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 <http://www.gnu.org/licenses/>.
 */
 
#include "stdafx.h"
#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));
 
const uint EngineOverrideManager::NUM_DEFAULT_ENGINES = _engine_counts[VEH_TRAIN] + _engine_counts[VEH_ROAD] + _engine_counts[VEH_SHIP] + _engine_counts[VEH_AIRCRAFT];
 
Engine::Engine(VehicleType type, EngineID base)
{
  this->type = type;
  this->grf_prop.local_id = base;
  this->list_position = base;
  this->preview_company = INVALID_COMPANY;
  this->display_last_variant = INVALID_ENGINE;
 
  /* Check if this base engine is within the original engine data range */
  if (base >= _engine_counts[type]) {
    /* 'power' defaults to zero, so we also have to default to 'wagon' */
    if (type == VEH_TRAIN) this->u.rail.railveh_type = RAILVEH_WAGON;
    /* Set model life to maximum to make wagons available */
    this->info.base_life = 0xFF;
    /* Set road vehicle tractive effort to the default value */
    if (type == VEH_ROAD) this->u.road.tractive_effort = 0x4C;
    /* Aircraft must have INVALID_CARGO as default, as there is no property */
    if (type == VEH_AIRCRAFT) this->info.cargo_type = INVALID_CARGO;
    /* Ships must have a non-zero acceleration. */
    if (type == VEH_SHIP) this->u.ship.acceleration = 1;
    /* Set visual effect to the default value */
    switch (type) {
      case VEH_TRAIN: this->u.rail.visual_effect = VE_DEFAULT; break;
      case VEH_ROAD:  this->u.road.visual_effect = VE_DEFAULT; break;
      case VEH_SHIP:  this->u.ship.visual_effect = VE_DEFAULT; break;
      default: break; // The aircraft, disasters and especially visual effects have no NewGRF configured visual effects
    }
    /* Set cargo aging period to the default value. */
    this->info.cargo_age_period = Ticks::CARGO_AGING_TICKS;
    /* Not a variant */
    this->info.variant_id = INVALID_ENGINE;
    return;
  }
 
  /* Copy the original engine info for this slot */
  this->info = _orig_engine_info[_engine_offsets[type] + base];
 
  /* Copy the original engine data for this slot */
  switch (type) {
    default: NOT_REACHED();
 
    case VEH_TRAIN:
      this->u.rail = _orig_rail_vehicle_info[base];
      this->original_image_index = this->u.rail.image_index;
      this->info.string_id = STR_VEHICLE_NAME_TRAIN_ENGINE_RAIL_KIRBY_PAUL_TANK_STEAM + base;
 
      /* Set the default model life of original wagons to "infinite" */
      if (this->u.rail.railveh_type == RAILVEH_WAGON) this->info.base_life = 0xFF;
 
      break;
 
    case VEH_ROAD:
      this->u.road = _orig_road_vehicle_info[base];
      this->original_image_index = this->u.road.image_index;
      this->info.string_id = STR_VEHICLE_NAME_ROAD_VEHICLE_MPS_REGAL_BUS + base;
      break;
 
    case VEH_SHIP:
      this->u.ship = _orig_ship_vehicle_info[base];
      this->original_image_index = this->u.ship.image_index;
      this->info.string_id = STR_VEHICLE_NAME_SHIP_MPS_OIL_TANKER + base;
      break;
 
    case VEH_AIRCRAFT:
      this->u.air = _orig_aircraft_vehicle_info[base];
      this->original_image_index = this->u.air.image_index;
      this->info.string_id = STR_VEHICLE_NAME_AIRCRAFT_SAMPSON_U52 + base;
      break;
  }
}
 
bool Engine::IsEnabled() const
{
  return this->info.string_id != STR_NEWGRF_INVALID_ENGINE && HasBit(this->info.climates, _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->u.rail.capacity == 0) return false;
      break;
 
    case VEH_ROAD:
      if (this->u.road.capacity == 0) return false;
      break;
 
    case VEH_SHIP:
    case VEH_AIRCRAFT:
      break;
 
