#include "cache.h"
#include "object.h"
#include "blob.h"
#include "tree.h"
#include "commit.h"
#include "tag.h"

static struct object **obj_hash;
static int nr_objs, obj_hash_size;

unsigned int get_max_object_index(void)
{
        return obj_hash_size;
}

struct object *get_indexed_object(unsigned int idx)
{
        return obj_hash[idx];
}

static const char *object_type_strings[] = {
        NULL,           /* OBJ_NONE = 0 */
        "commit",       /* OBJ_COMMIT = 1 */
        "tree",         /* OBJ_TREE = 2 */
        "blob",         /* OBJ_BLOB = 3 */
        "tag",          /* OBJ_TAG = 4 */
};

const char *typename(unsigned int type)
{
        if (type >= ARRAY_SIZE(object_type_strings))
                return NULL;
        return object_type_strings[type];
}

int type_from_string(const char *str)
{
        int i;

        for (i = 1; i < ARRAY_SIZE(object_type_strings); i++)
                if (!strcmp(str, object_type_strings[i]))
                        return i;
        die("invalid object type \"%s\"", str);
}

/*
 * Return a numerical hash value between 0 and n-1 for the object with
 * the specified sha1.  n must be a power of 2.  Please note that the
 * return value is *not* consistent across computer architectures.
 */
static unsigned int hash_obj(const unsigned char *sha1, unsigned int n)
{
        unsigned int hash;

        /*
         * Since the sha1 is essentially random, we just take the
         * required number of bits directly from the first
         * sizeof(unsigned int) bytes of sha1.  First we have to copy
         * the bytes into a properly aligned integer.  If we cared
         * about getting consistent results across architectures, we
         * would have to call ntohl() here, too.
         */
        memcpy(&hash, sha1, sizeof(unsigned int));
        return hash & (n - 1);
}

/*
 * Insert obj into the hash table hash, which has length size (which
 * must be a power of 2).  On collisions, simply overflow to the next
 * empty bucket.
 */
static void insert_obj_hash(struct object *obj, struct object **hash, unsigned int size)
{
        unsigned int j = hash_obj(obj->sha1, size);

        while (hash[j]) {
                j++;
                if (j >= size)
                        j = 0;
        }
        hash[j] = obj;
}

/*
 * Look up the record for the given sha1 in the hash map stored in
 * obj_hash.  Return NULL if it was not found.
 */
struct object *lookup_object(const unsigned char *sha1)
{
        unsigned int i, first;
        struct object *obj;

        if (!obj_hash)
                return NULL;

        first = i = hash_obj(sha1, obj_hash_size);
        while ((obj = obj_hash[i]) != NULL) {
                if (!hashcmp(sha1, obj->sha1))
                        break;
                i++;
                if (i == obj_hash_size)
                        i = 0;
        }
        if (obj && i != first) {
                /*
                 * Move object to where we started to look for it so
                 * that we do not need to walk the hash table the next
                 * time we look for it.
                 */
                struct object *tmp = obj_hash[i];
                obj_hash[i] = obj_hash[first];
                obj_hash[first] = tmp;
        }
        return obj;
}

/*
 * Increase the size of the hash map stored in obj_hash to the next
 * power of 2 (but at least 32).  Copy the existing values to the new
 * hash map.
 */
static void grow_object_hash(void)
{
        int i;
        /*
         * Note that this size must always be power-of-2 to match hash_obj
         * above.
         */
        int new_hash_size = obj_hash_size < 32 ? 32 : 2 * obj_hash_size;
        struct object **new_hash;

        new_hash = xcalloc(new_hash_size, sizeof(struct object *));
        for (i = 0; i < obj_hash_size; i++) {
                struct object *obj = obj_hash[i];
                if (!obj)
                        continue;
                insert_obj_hash(obj, new_hash, new_hash_size);
        }
        free(obj_hash);
        obj_hash = new_hash;
        obj_hash_size = new_hash_size;
}

