/* $Id$ */

/*

 * 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/>.

 */

/** @file newgrf_station.cpp Functions for dealing with station classes and custom stations. */

#include "stdafx.h"

#include "variables.h"

#include "landscape.h"

#include "debug.h"

#include "station_base.h"

#include "waypoint_base.h"

#include "roadstop_base.h"

#include "newgrf_cargo.h"

#include "newgrf_commons.h"

#include "newgrf_station.h"

#include "newgrf_spritegroup.h"

#include "newgrf_sound.h"

#include "town.h"

#include "newgrf_town.h"

#include "gfx_func.h"

#include "date_func.h"

#include "company_func.h"

#include "animated_tile_func.h"

#include "functions.h"

#include "tunnelbridge_map.h"

#include "spritecache.h"

#include "table/strings.h"

static StationClass _station_classes[STAT_CLASS_MAX];

enum {

	MAX_SPECLIST = 255,

};

enum TriggerArea {

	TA_TILE,

	TA_PLATFORM,

	TA_WHOLE,

};

struct ETileArea : TileArea {

	ETileArea(const BaseStation *st, TileIndex tile, TriggerArea ta)

	{

		switch (ta) {

			default: NOT_REACHED();

			case TA_TILE:

				this->tile = tile;

				this->w    = 1;

				this->h    = 1;

				break;

			case TA_PLATFORM: {

				TileIndex start, end;

				Axis axis = GetRailStationAxis(tile);

				TileIndexDiff delta = TileOffsByDiagDir(AxisToDiagDir(axis));

				for (end = tile; IsRailStationTile(end + delta) && IsCompatibleTrainStationTile(tile, end + delta); end += delta) { /* Nothing */ }

				for (start = tile; IsRailStationTile(start - delta) && IsCompatibleTrainStationTile(tile, start - delta); start -= delta) { /* Nothing */ }

				this->tile = start;

				this->w = TileX(end) - TileX(start) + 1;

				this->h = TileY(end) - TileY(start) + 1;

				break;

			}

			case TA_WHOLE:

				st->GetTileArea(this, Station::IsExpected(st) ? STATION_RAIL : STATION_WAYPOINT);

				break;

		}

	}

};

/**

 * Reset station classes to their default state.

 * This includes initialising the Default and Waypoint classes with an empty

 * entry, for standard stations and waypoints.

 */

void ResetStationClasses()

{

	for (StationClassID i = STAT_CLASS_BEGIN; i < STAT_CLASS_MAX; i++) {

		_station_classes[i].id = 0;

		_station_classes[i].name = STR_EMPTY;

		_station_classes[i].stations = 0;

		free(_station_classes[i].spec);

		_station_classes[i].spec = NULL;

	}

	/* Set up initial data */

	_station_classes[0].id = 'DFLT';

	_station_classes[0].name = STR_STATION_CLASS_DFLT;

	_station_classes[0].stations = 1;

	_station_classes[0].spec = MallocT<StationSpec*>(1);

	_station_classes[0].spec[0] = NULL;

	_station_classes[1].id = 'WAYP';

	_station_classes[1].name = STR_STATION_CLASS_WAYP;

	_station_classes[1].stations = 1;

	_station_classes[1].spec = MallocT<StationSpec*>(1);

	_station_classes[1].spec[0] = NULL;

}

/**

 * Allocate a station class for the given class id.

 * @param cls A 32 bit value identifying the class.

 * @return Index into _station_classes of allocated class.

 */

StationClassID AllocateStationClass(uint32 cls)

{

	for (StationClassID i = STAT_CLASS_BEGIN; i < STAT_CLASS_MAX; i++) {

		if (_station_classes[i].id == cls) {

			/* ClassID is already allocated, so reuse it. */

			return i;

		} else if (_station_classes[i].id == 0) {

			/* This class is empty, so allocate it to the ClassID. */

			_station_classes[i].id = cls;

			return i;

		}

	}

	grfmsg(2, "StationClassAllocate: already allocated %d classes, using default", STAT_CLASS_MAX);

	return STAT_CLASS_DFLT;

}

/** Set the name of a custom station class */

void SetStationClassName(StationClassID sclass, StringID name)

{

	assert(sclass < STAT_CLASS_MAX);

	_station_classes[sclass].name = name;

}

/** Retrieve the name of a custom station class */

StringID GetStationClassName(StationClassID sclass)

{

	assert(sclass < STAT_CLASS_MAX);

	return _station_classes[sclass].name;

}

/**

 * Get the number of station classes in use.

