#include "builtin.h"
#include "cache.h"
#include "refs.h"
#include "object.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "quote.h"
#include "parse-options.h"
#include "remote.h"

/* Quoting styles */
#define QUOTE_NONE 0
#define QUOTE_SHELL 1
#define QUOTE_PERL 2
#define QUOTE_PYTHON 4
#define QUOTE_TCL 8

typedef enum { FIELD_STR, FIELD_ULONG, FIELD_TIME } cmp_type;

struct atom_value {
        const char *s;
        unsigned long ul; /* used for sorting when not FIELD_STR */
};

struct ref_sort {
        struct ref_sort *next;
        int atom; /* index into used_atom array */
        unsigned reverse : 1;
};

struct refinfo {
        char *refname;
        unsigned char objectname[20];
        struct atom_value *value;
};

static struct {
        const char *name;
        cmp_type cmp_type;
} valid_atom[] = {
        { "refname" },
        { "objecttype" },
        { "objectsize", FIELD_ULONG },
        { "objectname" },
        { "tree" },
        { "parent" },
        { "numparent", FIELD_ULONG },
        { "object" },
        { "type" },
        { "tag" },
        { "author" },
        { "authorname" },
        { "authoremail" },
        { "authordate", FIELD_TIME },
        { "committer" },
        { "committername" },
        { "committeremail" },
        { "committerdate", FIELD_TIME },
        { "tagger" },
        { "taggername" },
        { "taggeremail" },
        { "taggerdate", FIELD_TIME },
        { "creator" },
        { "creatordate", FIELD_TIME },
        { "subject" },
        { "body" },
        { "contents" },
        { "upstream" },
};

/*
 * An atom is a valid field atom listed above, possibly prefixed with
 * a "*" to denote deref_tag().
 *
 * We parse given format string and sort specifiers, and make a list
 * of properties that we need to extract out of objects.  refinfo
 * structure will hold an array of values extracted that can be
 * indexed with the "atom number", which is an index into this
 * array.
 */
static const char **used_atom;
static cmp_type *used_atom_type;
static int used_atom_cnt, sort_atom_limit, need_tagged;

/*
 * Used to parse format string and sort specifiers
 */
static int parse_atom(const char *atom, const char *ep)
{
        const char *sp;
        int i, at;

        sp = atom;
        if (*sp == '*' && sp < ep)
                sp++; /* deref */
        if (ep <= sp)
                die("malformed field name: %.*s", (int)(ep-atom), atom);

        /* Do we have the atom already used elsewhere? */
        for (i = 0; i < used_atom_cnt; i++) {
                int len = strlen(used_atom[i]);
                if (len == ep - atom && !memcmp(used_atom[i], atom, len))
                        return i;
        }

        /* Is the atom a valid one? */
        for (i = 0; i < ARRAY_SIZE(valid_atom); i++) {
                int len = strlen(valid_atom[i].name);
                /*
                 * If the atom name has a colon, strip it and everything after
                 * it off - it specifies the format for this entry, and
                 * shouldn't be used for checking against the valid_atom
                 * table.
                 */
                const char *formatp = strchr(sp, ':');
                if (!formatp || ep < formatp)
                        formatp = ep;
                if (len == formatp - sp && !memcmp(valid_atom[i].name, sp, len))
                        break;
        }

        if (ARRAY_SIZE(valid_atom) <= i)
                die("unknown field name: %.*s", (int)(ep-atom), atom);

        /* Add it in, including the deref prefix */
        at = used_atom_cnt;
        used_atom_cnt++;
        used_atom = xrealloc(used_atom,
                             (sizeof *used_atom) * used_atom_cnt);
        used_atom_type = xrealloc(used_atom_type,
                                  (sizeof(*used_atom_type) * used_atom_cnt));
        used_atom[at] = xmemdupz(atom, ep - atom);
        used_atom_type[at] = valid_atom[i].cmp_type;
        return at;
}

/*
 * In a format string, find the next occurrence of %(atom).
 */
static const char *find_next(const char *cp)
{
        while (*cp) {
                if (*cp == '%') {
                        /* %( is the start of an atom;
                         * %% is a quoted per-cent.
                         */
                        if (cp[1] == '(')
                                return cp;
                        else if (cp[1] == '%')
                                cp++; /* skip over two % */
                        /* otherwise this is a singleton, literal % */
                }
                cp++;
        }
        return NULL;
}

