;
}
 
void EngineOverrideManager::SetID(VehicleType type, uint16_t grf_local_id, uint32_t grfid, uint8_t substitute_id, EngineID engine)
{
  auto &map = this->mappings[type];
  const auto key = EngineIDMapping::Key(grfid, grf_local_id);
  auto it = std::ranges::lower_bound(map, key, std::less{}, EngineIDMappingKeyProjection{});
  if (it == std::end(map) || it->Key() != key) {
    map.emplace(it, grfid, grf_local_id, type, substitute_id, engine);
  } else {
    it->engine = engine;
  }
}

bool EngineOverrideManager::ResetToCurrentNewGRFConfig()
{
  for (const Vehicle *v : Vehicle::Iterate()) {
    if (IsCompanyBuildableVehicleType(v)) return false;
  }
 
  /* Reset the engines, they will get new EngineIDs */
  _engine_mngr.ResetToDefaultMapping();
  ReloadNewGRFData();
 
  return true;
}

void SetupEngines()
{
  CloseWindowByClass(WC_ENGINE_PREVIEW);
  _engine_pool.CleanPool();
 
  for (VehicleType type = VEH_BEGIN; type != VEH_COMPANY_END; type++) {
    const auto &mapping = _engine_mngr.mappings[type];
 
    /* Verify that the engine override manager has at least been set up with the default engines. */
    assert(std::size(mapping) >= _engine_counts[type]);
 
    for (const EngineIDMapping &eid : mapping) {
      Engine::CreateAtIndex(eid.engine, type, eid.internal_id);
    }
  }
}
 
void ShowEnginePreviewWindow(EngineID engine);

static bool IsWagon(EngineID index)
{
  const Engine *e = Engine::Get(index);
  return e->type == VEH_TRAIN && e->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_WAGON;
}

static void ClearLastVariant(EngineID engine_id, VehicleType type)
{
  for (Engine *e : Engine::IterateType(type)) {
    if (e->display_last_variant == engine_id) e->display_last_variant = EngineID::Invalid();
  }
}

void CalcEngineReliability(Engine *e, bool new_month)
{
  /* Get source engine for reliability age. This is normally our engine unless variant reliability syncing is requested. */
  Engine *re = e;
  while (re->info.variant_id != EngineID::Invalid() && re->info.extra_flags.Test(ExtraEngineFlag::SyncReliability)) {
    re = Engine::Get(re->info.variant_id);
  }
 
  uint32_t age = re->age;
  if (new_month && re->index > e->index && age != INT32_MAX) age++; /* parent variant's age has not yet updated. */
 
  /* Check for early retirement */
  if (e->company_avail.Any() && !_settings_game.vehicle.never_expire_vehicles && e->info.base_life != 0xFF) {
    int retire_early = e->info.retire_early;
    uint retire_early_max_age = std::max(0, e->duration_phase_1 + e->duration_phase_2 - retire_early * 12);
    if (retire_early != 0 && age >= retire_early_max_age) {
      /* Early retirement is enabled and we're past the date... */
      e->company_avail = CompanyMask{};
      ClearLastVariant(e->index, e->type);
      AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
    }
  }
 
  if (age < e->duration_phase_1) {
    uint start = e->reliability_start;
    e->reliability = age * (e->reliability_max - start) / e->duration_phase_1 + start;
  } else if ((age -= e->duration_phase_1) < e->duration_phase_2 || _settings_game.vehicle.never_expire_vehicles || e->info.base_life == 0xFF) {
    /* We are at the peak of this engines life. It will have max reliability.
     * This is also true if the engines never expire. They will not go bad over time */
    e->reliability = e->reliability_max;
  } else if ((age -= e->duration_phase_2) < e->duration_phase_3) {
    uint max = e->reliability_max;
    e->reliability = (int)age * (int)(e->reliability_final - max) / e->duration_phase_3 + max;
  } else {
    /* time's up for this engine.
     * We will now completely retire this design */
    e->company_avail = CompanyMask{};
    e->reliability = e->reliability_final;
    /* Kick this engine out of the lists */
    ClearLastVariant(e->index, e->type);
    AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
  }
 
}

void SetYearEngineAgingStops()
{
  /* Determine last engine aging year, default to 2050 as previously. */
  _year_engine_aging_stops = TimerGameCalendar::Year{2050};
 
  for (const Engine *e : Engine::Iterate()) {
    const EngineInfo *ei = &e->info;
 