 * @return Number of station classes.

 */

uint GetNumStationClasses()

{

	uint i;

	for (i = 0; i < STAT_CLASS_MAX && _station_classes[i].id != 0; i++) {}

	return i;

}

/**

 * Return the number of stations for the given station class.

 * @param sclass Index of the station class.

 * @return Number of stations in the class.

 */

uint GetNumCustomStations(StationClassID sclass)

{

	assert(sclass < STAT_CLASS_MAX);

	return _station_classes[sclass].stations;

}

/**

 * Tie a station spec to its station class.

 * @param statspec The station spec.

 */

void SetCustomStationSpec(StationSpec *statspec)

{

	StationClass *station_class;

	int i;

	/* If the station has already been allocated, don't reallocate it. */

	if (statspec->allocated) return;

	assert(statspec->sclass < STAT_CLASS_MAX);

	station_class = &_station_classes[statspec->sclass];

	i = station_class->stations++;

	station_class->spec = ReallocT(station_class->spec, station_class->stations);

	station_class->spec[i] = statspec;

	statspec->allocated = true;

}

/**

 * Retrieve a station spec from a class.

 * @param sclass Index of the station class.

 * @param station The station index with the class.

 * @return The station spec.

 */

const StationSpec *GetCustomStationSpec(StationClassID sclass, uint station)

{

	assert(sclass < STAT_CLASS_MAX);

	if (station < _station_classes[sclass].stations)

		return _station_classes[sclass].spec[station];

	/* If the custom station isn't defined any more, then the GRF file

	 * probably was not loaded. */

	return NULL;

}

/**

 * Retrieve a station spec by GRF location.

 * @param grfid    GRF ID of station spec.

 * @param localidx Index within GRF file of station spec.

 * @param index    Pointer to return the index of the station spec in its station class. If NULL then not used.

 * @return The station spec.

 */

const StationSpec *GetCustomStationSpecByGrf(uint32 grfid, byte localidx, int *index)

{

	uint j;

	for (StationClassID i = STAT_CLASS_BEGIN; i < STAT_CLASS_MAX; i++) {

		for (j = 0; j < _station_classes[i].stations; j++) {

			const StationSpec *statspec = _station_classes[i].spec[j];

			if (statspec == NULL) continue;

			if (statspec->grffile->grfid == grfid && statspec->localidx == localidx) {

				if (index != NULL) *index = j;

				return statspec;

			}

		}

	}

	return NULL;

}

/* Evaluate a tile's position within a station, and return the result a bitstuffed format.

 * if not centred: .TNLcCpP, if centred: .TNL..CP

 * T = Tile layout number (GetStationGfx), N = Number of platforms, L = Length of platforms

 * C = Current platform number from start, c = from end

 * P = Position along platform from start, p = from end

 * if centred, C/P start from the centre and c/p are not available.

 */

uint32 GetPlatformInfo(Axis axis, byte tile, int platforms, int length, int x, int y, bool centred)

{

	uint32 retval = 0;

	if (axis == AXIS_X) {

		Swap(platforms, length);

		Swap(x, y);

	}

	/* Limit our sizes to 4 bits */

	platforms = min(15, platforms);

	length    = min(15, length);

	x = min(15, x);

	y = min(15, y);

	if (centred) {

		x -= platforms / 2;

		y -= length / 2;

		SB(retval,  0, 4, y & 0xF);

		SB(retval,  4, 4, x & 0xF);

	} else {

		SB(retval,  0, 4, y);

		SB(retval,  4, 4, length - y - 1);

		SB(retval,  8, 4, x);

		SB(retval, 12, 4, platforms - x - 1);

	}

	SB(retval, 16, 4, length);

	SB(retval, 20, 4, platforms);

	SB(retval, 24, 4, tile);

	return retval;

}

/* Find the end of a railway station, from the tile, in the direction of delta.