/*
 * Make sure the format string is well formed, and parse out
 * the used atoms.
 */
static int verify_format(const char *format)
{
        const char *cp, *sp;
        for (cp = format; *cp && (sp = find_next(cp)); ) {
                const char *ep = strchr(sp, ')');
                if (!ep)
                        return error("malformed format string %s", sp);
                /* sp points at "%(" and ep points at the closing ")" */
                parse_atom(sp + 2, ep);
                cp = ep + 1;
        }
        return 0;
}

/*
 * Given an object name, read the object data and size, and return a
 * "struct object".  If the object data we are returning is also borrowed
 * by the "struct object" representation, set *eaten as well---it is a
 * signal from parse_object_buffer to us not to free the buffer.
 */
static void *get_obj(const unsigned char *sha1, struct object **obj, unsigned long *sz, int *eaten)
{
        enum object_type type;
        void *buf = read_sha1_file(sha1, &type, sz);

        if (buf)
                *obj = parse_object_buffer(sha1, type, *sz, buf, eaten);
        else
                *obj = NULL;
        return buf;
}

/* See grab_values */
static void grab_common_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        int i;

        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;
                if (!strcmp(name, "objecttype"))
                        v->s = typename(obj->type);
                else if (!strcmp(name, "objectsize")) {
                        char *s = xmalloc(40);
                        sprintf(s, "%lu", sz);
                        v->ul = sz;
                        v->s = s;
                }
                else if (!strcmp(name, "objectname")) {
                        char *s = xmalloc(41);
                        strcpy(s, sha1_to_hex(obj->sha1));
                        v->s = s;
                }
        }
}

/* See grab_values */
static void grab_tag_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        int i;
        struct tag *tag = (struct tag *) obj;

        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;
                if (!strcmp(name, "tag"))
                        v->s = tag->tag;
                else if (!strcmp(name, "type") && tag->tagged)
                        v->s = typename(tag->tagged->type);
                else if (!strcmp(name, "object") && tag->tagged) {
                        char *s = xmalloc(41);
                        strcpy(s, sha1_to_hex(tag->tagged->sha1));
                        v->s = s;
                }
        }
}

static int num_parents(struct commit *commit)
{
        struct commit_list *parents;
        int i;

        for (i = 0, parents = commit->parents;
             parents;
             parents = parents->next)
                i++;
        return i;
}

/* See grab_values */
static void grab_commit_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        int i;
        struct commit *commit = (struct commit *) obj;

        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;
                if (!strcmp(name, "tree")) {
                        char *s = xmalloc(41);
                        strcpy(s, sha1_to_hex(commit->tree->object.sha1));
                        v->s = s;
                }
                if (!strcmp(name, "numparent")) {
                        char *s = xmalloc(40);
                        v->ul = num_parents(commit);
                        sprintf(s, "%lu", v->ul);
                        v->s = s;
                }
                else if (!strcmp(name, "parent")) {
                        int num = num_parents(commit);
                        int i;
                        struct commit_list *parents;
                        char *s = xmalloc(41 * num + 1);
                        v->s = s;
                        for (i = 0, parents = commit->parents;
                             parents;
                             parents = parents->next, i = i + 41) {
                                struct commit *parent = parents->item;
                                strcpy(s+i, sha1_to_hex(parent->object.sha1));
                                if (parents->next)
                                        s[i+40] = ' ';
                        }
                        if (!i)
                                *s = '\0';
                }
        }
}

static const char *find_wholine(const char *who, int wholen, const char *buf, unsigned long sz)
{
        const char *eol;
        while (*buf) {
                if (!strncmp(buf, who, wholen) &&
                    buf[wholen] == ' ')
                        return buf + wholen + 1;
                eol = strchr(buf, '\n');
                if (!eol)
                        return "";
                eol++;
                if (*eol == '\n')
                        return ""; /* end of header */
                buf = eol;
        }
        return "";
}

static const char *copy_line(const char *buf)
{
        const char *eol = strchrnul(buf, '\n');
        return xmemdupz(buf, eol - buf);
}

static const char *copy_name(const char *buf)
{
        const char *cp;
        for (cp = buf; *cp && *cp != '\n'; cp++) {
                if (!strncmp(cp, " <", 2))
                        return xmemdupz(buf, cp - buf);
        }
        return "";
}

static const char *copy_email(const char *buf)
{
        const char *email = strchr(buf, '<');
        const char *eoemail;
        if (!email)
                return "";
        eoemail = strchr(email, '>');
        if (!eoemail)
                return "";
        return xmemdupz(email, eoemail + 1 - email);
}

static void grab_date(const char *buf, struct atom_value *v, const char *atomname)
{
        const char *eoemail = strstr(buf, "> ");
        char *zone;
        unsigned long timestamp;
        long tz;
        enum date_mode date_mode = DATE_NORMAL;
        const char *formatp;

