#ifndef SPRITE_H
#define SPRITE_H


/* The following describes bunch of sprites to be drawn together in a single 3D
 * bounding box. Used especially for various multi-sprite buildings (like
 * depots or stations): */

typedef struct DrawTileSeqStruct {
	int8 delta_x; // 0x80 is sequence terminator
	int8 delta_y;
	int8 delta_z;
	byte width,height;
	byte unk; // 'depth', just z-size; TODO: rename
	uint32 image;
} DrawTileSeqStruct;

typedef struct DrawTileSprites {
	SpriteID ground_sprite;
	DrawTileSeqStruct const *seq;
} DrawTileSprites;

// Iterate through all DrawTileSeqStructs in DrawTileSprites.
#define foreach_draw_tile_seq(idx, list) for (idx = list; ((byte) idx->delta_x) != 0x80; idx++)


/* This is for custom sprites: */


struct SpriteGroup;

struct RealSpriteGroup {
	// XXX: Would anyone ever need more than 16 spritesets? Maybe we should
	// use even less, now we take whole 8kb for custom sprites table, oh my!
	byte sprites_per_set; // means number of directions - 4 or 8

	// Loaded = in motion, loading = not moving
	// Each group contains several spritesets, for various loading stages

	// XXX: For stations the meaning is different - loaded is for stations
	// with small amount of cargo whilst loading is for stations with a lot
	// of da stuff.

	byte loaded_count;
	uint16 loaded[16]; // sprite ids
	byte loading_count;
	uint16 loading[16]; // sprite ids
};

/* Shared by deterministic and random groups. */
enum VarSpriteGroupScope {
	VSG_SCOPE_SELF,
	// Engine of consists for vehicles, city for stations.
	VSG_SCOPE_PARENT,
};

struct DeterministicSpriteGroupRanges;

struct DeterministicSpriteGroup {
	// Take this variable:
	enum VarSpriteGroupScope var_scope;
	byte variable;

	// Do this with it:
	byte shift_num;
	byte and_mask;

	// Then do this with it:
	enum DeterministicSpriteGroupOperation {
		DSG_OP_NONE,
		DSG_OP_DIV,
		DSG_OP_MOD,
	} operation;
	byte add_val;
	byte divmod_val;
	
	// And apply it to this:
	byte num_ranges;
	struct DeterministicSpriteGroupRange *ranges; // Dynamically allocated

	// Dynamically allocated, this is the sole owner
	struct SpriteGroup *default_group;
};

struct SpriteGroup {
	enum SpriteGroupType {
		SGT_REAL,
		SGT_DETERMINISTIC,
		SGT_RANDOM, /* TODO */
	} type;

	union {
		struct RealSpriteGroup real;
		struct DeterministicSpriteGroup determ;
	} g;
};

struct DeterministicSpriteGroupRange {
	struct SpriteGroup group;
	byte low;
	byte high;
};

/* This is a temporary helper for SpriteGroup users not supporting variational
 * sprite groups yet - it just traverses those cowardly, always taking the
 * default choice until it hits a real sprite group, returning it. */
static struct RealSpriteGroup *TriviallyGetRSG(struct SpriteGroup *sg);
/* This takes value (probably of the variable specified in the group) and
 * chooses corresponding SpriteGroup accordingly to the given
 * DeterministicSpriteGroup. */
struct SpriteGroup *EvalDeterministicSpriteGroup(struct DeterministicSpriteGroup *dsg, int value);
/* Get value of a common deterministic SpriteGroup variable. */
int GetDeterministicSpriteValue(byte var);



/**** Inline functions ****/

static INLINE struct RealSpriteGroup *TriviallyGetRSG(struct SpriteGroup *sg)
{
	if (sg->type == SGT_REAL)
		return &sg->g.real;
	return TriviallyGetRSG(sg->g.determ.default_group);
}

#endif