 * If check_type is set, we stop if the custom station type changes.

 * If check_axis is set, we stop if the station direction changes.

 */

static TileIndex FindRailStationEnd(TileIndex tile, TileIndexDiff delta, bool check_type, bool check_axis)

{

	byte orig_type = 0;

	Axis orig_axis = AXIS_X;

	StationID sid = GetStationIndex(tile);

	if (check_type) orig_type = GetCustomStationSpecIndex(tile);

	if (check_axis) orig_axis = GetRailStationAxis(tile);

	while (true) {

		TileIndex new_tile = TILE_ADD(tile, delta);

		if (!IsTileType(new_tile, MP_STATION) || GetStationIndex(new_tile) != sid) break;

		if (!HasStationRail(new_tile)) break;

		if (check_type && GetCustomStationSpecIndex(new_tile) != orig_type) break;

		if (check_axis && GetRailStationAxis(new_tile) != orig_axis) break;

		tile = new_tile;

	}

	return tile;

}

static uint32 GetPlatformInfoHelper(TileIndex tile, bool check_type, bool check_axis, bool centred)

{

	int tx = TileX(tile);

	int ty = TileY(tile);

	int sx = TileX(FindRailStationEnd(tile, TileDiffXY(-1,  0), check_type, check_axis));

	int sy = TileY(FindRailStationEnd(tile, TileDiffXY( 0, -1), check_type, check_axis));

	int ex = TileX(FindRailStationEnd(tile, TileDiffXY( 1,  0), check_type, check_axis)) + 1;

	int ey = TileY(FindRailStationEnd(tile, TileDiffXY( 0,  1), check_type, check_axis)) + 1;

	tx -= sx; ex -= sx;

	ty -= sy; ey -= sy;

	return GetPlatformInfo(GetRailStationAxis(tile), GetStationGfx(tile), ex, ey, tx, ty, centred);

}

static uint32 GetRailContinuationInfo(TileIndex tile)

{

	/* Tile offsets and exit dirs for X axis */

	static const Direction x_dir[8] = { DIR_SW, DIR_NE, DIR_SE, DIR_NW, DIR_S, DIR_E, DIR_W, DIR_N };

	static const DiagDirection x_exits[8] = { DIAGDIR_SW, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NE, DIAGDIR_SW, DIAGDIR_NE };

	/* Tile offsets and exit dirs for Y axis */

	static const Direction y_dir[8] = { DIR_SE, DIR_NW, DIR_SW, DIR_NE, DIR_S, DIR_W, DIR_E, DIR_N };

	static const DiagDirection y_exits[8] = { DIAGDIR_SE, DIAGDIR_NW, DIAGDIR_SW, DIAGDIR_NE, DIAGDIR_SE, DIAGDIR_NW, DIAGDIR_SE, DIAGDIR_NW };

	Axis axis = GetRailStationAxis(tile);

	/* Choose appropriate lookup table to use */

	const Direction *dir = axis == AXIS_X ? x_dir : y_dir;

	const DiagDirection *diagdir = axis == AXIS_X ? x_exits : y_exits;

	uint32 res = 0;

	uint i;

	for (i = 0; i < lengthof(x_dir); i++, dir++, diagdir++) {

		TileIndex neighbour_tile = tile + TileOffsByDir(*dir);

		TrackBits trackbits = TrackStatusToTrackBits(GetTileTrackStatus(neighbour_tile, TRANSPORT_RAIL, 0));

		if (trackbits != TRACK_BIT_NONE) {

			/* If there is any track on the tile, set the bit in the second byte */

			SetBit(res, i + 8);

			/* With tunnels and bridges the tile has tracks, but they are not necessarily connected

