#include "builtin.h"
#include "cache.h"
#include "repository.h"
#include "config.h"
#include "commit.h"
#include "tag.h"
#include "refs.h"
#include "parse-options.h"
#include "sha1-lookup.h"
#include "commit-slab.h"

#define CUTOFF_DATE_SLOP 86400 /* one day */

typedef struct rev_name {
        const char *tip_name;
        timestamp_t taggerdate;
        int generation;
        int distance;
        int from_tag;
} rev_name;

define_commit_slab(commit_rev_name, struct rev_name *);

static timestamp_t cutoff = TIME_MAX;
static struct commit_rev_name rev_names;

/* How many generations are maximally preferred over _one_ merge traversal? */
#define MERGE_TRAVERSAL_WEIGHT 65535

static struct rev_name *get_commit_rev_name(struct commit *commit)
{
        struct rev_name **slot = commit_rev_name_peek(&rev_names, commit);

        return slot ? *slot : NULL;
}

static void set_commit_rev_name(struct commit *commit, struct rev_name *name)
{
        *commit_rev_name_at(&rev_names, commit) = name;
}

static int is_better_name(struct rev_name *name,
                          timestamp_t taggerdate,
                          int distance,
                          int from_tag)
{
        /*
         * When comparing names based on tags, prefer names
         * based on the older tag, even if it is farther away.
         */
        if (from_tag && name->from_tag)
                return (name->taggerdate > taggerdate ||
                        (name->taggerdate == taggerdate &&
                         name->distance > distance));

        /*
         * We know that at least one of them is a non-tag at this point.
         * favor a tag over a non-tag.
         */
        if (name->from_tag != from_tag)
                return from_tag;

        /*
         * We are now looking at two non-tags.  Tiebreak to favor
         * shorter hops.
         */
        if (name->distance != distance)
                return name->distance > distance;

        /* ... or tiebreak to favor older date */
        if (name->taggerdate != taggerdate)
                return name->taggerdate > taggerdate;

        /* keep the current one if we cannot decide */
        return 0;
}

static void name_rev(struct commit *commit,
                const char *tip_name, timestamp_t taggerdate,
                int generation, int distance, int from_tag,
                int deref)
{
        struct rev_name *name = get_commit_rev_name(commit);
        struct commit_list *parents;
        int parent_number = 1;
        char *to_free = NULL;

        parse_commit(commit);

        if (commit->date < cutoff)
                return;

        if (deref) {
                tip_name = to_free = xstrfmt("%s^0", tip_name);

                if (generation)
                        die("generation: %d, but deref?", generation);
        }

        if (name == NULL) {
                name = xmalloc(sizeof(rev_name));
                set_commit_rev_name(commit, name);
                goto copy_data;
        } else if (is_better_name(name, taggerdate, distance, from_tag)) {
copy_data:
                name->tip_name = tip_name;
                name->taggerdate = taggerdate;
                name->generation = generation;
                name->distance = distance;
                name->from_tag = from_tag;
        } else {
                free(to_free);
                return;
        }

        for (parents = commit->parents;
                        parents;
                        parents = parents->next, parent_number++) {
                if (parent_number > 1) {
                        size_t len;
                        char *new_name;

                        strip_suffix(tip_name, "^0", &len);
                        if (generation > 0)
                                new_name = xstrfmt("%.*s~%d^%d", (int)len, tip_name,
                                                   generation, parent_number);
                        else
                                new_name = xstrfmt("%.*s^%d", (int)len, tip_name,
                                                   parent_number);