void *create_object(const unsigned char *sha1, void *o)
{
        struct object *obj = o;

        obj->parsed = 0;
        obj->used = 0;
        obj->flags = 0;
        hashcpy(obj->sha1, sha1);

        if (obj_hash_size - 1 <= nr_objs * 2)
                grow_object_hash();

        insert_obj_hash(obj, obj_hash, obj_hash_size);
        nr_objs++;
        return obj;
}

void *object_as_type(struct object *obj, enum object_type type, int quiet)
{
        if (obj->type == type)
                return obj;
        else if (obj->type == OBJ_NONE) {
                obj->type = type;
                return obj;
        }
        else {
                if (!quiet)
                        error("object %s is a %s, not a %s",
                              sha1_to_hex(obj->sha1),
                              typename(obj->type), typename(type));
                return NULL;
        }
}

struct object *lookup_unknown_object(const unsigned char *sha1)
{
        struct object *obj = lookup_object(sha1);
        if (!obj)
                obj = create_object(sha1, alloc_object_node());
        return obj;
}

struct object *parse_object_buffer(const unsigned char *sha1, enum object_type type, unsigned long size, void *buffer, int *eaten_p)
{
        struct object *obj;
        *eaten_p = 0;

        obj = NULL;
        if (type == OBJ_BLOB) {
                struct blob *blob = lookup_blob(sha1);
                if (blob) {
                        if (parse_blob_buffer(blob, buffer, size))
                                return NULL;
                        obj = &blob->object;
                }
        } else if (type == OBJ_TREE) {
                struct tree *tree = lookup_tree(sha1);
                if (tree) {
                        obj = &tree->object;
                        if (!tree->buffer)
                                tree->object.parsed = 0;
                        if (!tree->object.parsed) {
                                if (parse_tree_buffer(tree, buffer, size))
                                        return NULL;
                                *eaten_p = 1;
                        }
                }
        } else if (type == OBJ_COMMIT) {
                struct commit *commit = lookup_commit(sha1);
                if (commit) {
                        if (parse_commit_buffer(commit, buffer, size))
                                return NULL;
                        if (!get_cached_commit_buffer(commit, NULL)) {
                                set_commit_buffer(commit, buffer, size);
                                *eaten_p = 1;
                        }
                        obj = &commit->object;
                }
        } else if (type == OBJ_TAG) {
                struct tag *tag = lookup_tag(sha1);
                if (tag) {
                        if (parse_tag_buffer(tag, buffer, size))
                               return NULL;
                        obj = &tag->object;
                }
        } else {
                warning("object %s has unknown type id %d", sha1_to_hex(sha1), type);
                obj = NULL;
        }
        return obj;
}

struct object *parse_object_or_die(const unsigned char *sha1,
                                   const char *name)
{
        struct object *o = parse_object(sha1);
        if (o)
                return o;

        die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
}

struct object *parse_object(const unsigned char *sha1)
{
        unsigned long size;
        enum object_type type;
        int eaten;
        const unsigned char *repl = lookup_replace_object(sha1);
        void *buffer;
        struct object *obj;

        obj = lookup_object(sha1);
        if (obj && obj->parsed)
                return obj;

        if ((obj && obj->type == OBJ_BLOB) ||
            (!obj && has_sha1_file(sha1) &&
             sha1_object_info(sha1, NULL) == OBJ_BLOB)) {
                if (check_sha1_signature(repl, NULL, 0, NULL) < 0) {
                        error("sha1 mismatch %s", sha1_to_hex(repl));
                        return NULL;
                }
                parse_blob_buffer(lookup_blob(sha1), NULL, 0);
                return lookup_object(sha1);
        }

        buffer = read_sha1_file(sha1, &type, &size);
        if (buffer) {
                if (check_sha1_signature(repl, buffer, size, typename(type)) < 0) {
                        free(buffer);
                        error("sha1 mismatch %s", sha1_to_hex(repl));
                        return NULL;
                }

