#include "cache.h"
#include "commit.h"
#include "tag.h"
#include "refs.h"
#include "diff.h"
#include "diffcore.h"
#include "revision.h"
#include "builtin.h"

static const char describe_usage[] =
"git-describe [--all] [--tags] [--abbrev=<n>] <committish>*";

static int all; /* Default to annotated tags only */
static int tags;        /* But allow any tags if --tags is specified */
static int abbrev = DEFAULT_ABBREV;

static unsigned int names[256], allocs[256];
static struct commit_name {
        struct commit *commit;
        int prio; /* annotated tag = 2, tag = 1, head = 0 */
        char path[FLEX_ARRAY]; /* more */
} **name_array[256];

static struct commit_name *match(struct commit *cmit)
{
        unsigned char m = cmit->object.sha1[0];
        unsigned int i = names[m];
        struct commit_name **p = name_array[m];

        while (i-- > 0) {
                struct commit_name *n = *p++;
                if (n->commit == cmit)
                        return n;
        }
        return NULL;
}

static void add_to_known_names(const char *path,
                               struct commit *commit,
                               int prio)
{
        int idx;
        int len = strlen(path)+1;
        struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
        unsigned char m = commit->object.sha1[0];

        name->commit = commit;
        name->prio = prio;
        memcpy(name->path, path, len);
        idx = names[m];
        if (idx >= allocs[m]) {
                allocs[m] = (idx + 50) * 3 / 2;
                name_array[m] = xrealloc(name_array[m],
                        allocs[m] * sizeof(*name_array));
        }
        name_array[m][idx] = name;
        names[m] = ++idx;
}

static int get_name(const char *path, const unsigned char *sha1, int flag, void *cb_data)
{
        struct commit *commit = lookup_commit_reference_gently(sha1, 1);
        struct object *object;
        int prio;

        if (!commit)
                return 0;
        object = parse_object(sha1);
        /* If --all, then any refs are used.
         * If --tags, then any tags are used.
         * Otherwise only annotated tags are used.
         */
        if (!strncmp(path, "refs/tags/", 10)) {
                if (object->type == OBJ_TAG)
                        prio = 2;
                else
                        prio = 1;
        }
        else
                prio = 0;

        if (!all) {
                if (!prio)
                        return 0;
                if (!tags && prio < 2)
                        return 0;
        }
        add_to_known_names(all ? path + 5 : path + 10, commit, prio);
        return 0;
}

static int compare_names(const void *_a, const void *_b)
{
        struct commit_name *a = *(struct commit_name **)_a;
        struct commit_name *b = *(struct commit_name **)_b;
        unsigned long a_date = a->commit->date;
        unsigned long b_date = b->commit->date;

        if (a->prio != b->prio)
                return b->prio - a->prio;
        return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
}

struct possible_tag {
        struct possible_tag *next;
        struct commit_name *name;
        unsigned long depth;
};

static void describe(const char *arg, int last_one)
{
        unsigned char sha1[20];
        struct commit *cmit;
        struct commit_list *list;
        static int initialized = 0;
        struct commit_name *n;
        struct possible_tag *all_matches, *min_match, *cur_match;

        if (get_sha1(arg, sha1))
                die("Not a valid object name %s", arg);
        cmit = lookup_commit_reference(sha1);
        if (!cmit)
                die("%s is not a valid '%s' object", arg, commit_type);

        if (!initialized) {
                unsigned int m;
                initialized = 1;
                for_each_ref(get_name, NULL);
                for (m = 0; m < ARRAY_SIZE(name_array); m++)
                        qsort(name_array[m], names[m],
                                sizeof(*name_array[m]), compare_names);
        }

        n = match(cmit);
        if (n) {
                printf("%s\n", n->path);
                return;
        }

        list = NULL;
        all_matches = NULL;
        cur_match = NULL;
        commit_list_insert(cmit, &list);
        while (list) {
                struct commit *c = pop_commit(&list);
                struct commit_list *parents = c->parents;
                n = match(c);
                if (n) {
                        struct possible_tag *p = xmalloc(sizeof(*p));
                        p->name = n;
                        p->next = NULL;
                        if (cur_match)
                                cur_match->next = p;
                        else
                                all_matches = p;
                        cur_match = p;
                        if (n->prio == 2)
                                continue;
                }
                while (parents) {
                        struct commit *p = parents->item;
                        parse_commit(p);
                        if (!(p->object.flags & SEEN)) {
                                p->object.flags |= SEEN;
                                insert_by_date(p, &list);
                        }
                        parents = parents->next;
                }
        }

        if (!all_matches)
                die("cannot describe '%s'", sha1_to_hex(cmit->object.sha1));

        min_match = NULL;
        for (cur_match = all_matches; cur_match; cur_match = cur_match->next) {
                struct rev_info revs;
                struct commit *tagged = cur_match->name->commit;

                clear_commit_marks(cmit, -1);
                init_revisions(&revs, NULL);
                tagged->object.flags |= UNINTERESTING;
                add_pending_object(&revs, &tagged->object, NULL);
                add_pending_object(&revs, &cmit->object, NULL);

                prepare_revision_walk(&revs);
                cur_match->depth = 0;
                while ((!min_match || cur_match->depth < min_match->depth)
                        && get_revision(&revs))
                        cur_match->depth++;
                if (!min_match || (cur_match->depth < min_match->depth
                        && cur_match->name->prio >= min_match->name->prio))
                        min_match = cur_match;
                free_commit_list(revs.commits);
        }
        printf("%s-g%s\n", min_match->name->path,
                   find_unique_abbrev(cmit->object.sha1, abbrev));

        if (!last_one) {
                for (cur_match = all_matches; cur_match; cur_match = min_match) {
                        min_match = cur_match->next;
                        free(cur_match);
                }
                clear_commit_marks(cmit, SEEN);
        }
}

int cmd_describe(int argc, const char **argv, const char *prefix)
{
        int i;

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];

                if (*arg != '-')
                        break;
                else if (!strcmp(arg, "--all"))
                        all = 1;
                else if (!strcmp(arg, "--tags"))
                        tags = 1;
                else if (!strncmp(arg, "--abbrev=", 9)) {
                        abbrev = strtoul(arg + 9, NULL, 10);
                        if (abbrev < MINIMUM_ABBREV || 40 < abbrev)
                                abbrev = DEFAULT_ABBREV;
                }
                else
                        usage(describe_usage);
        }

        save_commit_buffer = 0;

        if (argc <= i)
                describe("HEAD", 1);
        else
                while (i < argc) {
                        describe(argv[i], (i == argc - 1));
                        i++;
                }

        return 0;
}