                        name_rev(parents->item, new_name, taggerdate, 0,
                                 distance + MERGE_TRAVERSAL_WEIGHT,
                                 from_tag, 0);
                } else {
                        name_rev(parents->item, tip_name, taggerdate,
                                 generation + 1, distance + 1,
                                 from_tag, 0);
                }
        }
}

static int subpath_matches(const char *path, const char *filter)
{
        const char *subpath = path;

        while (subpath) {
                if (!wildmatch(filter, subpath, 0))
                        return subpath - path;
                subpath = strchr(subpath, '/');
                if (subpath)
                        subpath++;
        }
        return -1;
}

static const char *name_ref_abbrev(const char *refname, int shorten_unambiguous)
{
        if (shorten_unambiguous)
                refname = shorten_unambiguous_ref(refname, 0);
        else if (starts_with(refname, "refs/heads/"))
                refname = refname + 11;
        else if (starts_with(refname, "refs/"))
                refname = refname + 5;
        return refname;
}

struct name_ref_data {
        int tags_only;
        int name_only;
        struct string_list ref_filters;
        struct string_list exclude_filters;
};

static struct tip_table {
        struct tip_table_entry {
                struct object_id oid;
                const char *refname;
        } *table;
        int nr;
        int alloc;
        int sorted;
} tip_table;

static void add_to_tip_table(const struct object_id *oid, const char *refname,
                             int shorten_unambiguous)
{
        refname = name_ref_abbrev(refname, shorten_unambiguous);

        ALLOC_GROW(tip_table.table, tip_table.nr + 1, tip_table.alloc);
        oidcpy(&tip_table.table[tip_table.nr].oid, oid);
        tip_table.table[tip_table.nr].refname = xstrdup(refname);
        tip_table.nr++;
        tip_table.sorted = 0;
}

static int tipcmp(const void *a_, const void *b_)
{
        const struct tip_table_entry *a = a_, *b = b_;
        return oidcmp(&a->oid, &b->oid);
}

static int name_ref(const char *path, const struct object_id *oid, int flags, void *cb_data)
{
        struct object *o = parse_object(the_repository, oid);
        struct name_ref_data *data = cb_data;
        int can_abbreviate_output = data->tags_only && data->name_only;
        int deref = 0;
        timestamp_t taggerdate = TIME_MAX;

        if (data->tags_only && !starts_with(path, "refs/tags/"))
                return 0;

        if (data->exclude_filters.nr) {
                struct string_list_item *item;

                for_each_string_list_item(item, &data->exclude_filters) {
                        if (subpath_matches(path, item->string) >= 0)
                                return 0;
                }
        }

        if (data->ref_filters.nr) {
                struct string_list_item *item;
                int matched = 0;

                /* See if any of the patterns match. */
                for_each_string_list_item(item, &data->ref_filters) {
                        /*
                         * Check all patterns even after finding a match, so
                         * that we can see if a match with a subpath exists.
                         * When a user asked for 'refs/tags/v*' and 'v1.*',
                         * both of which match, the user is showing her
                         * willingness to accept a shortened output by having
                         * the 'v1.*' in the acceptable refnames, so we
                         * shouldn't stop when seeing 'refs/tags/v1.4' matches
                         * 'refs/tags/v*'.  We should show it as 'v1.4'.
                         */
                        switch (subpath_matches(path, item->string)) {
                        case -1: /* did not match */
                                break;
                        case 0: /* matched fully */
                                matched = 1;
                                break;
                        default: /* matched subpath */
                                matched = 1;
                                can_abbreviate_output = 1;
                                break;
                        }
                }

                /* If none of the patterns matched, stop now */
                if (!matched)
                        return 0;
        }

        add_to_tip_table(oid, path, can_abbreviate_output);

        while (o && o->type == OBJ_TAG) {
                struct tag *t = (struct tag *) o;
                if (!t->tagged)
                        break; /* broken repository */
                o = parse_object(the_repository, &t->tagged->oid);
                deref = 1;
                taggerdate = t->date;
        }
        if (o && o->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *)o;
                int from_tag = starts_with(path, "refs/tags/");

                if (taggerdate == TIME_MAX)
                        taggerdate = ((struct commit *)o)->date;
                path = name_ref_abbrev(path, can_abbreviate_output);
                name_rev(commit, xstrdup(path), taggerdate, 0, 0,
                         from_tag, deref);
        }
        return 0;
}