                obj = parse_object_buffer(sha1, type, size, buffer, &eaten);
                if (!eaten)
                        free(buffer);
                return obj;
        }
        return NULL;
}

struct object_list *object_list_insert(struct object *item,
                                       struct object_list **list_p)
{
        struct object_list *new_list = xmalloc(sizeof(struct object_list));
        new_list->item = item;
        new_list->next = *list_p;
        *list_p = new_list;
        return new_list;
}

int object_list_contains(struct object_list *list, struct object *obj)
{
        while (list) {
                if (list->item == obj)
                        return 1;
                list = list->next;
        }
        return 0;
}

/*
 * A zero-length string to which object_array_entry::name can be
 * initialized without requiring a malloc/free.
 */
static char object_array_slopbuf[1];

static void add_object_array_with_mode_context(struct object *obj, const char *name,
                                               struct object_array *array,
                                               unsigned mode,
                                               struct object_context *context)
{
        unsigned nr = array->nr;
        unsigned alloc = array->alloc;
        struct object_array_entry *objects = array->objects;
        struct object_array_entry *entry;

        if (nr >= alloc) {
                alloc = (alloc + 32) * 2;
                objects = xrealloc(objects, alloc * sizeof(*objects));
                array->alloc = alloc;
                array->objects = objects;
        }
        entry = &objects[nr];
        entry->item = obj;
        if (!name)
                entry->name = NULL;
        else if (!*name)
                /* Use our own empty string instead of allocating one: */
                entry->name = object_array_slopbuf;
        else
                entry->name = xstrdup(name);
        entry->mode = mode;
        entry->context = context;
        array->nr = ++nr;
}

void add_object_array(struct object *obj, const char *name, struct object_array *array)
{
        add_object_array_with_mode(obj, name, array, S_IFINVALID);
}

void add_object_array_with_mode(struct object *obj, const char *name, struct object_array *array, unsigned mode)
{
        add_object_array_with_mode_context(obj, name, array, mode, NULL);
}

void add_object_array_with_context(struct object *obj, const char *name, struct object_array *array, struct object_context *context)
{
        if (context)
                add_object_array_with_mode_context(obj, name, array, context->mode, context);
        else
                add_object_array_with_mode_context(obj, name, array, S_IFINVALID, context);
}

void object_array_filter(struct object_array *array,
                         object_array_each_func_t want, void *cb_data)
{
        unsigned nr = array->nr, src, dst;
        struct object_array_entry *objects = array->objects;

        for (src = dst = 0; src < nr; src++) {
                if (want(&objects[src], cb_data)) {
                        if (src != dst)
                                objects[dst] = objects[src];
                        dst++;
                } else {
                        if (objects[src].name != object_array_slopbuf)
                                free(objects[src].name);
                }
        }
        array->nr = dst;
}

/*
 * Return true iff array already contains an entry with name.
 */
static int contains_name(struct object_array *array, const char *name)
{
        unsigned nr = array->nr, i;
        struct object_array_entry *object = array->objects;

        for (i = 0; i < nr; i++, object++)
                if (!strcmp(object->name, name))
                        return 1;
        return 0;
}

void object_array_remove_duplicates(struct object_array *array)
{
        unsigned nr = array->nr, src;
        struct object_array_entry *objects = array->objects;

        array->nr = 0;
        for (src = 0; src < nr; src++) {
                if (!contains_name(array, objects[src].name)) {
                        if (src != array->nr)
                                objects[array->nr] = objects[src];
                        array->nr++;
                } else {
                        if (objects[src].name != object_array_slopbuf)
                                free(objects[src].name);
                }
        }
}

void clear_object_flags(unsigned flags)
{
        int i;

        for (i=0; i < obj_hash_size; i++) {
                struct object *obj = obj_hash[i];
                if (obj)
                        obj->flags &= ~flags;
        }
}