			 * with the next tile because the ramp is not going in the right direction. */

			if (IsTileType(neighbour_tile, MP_TUNNELBRIDGE) && GetTunnelBridgeDirection(neighbour_tile) != *diagdir) {

				continue;

			}

			/* If any track reaches our exit direction, set the bit in the lower byte */

			if (trackbits & DiagdirReachesTracks(*diagdir)) SetBit(res, i);

		}

	}

	return res;

}

/* Station Resolver Functions */

static uint32 StationGetRandomBits(const ResolverObject *object)

{

	const BaseStation *st = object->u.station.st;

	const TileIndex tile = object->u.station.tile;

	return (st == NULL ? 0 : st->random_bits) | (tile == INVALID_TILE ? 0 : GetStationTileRandomBits(tile) << 16);

}

static uint32 StationGetTriggers(const ResolverObject *object)

{

	const BaseStation *st = object->u.station.st;

	return st == NULL ? 0 : st->waiting_triggers;

}

static void StationSetTriggers(const ResolverObject *object, int triggers)

{

	BaseStation *st = const_cast<BaseStation *>(object->u.station.st);

	assert(st != NULL);

	st->waiting_triggers = triggers;

}

/**

 * Station variable cache

 * This caches 'expensive' station variable lookups which iterate over

 * several tiles that may be called multiple times per Resolve().

 */

static struct {

	uint32 v40;

	uint32 v41;

	uint32 v45;

	uint32 v46;

	uint32 v47;

	uint32 v49;

	uint8 valid;

} _svc;

static uint32 StationGetVariable(const ResolverObject *object, byte variable, byte parameter, bool *available)

{

	const BaseStation *st = object->u.station.st;

	TileIndex tile = object->u.station.tile;

	if (object->scope == VSG_SCOPE_PARENT) {

		/* Pass the request on to the town of the station */

		const Town *t;

		if (st != NULL) {

			t = st->town;

		} else if (tile != INVALID_TILE) {

			t = ClosestTownFromTile(tile, UINT_MAX);

		} else {

			*available = false;

			return UINT_MAX;

		}

		return TownGetVariable(variable, parameter, available, t);

	}

	if (st == NULL) {

		/* Station does not exist, so we're in a purchase list */

		switch (variable) {

			case 0x40:

			case 0x41:

			case 0x46:

			case 0x47:

			case 0x49: return 0x2110000;        // Platforms, tracks & position

			case 0x42: return 0;                // Rail type (XXX Get current type from GUI?)

			case 0x43: return _current_company; // Station owner

			case 0x44: return 2;                // PBS status

			case 0xFA: return Clamp(_date - DAYS_TILL_ORIGINAL_BASE_YEAR, 0, 65535); // Build date, clamped to a 16 bit value

		}

		*available = false;

		return UINT_MAX;

	}

	switch (variable) {

		/* Calculated station variables */

		case 0x40:

			if (!HasBit(_svc.valid, 0)) { _svc.v40 = GetPlatformInfoHelper(tile, false, false, false); SetBit(_svc.valid, 0); }

			return _svc.v40;

		case 0x41:

			if (!HasBit(_svc.valid, 1)) { _svc.v41 = GetPlatformInfoHelper(tile, true,  false, false); SetBit(_svc.valid, 1); }

			return _svc.v41;

		case 0x42: return GetTerrainType(tile) | (GetRailType(tile) << 8);

		case 0x43: return st->owner; // Station owner

		case 0x44: return HasStationReservation(tile) ? 7 : 4; // PBS status

		case 0x45:

			if (!HasBit(_svc.valid, 2)) { _svc.v45 = GetRailContinuationInfo(tile); SetBit(_svc.valid, 2); }

			return _svc.v45;

		case 0x46:

			if (!HasBit(_svc.valid, 3)) { _svc.v46 = GetPlatformInfoHelper(tile, false, false, true); SetBit(_svc.valid, 3); }

			return _svc.v46;

		case 0x47:

			if (!HasBit(_svc.valid, 4)) { _svc.v47 = GetPlatformInfoHelper(tile, true,  false, true); SetBit(_svc.valid, 4); }

			return _svc.v47;

		case 0x49:

			if (!HasBit(_svc.valid, 5)) { _svc.v49 = GetPlatformInfoHelper(tile, false, true, false); SetBit(_svc.valid, 5); }

			return _svc.v49;

		case 0x4A: // Animation frame of tile

			return GetStationAnimationFrame(tile);