    /* Exclude certain engines */
    if (!ei->climates.Test(_settings_game.game_creation.landscape)) continue;
    if (e->type == VEH_TRAIN && e->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_WAGON) continue;
 
    /* Base year ending date on half the model life */
    TimerGameCalendar::YearMonthDay ymd = TimerGameCalendar::ConvertDateToYMD(ei->base_intro + (ei->lifelength.base() * CalendarTime::DAYS_IN_LEAP_YEAR) / 2);
 
    _year_engine_aging_stops = std::max(_year_engine_aging_stops, ymd.year);
  }
}

void StartupOneEngine(Engine *e, const TimerGameCalendar::YearMonthDay &aging_ymd, uint32_t seed)
{
  const EngineInfo *ei = &e->info;
 
  e->age = 0;
  e->flags = {};
  e->company_avail = CompanyMask{};
  e->company_hidden = CompanyMask{};
 
  /* Vehicles with the same base_intro date shall be introduced at the same time.
   * Make sure they use the same randomisation of the date. */
  SavedRandomSeeds saved_seeds;
  SaveRandomSeeds(&saved_seeds);
  SetRandomSeed(_settings_game.game_creation.generation_seed ^ seed ^
                ei->base_intro.base() ^
                e->type ^
                e->GetGRFID());
  uint32_t r = Random();
 
  /* Don't randomise the start-date in the first two years after gamestart to ensure availability
   * of engines in early starting games.
   * Note: TTDP uses fixed 1922 */
  e->intro_date = ei->base_intro <= TimerGameCalendar::ConvertYMDToDate(_settings_game.game_creation.starting_year + 2, 0, 1) ? ei->base_intro : (TimerGameCalendar::Date)GB(r, 0, 9) + ei->base_intro;
  if (e->intro_date <= TimerGameCalendar::date) {
    TimerGameCalendar::YearMonthDay intro_ymd = TimerGameCalendar::ConvertDateToYMD(e->intro_date);
    int aging_months = aging_ymd.year.base() * 12 + aging_ymd.month;
    int intro_months = intro_ymd.year.base() * 12 + intro_ymd.month;
    if (intro_ymd.day > 1) intro_months++; // Engines are introduced at the first month start at/after intro date.
    e->age = aging_months - intro_months;
    e->company_avail.Set();
    e->flags.Set(EngineFlag::Available);
  }
 
  /* Get parent variant index for syncing reliability via random seed. */
  const Engine *re = e;
  while (re->info.variant_id != EngineID::Invalid() && re->info.extra_flags.Test(ExtraEngineFlag::SyncReliability)) {
    re = Engine::Get(re->info.variant_id);
  }
 
  SetRandomSeed(_settings_game.game_creation.generation_seed ^ seed ^
                (re->index.base() << 16) ^ (re->info.base_intro.base() << 12) ^ (re->info.decay_speed << 8) ^
                (re->info.lifelength.base() << 4) ^ re->info.retire_early ^
                e->type ^
                e->GetGRFID());
 
  /* Base reliability defined as a percentage of UINT16_MAX. */
  const uint16_t RELIABILITY_START = UINT16_MAX * 48 / 100;
  const uint16_t RELIABILITY_MAX   = UINT16_MAX * 75 / 100;
  const uint16_t RELIABILITY_FINAL = UINT16_MAX * 25 / 100;
 
  static_assert(RELIABILITY_START == 0x7AE0);
  static_assert(RELIABILITY_MAX   == 0xBFFF);
  static_assert(RELIABILITY_FINAL == 0x3FFF);
 
  r = Random();
  /* 14 bits gives a value between 0 and 16383, which is up to an additional 25%p reliability on top of the base reliability. */
  e->reliability_start = GB(r, 16, 14) + RELIABILITY_START;
  e->reliability_max   = GB(r,  0, 14) + RELIABILITY_MAX;
 
  r = Random();
  e->reliability_final = GB(r, 16, 14) + RELIABILITY_FINAL;
 
  e->duration_phase_1 = GB(r, 0, 5) + 7;
  e->duration_phase_2 = std::max(0, int(GB(r, 5, 4)) + ei->base_life.base() * 12 - 96);
  e->duration_phase_3 = GB(r, 9, 7) + 120;
 
