/* $Id$ */

/** @file engine.cpp Base for all engine handling. */

#include "stdafx.h"
#include "openttd.h"
#include "debug.h"
#include "company_base.h"
#include "company_func.h"
#include "command_func.h"
#include "news_func.h"
#include "saveload.h"
#include "variables.h"
#include "train.h"
#include "aircraft.h"
#include "newgrf_cargo.h"
#include "newgrf_engine.h"
#include "group.h"
#include "strings_func.h"
#include "gfx_func.h"
#include "functions.h"
#include "window_func.h"
#include "date_func.h"
#include "autoreplace_gui.h"
#include "string_func.h"
#include "settings_type.h"
#include "oldpool_func.h"
#include "core/alloc_func.hpp"
#include "vehicle_func.h"
#include <map>

#include "table/strings.h"
#include "table/engines.h"

DEFINE_OLD_POOL_GENERIC(Engine, Engine)

enum {
	YEAR_ENGINE_AGING_STOPS = 2050,
};


/** Number of engines of each vehicle type in original engine data */
const uint8 _engine_counts[4] = {
	lengthof(_orig_rail_vehicle_info),
	lengthof(_orig_road_vehicle_info),
	lengthof(_orig_ship_vehicle_info),
	lengthof(_orig_aircraft_vehicle_info),
};

/** Offset of the first engine of each vehicle type in original engine data */
const uint8 _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),
};

Engine::Engine() :
	name(NULL),
	overrides_count(0),
	overrides(NULL)
{
}

Engine::Engine(VehicleType type, EngineID base)
{
	this->type = type;
	this->internal_id = base;
	this->list_position = base;

	/* Check if this base engine is within the original engine data range */
	if (base >= _engine_counts[type]) {
		/* Mark engine as valid anyway */
		this->info.climates = 0x80;
		/* Set model life to maximum to make wagons available */
		this->info.base_life = 0xFF;
		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->image_index = this->u.rail.image_index;
			this->info.string_id = STR_8000_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->image_index = this->u.road.image_index;
			this->info.string_id = STR_8074_MPS_REGAL_BUS + base;
			break;

		case VEH_SHIP:
			this->u.ship = _orig_ship_vehicle_info[base];
			this->image_index = this->u.ship.image_index;
			this->info.string_id = STR_80CC_MPS_OIL_TANKER + base;
			break;

		case VEH_AIRCRAFT:
			this->u.air = _orig_aircraft_vehicle_info[base];
			this->image_index = this->u.air.image_index;
			this->info.string_id = STR_80D7_SAMPSON_U52 + base;
			break;
	}
}

Engine::~Engine()
{
	UnloadWagonOverrides(this);
	free(this->name);
}

/** Sets cached values in Company::num_vehicles and Group::num_vehicles
 */
void SetCachedEngineCounts()
{
	uint engines = GetEnginePoolSize();

	/* Set up the engine count for all companies */
	Company *c;
	FOR_ALL_COMPANIES(c) {
		free(c->num_engines);
		c->num_engines = CallocT<EngineID>(engines);
	}

	/* Recalculate */
	Group *g;
	FOR_ALL_GROUPS(g) {
		free(g->num_engines);
		g->num_engines = CallocT<EngineID>(engines);
	}

	const Vehicle *v;
	FOR_ALL_VEHICLES(v) {
		if (!IsEngineCountable(v)) continue;

		assert(v->engine_type < engines);

		GetCompany(v->owner)->num_engines[v->engine_type]++;

		if (v->group_id == DEFAULT_GROUP) continue;

		g = GetGroup(v->group_id);
		assert(v->type == g->vehicle_type);
		assert(v->owner == g->owner);

		g->num_engines[v->engine_type]++;
	}
}

void SetupEngines()
{
	_Engine_pool.CleanPool();
	_Engine_pool.AddBlockToPool();

	for (uint i = 0; i < lengthof(_orig_rail_vehicle_info); i++) new Engine(VEH_TRAIN, i);
	for (uint i = 0; i < lengthof(_orig_road_vehicle_info); i++) new Engine(VEH_ROAD, i);
	for (uint i = 0; i < lengthof(_orig_ship_vehicle_info); i++) new Engine(VEH_SHIP, i);
	for (uint i = 0; i < lengthof(_orig_aircraft_vehicle_info); i++) new Engine(VEH_AIRCRAFT, i);
}


void ShowEnginePreviewWindow(EngineID engine);

void DeleteCustomEngineNames()
{
	Engine *e;
	FOR_ALL_ENGINES(e) {
		free(e->name);
		e->name = NULL;
	}