		/* Variables which use the parameter */

		/* Variables 0x60 to 0x65 are handled separately below */

		case 0x66: // Animation frame of nearby tile

			if (parameter != 0) tile = GetNearbyTile(parameter, tile);

			return st->TileBelongsToRailStation(tile) ? GetStationAnimationFrame(tile) : UINT_MAX;

		case 0x67: { // Land info of nearby tile

			Axis axis = GetRailStationAxis(tile);

			if (parameter != 0) tile = GetNearbyTile(parameter, tile); // only perform if it is required

			Slope tileh = GetTileSlope(tile, NULL);

			bool swap = (axis == AXIS_Y && HasBit(tileh, SLOPE_W) != HasBit(tileh, SLOPE_E));

			return GetNearbyTileInformation(tile) ^ (swap ? SLOPE_EW : 0);

		}

		case 0x68: { // Station info of nearby tiles

			TileIndex nearby_tile = GetNearbyTile(parameter, tile);

			if (!HasStationTileRail(nearby_tile)) return 0xFFFFFFFF;

			uint32 grfid = st->speclist[GetCustomStationSpecIndex(tile)].grfid;

			bool perpendicular = GetRailStationAxis(tile) != GetRailStationAxis(nearby_tile);

			bool same_station = st->TileBelongsToRailStation(nearby_tile);

			uint32 res = GB(GetStationGfx(nearby_tile), 1, 2) << 12 | !!perpendicular << 11 | !!same_station << 10;

			if (IsCustomStationSpecIndex(nearby_tile)) {

				const StationSpecList ssl = BaseStation::GetByTile(nearby_tile)->speclist[GetCustomStationSpecIndex(nearby_tile)];

				res |= 1 << (ssl.grfid != grfid ? 9 : 8) | ssl.localidx;

			}

			return res;

		}

		/* General station variables */

		case 0x82: return 50;

		case 0x84: return st->string_id;

		case 0x86: return 0;

		case 0xF0: return st->facilities;

		case 0xFA: return Clamp(st->build_date - DAYS_TILL_ORIGINAL_BASE_YEAR, 0, 65535);

	}

	return st->GetNewGRFVariable(object, variable, parameter, available);

}

uint32 Station::GetNewGRFVariable(const ResolverObject *object, byte variable, byte parameter, bool *available) const

{

	switch (variable) {

		case 0x48: { // Accepted cargo types

			CargoID cargo_type;

			uint32 value = 0;

			for (cargo_type = 0; cargo_type < NUM_CARGO; cargo_type++) {

				if (HasBit(this->goods[cargo_type].acceptance_pickup, GoodsEntry::PICKUP)) SetBit(value, cargo_type);

			}

			return value;

		}

		case 0x8A: return this->had_vehicle_of_type;

		case 0xF1: return this->airport_type;

		case 0xF2: return this->truck_stops->status;

		case 0xF3: return this->bus_stops->status;

		case 0xF6: return this->airport_flags;

		case 0xF7: return GB(this->airport_flags, 8, 8);

	}

	/* Handle cargo variables with parameter, 0x60 to 0x65 */

	if (variable >= 0x60 && variable <= 0x65) {

		CargoID c = GetCargoTranslation(parameter, object->u.station.statspec->grffile);

		if (c == CT_INVALID) return 0;

		const GoodsEntry *ge = &this->goods[c];

		switch (variable) {

			case 0x60: return min(ge->cargo.Count(), 4095);

			case 0x61: return ge->days_since_pickup;

			case 0x62: return ge->rating;

			case 0x63: return ge->cargo.DaysInTransit();

			case 0x64: return ge->last_speed | (ge->last_age << 8);

			case 0x65: return GB(ge->acceptance_pickup, GoodsEntry::ACCEPTANCE, 1) << 3;

