/* $Id$ */

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

#include "stdafx.h"
#include "openttd.h"
#include "debug.h"
#include "sprite.h"
#include "table/strings.h"
#include "station.h"
#include "station_map.h"
#include "newgrf_station.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;
}

static const RealSpriteGroup *ResolveStationSpriteGroup(const SpriteGroup *spg, const Station *st)
{
	if (spg == NULL) return NULL;
	switch (spg->type) {
		case SGT_REAL:
			return &spg->g.real;

		case SGT_DETERMINISTIC: {
			const DeterministicSpriteGroup *dsg = &spg->g.determ;
			SpriteGroup *target;
			int value = -1;
			byte variable = dsg->adjusts[0].variable;

			if ((variable >> 6) == 0) {
				/* General property */
				value = GetDeterministicSpriteValue(variable);
			} else {
				if (st == NULL) {
					/* We are in a build dialog of something,
					 * and we are checking for something undefined.
					 * That means we should get the first target
					 * (NOT the default one). */
					if (dsg->num_ranges > 0) {
						target = dsg->ranges[0].group;
					} else {
						target = dsg->default_group;
					}
					return ResolveStationSpriteGroup(target, NULL);
				}

				/* Station-specific property. */
				if (dsg->var_scope == VSG_SCOPE_PARENT) {
					/* TODO: Town structure. */

				} else /* VSG_SELF */ {
					if (variable == 0x40 || variable == 0x41) {
						/* FIXME: This is ad hoc only
						 * for waypoints. */
						value = 0x01010000;
					} else {
						/* TODO: Only small fraction done. */
						// TTDPatch runs on little-endian arch;
						// Variable is 0x70 + offset in the TTD's station structure
						switch (variable - 0x70) {
							case 0x80: value = st->facilities;             break;
							case 0x81: value = st->airport_type;           break;
							case 0x82: value = st->truck_stops->status;    break;
							case 0x83: value = st->bus_stops->status;      break;
							case 0x86: value = st->airport_flags & 0xFFFF; break;
							case 0x87: value = st->airport_flags & 0xFF;   break;
							case 0x8A: value = st->build_date;             break;
						}
					}
				}
			}

			target = value != -1 ? EvalDeterministicSpriteGroup(dsg, value) : dsg->default_group;
			return ResolveStationSpriteGroup(target, st);
		}

		default:
		case SGT_RANDOMIZED:
			DEBUG(grf, 6)("I don't know how to handle random spritegroups yet!");
			return NULL;
	}
}

SpriteID GetCustomStationRelocation(const StationSpec *statspec, const Station *st, TileIndex tile, byte ctype)
{
	const RealSpriteGroup *rsg = ResolveStationSpriteGroup(statspec->spritegroup[ctype], st);
	if (rsg == NULL) return 0;

	if (rsg->num_loading != 0) return rsg->loading[0]->g.result.sprite;
	if (rsg->num_loaded  != 0) return rsg->loaded[0]->g.result.sprite;

	DEBUG(grf, 6)("Custom station 0x%08x::0x%02x has no sprites associated.",
		statspec->grfid, statspec->localidx);
	/* This is what gets subscribed of dtss->image in newgrf.c,
	 * so it's probably kinda "default offset". Try to use it as
	 * emergency measure. */
	return 0;
}


/**
 * 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;
}