    default: NOT_REACHED();
  }
  return IsValidCargoID(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 = HasBit(this->info.misc_flags, EF_NO_DEFAULT_CARGO_MULTIPLIER);
  CargoID default_cargo = this->GetDefaultCargoType();
  CargoID cargo_type = (v != nullptr) ? v->cargo_type : default_cargo;
 
  if (mail_capacity != nullptr && this->type == VEH_AIRCRAFT && IsCargoInClass(cargo_type, CC_PASSENGERS)) {
    *mail_capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->u.air.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 (HasBit(this->info.callback_mask, CBM_VEHICLE_REFIT_CAPACITY) &&
      (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->u.rail.capacity, v);
 
      /* In purchase list add the capacity of the second head. Always use the plain property for this. */
      if (v == nullptr && this->u.rail.railveh_type == RAILVEH_MULTIHEAD) capacity += this->u.rail.capacity;
      break;
 
    case VEH_ROAD:
      capacity = GetEngineProperty(this->index, PROP_ROADVEH_CARGO_CAPACITY,      this->u.road.capacity, v);
      break;
 
    case VEH_SHIP:
      capacity = GetEngineProperty(this->index, PROP_SHIP_CARGO_CAPACITY,         this->u.ship.capacity, v);
      break;
 
    case VEH_AIRCRAFT:
      capacity = GetEngineProperty(this->index, PROP_AIRCRAFT_PASSENGER_CAPACITY, this->u.air.passenger_capacity, v);
      if (!IsCargoInClass(cargo_type, CC_PASSENGERS)) {
        extra_mail_cap = GetEngineProperty(this->index, PROP_AIRCRAFT_MAIL_CAPACITY, this->u.air.mail_capacity, v);
      }
      if (!new_multipliers && cargo_type == CT_MAIL) return capacity + extra_mail_cap;
      default_cargo = 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) {
      uint mail_multiplier = CargoSpec::Get(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->u.road.running_cost_class;
      if (base_price == INVALID_PRICE) return 0;
      cost_factor = GetEngineProperty(this->index, PROP_ROADVEH_RUNNING_COST_FACTOR, this->u.road.running_cost);
      break;
 
    case VEH_TRAIN:
      base_price = this->u.rail.running_cost_class;
      if (base_price == INVALID_PRICE) return 0;
      cost_factor = GetEngineProperty(this->index, PROP_TRAIN_RUNNING_COST_FACTOR, this->u.rail.running_cost);
      break;
 
    case VEH_SHIP:
      base_price = PR_RUNNING_SHIP;
      cost_factor = GetEngineProperty(this->index, PROP_SHIP_RUNNING_COST_FACTOR, this->u.ship.running_cost);
      break;
 
    case VEH_AIRCRAFT:
      base_price = PR_RUNNING_AIRCRAFT;
      cost_factor = GetEngineProperty(this->index, PROP_AIRCRAFT_RUNNING_COST_FACTOR, this->u.air.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 = PR_BUILD_VEHICLE_ROAD;
      cost_factor = GetEngineProperty(this->index, PROP_ROADVEH_COST_FACTOR, this->u.road.cost_factor);
      break;
 
    case VEH_TRAIN:
      if (this->u.rail.railveh_type == RAILVEH_WAGON) {
        base_price = PR_BUILD_VEHICLE_WAGON;
        cost_factor = GetEngineProperty(this->index, PROP_TRAIN_COST_FACTOR, this->u.rail.cost_factor);
      } else {
        base_price = PR_BUILD_VEHICLE_TRAIN;
        cost_factor = GetEngineProperty(this->index, PROP_TRAIN_COST_FACTOR, this->u.rail.cost_factor);
      }
      break;
 
    case VEH_SHIP:
      base_price = PR_BUILD_VEHICLE_SHIP;
      cost_factor = GetEngineProperty(this->index, PROP_SHIP_COST_FACTOR, this->u.ship.cost_factor);
      break;
 
    case VEH_AIRCRAFT:
      base_price = PR_BUILD_VEHICLE_AIRCRAFT;
      cost_factor = GetEngineProperty(this->index, PROP_AIRCRAFT_COST_FACTOR, this->u.air.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->u.rail.max_speed);
 