static const unsigned char *nth_tip_table_ent(size_t ix, void *table_)
{
        struct tip_table_entry *table = table_;
        return table[ix].oid.hash;
}

static const char *get_exact_ref_match(const struct object *o)
{
        int found;

        if (!tip_table.table || !tip_table.nr)
                return NULL;

        if (!tip_table.sorted) {
                QSORT(tip_table.table, tip_table.nr, tipcmp);
                tip_table.sorted = 1;
        }

        found = sha1_pos(o->oid.hash, tip_table.table, tip_table.nr,
                         nth_tip_table_ent);
        if (0 <= found)
                return tip_table.table[found].refname;
        return NULL;
}

/* may return a constant string or use "buf" as scratch space */
static const char *get_rev_name(const struct object *o, struct strbuf *buf)
{
        struct rev_name *n;
        struct commit *c;

        if (o->type != OBJ_COMMIT)
                return get_exact_ref_match(o);
        c = (struct commit *) o;
        n = get_commit_rev_name(c);
        if (!n)
                return NULL;

        if (!n->generation)
                return n->tip_name;
        else {
                int len = strlen(n->tip_name);
                if (len > 2 && !strcmp(n->tip_name + len - 2, "^0"))
                        len -= 2;
                strbuf_reset(buf);
                strbuf_addf(buf, "%.*s~%d", len, n->tip_name, n->generation);
                return buf->buf;
        }
}

static void show_name(const struct object *obj,
                      const char *caller_name,
                      int always, int allow_undefined, int name_only)
{
        const char *name;
        const struct object_id *oid = &obj->oid;
        struct strbuf buf = STRBUF_INIT;

        if (!name_only)
                printf("%s ", caller_name ? caller_name : oid_to_hex(oid));
        name = get_rev_name(obj, &buf);
        if (name)
                printf("%s\n", name);
        else if (allow_undefined)
                printf("undefined\n");
        else if (always)
                printf("%s\n", find_unique_abbrev(oid, DEFAULT_ABBREV));
        else
                die("cannot describe '%s'", oid_to_hex(oid));
        strbuf_release(&buf);
}

static char const * const name_rev_usage[] = {
        N_("git name-rev [<options>] <commit>..."),
        N_("git name-rev [<options>] --all"),
        N_("git name-rev [<options>] --stdin"),
        NULL
};

static void name_rev_line(char *p, struct name_ref_data *data)
{
        struct strbuf buf = STRBUF_INIT;
        int counter = 0;
        char *p_start;
        const unsigned hexsz = the_hash_algo->hexsz;

        for (p_start = p; *p; p++) {
#define ishex(x) (isdigit((x)) || ((x) >= 'a' && (x) <= 'f'))
                if (!ishex(*p))
                        counter = 0;
                else if (++counter == hexsz &&
                         !ishex(*(p+1))) {
                        struct object_id oid;
                        const char *name = NULL;
                        char c = *(p+1);
                        int p_len = p - p_start + 1;

                        counter = 0;

                        *(p+1) = 0;
                        if (!get_oid(p - (hexsz - 1), &oid)) {
                                struct object *o =
                                        lookup_object(the_repository,
                                                      oid.hash);
                                if (o)
                                        name = get_rev_name(o, &buf);
                        }
                        *(p+1) = c;

                        if (!name)
                                continue;

                        if (data->name_only)
                                printf("%.*s%s", p_len - hexsz, p_start, name);
                        else
                                printf("%.*s (%s)", p_len, p_start, name);
                        p_start = p + 1;
                }
        }

