#include "cache.h"
#include "config.h"
#include "lockfile.h"
#include "commit.h"
#include "tag.h"
#include "blob.h"
#include "refs.h"
#include "builtin.h"
#include "exec_cmd.h"
#include "parse-options.h"
#include "diff.h"
#include "hashmap.h"
#include "argv-array.h"
#include "run-command.h"
#include "revision.h"
#include "list-objects.h"

#define MAX_TAGS        (FLAG_BITS - 1)

static const char * const describe_usage[] = {
        N_("git describe [<options>] [<commit-ish>...]"),
        N_("git describe [<options>] --dirty"),
        NULL
};

static int debug;       /* Display lots of verbose info */
static int all; /* Any valid ref can be used */
static int tags;        /* Allow lightweight tags */
static int longformat;
static int first_parent;
static int abbrev = -1; /* unspecified */
static int max_candidates = 10;
static struct hashmap names;
static int have_util;
static struct string_list patterns = STRING_LIST_INIT_NODUP;
static struct string_list exclude_patterns = STRING_LIST_INIT_NODUP;
static int always;
static const char *suffix, *dirty, *broken;

/* diff-index command arguments to check if working tree is dirty. */
static const char *diff_index_args[] = {
        "diff-index", "--quiet", "HEAD", "--", NULL
};

struct commit_name {
        struct hashmap_entry entry;
        struct object_id peeled;
        struct tag *tag;
        unsigned prio:2; /* annotated tag = 2, tag = 1, head = 0 */
        unsigned name_checked:1;
        struct object_id oid;
        char *path;
};

static const char *prio_names[] = {
        N_("head"), N_("lightweight"), N_("annotated"),
};

static int commit_name_cmp(const void *unused_cmp_data,
                           const void *entry,
                           const void *entry_or_key,
                           const void *peeled)
{
        const struct commit_name *cn1 = entry;
        const struct commit_name *cn2 = entry_or_key;

        return oidcmp(&cn1->peeled, peeled ? peeled : &cn2->peeled);
}

static inline struct commit_name *find_commit_name(const struct object_id *peeled)
{
        return hashmap_get_from_hash(&names, sha1hash(peeled->hash), peeled->hash);
}

static int replace_name(struct commit_name *e,
                               int prio,
                               const struct object_id *oid,
                               struct tag **tag)
{
        if (!e || e->prio < prio)
                return 1;

        if (e->prio == 2 && prio == 2) {
                /* Multiple annotated tags point to the same commit.
                 * Select one to keep based upon their tagger date.
                 */
                struct tag *t;

                if (!e->tag) {
                        t = lookup_tag(&e->oid);
                        if (!t || parse_tag(t))
                                return 1;
                        e->tag = t;
                }

                t = lookup_tag(oid);
                if (!t || parse_tag(t))
                        return 0;
                *tag = t;

                if (e->tag->date < t->date)
                        return 1;
        }

        return 0;
}

static void add_to_known_names(const char *path,
                               const struct object_id *peeled,
                               int prio,
                               const struct object_id *oid)
{
        struct commit_name *e = find_commit_name(peeled);
        struct tag *tag = NULL;
        if (replace_name(e, prio, oid, &tag)) {
                if (!e) {
                        e = xmalloc(sizeof(struct commit_name));
                        oidcpy(&e->peeled, peeled);
                        hashmap_entry_init(e, sha1hash(peeled->hash));
                        hashmap_add(&names, e);
                        e->path = NULL;
                }
                e->tag = tag;
                e->prio = prio;
                e->name_checked = 0;
                oidcpy(&e->oid, oid);
                free(e->path);
                e->path = xstrdup(path);
        }
}

static int get_name(const char *path, const struct object_id *oid, int flag, void *cb_data)
{
        int is_tag = 0;
        struct object_id peeled;
        int is_annotated, prio;
        const char *path_to_match = NULL;

        if (skip_prefix(path, "refs/tags/", &path_to_match)) {
                is_tag = 1;
        } else if (all) {
                if ((exclude_patterns.nr || patterns.nr) &&
                    !skip_prefix(path, "refs/heads/", &path_to_match) &&
                    !skip_prefix(path, "refs/remotes/", &path_to_match)) {
                        /* Only accept reference of known type if there are match/exclude patterns */
                        return 0;
                }
        } else {
                /* Reject anything outside refs/tags/ unless --all */
                return 0;
        }