	_vehicle_design_names &= ~1;
}

void LoadCustomEngineNames()
{
	/* XXX: not done */
	DEBUG(misc, 1, "LoadCustomEngineNames: not done");
}

/* Determine if an engine type is a wagon (and not a loco) */
static bool IsWagon(EngineID index)
{
	const Engine *e = GetEngine(index);
	return e->type == VEH_TRAIN && e->u.rail.railveh_type == RAILVEH_WAGON;
}

static void CalcEngineReliability(Engine *e)
{
	uint age = e->age;

	/* 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 = 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;
			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 */
		AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
	}
	InvalidateWindowClasses(WC_BUILD_VEHICLE); // Update to show the new reliability
	InvalidateWindowClasses(WC_REPLACE_VEHICLE);
}

void StartupEngines()
{
	Engine *e;
	/* Aging of vehicles stops, so account for that when starting late */
	const Date aging_date = min(_date, ConvertYMDToDate(YEAR_ENGINE_AGING_STOPS, 0, 1));

	FOR_ALL_ENGINES(e) {
		const EngineInfo *ei = &e->info;
		uint32 r;

		e->age = 0;
		e->flags = 0;
		e->company_avail = 0;

		/* The magic value of 729 days below comes from the NewGRF spec. If the
		 * base intro date is before 1922 then the random number of days is not
		 * added. */
		r = Random();
		e->intro_date = ei->base_intro <= ConvertYMDToDate(1922, 0, 1) ? ei->base_intro : (Date)GB(r, 0, 9) + ei->base_intro;
		if (e->intro_date <= _date) {
			e->age = (aging_date - e->intro_date) >> 5;
			e->company_avail = (CompanyMask)-1;
			e->flags |= ENGINE_AVAILABLE;
		}

		e->reliability_start = GB(r, 16, 14) + 0x7AE0;
		r = Random();
		e->reliability_max   = GB(r,  0, 14) + 0xBFFF;
		e->reliability_final = GB(r, 16, 14) + 0x3FFF;

		r = Random();
		e->duration_phase_1 = GB(r, 0, 5) + 7;
		e->duration_phase_2 = GB(r, 5, 4) + ei->base_life * 12 - 96;
		e->duration_phase_3 = GB(r, 9, 7) + 120;

		e->reliability_spd_dec = ei->decay_speed << 2;

		CalcEngineReliability(e);

		e->lifelength = ei->lifelength + _settings_game.vehicle.extend_vehicle_life;

		/* prevent certain engines from ever appearing. */
		if (!HasBit(ei->climates, _settings_game.game_creation.landscape)) {
			e->flags |= ENGINE_AVAILABLE;
			e->company_avail = 0;
		}
	}

	/* Update the bitmasks for the vehicle lists */
	Company *c;
	FOR_ALL_COMPANIES(c) {
		c->avail_railtypes = GetCompanyRailtypes(c->index);
		c->avail_roadtypes = GetCompanyRoadtypes(c->index);
	}
}

static void AcceptEnginePreview(EngineID eid, CompanyID company)
{
	Engine *e = GetEngine(eid);
	Company *c = GetCompany(company);

	SetBit(e->company_avail, company);
	if (e->type == VEH_TRAIN) {
		const RailVehicleInfo *rvi = RailVehInfo(eid);

		assert(rvi->railtype < RAILTYPE_END);
		SetBit(c->avail_railtypes, rvi->railtype);
	} else if (e->type == VEH_ROAD) {
		SetBit(c->avail_roadtypes, HasBit(EngInfo(eid)->misc_flags, EF_ROAD_TRAM) ? ROADTYPE_TRAM : ROADTYPE_ROAD);
	}

	e->preview_company_rank = 0xFF;
	if (company == _local_company) {
		AddRemoveEngineFromAutoreplaceAndBuildWindows(e->type);
	}
}

static CompanyID GetBestCompany(uint8 pp)
{
	const Company *c;
	int32 best_hist;
	CompanyID best_company;
	CompanyMask mask = 0;

	do {
		best_hist = -1;
		best_company = INVALID_COMPANY;
		FOR_ALL_COMPANIES(c) {
			if (c->block_preview == 0 && !HasBit(mask, c->index) &&
					c->old_economy[0].performance_history > best_hist) {
				best_hist = c->old_economy[0].performance_history;
				best_company = c->index;
			}
		}

		if (best_company == INVALID_COMPANY) return INVALID_COMPANY;