        /* flush */
        if (p_start != p)
                fwrite(p_start, p - p_start, 1, stdout);

        strbuf_release(&buf);
}

int cmd_name_rev(int argc, const char **argv, const char *prefix)
{
        struct object_array revs = OBJECT_ARRAY_INIT;
        int all = 0, transform_stdin = 0, allow_undefined = 1, always = 0, peel_tag = 0;
        struct name_ref_data data = { 0, 0, STRING_LIST_INIT_NODUP, STRING_LIST_INIT_NODUP };
        struct option opts[] = {
                OPT_BOOL(0, "name-only", &data.name_only, N_("print only names (no SHA-1)")),
                OPT_BOOL(0, "tags", &data.tags_only, N_("only use tags to name the commits")),
                OPT_STRING_LIST(0, "refs", &data.ref_filters, N_("pattern"),
                                   N_("only use refs matching <pattern>")),
                OPT_STRING_LIST(0, "exclude", &data.exclude_filters, N_("pattern"),
                                   N_("ignore refs matching <pattern>")),
                OPT_GROUP(""),
                OPT_BOOL(0, "all", &all, N_("list all commits reachable from all refs")),
                OPT_BOOL(0, "stdin", &transform_stdin, N_("read from stdin")),
                OPT_BOOL(0, "undefined", &allow_undefined, N_("allow to print `undefined` names (default)")),
                OPT_BOOL(0, "always",     &always,
                           N_("show abbreviated commit object as fallback")),
                {
                        /* A Hidden OPT_BOOL */
                        OPTION_SET_INT, 0, "peel-tag", &peel_tag, NULL,
                        N_("dereference tags in the input (internal use)"),
                        PARSE_OPT_NOARG | PARSE_OPT_HIDDEN, NULL, 1,
                },
                OPT_END(),
        };

        init_commit_rev_name(&rev_names);
        git_config(git_default_config, NULL);
        argc = parse_options(argc, argv, prefix, opts, name_rev_usage, 0);
        if (all + transform_stdin + !!argc > 1) {
                error("Specify either a list, or --all, not both!");
                usage_with_options(name_rev_usage, opts);
        }
        if (all || transform_stdin)
                cutoff = 0;

        for (; argc; argc--, argv++) {
                struct object_id oid;
                struct object *object;
                struct commit *commit;

                if (get_oid(*argv, &oid)) {
                        fprintf(stderr, "Could not get sha1 for %s. Skipping.\n",
                                        *argv);
                        continue;
                }

                commit = NULL;
                object = parse_object(the_repository, &oid);
                if (object) {
                        struct object *peeled = deref_tag(the_repository,
                                                          object, *argv, 0);
                        if (peeled && peeled->type == OBJ_COMMIT)
                                commit = (struct commit *)peeled;
                }

                if (!object) {
                        fprintf(stderr, "Could not get object for %s. Skipping.\n",
                                        *argv);
                        continue;
                }

                if (commit) {
                        if (cutoff > commit->date)
                                cutoff = commit->date;
                }

                if (peel_tag) {
                        if (!commit) {
                                fprintf(stderr, "Could not get commit for %s. Skipping.\n",
                                        *argv);
                                continue;
                        }
                        object = (struct object *)commit;
                }
                add_object_array(object, *argv, &revs);
        }

        if (cutoff)
                cutoff = cutoff - CUTOFF_DATE_SLOP;
        for_each_ref(name_ref, &data);

        if (transform_stdin) {
                char buffer[2048];

                while (!feof(stdin)) {
                        char *p = fgets(buffer, sizeof(buffer), stdin);
                        if (!p)
                                break;
                        name_rev_line(p, &data);
                }
        } else if (all) {
                int i, max;

                max = get_max_object_index();
                for (i = 0; i < max; i++) {
                        struct object *obj = get_indexed_object(i);
                        if (!obj || obj->type != OBJ_COMMIT)
                                continue;
                        show_name(obj, NULL,
                                  always, allow_undefined, data.name_only);
                }
        } else {
                int i;
                for (i = 0; i < revs.nr; i++)
                        show_name(revs.objects[i].item, revs.objects[i].name,
                                  always, allow_undefined, data.name_only);
        }

        UNLEAK(revs);
        return 0;
}