    case VEH_ROAD: {
      uint max_speed = GetEngineProperty(this->index, PROP_ROADVEH_SPEED, 0);
      return (max_speed != 0) ? max_speed * 2 : this->u.road.max_speed / 2;
    }
 
    case VEH_SHIP:
      return GetEngineProperty(this->index, PROP_SHIP_SPEED, this->u.ship.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->u.air.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->u.rail.power);
    case VEH_ROAD:
      return GetEngineProperty(this->index, PROP_ROADVEH_POWER, this->u.road.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->u.rail.weight) << (this->u.rail.railveh_type == RAILVEH_MULTIHEAD ? 1 : 0);
    case VEH_ROAD:
      return GetEngineProperty(this->index, PROP_ROADVEH_WEIGHT, this->u.road.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->u.rail.tractive_effort)) / 256;
    case VEH_ROAD:
      return (GROUND_ACCELERATION * this->GetDisplayWeight() * GetEngineProperty(this->index, PROP_ROADVEH_TRACTIVE_EFFORT, this->u.road.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 (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->u.air.max_range);
 
    default: NOT_REACHED();
  }
}
 
StringID Engine::GetAircraftTypeText() const
{
  switch (this->type) {
    case VEH_AIRCRAFT:
      switch (this->u.air.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 != INVALID_ENGINE) {
    re = Engine::Get(re->info.variant_id);
    ve = re->GetDisplayVariant();
  }
  return ve->IsHidden(c);
}
 
void EngineOverrideManager::ResetToDefaultMapping()
{
  this->clear();
  for (VehicleType type = VEH_TRAIN; type <= VEH_AIRCRAFT; type++) {
    for (uint internal_id = 0; internal_id < _engine_counts[type]; internal_id++) {
      EngineIDMapping &eid = this->emplace_back();
      eid.type            = type;
      eid.grfid           = INVALID_GRFID;
      eid.internal_id     = internal_id;
      eid.substitute_id   = internal_id;
    }
  }
}
 
EngineID EngineOverrideManager::GetID(VehicleType type, uint16_t grf_local_id, uint32_t grfid)
{
  EngineID index = 0;
  for (const EngineIDMapping &eid : *this) {
    if (eid.type == type && eid.grfid == grfid && eid.internal_id == grf_local_id) {
      return index;
    }
    index++;
  }
  return INVALID_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();
 
  assert(_engine_mngr.size() >= _engine_mngr.NUM_DEFAULT_ENGINES);
  [[maybe_unused]] uint index = 0;
  for (const EngineIDMapping &eid : _engine_mngr) {
    /* Assert is safe; there won't be more than 256 original vehicles
     * in any case, and we just cleaned the pool. */
    assert(Engine::CanAllocateItem());
    [[maybe_unused]] const Engine *e = new Engine(eid.type, eid.internal_id);
    assert(e->index == index);
    index++;
  }
}
 
void ShowEnginePreviewWindow(EngineID engine);
 
static bool IsWagon(EngineID index)
{
  const Engine *e = Engine::Get(index);
  return e->type == VEH_TRAIN && e->u.rail.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 = INVALID_ENGINE;
  }
}
 
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 != INVALID_ENGINE && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) {
    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 != 0 && !_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 = 0;
      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 = 0;
    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 = 2050;
 
  for (const Engine *e : Engine::Iterate()) {
    const EngineInfo *ei = &e->info;
 
    /* Exclude certain engines */
    if (!HasBit(ei->climates, _settings_game.game_creation.landscape)) continue;
    if (e->type == VEH_TRAIN && e->u.rail.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 = 0;
  e->company_avail = 0;
  e->company_hidden = 0;
 
  /* 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 = MAX_UVALUE(CompanyMask);
    e->flags |= ENGINE_AVAILABLE;
  }
 
  /* Get parent variant index for syncing reliability via random seed. */
  const Engine *re = e;
  while (re->info.variant_id != INVALID_ENGINE && (re->info.extra_flags & ExtraEngineFlags::SyncReliability) != ExtraEngineFlags::None) {
    re = Engine::Get(re->info.variant_id);
  }
 