		SetBit(mask, best_company);
	} while (--pp != 0);

	return best_company;
}

void EnginesDailyLoop()
{
	if (_cur_year >= YEAR_ENGINE_AGING_STOPS) return;

	Engine *e;
	FOR_ALL_ENGINES(e) {
		EngineID i = e->index;
		if (e->flags & ENGINE_EXCLUSIVE_PREVIEW) {
			if (e->flags & ENGINE_OFFER_WINDOW_OPEN) {
				if (e->preview_company_rank != 0xFF && !--e->preview_wait) {
					e->flags &= ~ENGINE_OFFER_WINDOW_OPEN;
					DeleteWindowById(WC_ENGINE_PREVIEW, i);
					e->preview_company_rank++;
				}
			} else if (e->preview_company_rank != 0xFF) {
				CompanyID best_company = GetBestCompany(e->preview_company_rank);

				if (best_company == INVALID_COMPANY) {
					e->preview_company_rank = 0xFF;
					continue;
				}

				if (!IsHumanCompany(best_company)) {
					/* XXX - TTDBUG: TTD has a bug here ???? */
					AcceptEnginePreview(i, best_company);
				} else {
					e->flags |= ENGINE_OFFER_WINDOW_OPEN;
					e->preview_wait = 20;
					if (IsInteractiveCompany(best_company)) ShowEnginePreviewWindow(i);
				}
			}
		}
	}
}

/** Accept an engine prototype. XXX - it is possible that the top-company
 * changes while you are waiting to accept the offer? Then it becomes invalid
 * @param tile unused
 * @param flags operation to perfom
 * @param p1 engine-prototype offered
 * @param p2 unused
 */
CommandCost CmdWantEnginePreview(TileIndex tile, uint32 flags, uint32 p1, uint32 p2, const char *text)
{
	Engine *e;

	if (!IsEngineIndex(p1)) return CMD_ERROR;
	e = GetEngine(p1);
	if (GetBestCompany(e->preview_company_rank) != _current_company) return CMD_ERROR;

	if (flags & DC_EXEC) AcceptEnginePreview(p1, _current_company);

	return CommandCost();
}

StringID GetEngineCategoryName(EngineID engine);

static void NewVehicleAvailable(Engine *e)
{
	Vehicle *v;
	Company *c;
	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_ALL_COMPANIES(c) {
			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_ALL_VEHICLES(v) {
				if (v->type == VEH_TRAIN || v->type == VEH_ROAD || v->type == VEH_SHIP ||
						(v->type == VEH_AIRCRAFT && IsNormalAircraft(v))) {
					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 = (CompanyMask)-1;

	/* Do not introduce new rail wagons */
	if (IsWagon(index)) return;

	if (e->type == VEH_TRAIN) {
		/* maybe make another rail type available */
		RailType railtype = e->u.rail.railtype;
		assert(railtype < RAILTYPE_END);
		FOR_ALL_COMPANIES(c) SetBit(c->avail_railtypes, railtype);
	} else if (e->type == VEH_ROAD) {
		/* maybe make another road type available */
		FOR_ALL_COMPANIES(c) SetBit(c->avail_roadtypes, HasBit(e->info.misc_flags, EF_ROAD_TRAM) ? ROADTYPE_TRAM : ROADTYPE_ROAD);
	}

	SetDParam(0, GetEngineCategoryName(index));
	SetDParam(1, index);
	AddNewsItem(STR_NEW_VEHICLE_NOW_AVAILABLE_WITH_TYPE, NS_NEW_VEHICLES, index, 0);
}

void EnginesMonthlyLoop()
{
	if (_cur_year < YEAR_ENGINE_AGING_STOPS) {
		Engine *e;
		FOR_ALL_ENGINES(e) {
			/* Age the vehicle */
			if (e->flags & ENGINE_AVAILABLE && e->age != 0xFFFF) {
				e->age++;
				CalcEngineReliability(e);
			}

			if (!(e->flags & ENGINE_AVAILABLE) && _date >= (e->intro_date + 365)) {
				/* Introduce it to all companies */
				NewVehicleAvailable(e);
			} else if (!(e->flags & (ENGINE_AVAILABLE|ENGINE_EXCLUSIVE_PREVIEW)) && _date >= e->intro_date) {
				/* Introduction date has passed.. show introducing dialog to one companies. */
				e->flags |= ENGINE_EXCLUSIVE_PREVIEW;

