/* $Id$ */

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

#include "stdafx.h"
#include "openttd.h"
#include "variables.h"
#include "debug.h"
#include "sprite.h"
#include "table/strings.h"
#include "station.h"
#include "station_map.h"
#include "newgrf_station.h"
#include "newgrf_spritegroup.h"

static StationClass station_classes[STAT_CLASS_MAX];

/**
 * 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(void)
{
	StationClassID i;
	for (i = 0; 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_STAT_CLASS_DFLT;
	station_classes[0].stations = 1;
	station_classes[0].spec = malloc(sizeof(*station_classes[0].spec));
	station_classes[0].spec[0] = NULL;

	station_classes[1].id = 'WAYP';
	station_classes[1].name = STR_STAT_CLASS_WAYP;
	station_classes[1].stations = 1;
	station_classes[1].spec = malloc(sizeof(*station_classes[1].spec));
	station_classes[1].spec[0] = NULL;
}

/**
 * Allocate a station class for the given class id.
 * @param classid A 32 bit value identifying the class.
 * @return Index into station_classes of allocated class.
 */
StationClassID AllocateStationClass(uint32 class)
{
	StationClassID i;

	for (i = 0; i < STAT_CLASS_MAX; i++) {
		if (station_classes[i].id == class) {
			// 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 = class;
			return i;
		}
	}

	DEBUG(grf, 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;
}

/** Build a list of station class name StringIDs to use in a dropdown list
 * @return Pointer to a (static) array of StringIDs
 */
StringID *BuildStationClassDropdown(void)
{
	/* Allow room for all station classes, plus a terminator entry */
	static StringID names[STAT_CLASS_MAX + 1];
	uint i;

	/* Add each name */
	for (i = 0; i < STAT_CLASS_MAX && station_classes[i].id != 0; i++) {
		names[i] = station_classes[i].name;
	}
	/* Terminate the list */
	names[i] = INVALID_STRING_ID;

	return names;
}

/**
 * Get the number of station classes in use.
 * @return Number of station classes.
 */
uint GetNumStationClasses(void)
{
	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 spec The station spec.
 */
void SetCustomStationSpec(StationSpec *statspec)
{
	StationClass *station_class;
	int i;

	assert(statspec->sclass < STAT_CLASS_MAX);
	station_class = &station_classes[statspec->sclass];

	i = station_class->stations++;
	station_class->spec = realloc(station_class->spec, station_class->stations * sizeof(*station_class->spec));

	station_class->spec[i] = statspec;
}

/**
 * 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;
}


/* Station Resolver Functions */
static uint32 StationGetRandomBits(const ResolverObject *object)
{
	const Station *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 Station *st = object->u.station.st;
	return st == NULL ? 0 : st->waiting_triggers;
}


static void StationSetTriggers(const ResolverObject *object, int triggers)
{
	Station *st = (Station*)object->u.station.st;
	assert(st != NULL);
	st->waiting_triggers = triggers;
}


static uint32 StationGetVariable(const ResolverObject *object, byte variable, byte parameter)
{
	const Station *st = object->u.station.st;

	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_player; /* Station owner */
			case 0xFA: return _date;           /* Build date */
			default:   return -1;
		}
	}

	switch (variable) {
		/* Calculated station variables */
		case 0x42: GetRailType(object->u.station.tile) << 8; /* Rail type */
		case 0x43: return st->owner; /* Station owner */
		case 0x44: return 0;         /* PBS status */
		case 0x48: { /* Accepted cargo types */
			CargoID cargo_type;
			uint32 value = 0;

			for (cargo_type = 0; cargo_type < NUM_CARGO; cargo_type++) {
				if (HASBIT(st->goods[cargo_type].waiting_acceptance, 15)) SETBIT(value, cargo_type);
			}
			return value;
		}

		/* Variables which use the parameter */
		case 0x60: return GB(st->goods[parameter].waiting_acceptance, 0, 12);
		case 0x61: return st->goods[parameter].days_since_pickup;
		case 0x62: return st->goods[parameter].rating;
		case 0x63: return st->goods[parameter].enroute_time;
		case 0x64: return st->goods[parameter].last_speed | (st->goods[parameter].last_age << 8);

		/* General station properties */
		case 0x82: return 50;
		case 0x84: return st->string_id;
		case 0x86: return 0;
		case 0x8A: return st->had_vehicle_of_type;
		case 0xF0: return st->facilities;
		case 0xF1: return st->airport_type;
		case 0xF2: return st->truck_stops->status;
		case 0xF3: return st->bus_stops->status;
		case 0xF6: return st->airport_flags;
		case 0xF7: return st->airport_flags & 0xFF;
		case 0xFA: return st->build_date;
	}

	/* Handle cargo variables (deprecated) */
	if (variable >= 0x8C && variable <= 0xEC) {
		const GoodsEntry *g = &st->goods[GB(variable - 0x8C, 3, 4)];
		switch (GB(variable - 0x8C, 0, 3)) {
			case 0: return g->waiting_acceptance;
			case 1: return g->waiting_acceptance & 0xFF;
			case 2: return g->days_since_pickup;
			case 3: return g->rating;
			case 4: return g->enroute_from;
			case 5: return g->enroute_time;
			case 6: return g->last_speed;
			case 7: return g->last_age;
		}
	}