  SetRandomSeed(_settings_game.game_creation.generation_seed ^ seed ^
                (re->index << 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 (!HasBit(ei->climates, _settings_game.game_creation.landscape)) {
    e->flags |= ENGINE_AVAILABLE;
    e->company_avail = 0;
  }
}
 
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);
 
  SetBit(e->company_avail, 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);
 
  ClrBit(e->company_avail, 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 = INVALID_COMPANY;
  e->preview_asked = MAX_UVALUE(CompanyMask);
 
  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 & ExtraEngineFlags::JoinPreview) != ExtraEngineFlags::None) {
      AcceptEnginePreview(ve->index, company, recursion_depth + 1);
    }
  }
}
 
static CompanyID GetPreviewCompany(Engine *e)
{
  CompanyID best_company = INVALID_COMPANY;
 
  /* 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 && !HasBit(e->preview_asked, 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 IntervalTimer<TimerGameCalendar> _calendar_engines_daily({TimerGameCalendar::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 & ENGINE_EXCLUSIVE_PREVIEW) {
      if (e->preview_company != INVALID_COMPANY) {
        if (!--e->preview_wait) {
          CloseWindowById(WC_ENGINE_PREVIEW, i);
          e->preview_company = INVALID_COMPANY;
        }
      } else if (CountBits(e->preview_asked) < MAX_COMPANIES) {
        e->preview_company = GetPreviewCompany(e);
 
        if (e->preview_company == INVALID_COMPANY) {
          e->preview_asked = MAX_UVALUE(CompanyMask);
          continue;
        }
 
        SetBit(e->preview_asked, 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()) {
    SB(e->company_hidden, cid, 1, 0);
  }
}
 
CommandCost CmdSetVehicleVisibility(DoCommandFlag 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 & DC_EXEC) != 0) {
    SB(e->company_hidden, _current_company, 1, hide ? 1 : 0);
    AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
  }
 
  return CommandCost();
}
 
CommandCost CmdWantEnginePreview(DoCommandFlag flags, EngineID engine_id)
{
  Engine *e = Engine::GetIfValid(engine_id);
  if (e == nullptr || !(e->flags & ENGINE_EXCLUSIVE_PREVIEW) || e->preview_company != _current_company) return CMD_ERROR;
 
  if (flags & DC_EXEC) AcceptEnginePreview(engine_id, _current_company);
 
  return CommandCost();
}
 
CommandCost CmdEngineCtrl(DoCommandFlag 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 & DC_EXEC) {
    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 & ENGINE_EXCLUSIVE_PREVIEW) {
    for (Company *c : Company::Iterate()) {
      uint block_preview = c->block_preview;
 
      if (!HasBit(e->company_avail, c->index)) continue;
 
      /* We assume the user did NOT build it.. prove me wrong ;) */
      c->block_preview = 20;
 
      for (const Vehicle *v : Vehicle::Iterate()) {
        if (v->type == VEH_TRAIN || v->type == VEH_ROAD || v->type == VEH_SHIP ||
            (v->type == VEH_AIRCRAFT && Aircraft::From(v)->IsNormalAircraft())) {
          if (v->owner == c->index && v->engine_type == index) {
            /* The user did prove me wrong, so restore old value */
            c->block_preview = block_preview;
            break;
          }
        }
      }
    }
  }
 
  e->flags = (e->flags & ~ENGINE_EXCLUSIVE_PREVIEW) | ENGINE_AVAILABLE;
  AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
 
  /* Now available for all companies */
  e->company_avail = MAX_UVALUE(CompanyMask);
 
