#include "builtin.h"
#include "cache.h"
#include "refs.h"
#include "object.h"
#include "tag.h"
#include "string-list.h"
#include "parse-options.h"

static const char * const show_ref_usage[] = {
        N_("git show-ref [-q | --quiet] [--verify] [--head] [-d | --dereference] [-s | --hash[=<n>]] [--abbrev[=<n>]] [--tags] [--heads] [--] [<pattern>...]"),
        N_("git show-ref --exclude-existing[=<pattern>]"),
        NULL
};

static int deref_tags, show_head, tags_only, heads_only, found_match, verify,
           quiet, hash_only, abbrev, exclude_arg;
static const char **pattern;
static const char *exclude_existing_arg;

static void show_one(const char *refname, const struct object_id *oid)
{
        const char *hex;
        struct object_id peeled;

        /* This changes the semantics slightly that even under quiet we
         * detect and return error if the repository is corrupt and
         * ref points at a nonexistent object.
         */
        if (!has_sha1_file(oid->hash))
                die("git show-ref: bad ref %s (%s)", refname,
                    oid_to_hex(oid));

        if (quiet)
                return;

        hex = find_unique_abbrev(oid->hash, abbrev);
        if (hash_only)
                printf("%s\n", hex);
        else
                printf("%s %s\n", hex, refname);

        if (!deref_tags)
                return;

        if (!peel_ref(refname, peeled.hash)) {
                hex = find_unique_abbrev(peeled.hash, abbrev);
                printf("%s %s^{}\n", hex, refname);
        }
}

static int show_ref(const char *refname, const struct object_id *oid,
                    int flag, void *cbdata)
{
        if (show_head && !strcmp(refname, "HEAD"))
                goto match;

        if (tags_only || heads_only) {
                int match;

                match = heads_only && starts_with(refname, "refs/heads/");
                match |= tags_only && starts_with(refname, "refs/tags/");
                if (!match)
                        return 0;
        }
        if (pattern) {
                int reflen = strlen(refname);
                const char **p = pattern, *m;
                while ((m = *p++) != NULL) {
                        int len = strlen(m);
                        if (len > reflen)
                                continue;
                        if (memcmp(m, refname + reflen - len, len))
                                continue;
                        if (len == reflen)
                                goto match;
                        if (refname[reflen - len - 1] == '/')
                                goto match;
                }
                return 0;
        }

match:
        found_match++;

        show_one(refname, oid);

        return 0;
}

static int add_existing(const char *refname, const struct object_id *oid,
                        int flag, void *cbdata)
{
        struct string_list *list = (struct string_list *)cbdata;
        string_list_insert(list, refname);
        return 0;
}

/*
 * read "^(?:<anything>\s)?<refname>(?:\^\{\})?$" from the standard input,
 * and
 * (1) strip "^{}" at the end of line if any;
 * (2) ignore if match is provided and does not head-match refname;
 * (3) warn if refname is not a well-formed refname and skip;
 * (4) ignore if refname is a ref that exists in the local repository;
 * (5) otherwise output the line.
 */
static int exclude_existing(const char *match)
{
        static struct string_list existing_refs = STRING_LIST_INIT_DUP;
        char buf[1024];
        int matchlen = match ? strlen(match) : 0;

        for_each_ref(add_existing, &existing_refs);
        while (fgets(buf, sizeof(buf), stdin)) {
                char *ref;
                int len = strlen(buf);

                if (len > 0 && buf[len - 1] == '\n')
                        buf[--len] = '\0';
                if (3 <= len && !strcmp(buf + len - 3, "^{}")) {
                        len -= 3;
                        buf[len] = '\0';
                }
                for (ref = buf + len; buf < ref; ref--)
                        if (isspace(ref[-1]))
                                break;
                if (match) {
                        int reflen = buf + len - ref;
                        if (reflen < matchlen)
                                continue;
                        if (strncmp(ref, match, matchlen))
                                continue;
                }
                if (check_refname_format(ref, 0)) {
                        warning("ref '%s' ignored", ref);
                        continue;
                }
                if (!string_list_has_string(&existing_refs, ref)) {
                        printf("%s\n", buf);
                }
        }
        return 0;
}

static int hash_callback(const struct option *opt, const char *arg, int unset)
{
        hash_only = 1;
        /* Use full length SHA1 if no argument */
        if (!arg)
                return 0;
        return parse_opt_abbrev_cb(opt, arg, unset);
}

static int exclude_existing_callback(const struct option *opt, const char *arg,
                                     int unset)
{
        exclude_arg = 1;
        *(const char **)opt->value = arg;
        return 0;
}

static const struct option show_ref_options[] = {
        OPT_BOOL(0, "tags", &tags_only, N_("only show tags (can be combined with heads)")),
        OPT_BOOL(0, "heads", &heads_only, N_("only show heads (can be combined with tags)")),
        OPT_BOOL(0, "verify", &verify, N_("stricter reference checking, "
                    "requires exact ref path")),
        OPT_HIDDEN_BOOL('h', NULL, &show_head,
                        N_("show the HEAD reference, even if it would be filtered out")),
        OPT_BOOL(0, "head", &show_head,
          N_("show the HEAD reference, even if it would be filtered out")),
        OPT_BOOL('d', "dereference", &deref_tags,
                    N_("dereference tags into object IDs")),
        { OPTION_CALLBACK, 's', "hash", &abbrev, N_("n"),
          N_("only show SHA1 hash using <n> digits"),
          PARSE_OPT_OPTARG, &hash_callback },
        OPT__ABBREV(&abbrev),
        OPT__QUIET(&quiet,
                   N_("do not print results to stdout (useful with --verify)")),
        { OPTION_CALLBACK, 0, "exclude-existing", &exclude_existing_arg,
          N_("pattern"), N_("show refs from stdin that aren't in local repository"),
          PARSE_OPT_OPTARG | PARSE_OPT_NONEG, exclude_existing_callback },
        OPT_END()
};

int cmd_show_ref(int argc, const char **argv, const char *prefix)
{
        argc = parse_options(argc, argv, prefix, show_ref_options,
                             show_ref_usage, 0);

        if (exclude_arg)
                return exclude_existing(exclude_existing_arg);

        pattern = argv;
        if (!*pattern)
                pattern = NULL;

        if (verify) {
                if (!pattern)
                        die("--verify requires a reference");
                while (*pattern) {
                        struct object_id oid;

                        if ((starts_with(*pattern, "refs/") || !strcmp(*pattern, "HEAD")) &&
                            !read_ref(*pattern, oid.hash)) {
                                show_one(*pattern, &oid);
                        }
                        else if (!quiet)
                                die("'%s' - not a valid ref", *pattern);
                        else
                                return 1;
                        pattern++;
                }
                return 0;
        }

        if (show_head)
                head_ref(show_ref, NULL);
        for_each_ref(show_ref, NULL);
        if (!found_match) {
                if (verify && !quiet)
                        die("No match");
                return 1;
        }
        return 0;
}