		}

	}

	/* Handle cargo variables (deprecated) */

	if (variable >= 0x8C && variable <= 0xEC) {

		const GoodsEntry *g = &this->goods[GB(variable - 0x8C, 3, 4)];

		switch (GB(variable - 0x8C, 0, 3)) {

			case 0: return g->cargo.Count();

			case 1: return GB(min(g->cargo.Count(), 4095), 0, 4) | (GB(g->acceptance_pickup, GoodsEntry::ACCEPTANCE, 1) << 7);

			case 2: return g->days_since_pickup;

			case 3: return g->rating;

			case 4: return g->cargo.Source();

			case 5: return g->cargo.DaysInTransit();

			case 6: return g->last_speed;

			case 7: return g->last_age;

		}

	}

	DEBUG(grf, 1, "Unhandled station variable 0x%X", variable);

	*available = false;

	return UINT_MAX;

}

uint32 Waypoint::GetNewGRFVariable(const ResolverObject *object, byte variable, byte parameter, bool *available) const

{

	switch (variable) {

		case 0x48: return 0; // Accepted cargo types

		case 0x8A: return HVOT_WAYPOINT;

		case 0xF1: return 0; // airport type

		case 0xF2: return 0; // truck stop status

		case 0xF3: return 0; // bus stop status

		case 0xF6: return 0; // airport flags

		case 0xF7: return 0; // airport flags cont.

	}

	/* Handle cargo variables with parameter, 0x60 to 0x65 */

	if (variable >= 0x60 && variable <= 0x65) {

		return 0;

	}

	/* Handle cargo variables (deprecated) */

	if (variable >= 0x8C && variable <= 0xEC) {

		switch (GB(variable - 0x8C, 0, 3)) {

			case 3: return INITIAL_STATION_RATING;

			case 4: return INVALID_STATION;

			default: return 0;

		}

	}

	DEBUG(grf, 1, "Unhandled station variable 0x%X", variable);

	*available = false;

	return UINT_MAX;

}

static const SpriteGroup *StationResolveReal(const ResolverObject *object, const RealSpriteGroup *group)

{

	const BaseStation *bst = object->u.station.st;

	const StationSpec *statspec = object->u.station.statspec;

	uint set;

	uint cargo = 0;

	CargoID cargo_type = object->u.station.cargo_type;

	if (bst == NULL || statspec->sclass == STAT_CLASS_WAYP) {

		return group->loading[0];

	}

	const Station *st = Station::From(bst);

	switch (cargo_type) {

		case CT_INVALID:

		case CT_DEFAULT_NA:

		case CT_PURCHASE:

			cargo = 0;

			break;

		case CT_DEFAULT:

			for (cargo_type = 0; cargo_type < NUM_CARGO; cargo_type++) {

				cargo += st->goods[cargo_type].cargo.Count();

			}

			break;

		default:

			cargo = st->goods[cargo_type].cargo.Count();

			break;

	}

	if (HasBit(statspec->flags, SSF_DIV_BY_STATION_SIZE)) cargo /= (st->train_station.w + st->train_station.h);

	cargo = min(0xfff, cargo);

	if (cargo > statspec->cargo_threshold) {

		if (group->num_loading > 0) {

			set = ((cargo - statspec->cargo_threshold) * group->num_loading) / (4096 - statspec->cargo_threshold);

			return group->loading[set];

		}

	} else {

		if (group->num_loaded > 0) {

			set = (cargo * group->num_loaded) / (statspec->cargo_threshold + 1);

			return group->loaded[set];

		}

	}

	return group->loading[0];

}

static void NewStationResolver(ResolverObject *res, const StationSpec *statspec, const BaseStation *st, TileIndex tile)

