#ifndef PACK_OBJECTS_H
#define PACK_OBJECTS_H

#define OE_DFS_STATE_BITS	2
#define OE_DEPTH_BITS		12
#define OE_IN_PACK_BITS		14
#define OE_Z_DELTA_BITS		16

/*
 * State flags for depth-first search used for analyzing delta cycles.
 *
 * The depth is measured in delta-links to the base (so if A is a delta
 * against B, then A has a depth of 1, and B a depth of 0).
 */
enum dfs_state {
	DFS_NONE = 0,
	DFS_ACTIVE,
	DFS_DONE,
	DFS_NUM_STATES
};

/*
 * The size of struct nearly determines pack-objects's memory
 * consumption. This struct is packed tight for that reason. When you
 * add or reorder something in this struct, think a bit about this.
 *
 * basic object info
 * -----------------
 * idx.oid is filled up before delta searching starts. idx.crc32 and
 * is only valid after the object is written down and will be used for
 * generating the index. idx.offset will be both gradually set and
 * used in writing phase (base objects get offset first, then deltas
 * refer to them)
 *
 * "size" is the uncompressed object size. Compressed size is not
 * cached (ie. raw data in a pack) but available via revindex.
 *
 * "hash" contains a path name hash which is used for sorting the
 * delta list and also during delta searching. Once prepare_pack()
 * returns it's no longer needed.
 *
 * source pack info
 * ----------------
 * The (in_pack, in_pack_offset, in_pack_header_size) tuple contains
 * the location of the object in the source pack, with or without
 * header.
 *
 * "type" and "in_pack_type" both describe object type. in_pack_type
 * may contain a delta type, while type is always the canonical type.
 *
 * deltas
 * ------
 * Delta links (delta, delta_child and delta_sibling) are created
 * reflect that delta graph from the source pack then updated or added
 * during delta searching phase when we find better deltas.
 *
 * delta_child and delta_sibling are last needed in
 * compute_write_order(). "delta" and "delta_size" must remain valid
 * at object writing phase in case the delta is not cached.
 *
 * If a delta is cached in memory and is compressed, "delta" points to
 * the data and z_delta_size contains the compressed size. If it's
 * uncompressed [1], z_delta_size must be zero. delta_size is always
 * the uncompressed size and must be valid even if the delta is not
 * cached. Delta recreation technically only depends on "delta"
 * pointer, but delta_size is still used to verify it's the same as
 * before.
 *
 * [1] during try_delta phase we don't bother with compressing because
 * the delta could be quickly replaced with a better one.
 */
struct object_entry {
	struct pack_idx_entry idx;
	unsigned long size;	/* uncompressed size */
	off_t in_pack_offset;
	uint32_t delta_idx;	/* delta base object */
	uint32_t delta_child_idx; /* deltified objects who bases me */
	uint32_t delta_sibling_idx; /* other deltified objects who
				     * uses the same base as me
				     */
	uint32_t hash;			/* name hint hash */
	void *delta_data;	/* cached delta (uncompressed) */
	unsigned long delta_size;	/* delta data size (uncompressed) */
	unsigned char in_pack_header_size; /* note: spare bits available! */
	unsigned in_pack_idx:OE_IN_PACK_BITS;	/* already in pack */
	unsigned type:TYPE_BITS;
	unsigned in_pack_type:TYPE_BITS; /* could be delta */
	unsigned preferred_base:1; /*
				    * we do not pack this, but is available
				    * to be used as the base object to delta
				    * objects against.
				    */
	unsigned no_try_delta:1;
	unsigned tagged:1; /* near the very tip of refs */
	unsigned filled:1; /* assigned write-order */

	/* XXX 8 bits hole, try to pack */

	unsigned dfs_state:OE_DFS_STATE_BITS;
	unsigned depth:OE_DEPTH_BITS;
	/*
	 * if delta_data contains a compressed delta, this contains
	 * the compressed length
	*/
	unsigned z_delta_size:OE_Z_DELTA_BITS;