        /*
         * If we're given exclude patterns, first exclude any tag which match
         * any of the exclude pattern.
         */
        if (exclude_patterns.nr) {
                struct string_list_item *item;

                for_each_string_list_item(item, &exclude_patterns) {
                        if (!wildmatch(item->string, path_to_match, 0))
                                return 0;
                }
        }

        /*
         * If we're given patterns, accept only tags which match at least one
         * pattern.
         */
        if (patterns.nr) {
                int found = 0;
                struct string_list_item *item;

                for_each_string_list_item(item, &patterns) {
                        if (!wildmatch(item->string, path_to_match, 0)) {
                                found = 1;
                                break;
                        }
                }

                if (!found)
                        return 0;
        }

        /* Is it annotated? */
        if (!peel_ref(path, peeled.hash)) {
                is_annotated = !!oidcmp(oid, &peeled);
        } else {
                oidcpy(&peeled, oid);
                is_annotated = 0;
        }

        /*
         * By default, we only use annotated tags, but with --tags
         * we fall back to lightweight ones (even without --tags,
         * we still remember lightweight ones, only to give hints
         * in an error message).  --all allows any refs to be used.
         */
        if (is_annotated)
                prio = 2;
        else if (is_tag)
                prio = 1;
        else
                prio = 0;

        add_to_known_names(all ? path + 5 : path + 10, &peeled, prio, oid);
        return 0;
}

struct possible_tag {
        struct commit_name *name;
        int depth;
        int found_order;
        unsigned flag_within;
};

static int compare_pt(const void *a_, const void *b_)
{
        struct possible_tag *a = (struct possible_tag *)a_;
        struct possible_tag *b = (struct possible_tag *)b_;
        if (a->depth != b->depth)
                return a->depth - b->depth;
        if (a->found_order != b->found_order)
                return a->found_order - b->found_order;
        return 0;
}

static unsigned long finish_depth_computation(
        struct commit_list **list,
        struct possible_tag *best)
{
        unsigned long seen_commits = 0;
        while (*list) {
                struct commit *c = pop_commit(list);
                struct commit_list *parents = c->parents;
                seen_commits++;
                if (c->object.flags & best->flag_within) {
                        struct commit_list *a = *list;
                        while (a) {
                                struct commit *i = a->item;
                                if (!(i->object.flags & best->flag_within))
                                        break;
                                a = a->next;
                        }
                        if (!a)
                                break;
                } else
                        best->depth++;
                while (parents) {
                        struct commit *p = parents->item;
                        parse_commit(p);
                        if (!(p->object.flags & SEEN))
                                commit_list_insert_by_date(p, list);
                        p->object.flags |= c->object.flags;
                        parents = parents->next;
                }
        }
        return seen_commits;
}

static void append_name(struct commit_name *n, struct strbuf *dst)
{
        if (n->prio == 2 && !n->tag) {
                n->tag = lookup_tag(&n->oid);
                if (!n->tag || parse_tag(n->tag))
                        die(_("annotated tag %s not available"), n->path);
        }
        if (n->tag && !n->name_checked) {
                if (!n->tag->tag)
                        die(_("annotated tag %s has no embedded name"), n->path);
                if (strcmp(n->tag->tag, all ? n->path + 5 : n->path))
                        warning(_("tag '%s' is really '%s' here"), n->tag->tag, n->path);
                n->name_checked = 1;
        }

        if (n->tag)
                strbuf_addstr(dst, n->tag->tag);
        else
                strbuf_addstr(dst, n->path);
}

static void append_suffix(int depth, const struct object_id *oid, struct strbuf *dst)
{
        strbuf_addf(dst, "-%d-g%s", depth, find_unique_abbrev(oid->hash, abbrev));
}