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

	return -1;
}


static const SpriteGroup *StationResolveReal(const ResolverObject *object, const SpriteGroup *group)
{
	const Station *st = object->u.station.st;
	const StationSpec *statspec = object->u.station.statspec;
	uint set;

	uint cargo = 0;
	CargoID cargo_type = CT_INVALID; /* XXX Pick the correct cargo type */

	if (st == NULL || statspec->sclass == STAT_CLASS_WAYP) {
		return group->g.real.loading[0];
	}

	if (cargo_type == CT_INVALID) {
		for (cargo_type = 0; cargo_type < NUM_CARGO; cargo_type++) {
			cargo += GB(st->goods[cargo_type].waiting_acceptance, 0, 12);
		}
	} else {
		cargo = GB(st->goods[cargo_type].waiting_acceptance, 0, 12);
	}

	if (HASBIT(statspec->flags, 1)) cargo /= (st->trainst_w + st->trainst_h);
	cargo = min(0xfff, cargo);

	if (cargo > statspec->cargo_threshold) {
		if (group->g.real.num_loaded > 0) {
			set = ((cargo - statspec->cargo_threshold) * group->g.real.num_loaded) / (0xfff - statspec->cargo_threshold);
			return group->g.real.loaded[set];
		}
	} else {
		if (group->g.real.num_loading > 0) {
			set = (cargo * group->g.real.num_loading) / (statspec->cargo_threshold + 1);
			return group->g.real.loading[set];
		}
	}

	return group->g.real.loading[0];
}


static void NewStationResolver(ResolverObject *res, const StationSpec *statspec, const Station *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        = 0;
	res->callback_param1 = 0;
	res->callback_param2 = 0;
	res->last_value      = 0;
	res->trigger         = 0;
	res->reseed          = 0;
}


SpriteID GetCustomStationRelocation(const StationSpec *statspec, const Station *st, TileIndex tile, CargoID ctype)
{
	const SpriteGroup *group;
	ResolverObject object;

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

	group = Resolve(statspec->spritegroup[ctype], &object);
	if ((group == NULL || group->type != SGT_RESULT) && ctype != GC_DEFAULT) {
		group = Resolve(statspec->spritegroup[GC_DEFAULT], &object);
	}

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

	return group->g.result.sprite;
}


/**
 * Allocate a StationSpec to a Station. This is called once per build operation.
 * @param spec 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, Station *st, bool exec)
{
	uint i;

	if (statspec == NULL) return 0;

	/* Check if this spec has already been allocated */
	for (i = 1; i < st->num_specs && i < 256; i++) {
		if (st->speclist[i].spec == statspec) return i;
	}

	for (i = 1; i < st->num_specs && i < 256; i++) {
		if (st->speclist[i].spec == NULL && st->speclist[i].grfid == 0) break;
	}

	if (i == 256) return -1;

	if (exec) {
		if (i >= st->num_specs) {
			st->num_specs = i + 1;
			st->speclist = realloc(st->speclist, st->num_specs * sizeof(*st->speclist));

			if (st->num_specs == 2) {
				/* Initial allocation */
				st->speclist[0].spec     = NULL;
				st->speclist[0].grfid    = 0;
				st->speclist[0].localidx = 0;
			}
		}

		st->speclist[i].spec     = statspec;
		st->speclist[i].grfid    = statspec->grfid;
		st->speclist[i].localidx = statspec->localidx;
	}

	return i;
}


/** Deallocate a StationSpec from a Station. Called when removing a single station tile.
 * @param st Station to work with.
 * @param specindex Index of the custom station within the Station's spec list.
 * @return Indicates whether the StationSpec was deallocated.
 */
bool DeallocateSpecFromStation(Station *st, byte specindex)
{
	bool freeable = true;

	/* specindex of 0 (default) is never freeable */
	if (specindex == 0) return false;

	/* Check all tiles over the station to check if the specindex is still in use */
	BEGIN_TILE_LOOP(tile, st->trainst_w, st->trainst_h, st->train_tile) {
		if (IsTileType(tile, MP_STATION) && GetStationIndex(tile) == st->index && IsRailwayStation(tile) && GetCustomStationSpecIndex(tile) == specindex) {
			freeable = false;
			break;
		}
	} END_TILE_LOOP(tile, st->trainst_w, st->trainst_h, st->train_tile)

	if (freeable) {
		/* This specindex is no longer in use, so deallocate it */
		st->speclist[specindex].spec     = NULL;
		st->speclist[specindex].grfid    = 0;
		st->speclist[specindex].localidx = 0;

		/* If this was the highest spec index, reallocate */
		if (specindex == st->num_specs - 1) {
			for (; st->speclist[st->num_specs - 1].grfid == 0 && st->num_specs > 1; st->num_specs--);

			if (st->num_specs > 1) {
				st->speclist = realloc(st->speclist, st->num_specs * sizeof(*st->speclist));
			} else {
				free(st->speclist);
				st->num_specs = 0;
				st->speclist  = NULL;
			}
		}
	}

	return freeable;
}