  /* Do not introduce new rail wagons */
  if (IsWagon(index)) return;
 
  if (e->type == VEH_TRAIN) {
    /* maybe make another rail type available */
    assert(e->u.rail.railtype < RAILTYPE_END);
    for (Company *c : Company::Iterate()) c->avail_railtypes = AddDateIntroducedRailTypes(c->avail_railtypes | GetRailTypeInfo(e->u.rail.railtype)->introduces_railtypes, TimerGameCalendar::date);
  } else if (e->type == VEH_ROAD) {
    /* maybe make another road type available */
    assert(e->u.road.roadtype < ROADTYPE_END);
    for (Company *c : Company::Iterate()) c->avail_roadtypes = AddDateIntroducedRoadTypes(c->avail_roadtypes | GetRoadTypeInfo(e->u.road.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 & ExtraEngineFlags::NoNews) == ExtraEngineFlags::None) {
    SetDParam(0, GetEngineCategoryName(index));
    SetDParam(1, PackEngineNameDParam(index, EngineNameContext::PreviewNews));
    AddNewsItem(STR_NEWS_NEW_VEHICLE_NOW_AVAILABLE_WITH_TYPE, NT_NEW_VEHICLES, NF_VEHICLE, NR_ENGINE, 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 & ENGINE_AVAILABLE) && e->age != INT32_MAX) {
        e->age++;
        CalcEngineReliability(e, true);
        refresh = true;
      }
 
      /* Do not introduce invalid engines */
      if (!e->IsEnabled()) continue;
 
      if (!(e->flags & ENGINE_AVAILABLE) && TimerGameCalendar::date >= (e->intro_date + CalendarTime::DAYS_IN_YEAR)) {
        /* Introduce it to all companies */
        NewVehicleAvailable(e);
      } else if (!(e->flags & (ENGINE_AVAILABLE | ENGINE_EXCLUSIVE_PREVIEW)) && 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 & ExtraEngineFlags::NoPreview) != ExtraEngineFlags::None) continue;
 
        /* Show preview dialog to one of the companies. */
        e->flags |= ENGINE_EXCLUSIVE_PREVIEW;
        e->preview_company = INVALID_COMPANY;
        e->preview_asked = 0;
      }
    }
 
    InvalidateWindowClassesData(WC_BUILD_VEHICLE); // rebuild the purchase list (esp. when sorted by reliability)
 
    if (refresh) {
      SetWindowClassesDirty(WC_BUILD_VEHICLE);
      SetWindowClassesDirty(WC_REPLACE_VEHICLE);
    }
  }
}
 
static IntervalTimer<TimerGameCalendar> _calendar_engines_monthly({TimerGameCalendar::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(DoCommandFlag 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_cmd_error(STR_ERROR_NAME_MUST_BE_UNIQUE);
  }
 
  if (flags & DC_EXEC) {
    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 & ENGINE_AVAILABLE) || e->company_avail == 0) return false;
  } else {
    /* ... for this company */
    if (!HasBit(e->company_avail, 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 (((GetRailTypeInfo(e->u.rail.railtype))->compatible_railtypes & c->avail_railtypes) == 0) 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->u.road.roadtype)->powered_roadtypes & c->avail_roadtypes) == ROADTYPES_NONE) 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 (HasBit(ei->callback_mask, CBM_VEHICLE_CARGO_SUFFIX)) return true;
 
  /* Is there any cargo except the default cargo? */
  CargoID default_cargo = e->GetDefaultCargoType();
  CargoTypes default_cargo_mask = 0;
  SetBit(default_cargo_mask, default_cargo);
  return IsValidCargoID(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->u.rail.railveh_type == RAILVEH_WAGON) continue;
 
    /* We have an available engine... yay! */
    if ((e->flags & ENGINE_AVAILABLE) != 0 && e->company_avail != 0) return;
 
    /* Okay, try to find the earliest date. */
    min_date = std::min(min_date, e->info.base_intro);
  }
 
  if (min_date < INT32_MAX) {
    SetDParam(0, min_date);
    ShowErrorMessage(STR_ERROR_NO_VEHICLES_AVAILABLE_YET, STR_ERROR_NO_VEHICLES_AVAILABLE_YET_EXPLANATION, WL_WARNING);
  } else {
    ShowErrorMessage(STR_ERROR_NO_VEHICLES_AVAILABLE_AT_ALL, STR_ERROR_NO_VEHICLES_AVAILABLE_AT_ALL_EXPLANATION, WL_WARNING);
  }
}