  RestoreRandomSeeds(saved_seeds);
 
  e->reliability_spd_dec = ei->decay_speed << 2;
 
  /* prevent certain engines from ever appearing. */
  if (!ei->climates.Test(_settings_game.game_creation.landscape)) {
    e->flags.Set(EngineFlag::Available);
    e->company_avail = CompanyMask{};
  }
}

void StartupEngines()
{
  /* Aging of vehicles stops, so account for that when starting late */
  const TimerGameCalendar::Date aging_date = std::min(TimerGameCalendar::date, TimerGameCalendar::ConvertYMDToDate(_year_engine_aging_stops, 0, 1));
  TimerGameCalendar::YearMonthDay aging_ymd = TimerGameCalendar::ConvertDateToYMD(aging_date);
  uint32_t seed = Random();
 
  for (Engine *e : Engine::Iterate()) {
    StartupOneEngine(e, aging_ymd, seed);
  }
  for (Engine *e : Engine::Iterate()) {
    CalcEngineReliability(e, false);
  }
 
  /* Update the bitmasks for the vehicle lists */
  for (Company *c : Company::Iterate()) {
    c->avail_railtypes = GetCompanyRailTypes(c->index);
    c->avail_roadtypes = GetCompanyRoadTypes(c->index);
  }
 
  /* Invalidate any open purchase lists */
  InvalidateWindowClassesData(WC_BUILD_VEHICLE);
 
  SetWindowClassesDirty(WC_BUILD_VEHICLE);
  SetWindowClassesDirty(WC_REPLACE_VEHICLE);
}

static void EnableEngineForCompany(EngineID eid, CompanyID company)
{
  Engine *e = Engine::Get(eid);
  Company *c = Company::Get(company);
 
  e->company_avail.Set(company);
  if (e->type == VEH_TRAIN) {
    c->avail_railtypes = GetCompanyRailTypes(c->index);
  } else if (e->type == VEH_ROAD) {
    c->avail_roadtypes = GetCompanyRoadTypes(c->index);
  }
 
  if (company == _local_company) {
    AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
 
    /* Update the toolbar. */
    InvalidateWindowData(WC_MAIN_TOOLBAR, 0);
    if (e->type == VEH_ROAD) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_ROAD);
    if (e->type == VEH_SHIP) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_WATER);
    if (e->type == VEH_AIRCRAFT) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_AIR);
  }
}

static void DisableEngineForCompany(EngineID eid, CompanyID company)
{
  Engine *e = Engine::Get(eid);
  Company *c = Company::Get(company);
 
  e->company_avail.Reset(company);
  if (e->type == VEH_TRAIN) {
    c->avail_railtypes = GetCompanyRailTypes(c->index);
  } else if (e->type == VEH_ROAD) {
    c->avail_roadtypes = GetCompanyRoadTypes(c->index);
  }
 
  if (company == _local_company) {
    ClearLastVariant(e->index, e->type);
    AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
  }
}

static void AcceptEnginePreview(EngineID eid, CompanyID company, int recursion_depth = 0)
{
  Engine *e = Engine::Get(eid);
 
  e->preview_company = CompanyID::Invalid();
  e->preview_asked.Set();
 
  EnableEngineForCompany(eid, company);
 
  /* Notify preview window, that it might want to close.
   * Note: We cannot directly close the window.
   *       In singleplayer this function is called from the preview window, so
   *       we have to use the GUI-scope scheduling of InvalidateWindowData.
   */
  InvalidateWindowData(WC_ENGINE_PREVIEW, eid);
 
  /* Don't search for variants to include if we are 10 levels deep already. */
  if (recursion_depth >= 10) return;
 
  /* Find variants to be included in preview. */
  for (Engine *ve : Engine::IterateType(e->type)) {
    if (ve->index != eid && ve->info.variant_id == eid && ve->info.extra_flags.Test(ExtraEngineFlag::JoinPreview)) {
      AcceptEnginePreview(ve->index, company, recursion_depth + 1);
    }
  }
}

static CompanyID GetPreviewCompany(Engine *e)
{
  CompanyID best_company = CompanyID::Invalid();
 