static void describe_commit(struct object_id *oid, struct strbuf *dst)
{
        struct commit *cmit, *gave_up_on = NULL;
        struct commit_list *list;
        struct commit_name *n;
        struct possible_tag all_matches[MAX_TAGS];
        unsigned int match_cnt = 0, annotated_cnt = 0, cur_match;
        unsigned long seen_commits = 0;
        unsigned int unannotated_cnt = 0;

        cmit = lookup_commit_reference(oid);

        n = find_commit_name(&cmit->object.oid);
        if (n && (tags || all || n->prio == 2)) {
                /*
                 * Exact match to an existing ref.
                 */
                append_name(n, dst);
                if (longformat)
                        append_suffix(0, n->tag ? &n->tag->tagged->oid : oid, dst);
                if (suffix)
                        strbuf_addstr(dst, suffix);
                return;
        }

        if (!max_candidates)
                die(_("no tag exactly matches '%s'"), oid_to_hex(&cmit->object.oid));
        if (debug)
                fprintf(stderr, _("No exact match on refs or tags, searching to describe\n"));

        if (!have_util) {
                struct hashmap_iter iter;
                struct commit *c;
                struct commit_name *n = hashmap_iter_first(&names, &iter);
                for (; n; n = hashmap_iter_next(&iter)) {
                        c = lookup_commit_reference_gently(&n->peeled, 1);
                        if (c)
                                c->util = n;
                }
                have_util = 1;
        }

        list = NULL;
        cmit->object.flags = SEEN;
        commit_list_insert(cmit, &list);
        while (list) {
                struct commit *c = pop_commit(&list);
                struct commit_list *parents = c->parents;
                seen_commits++;
                n = c->util;
                if (n) {
                        if (!tags && !all && n->prio < 2) {
                                unannotated_cnt++;
                        } else if (match_cnt < max_candidates) {
                                struct possible_tag *t = &all_matches[match_cnt++];
                                t->name = n;
                                t->depth = seen_commits - 1;
                                t->flag_within = 1u << match_cnt;
                                t->found_order = match_cnt;
                                c->object.flags |= t->flag_within;
                                if (n->prio == 2)
                                        annotated_cnt++;
                        }
                        else {
                                gave_up_on = c;
                                break;
                        }
                }
                for (cur_match = 0; cur_match < match_cnt; cur_match++) {
                        struct possible_tag *t = &all_matches[cur_match];
                        if (!(c->object.flags & t->flag_within))
                                t->depth++;
                }
                if (annotated_cnt && !list) {
                        if (debug)
                                fprintf(stderr, _("finished search at %s\n"),
                                        oid_to_hex(&c->object.oid));
                        break;
                }
                while (parents) {
                        struct commit *p = parents->item;
                        parse_commit(p);
                        if (!(p->object.flags & SEEN))
                                commit_list_insert_by_date(p, &list);
                        p->object.flags |= c->object.flags;
                        parents = parents->next;

                        if (first_parent)
                                break;
                }
        }

        if (!match_cnt) {
                struct object_id *cmit_oid = &cmit->object.oid;
                if (always) {
                        strbuf_addstr(dst, find_unique_abbrev(cmit_oid->hash, abbrev));
                        if (suffix)
                                strbuf_addstr(dst, suffix);
                        return;
                }
                if (unannotated_cnt)
                        die(_("No annotated tags can describe '%s'.\n"
                            "However, there were unannotated tags: try --tags."),
                            oid_to_hex(cmit_oid));
                else
                        die(_("No tags can describe '%s'.\n"
                            "Try --always, or create some tags."),
                            oid_to_hex(cmit_oid));
        }

