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

struct object **objs;
static int nr_objs;
int obj_allocs;

int track_object_refs = 1;

static int hashtable_index(const unsigned char *sha1)
{
        unsigned int i;
        memcpy(&i, sha1, sizeof(unsigned int));
        return (int)(i % obj_allocs);
}

static int find_object(const unsigned char *sha1)
{
        int i;

        if (!objs)
                return -1;

        i = hashtable_index(sha1);
        while (objs[i]) {
                if (memcmp(sha1, objs[i]->sha1, 20) == 0)
                        return i;
                i++;
                if (i == obj_allocs)
                        i = 0;
        }
        return -1 - i;
}

struct object *lookup_object(const unsigned char *sha1)
{
        int pos = find_object(sha1);
        if (pos >= 0)
                return objs[pos];
        return NULL;
}

void created_object(const unsigned char *sha1, struct object *obj)
{
        int pos;

        obj->parsed = 0;
        memcpy(obj->sha1, sha1, 20);
        obj->type = NULL;
        obj->refs = NULL;
        obj->used = 0;

        if (obj_allocs - 1 <= nr_objs * 2) {
                int i, count = obj_allocs;
                obj_allocs = (obj_allocs < 32 ? 32 : 2 * obj_allocs);
                objs = xrealloc(objs, obj_allocs * sizeof(struct object *));
                memset(objs + count, 0, (obj_allocs - count)
                                * sizeof(struct object *));
                for (i = 0; i < obj_allocs; i++)
                        if (objs[i]) {
                                int j = find_object(objs[i]->sha1);
                                if (j != i) {
                                        j = -1 - j;
                                        objs[j] = objs[i];
                                        objs[i] = NULL;
                                }
                        }
        }

        pos = find_object(sha1);
        if (pos >= 0)
                die("Inserting %s twice\n", sha1_to_hex(sha1));
        pos = -pos-1;

        objs[pos] = obj;
        nr_objs++;
}

struct object_refs *alloc_object_refs(unsigned count)
{
        struct object_refs *refs;
        size_t size = sizeof(*refs) + count*sizeof(struct object *);

        refs = xcalloc(1, size);
        refs->count = count;
        return refs;
}

static int compare_object_pointers(const void *a, const void *b)
{
        const struct object * const *pa = a;
        const struct object * const *pb = b;
        if (*pa == *pb)
                return 0;
        else if (*pa < *pb)
                return -1;
        else
                return 1;
}

void set_object_refs(struct object *obj, struct object_refs *refs)
{
        unsigned int i, j;

        /* Do not install empty list of references */
        if (refs->count < 1) {
                free(refs);
                return;
        }

        /* Sort the list and filter out duplicates */
        qsort(refs->ref, refs->count, sizeof(refs->ref[0]),
              compare_object_pointers);
        for (i = j = 1; i < refs->count; i++) {
                if (refs->ref[i] != refs->ref[i - 1])
                        refs->ref[j++] = refs->ref[i];
        }
        if (j < refs->count) {
                /* Duplicates were found - reallocate list */
                size_t size = sizeof(*refs) + j*sizeof(struct object *);
                refs->count = j;
                refs = xrealloc(refs, size);
        }

        for (i = 0; i < refs->count; i++)
                refs->ref[i]->used = 1;
        obj->refs = refs;
}

void mark_reachable(struct object *obj, unsigned int mask)
{
        if (!track_object_refs)
                die("cannot do reachability with object refs turned off");
        /* If we've been here already, don't bother */
        if (obj->flags & mask)
                return;
        obj->flags |= mask;
        if (obj->refs) {
                const struct object_refs *refs = obj->refs;
                unsigned i;
                for (i = 0; i < refs->count; i++)
                        mark_reachable(refs->ref[i], mask);
        }
}

struct object *lookup_object_type(const unsigned char *sha1, const char *type)
{
        if (!type) {
                return lookup_unknown_object(sha1);
        } else if (!strcmp(type, blob_type)) {
                return &lookup_blob(sha1)->object;
        } else if (!strcmp(type, tree_type)) {
                return &lookup_tree(sha1)->object;
        } else if (!strcmp(type, commit_type)) {
                return &lookup_commit(sha1)->object;
        } else if (!strcmp(type, tag_type)) {
                return &lookup_tag(sha1)->object;
        } else {
                error("Unknown type %s", type);
                return NULL;
        }
}

union any_object {
        struct object object;
        struct commit commit;
        struct tree tree;
        struct blob blob;
        struct tag tag;
};

struct object *lookup_unknown_object(const unsigned char *sha1)
{
        struct object *obj = lookup_object(sha1);
        if (!obj) {
                union any_object *ret = xcalloc(1, sizeof(*ret));
                created_object(sha1, &ret->object);
                ret->object.type = NULL;
                return &ret->object;
        }
        return obj;
}

struct object *parse_object(const unsigned char *sha1)
{
        unsigned long size;
        char type[20];
        void *buffer = read_sha1_file(sha1, type, &size);
        if (buffer) {
                struct object *obj;
                if (check_sha1_signature(sha1, buffer, size, type) < 0)
                        printf("sha1 mismatch %s\n", sha1_to_hex(sha1));
                if (!strcmp(type, blob_type)) {
                        struct blob *blob = lookup_blob(sha1);
                        parse_blob_buffer(blob, buffer, size);
                        obj = &blob->object;
                } else if (!strcmp(type, tree_type)) {
                        struct tree *tree = lookup_tree(sha1);
                        parse_tree_buffer(tree, buffer, size);
                        obj = &tree->object;
                } else if (!strcmp(type, commit_type)) {
                        struct commit *commit = lookup_commit(sha1);
                        parse_commit_buffer(commit, buffer, size);
                        if (!commit->buffer) {
                                commit->buffer = buffer;
                                buffer = NULL;
                        }
                        obj = &commit->object;
                } else if (!strcmp(type, tag_type)) {
                        struct tag *tag = lookup_tag(sha1);
                        parse_tag_buffer(tag, buffer, size);
                        obj = &tag->object;
                } else {
                        obj = NULL;
                }
                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;
}

void object_list_append(struct object *item,
                        struct object_list **list_p)
{
        while (*list_p) {
                list_p = &((*list_p)->next);
        }
        *list_p = xmalloc(sizeof(struct object_list));
        (*list_p)->next = NULL;
        (*list_p)->item = item;
}

unsigned object_list_length(struct object_list *list)
{
        unsigned ret = 0;
        while (list) {
                list = list->next;
                ret++;
        }
        return ret;
}

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