  /* For trains the cargomask has no useful meaning, since you can attach other wagons */
  CargoTypes cargomask = e->type != VEH_TRAIN ? GetUnionOfArticulatedRefitMasks(e->index, true) : ALL_CARGOTYPES;
 
  int32_t best_hist = -1;
  for (const Company *c : Company::Iterate()) {
    if (c->block_preview == 0 && !e->preview_asked.Test(c->index) &&
        c->old_economy[0].performance_history > best_hist) {
 
      /* Check whether the company uses similar vehicles */
      for (const Vehicle *v : Vehicle::Iterate()) {
        if (v->owner != c->index || v->type != e->type) continue;
        if (!v->GetEngine()->CanCarryCargo() || !HasBit(cargomask, v->cargo_type)) continue;
 
        best_hist = c->old_economy[0].performance_history;
        best_company = c->index;
        break;
      }
    }
  }
 
  return best_company;
}

static bool IsVehicleTypeDisabled(VehicleType type, bool ai)
{
  switch (type) {
    case VEH_TRAIN:    return _settings_game.vehicle.max_trains == 0   || (ai && _settings_game.ai.ai_disable_veh_train);
    case VEH_ROAD:     return _settings_game.vehicle.max_roadveh == 0  || (ai && _settings_game.ai.ai_disable_veh_roadveh);
    case VEH_SHIP:     return _settings_game.vehicle.max_ships == 0    || (ai && _settings_game.ai.ai_disable_veh_ship);
    case VEH_AIRCRAFT: return _settings_game.vehicle.max_aircraft == 0 || (ai && _settings_game.ai.ai_disable_veh_aircraft);
 
    default: NOT_REACHED();
  }
}

static const IntervalTimer<TimerGameCalendar> _calendar_engines_daily({TimerGameCalendar::Trigger::Day, TimerGameCalendar::Priority::Engine}, [](auto)
{
  for (Company *c : Company::Iterate()) {
    c->avail_railtypes = AddDateIntroducedRailTypes(c->avail_railtypes, TimerGameCalendar::date);
    c->avail_roadtypes = AddDateIntroducedRoadTypes(c->avail_roadtypes, TimerGameCalendar::date);
  }
 
  if (TimerGameCalendar::year >= _year_engine_aging_stops) return;
 
  for (Engine *e : Engine::Iterate()) {
    EngineID i = e->index;
    if (e->flags.Test(EngineFlag::ExclusivePreview)) {
      if (e->preview_company != CompanyID::Invalid()) {
        if (!--e->preview_wait) {
          CloseWindowById(WC_ENGINE_PREVIEW, i);
          e->preview_company = CompanyID::Invalid();
        }
      } else if (e->preview_asked.Count() < MAX_COMPANIES) {
        e->preview_company = GetPreviewCompany(e);
 
        if (e->preview_company == CompanyID::Invalid()) {
          e->preview_asked.Set();
          continue;
        }
 
        e->preview_asked.Set(e->preview_company);
        e->preview_wait = 20;
        /* AIs are intentionally not skipped for preview even if they cannot build a certain
         * vehicle type. This is done to not give poor performing human companies an "unfair"
         * boost that they wouldn't have gotten against other human companies. The check on
         * the line below is just to make AIs not notice that they have a preview if they
         * cannot build the vehicle. */
        if (!IsVehicleTypeDisabled(e->type, true)) AI::NewEvent(e->preview_company, new ScriptEventEnginePreview(i));
        if (IsInteractiveCompany(e->preview_company)) ShowEnginePreviewWindow(i);
      }
    }
  }
});

void ClearEnginesHiddenFlagOfCompany(CompanyID cid)
{
  for (Engine *e : Engine::Iterate()) {
    e->company_hidden.Reset(cid);
  }
}

CommandCost CmdSetVehicleVisibility(DoCommandFlags flags, EngineID engine_id, bool hide)
{
  Engine *e = Engine::GetIfValid(engine_id);
  if (e == nullptr || _current_company >= MAX_COMPANIES) return CMD_ERROR;
  if (!IsEngineBuildable(e->index, e->type, _current_company)) return CMD_ERROR;
 
  if (flags.Test(DoCommandFlag::Execute)) {
    e->company_hidden.Set(_current_company, hide);
    AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
  }
 
  return CommandCost();
}

CommandCost CmdWantEnginePreview(DoCommandFlags flags, EngineID engine_id)
{
  Engine *e = Engine::GetIfValid(engine_id);
  if (e == nullptr || !e->flags.Test(EngineFlag::ExclusivePreview) || e->preview_company != _current_company) return CMD_ERROR;
 