        QSORT(all_matches, match_cnt, compare_pt);

        if (gave_up_on) {
                commit_list_insert_by_date(gave_up_on, &list);
                seen_commits--;
        }
        seen_commits += finish_depth_computation(&list, &all_matches[0]);
        free_commit_list(list);

        if (debug) {
                static int label_width = -1;
                if (label_width < 0) {
                        int i, w;
                        for (i = 0; i < ARRAY_SIZE(prio_names); i++) {
                                w = strlen(_(prio_names[i]));
                                if (label_width < w)
                                        label_width = w;
                        }
                }
                for (cur_match = 0; cur_match < match_cnt; cur_match++) {
                        struct possible_tag *t = &all_matches[cur_match];
                        fprintf(stderr, " %-*s %8d %s\n",
                                label_width, _(prio_names[t->name->prio]),
                                t->depth, t->name->path);
                }
                fprintf(stderr, _("traversed %lu commits\n"), seen_commits);
                if (gave_up_on) {
                        fprintf(stderr,
                                _("more than %i tags found; listed %i most recent\n"
                                "gave up search at %s\n"),
                                max_candidates, max_candidates,
                                oid_to_hex(&gave_up_on->object.oid));
                }
        }

        append_name(all_matches[0].name, dst);
        if (abbrev)
                append_suffix(all_matches[0].depth, &cmit->object.oid, dst);
        if (suffix)
                strbuf_addstr(dst, suffix);
}

struct process_commit_data {
        struct object_id current_commit;
        struct object_id looking_for;
        struct strbuf *dst;
        struct rev_info *revs;
};

static void process_commit(struct commit *commit, void *data)
{
        struct process_commit_data *pcd = data;
        pcd->current_commit = commit->object.oid;
}

static void process_object(struct object *obj, const char *path, void *data)
{
        struct process_commit_data *pcd = data;

        if (!oidcmp(&pcd->looking_for, &obj->oid) && !pcd->dst->len) {
                reset_revision_walk();
                describe_commit(&pcd->current_commit, pcd->dst);
                strbuf_addf(pcd->dst, ":%s", path);
                free_commit_list(pcd->revs->commits);
                pcd->revs->commits = NULL;
        }
}

static void describe_blob(struct object_id oid, struct strbuf *dst)
{
        struct rev_info revs;
        struct argv_array args = ARGV_ARRAY_INIT;
        struct process_commit_data pcd = { null_oid, oid, dst, &revs};

        argv_array_pushl(&args, "internal: The first arg is not parsed",
                "--objects", "--in-commit-order", "--reverse", "HEAD",
                NULL);

        init_revisions(&revs, NULL);
        if (setup_revisions(args.argc, args.argv, &revs, NULL) > 1)
                BUG("setup_revisions could not handle all args?");

        if (prepare_revision_walk(&revs))
                die("revision walk setup failed");

        traverse_commit_list(&revs, process_commit, process_object, &pcd);
        reset_revision_walk();
}

static void describe(const char *arg, int last_one)
{
        struct object_id oid;
        struct commit *cmit;
        struct strbuf sb = STRBUF_INIT;

        if (debug)
                fprintf(stderr, _("describe %s\n"), arg);

        if (get_oid(arg, &oid))
                die(_("Not a valid object name %s"), arg);
        cmit = lookup_commit_reference_gently(&oid, 1);

        if (cmit)
                describe_commit(&oid, &sb);
        else if (lookup_blob(&oid))
                describe_blob(oid, &sb);
        else
                die(_("%s is neither a commit nor blob"), arg);

        puts(sb.buf);

        if (!last_one)
                clear_commit_marks(cmit, -1);