				/* Do not introduce new rail wagons */
				if (!IsWagon(e->index))
					e->preview_company_rank = 1; // Give to the company with the highest rating.
			}
		}
	}
}

static bool IsUniqueEngineName(const char *name)
{
	char buf[512];

	const Engine *e;
	FOR_ALL_ENGINES(e) {
		SetDParam(0, e->index);
		GetString(buf, STR_ENGINE_NAME, lastof(buf));
		if (strcmp(buf, name) == 0) return false;
	}

	return true;
}

/** Rename an engine.
 * @param tile unused
 * @param flags operation to perfom
 * @param p1 engine ID to rename
 * @param p2 unused
 */
CommandCost CmdRenameEngine(TileIndex tile, uint32 flags, uint32 p1, uint32 p2, const char *text)
{
	if (!IsEngineIndex(p1)) return CMD_ERROR;

	bool reset = StrEmpty(text);

	if (!reset) {
		if (strlen(text) >= MAX_LENGTH_ENGINE_NAME_BYTES) return CMD_ERROR;
		if (!IsUniqueEngineName(text)) return_cmd_error(STR_NAME_MUST_BE_UNIQUE);
	}

	if (flags & DC_EXEC) {
		Engine *e = GetEngine(p1);
		free(e->name);

		if (reset) {
			e->name = NULL;
			/* if we removed the last custom name, disable the 'Save custom names' button */
			_vehicle_design_names &= ~1;
			FOR_ALL_ENGINES(e) {
				if (e->name != NULL) {
					_vehicle_design_names |= 1;
					break;
				}
			}
		} else {
			e->name = strdup(text);
			_vehicle_design_names |= 3;
		}

		MarkWholeScreenDirty();
	}

	return CommandCost();
}


/** Check if an engine is buildable.
 * @param engine  index of the engine to check.
 * @param type    the type the engine should be.
 * @param company index of the company.
 * @return True if an engine is valid, of the specified type, and buildable by
 *              the given company.
 */
bool IsEngineBuildable(EngineID engine, VehicleType type, CompanyID company)
{
	/* check if it's an engine that is in the engine array */
	if (!IsEngineIndex(engine)) return false;

	const Engine *e = GetEngine(engine);

	/* check if it's an engine of specified type */
	if (e->type != type) return false;

	/* check if it's available */
	if (!HasBit(e->company_avail, company)) return false;

	if (type == VEH_TRAIN) {
		/* Check if the rail type is available to this company */
		const Company *c = GetCompany(company);
		if (!HasBit(c->avail_railtypes, RailVehInfo(engine)->railtype)) return false;
	}

	return true;
}

/**
 * Check if an engine is refittable.
 * @param engine index of the engine to check.
 * @return true if the engine is refittable.
 */
bool IsEngineRefittable(EngineID engine)
{
	/* check if it's an engine that is in the engine array */
	if (!IsEngineIndex(engine)) return false;

	const Engine *e = GetEngine(engine);

	if (e->type == VEH_SHIP && !e->u.ship.refittable) 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->callbackmask, CBM_VEHICLE_CARGO_SUFFIX)) return true;

	/* Is there any cargo except the default cargo? */
	CargoID default_cargo = GetEngineCargoType(engine);
	return default_cargo != CT_INVALID && ei->refit_mask != 1U << default_cargo;
}

/** Get the default cargo type for a certain engine type
 * @param engine The ID to get the cargo for
 * @return The cargo type. CT_INVALID means no cargo capacity
 */
CargoID GetEngineCargoType(EngineID engine)
{
	assert(IsEngineIndex(engine));

	switch (GetEngine(engine)->type) {
		case VEH_TRAIN:
			if (RailVehInfo(engine)->capacity == 0) return CT_INVALID;
			return RailVehInfo(engine)->cargo_type;

		case VEH_ROAD:
			if (RoadVehInfo(engine)->capacity == 0) return CT_INVALID;
			return RoadVehInfo(engine)->cargo_type;

		case VEH_SHIP:
			if (ShipVehInfo(engine)->capacity == 0) return CT_INVALID;
			return ShipVehInfo(engine)->cargo_type;

		case VEH_AIRCRAFT:
			/* all aircraft starts as passenger planes with cargo capacity */
			return CT_PASSENGERS;

