#ifndef PACK_OBJECTS_H
#define PACK_OBJECTS_H

#include "object-store.h"

#define OE_DFS_STATE_BITS       2
#define OE_DEPTH_BITS           12
#define OE_IN_PACK_BITS         10

/*
 * 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
};

/*
 * basic object info
 * -----------------
 * idx.oid is filled up before delta searching starts. idx.crc32 is
 * only valid after the object is written out 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 of the raw
 * data for an object in a pack is not stored anywhere but is computed
 * and made available when reverse .idx is made.
 *
 * "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) tuple contains the location of the
 * object in the source pack. in_pack_header_size allows quickly
 * skipping the header and going straight to the zlib stream.
 *
 * "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 to
 * 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_data 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.
 *
 * [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 */
        unsigned in_pack_idx:OE_IN_PACK_BITS;   /* already in pack */
        off_t in_pack_offset;
        struct object_entry *delta;     /* delta base object */
        struct object_entry *delta_child; /* deltified objects who bases me */
        struct object_entry *delta_sibling; /* other deltified objects who
                                             * uses the same base as me
                                             */
        void *delta_data;       /* cached delta (uncompressed) */
        unsigned long delta_size;       /* delta data size (uncompressed) */
        unsigned long z_delta_size;     /* delta data size (compressed) */
        unsigned type_:TYPE_BITS;
        unsigned in_pack_type:TYPE_BITS; /* could be delta */
        unsigned type_valid:1;
        uint32_t hash;                  /* name hint hash */
        unsigned char in_pack_header_size;
        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 */
        unsigned dfs_state:OE_DFS_STATE_BITS;
        unsigned depth:OE_DEPTH_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;

        /*
         * Only one of these can be non-NULL and they have different
         * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
         * the pack of an object using in_pack_idx field. If not,
         * in_pack[] array is used the same way as in_pack_pos[]
         */
        struct packed_git **in_pack_by_idx;
        struct packed_git **in_pack;
};

void prepare_packing_data(struct packing_data *pdata);
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 enum object_type oe_type(const struct object_entry *e)
{
        return e->type_valid ? e->type_ : OBJ_BAD;
}

static inline void oe_set_type(struct object_entry *e,
                               enum object_type type)
{
        if (type >= OBJ_ANY)
                BUG("OBJ_ANY cannot be set in pack-objects code");

        e->type_valid = type >= OBJ_NONE;
        e->type_ = (unsigned)type;
}

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 struct packed_git *oe_in_pack(const struct packing_data *pack,
                                            const struct object_entry *e)
{
        if (pack->in_pack_by_idx)
                return pack->in_pack_by_idx[e->in_pack_idx];
        else
                return pack->in_pack[e - pack->objects];
}

void oe_map_new_pack(struct packing_data *pack,
                     struct packed_git *p);
static inline void oe_set_in_pack(struct packing_data *pack,
                                  struct object_entry *e,
                                  struct packed_git *p)
{
        if (!p->index)
                oe_map_new_pack(pack, p);
        if (pack->in_pack_by_idx)
                e->in_pack_idx = p->index;
        else
                pack->in_pack[e - pack->objects] = p;
}

#endif