  if (flags.Test(DoCommandFlag::Execute)) AcceptEnginePreview(engine_id, _current_company);
 
  return CommandCost();
}

CommandCost CmdEngineCtrl(DoCommandFlags flags, EngineID engine_id, CompanyID company_id, bool allow)
{
  if (_current_company != OWNER_DEITY) return CMD_ERROR;
 
  if (!Engine::IsValidID(engine_id) || !Company::IsValidID(company_id)) return CMD_ERROR;
 
  if (flags.Test(DoCommandFlag::Execute)) {
    if (allow) {
      EnableEngineForCompany(engine_id, company_id);
    } else {
      DisableEngineForCompany(engine_id, company_id);
    }
  }
 
  return CommandCost();
}

static void NewVehicleAvailable(Engine *e)
{
  EngineID index = e->index;
 
  /* In case the company didn't build the vehicle during the intro period,
   * prevent that company from getting future intro periods for a while. */
  if (e->flags.Test(EngineFlag::ExclusivePreview)) {
    for (Company *c : Company::Iterate()) {
      if (!e->company_avail.Test(c->index)) continue;
 
      /* Check the company's 'ALL_GROUP' group statistics. This only includes countable vehicles, which is fine
       * as those are the only engines that can be given exclusive previews. */
      if (GetGroupNumEngines(c->index, ALL_GROUP, e->index) == 0) {
        /* The company did not build this engine during preview. */
        c->block_preview = 20;
      }
    }
  }
 
  e->flags.Reset(EngineFlag::ExclusivePreview).Set(EngineFlag::Available);
  AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
 
  /* Now available for all companies */
  e->company_avail.Set();
 
  /* Do not introduce new rail wagons */
  if (IsWagon(index)) return;
 
  if (e->type == VEH_TRAIN) {
    /* maybe make another rail type available */
    assert(e->VehInfo<RailVehicleInfo>().railtypes != RailTypes{});
    RailTypes introduced = GetAllIntroducesRailTypes(e->VehInfo<RailVehicleInfo>().railtypes);
    for (Company *c : Company::Iterate()) c->avail_railtypes = AddDateIntroducedRailTypes(c->avail_railtypes | introduced, TimerGameCalendar::date);
  } else if (e->type == VEH_ROAD) {
    /* maybe make another road type available */
    assert(e->VehInfo<RoadVehicleInfo>().roadtype < ROADTYPE_END);
    for (Company *c : Company::Iterate()) c->avail_roadtypes = AddDateIntroducedRoadTypes(c->avail_roadtypes | GetRoadTypeInfo(e->VehInfo<RoadVehicleInfo>().roadtype)->introduces_roadtypes, TimerGameCalendar::date);
  }
 
  /* Only broadcast event if AIs are able to build this vehicle type. */
  if (!IsVehicleTypeDisabled(e->type, true)) AI::BroadcastNewEvent(new ScriptEventEngineAvailable(index));
 
  /* Only provide the "New Vehicle available" news paper entry, if engine can be built. */
  if (!IsVehicleTypeDisabled(e->type, false) && !e->info.extra_flags.Test(ExtraEngineFlag::NoNews)) {
    AddNewsItem(GetEncodedString(STR_NEWS_NEW_VEHICLE_NOW_AVAILABLE_WITH_TYPE,
        GetEngineCategoryName(index),
        PackEngineNameDParam(index, EngineNameContext::PreviewNews)),
      NewsType::NewVehicles, NewsStyle::Vehicle, {}, index);
  }
 
  /* Update the toolbar. */
  if (e->type == VEH_ROAD) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_ROAD);
  if (e->type == VEH_SHIP) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_WATER);
  if (e->type == VEH_AIRCRAFT) InvalidateWindowData(WC_BUILD_TOOLBAR, TRANSPORT_AIR);
 
  /* Close pending preview windows */
  CloseWindowById(WC_ENGINE_PREVIEW, index);
}