		default: NOT_REACHED(); return CT_INVALID;
	}
}

static const SaveLoad _engine_desc[] = {
	SLE_CONDVAR(Engine, intro_date,          SLE_FILE_U16 | SLE_VAR_I32,  0,  30),
	SLE_CONDVAR(Engine, intro_date,          SLE_INT32,                  31, SL_MAX_VERSION),
	SLE_CONDVAR(Engine, age,                 SLE_FILE_U16 | SLE_VAR_I32,  0,  30),
	SLE_CONDVAR(Engine, age,                 SLE_INT32,                  31, SL_MAX_VERSION),
	    SLE_VAR(Engine, reliability,         SLE_UINT16),
	    SLE_VAR(Engine, reliability_spd_dec, SLE_UINT16),
	    SLE_VAR(Engine, reliability_start,   SLE_UINT16),
	    SLE_VAR(Engine, reliability_max,     SLE_UINT16),
	    SLE_VAR(Engine, reliability_final,   SLE_UINT16),
	    SLE_VAR(Engine, duration_phase_1,    SLE_UINT16),
	    SLE_VAR(Engine, duration_phase_2,    SLE_UINT16),
	    SLE_VAR(Engine, duration_phase_3,    SLE_UINT16),

	    SLE_VAR(Engine, lifelength,          SLE_UINT8),
	    SLE_VAR(Engine, flags,               SLE_UINT8),
	    SLE_VAR(Engine, preview_company_rank,SLE_UINT8),
	    SLE_VAR(Engine, preview_wait,        SLE_UINT8),
	SLE_CONDNULL(1, 0, 44),
	SLE_CONDVAR(Engine, company_avail,       SLE_FILE_U8  | SLE_VAR_U16,  0, 103),
	SLE_CONDVAR(Engine, company_avail,       SLE_UINT16,                104, SL_MAX_VERSION),
	SLE_CONDSTR(Engine, name,                SLE_STR, 0,                 84, SL_MAX_VERSION),

	/* reserve extra space in savegame here. (currently 16 bytes) */
	SLE_CONDNULL(16, 2, SL_MAX_VERSION),

	SLE_END()
};

static std::map<EngineID, Engine> _temp_engine;

Engine *GetTempDataEngine(EngineID index)
{
	return &_temp_engine[index];
}

static void Save_ENGN()
{
	Engine *e;
	FOR_ALL_ENGINES(e) {
		SlSetArrayIndex(e->index);
		SlObject(e, _engine_desc);
	}
}

static void Load_ENGN()
{
	/* As engine data is loaded before engines are initialized we need to load
	 * this information into a temporary array. This is then copied into the
	 * engine pool after processing NewGRFs by CopyTempEngineData(). */
	int index;
	while ((index = SlIterateArray()) != -1) {
		Engine *e = GetTempDataEngine(index);
		SlObject(e, _engine_desc);
	}
}

/**
 * Copy data from temporary engine array into the real engine pool.
 */
void CopyTempEngineData()
{
	Engine *e;
	FOR_ALL_ENGINES(e) {
		if (e->index >= _temp_engine.size()) break;

		const Engine *se = GetTempDataEngine(e->index);
		e->intro_date          = se->intro_date;
		e->age                 = se->age;
		e->reliability         = se->reliability;
		e->reliability_spd_dec = se->reliability_spd_dec;
		e->reliability_start   = se->reliability_start;
		e->reliability_max     = se->reliability_max;
		e->reliability_final   = se->reliability_final;
		e->duration_phase_1    = se->duration_phase_1;
		e->duration_phase_2    = se->duration_phase_2;
		e->duration_phase_3    = se->duration_phase_3;
		e->lifelength          = se->lifelength;
		e->flags               = se->flags;
		e->preview_company_rank= se->preview_company_rank;
		e->preview_wait        = se->preview_wait;
		e->company_avail       = se->company_avail;
		if (se->name != NULL) e->name = strdup(se->name);
	}

	/* Get rid of temporary data */
	_temp_engine.clear();
}

static void Load_ENGS()
{
	/* Load old separate String ID list into a temporary array. This
	 * was always 256 entries. */
	StringID names[256];

	SlArray(names, lengthof(names), SLE_STRINGID);

	/* Copy each string into the temporary engine array. */
	for (EngineID engine = 0; engine < lengthof(names); engine++) {
		Engine *e = GetTempDataEngine(engine);
		e->name = CopyFromOldName(names[engine]);
	}
}

extern const ChunkHandler _engine_chunk_handlers[] = {
	{ 'ENGN', Save_ENGN,     Load_ENGN,     CH_ARRAY          },
	{ 'ENGS', NULL,          Load_ENGS,     CH_RIFF | CH_LAST },
};