	/* size: 88, bit_padding: 2 bits */
};

struct packing_data {
	struct object_entry *objects;
	uint32_t nr_objects, nr_alloc;

	int32_t *index;
	uint32_t index_size;

	unsigned int *in_pack_pos;
	int in_pack_count;
	struct packed_git *in_pack[1 << OE_IN_PACK_BITS];
};

struct object_entry *packlist_alloc(struct packing_data *pdata,
				    const unsigned char *sha1,
				    uint32_t index_pos);

struct object_entry *packlist_find(struct packing_data *pdata,
				   const unsigned char *sha1,
				   uint32_t *index_pos);

static inline uint32_t pack_name_hash(const char *name)
{
	uint32_t c, hash = 0;

	if (!name)
		return 0;

	/*
	 * This effectively just creates a sortable number from the
	 * last sixteen non-whitespace characters. Last characters
	 * count "most", so things that end in ".c" sort together.
	 */
	while ((c = *name++) != 0) {
		if (isspace(c))
			continue;
		hash = (hash >> 2) + (c << 24);
	}
	return hash;
}

static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
					  const struct object_entry *e)
{
	return pack->in_pack_pos[e - pack->objects];
}

static inline void oe_set_in_pack_pos(const struct packing_data *pack,
				      const struct object_entry *e,
				      unsigned int pos)
{
	pack->in_pack_pos[e - pack->objects] = pos;
}

static inline unsigned int oe_add_pack(struct packing_data *pack,
				       struct packed_git *p)
{
	if (pack->in_pack_count >= (1 << OE_IN_PACK_BITS))
		die(_("too many packs to handle in one go. "
		      "Please add .keep files to exclude\n"
		      "some pack files and keep the number "
		      "of non-kept files below %d."),
		    1 << OE_IN_PACK_BITS);
	if (p) {
		if (p->index > 0)
			die("BUG: this packed is already indexed");
		p->index = pack->in_pack_count;
	}
	pack->in_pack[pack->in_pack_count] = p;
	return pack->in_pack_count++;
}

static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
					    const struct object_entry *e)
{
	return pack->in_pack[e->in_pack_idx];

}

static inline void oe_set_in_pack(struct object_entry *e,
				  struct packed_git *p)
{
	if (p->index <= 0)
		die("BUG: found_pack should be NULL "
		    "instead of having non-positive index");
	e->in_pack_idx = p->index;

}

static inline struct object_entry *oe_delta(
		const struct packing_data *pack,
		const struct object_entry *e)
{
	if (e->delta_idx)
		return &pack->objects[e->delta_idx - 1];
	return NULL;
}

static inline void oe_set_delta(struct packing_data *pack,
				struct object_entry *e,
				struct object_entry *delta)
{
	if (delta)
		e->delta_idx = (delta - pack->objects) + 1;
	else
		e->delta_idx = 0;
}

static inline struct object_entry *oe_delta_child(
		const struct packing_data *pack,
		const struct object_entry *e)
{
	if (e->delta_child_idx)
		return &pack->objects[e->delta_child_idx - 1];
	return NULL;
}

static inline void oe_set_delta_child(struct packing_data *pack,
				      struct object_entry *e,
				      struct object_entry *delta)
{
	if (delta)
		e->delta_child_idx = (delta - pack->objects) + 1;
	else
		e->delta_child_idx = 0;
}

static inline struct object_entry *oe_delta_sibling(
		const struct packing_data *pack,
		const struct object_entry *e)
{
	if (e->delta_sibling_idx)
		return &pack->objects[e->delta_sibling_idx - 1];
	return NULL;
}

static inline void oe_set_delta_sibling(struct packing_data *pack,
					struct object_entry *e,
					struct object_entry *delta)
{
	if (delta)
		e->delta_sibling_idx = (delta - pack->objects) + 1;
	else
		e->delta_sibling_idx = 0;
}

#endif