        strbuf_release(&sb);
}

int cmd_describe(int argc, const char **argv, const char *prefix)
{
        int contains = 0;
        struct option options[] = {
                OPT_BOOL(0, "contains",   &contains, N_("find the tag that comes after the commit")),
                OPT_BOOL(0, "debug",      &debug, N_("debug search strategy on stderr")),
                OPT_BOOL(0, "all",        &all, N_("use any ref")),
                OPT_BOOL(0, "tags",       &tags, N_("use any tag, even unannotated")),
                OPT_BOOL(0, "long",       &longformat, N_("always use long format")),
                OPT_BOOL(0, "first-parent", &first_parent, N_("only follow first parent")),
                OPT__ABBREV(&abbrev),
                OPT_SET_INT(0, "exact-match", &max_candidates,
                            N_("only output exact matches"), 0),
                OPT_INTEGER(0, "candidates", &max_candidates,
                            N_("consider <n> most recent tags (default: 10)")),
                OPT_STRING_LIST(0, "match", &patterns, N_("pattern"),
                           N_("only consider tags matching <pattern>")),
                OPT_STRING_LIST(0, "exclude", &exclude_patterns, N_("pattern"),
                           N_("do not consider tags matching <pattern>")),
                OPT_BOOL(0, "always",        &always,
                        N_("show abbreviated commit object as fallback")),
                {OPTION_STRING, 0, "dirty",  &dirty, N_("mark"),
                        N_("append <mark> on dirty working tree (default: \"-dirty\")"),
                        PARSE_OPT_OPTARG, NULL, (intptr_t) "-dirty"},
                {OPTION_STRING, 0, "broken",  &broken, N_("mark"),
                        N_("append <mark> on broken working tree (default: \"-broken\")"),
                        PARSE_OPT_OPTARG, NULL, (intptr_t) "-broken"},
                OPT_END(),
        };

        git_config(git_default_config, NULL);
        argc = parse_options(argc, argv, prefix, options, describe_usage, 0);
        if (abbrev < 0)
                abbrev = DEFAULT_ABBREV;

        if (max_candidates < 0)
                max_candidates = 0;
        else if (max_candidates > MAX_TAGS)
                max_candidates = MAX_TAGS;

        save_commit_buffer = 0;

        if (longformat && abbrev == 0)
                die(_("--long is incompatible with --abbrev=0"));

        if (contains) {
                struct string_list_item *item;
                struct argv_array args;

                argv_array_init(&args);
                argv_array_pushl(&args, "name-rev",
                                 "--peel-tag", "--name-only", "--no-undefined",
                                 NULL);
                if (always)
                        argv_array_push(&args, "--always");
                if (!all) {
                        argv_array_push(&args, "--tags");
                        for_each_string_list_item(item, &patterns)
                                argv_array_pushf(&args, "--refs=refs/tags/%s", item->string);
                        for_each_string_list_item(item, &exclude_patterns)
                                argv_array_pushf(&args, "--exclude=refs/tags/%s", item->string);
                }
                if (argc)
                        argv_array_pushv(&args, argv);
                else
                        argv_array_push(&args, "HEAD");
                return cmd_name_rev(args.argc, args.argv, prefix);
        }

        hashmap_init(&names, commit_name_cmp, NULL, 0);
        for_each_rawref(get_name, NULL);
        if (!hashmap_get_size(&names) && !always)
                die(_("No names found, cannot describe anything."));

        if (argc == 0) {
                if (broken) {
                        struct child_process cp = CHILD_PROCESS_INIT;
                        argv_array_pushv(&cp.args, diff_index_args);
                        cp.git_cmd = 1;
                        cp.no_stdin = 1;
                        cp.no_stdout = 1;

                        if (!dirty)
                                dirty = "-dirty";

                        switch (run_command(&cp)) {
                        case 0:
                                suffix = NULL;
                                break;
                        case 1:
                                suffix = dirty;
                                break;
                        default:
                                /* diff-index aborted abnormally */
                                suffix = broken;
                        }
                } else if (dirty) {
                        static struct lock_file index_lock;
                        int fd;

                        read_cache_preload(NULL);
                        refresh_index(&the_index, REFRESH_QUIET|REFRESH_UNMERGED,
                                      NULL, NULL, NULL);
                        fd = hold_locked_index(&index_lock, 0);
                        if (0 <= fd)
                                update_index_if_able(&the_index, &index_lock);

                        if (!cmd_diff_index(ARRAY_SIZE(diff_index_args) - 1,
                                            diff_index_args, prefix))
                                suffix = NULL;
                        else
                                suffix = dirty;
                }
                describe("HEAD", 1);
        } else if (dirty) {
                die(_("--dirty is incompatible with commit-ishes"));
        } else if (broken) {
                die(_("--broken is incompatible with commit-ishes"));
        } else {
                while (argc-- > 0)
                        describe(*argv++, argc == 0);
        }
        return 0;
}