{

	res->GetRandomBits = StationGetRandomBits;

	res->GetTriggers   = StationGetTriggers;

	res->SetTriggers   = StationSetTriggers;

	res->GetVariable   = StationGetVariable;

	res->ResolveReal   = StationResolveReal;

	res->u.station.st       = st;

	res->u.station.statspec = statspec;

	res->u.station.tile     = tile;

	res->callback        = CBID_NO_CALLBACK;

	res->callback_param1 = 0;

	res->callback_param2 = 0;

	res->last_value      = 0;

	res->trigger         = 0;

	res->reseed          = 0;

	res->count           = 0;

	res->grffile         = (statspec != NULL ? statspec->grffile : NULL);

}

static const SpriteGroup *ResolveStation(ResolverObject *object)

{

	const SpriteGroup *group;

	CargoID ctype = CT_DEFAULT_NA;

	if (object->u.station.st == NULL) {

		/* No station, so we are in a purchase list */

		ctype = CT_PURCHASE;

	} else if (Station::IsExpected(object->u.station.st)) {

		const Station *st = Station::From(object->u.station.st);

		/* Pick the first cargo that we have waiting */

		const CargoSpec *cs;

		FOR_ALL_CARGOSPECS(cs) {

			if (object->u.station.statspec->spritegroup[cs->Index()] != NULL &&

					!st->goods[cs->Index()].cargo.Empty()) {

				ctype = cs->Index();

				break;

			}

		}

	}

	group = object->u.station.statspec->spritegroup[ctype];

	if (group == NULL) {

		ctype = CT_DEFAULT;

		group = object->u.station.statspec->spritegroup[ctype];

	}

	if (group == NULL) return NULL;

	/* Remember the cargo type we've picked */

	object->u.station.cargo_type = ctype;

	/* Invalidate all cached vars */

	_svc.valid = 0;

	return SpriteGroup::Resolve(group, object);

}

SpriteID GetCustomStationRelocation(const StationSpec *statspec, const BaseStation *st, TileIndex tile)

{

	const SpriteGroup *group;

	ResolverObject object;

	NewStationResolver(&object, statspec, st, tile);

	group = ResolveStation(&object);

	if (group == NULL || group->type != SGT_RESULT) return 0;

	return group->GetResult() - 0x42D;

}

SpriteID GetCustomStationGroundRelocation(const StationSpec *statspec, const BaseStation *st, TileIndex tile)

{

	const SpriteGroup *group;

	ResolverObject object;

	NewStationResolver(&object, statspec, st, tile);

	if (HasBit(statspec->flags, SSF_SEPARATE_GROUND)) {

		object.callback_param1 = 1; // Indicate we are resolving the ground sprite

	}

	group = ResolveStation(&object);

	if (group == NULL || group->type != SGT_RESULT) return 0;

	return group->GetResult() - 0x42D;

}

uint16 GetStationCallback(CallbackID callback, uint32 param1, uint32 param2, const StationSpec *statspec, const BaseStation *st, TileIndex tile)

{

	const SpriteGroup *group;

	ResolverObject object;

	NewStationResolver(&object, statspec, st, tile);

	object.callback        = callback;

	object.callback_param1 = param1;

	object.callback_param2 = param2;

	group = ResolveStation(&object);

	if (group == NULL) return CALLBACK_FAILED;

	return group->GetCallbackResult();

}

/**

 * Allocate a StationSpec to a Station. This is called once per build operation.

 * @param statspec StationSpec to allocate.

 * @param st Station to allocate it to.

 * @param exec Whether to actually allocate the spec.

 * @return Index within the Station's spec list, or -1 if the allocation failed.

 */

int AllocateSpecToStation(const StationSpec *statspec, BaseStation *st, bool exec)

{

	uint i;

	if (statspec == NULL || st == NULL) return 0;

	for (i = 1; i < st->num_specs && i < MAX_SPECLIST; i++) {

		if (st->speclist[i].spec == NULL && st->speclist[i].grfid == 0) break;

	}

	if (i == MAX_SPECLIST) {

		/* As final effort when the spec list is already full...

		 * try to find the same spec and return that one. This might