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::Trigger::Month, TimerGameCalendar::Priority::Engine}, [](auto)
{
  CalendarEnginesMonthlyLoop();
});

static bool IsUniqueEngineName(const std::string &name)
{
  for (const Engine *e : Engine::Iterate()) {
    if (!e->name.empty() && e->name == name) return false;
  }
 
  return true;
}

CommandCost CmdRenameEngine(DoCommandFlags flags, EngineID engine_id, const std::string &text)
{
  Engine *e = Engine::GetIfValid(engine_id);
  if (e == nullptr) return CMD_ERROR;
 
  bool reset = text.empty();
 
  if (!reset) {
    if (Utf8StringLength(text) >= MAX_LENGTH_ENGINE_NAME_CHARS) return CMD_ERROR;
    if (!IsUniqueEngineName(text)) return CommandCost(STR_ERROR_NAME_MUST_BE_UNIQUE);
  }
 
  if (flags.Test(DoCommandFlag::Execute)) {
    if (reset) {
      e->name.clear();
    } else {
      e->name = text;
    }
 
    MarkWholeScreenDirty();
  }
 
  return CommandCost();
}
 

bool IsEngineBuildable(EngineID engine, VehicleType type, CompanyID company)
{
  const Engine *e = Engine::GetIfValid(engine);
 
  /* check if it's an engine that is in the engine array */
  if (e == nullptr) return false;
 
  /* check if it's an engine of specified type */
  if (e->type != type) return false;
 
  /* check if it's available ... */
  if (company == OWNER_DEITY) {
    /* ... for any company (preview does not count) */
    if (!e->flags.Test(EngineFlag::Available) || e->company_avail.None()) return false;
  } else {
    /* ... for this company */
    if (!e->company_avail.Test(company)) return false;
  }
 
  if (!e->IsEnabled()) return false;
 
  if (type == VEH_TRAIN && company != OWNER_DEITY) {
    /* Check if the rail type is available to this company */
    const Company *c = Company::Get(company);
    if (!GetAllCompatibleRailTypes(e->VehInfo<RailVehicleInfo>().railtypes).Any(c->avail_railtypes)) return false;
  }
  if (type == VEH_ROAD && company != OWNER_DEITY) {
    /* Check if the road type is available to this company */
    const Company *c = Company::Get(company);
    if (!GetRoadTypeInfo(e->VehInfo<RoadVehicleInfo>().roadtype)->powered_roadtypes.Any(c->avail_roadtypes)) return false;
  }
 
  return true;
}

bool IsEngineRefittable(EngineID engine)
{
  const Engine *e = Engine::GetIfValid(engine);
 
  /* check if it's an engine that is in the engine array */
  if (e == nullptr) return false;
 
  if (!e->CanCarryCargo()) return false;
 
  const EngineInfo *ei = &e->info;
  if (ei->refit_mask == 0) return false;
 
  /* Are there suffixes?
   * Note: This does not mean the suffixes are actually available for every consist at any time. */
  if (ei->callback_mask.Test(VehicleCallbackMask::CargoSuffix)) return true;
 
  /* Is there any cargo except the default cargo? */
  CargoType default_cargo = e->GetDefaultCargoType();
  CargoTypes default_cargo_mask = 0;
  SetBit(default_cargo_mask, default_cargo);
  return IsValidCargoType(default_cargo) && ei->refit_mask != default_cargo_mask;
}

void CheckEngines()
{
  TimerGameCalendar::Date min_date{INT32_MAX};
 
  for (const Engine *e : Engine::Iterate()) {
    if (!e->IsEnabled()) continue;
 
    /* Don't consider train wagons, we need a powered engine available. */
    if (e->type == VEH_TRAIN && e->VehInfo<RailVehicleInfo>().railveh_type == RAILVEH_WAGON) continue;
 
    /* We have an available engine... yay! */
    if (e->flags.Test(EngineFlag::Available) && e->company_avail.Any()) return;
 
    /* Okay, try to find the earliest date. */
    min_date = std::min(min_date, e->info.base_intro);
  }
 
  if (min_date < INT32_MAX) {
    ShowErrorMessage(GetEncodedString(STR_ERROR_NO_VEHICLES_AVAILABLE_YET),
      GetEncodedString(STR_ERROR_NO_VEHICLES_AVAILABLE_YET_EXPLANATION, min_date), WL_WARNING);
  } else {
    ShowErrorMessage(GetEncodedString(STR_ERROR_NO_VEHICLES_AVAILABLE_AT_ALL),
      GetEncodedString(STR_ERROR_NO_VEHICLES_AVAILABLE_AT_ALL_EXPLANATION), WL_WARNING);
  }
}