/* $Id$ */

/** @file newgrf_commons.h This file simplyfies and embeds a common mechanism of
 * loading/saving and mapping of grf entities.
 */

#ifndef NEWGRF_COMMONS_H
#define NEWGRF_COMMONS_H

#include "core/bitmath_func.hpp"

#include "table/sprites.h"

/**
 * Maps an entity id stored on the map to a GRF file.
 * Entities are objects used ingame (houses, industries, industry tiles) for
 * which we need to correlate the ids from the grf files with the ones in the
 * the savegames themselves.
 * An array of EntityIDMapping structs is saved with the savegame so
 * that those GRFs can be loaded in a different order, or removed safely. The
 * index in the array is the entity's ID stored on the map.
 *
 * The substitute ID is the ID of an original entity that should be used instead
 * if the GRF containing the new entity is not available.
 */
struct EntityIDMapping {
	uint32 grfid;          ///< The GRF ID of the file the entity belongs to
	uint8  entity_id;      ///< The entity ID within the GRF file
	uint8  substitute_id;  ///< The (original) entity ID to use if this GRF is not available
};

class OverrideManagerBase {
protected:
	uint16 *entity_overrides;
	uint32 *grfid_overrides;

	uint16 max_offset;       ///< what is the length of the original entity's array of specs
	uint16 max_new_entities; ///< what is the amount of entities, old and new summed

	uint16 invalid_ID;       ///< ID used to dected invalid entities;
	virtual bool CheckValidNewID(uint16 testid) { return true; }

public:
	EntityIDMapping *mapping_ID; ///< mapping of ids from grf files.  Public out of convenience

	OverrideManagerBase(uint16 offset, uint16 maximum, uint16 invalid);
	virtual ~OverrideManagerBase();

	void ResetOverride();
	void ResetMapping();

	void Add(uint8 local_id, uint32 grfid, uint entity_type);
	virtual uint16 AddEntityID(byte grf_local_id, uint32 grfid, byte substitute_id);

	uint16 GetSubstituteID(byte entity_id);
	virtual uint16 GetID(uint8 grf_local_id, uint32 grfid);

	inline uint16 GetMaxMapping() { return max_new_entities; }
	inline uint16 GetMaxOffset() { return max_offset; }
};


struct HouseSpec;
class HouseOverrideManager : public OverrideManagerBase {
public:
	HouseOverrideManager(uint16 offset, uint16 maximum, uint16 invalid) :
			OverrideManagerBase(offset, maximum, invalid) {}
	void SetEntitySpec(const HouseSpec *hs);
};


struct IndustrySpec;
class IndustryOverrideManager : public OverrideManagerBase {
public:
	IndustryOverrideManager(uint16 offset, uint16 maximum, uint16 invalid) :
			OverrideManagerBase(offset, maximum, invalid) {}

	virtual uint16 AddEntityID(byte grf_local_id, uint32 grfid, byte substitute_id);
	virtual uint16 GetID(uint8 grf_local_id, uint32 grfid);
	void SetEntitySpec(IndustrySpec *inds);
};


struct IndustryTileSpec;
class IndustryTileOverrideManager : public OverrideManagerBase {
protected:
	virtual bool CheckValidNewID(uint16 testid) { return testid != 0xFF; }
public:
	IndustryTileOverrideManager(uint16 offset, uint16 maximum, uint16 invalid) :
			OverrideManagerBase(offset, maximum, invalid) {}

	void SetEntitySpec(const IndustryTileSpec *indts);
};

extern HouseOverrideManager _house_mngr;
extern IndustryOverrideManager _industry_mngr;
extern IndustryTileOverrideManager _industile_mngr;

uint32 GetTerrainType(TileIndex tile);
TileIndex GetNearbyTile(byte parameter, TileIndex tile);
uint32 GetNearbyTileInformation(TileIndex tile);

/**
 * Applies PALETTE_MODIFIER_TRANSPARENT and PALETTE_MODIFIER_COLOUR to a palette entry of a sprite layout entry
 * @Note for ground sprites use #GroundSpritePaletteTransform
 * @Note Not useable for OTTD internal spritelayouts from table/xxx_land.h as PALETTE_MODIFIER_TRANSPARENT is only set
 *       when to use the default palette.
 *
 * @param image The sprite to draw
 * @param pal The palette from the sprite layout
 * @param default_pal The default recolour sprite to use (typically company colour resp. random industry/house colour)
 * @return The palette to use
 */
static inline SpriteID SpriteLayoutPaletteTransform(SpriteID image, SpriteID pal, SpriteID default_pal)
{
	if (HasBit(image, PALETTE_MODIFIER_TRANSPARENT) || HasBit(image, PALETTE_MODIFIER_COLOUR)) {
		return (pal != 0 ? pal : default_pal);
	} else {
		return PAL_NONE;
	}
}

/**
 * Applies PALETTE_MODIFIER_COLOUR to a palette entry of a ground sprite
 * @Note Not useable for OTTD internal spritelayouts from table/xxx_land.h as PALETTE_MODIFIER_TRANSPARENT is only set
 *       when to use the default palette.
 *
 * @param image The sprite to draw
 * @param pal The palette from the sprite layout
 * @param default_pal The default recolour sprite to use (typically company colour resp. random industry/house colour)
 * @return The palette to use
 */
static inline SpriteID GroundSpritePaletteTransform(SpriteID image, SpriteID pal, SpriteID default_pal)
{
	if (HasBit(image, PALETTE_MODIFIER_COLOUR)) {
		return (pal != 0 ? pal : default_pal);
	} else {
		return PAL_NONE;
	}
}

#endif /* NEWGRF_COMMONS_H */