        /*
         * We got here because atomname ends in "date" or "date<something>";
         * it's not possible that <something> is not ":<format>" because
         * parse_atom() wouldn't have allowed it, so we can assume that no
         * ":" means no format is specified, and use the default.
         */
        formatp = strchr(atomname, ':');
        if (formatp != NULL) {
                formatp++;
                date_mode = parse_date_format(formatp);
        }

        if (!eoemail)
                goto bad;
        timestamp = strtoul(eoemail + 2, &zone, 10);
        if (timestamp == ULONG_MAX)
                goto bad;
        tz = strtol(zone, NULL, 10);
        if ((tz == LONG_MIN || tz == LONG_MAX) && errno == ERANGE)
                goto bad;
        v->s = xstrdup(show_date(timestamp, tz, date_mode));
        v->ul = timestamp;
        return;
 bad:
        v->s = "";
        v->ul = 0;
}

/* See grab_values */
static void grab_person(const char *who, struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        int i;
        int wholen = strlen(who);
        const char *wholine = NULL;

        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;
                if (strncmp(who, name, wholen))
                        continue;
                if (name[wholen] != 0 &&
                    strcmp(name + wholen, "name") &&
                    strcmp(name + wholen, "email") &&
                    prefixcmp(name + wholen, "date"))
                        continue;
                if (!wholine)
                        wholine = find_wholine(who, wholen, buf, sz);
                if (!wholine)
                        return; /* no point looking for it */
                if (name[wholen] == 0)
                        v->s = copy_line(wholine);
                else if (!strcmp(name + wholen, "name"))
                        v->s = copy_name(wholine);
                else if (!strcmp(name + wholen, "email"))
                        v->s = copy_email(wholine);
                else if (!prefixcmp(name + wholen, "date"))
                        grab_date(wholine, v, name);
        }

        /* For a tag or a commit object, if "creator" or "creatordate" is
         * requested, do something special.
         */
        if (strcmp(who, "tagger") && strcmp(who, "committer"))
                return; /* "author" for commit object is not wanted */
        if (!wholine)
                wholine = find_wholine(who, wholen, buf, sz);
        if (!wholine)
                return;
        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;

                if (!prefixcmp(name, "creatordate"))
                        grab_date(wholine, v, name);
                else if (!strcmp(name, "creator"))
                        v->s = copy_line(wholine);
        }
}

static void find_subpos(const char *buf, unsigned long sz, const char **sub, const char **body)
{
        while (*buf) {
                const char *eol = strchr(buf, '\n');
                if (!eol)
                        return;
                if (eol[1] == '\n') {
                        buf = eol + 1;
                        break; /* found end of header */
                }
                buf = eol + 1;
        }
        while (*buf == '\n')
                buf++;
        if (!*buf)
                return;
        *sub = buf; /* first non-empty line */
        buf = strchr(buf, '\n');
        if (!buf) {
                *body = "";
                return; /* no body */
        }
        while (*buf == '\n')
                buf++; /* skip blank between subject and body */
        *body = buf;
}

/* See grab_values */
static void grab_sub_body_contents(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        int i;
        const char *subpos = NULL, *bodypos = NULL;

        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &val[i];
                if (!!deref != (*name == '*'))
                        continue;
                if (deref)
                        name++;
                if (strcmp(name, "subject") &&
                    strcmp(name, "body") &&
                    strcmp(name, "contents"))
                        continue;
                if (!subpos)
                        find_subpos(buf, sz, &subpos, &bodypos);
                if (!subpos)
                        return;

                if (!strcmp(name, "subject"))
                        v->s = copy_line(subpos);
                else if (!strcmp(name, "body"))
                        v->s = xstrdup(bodypos);
                else if (!strcmp(name, "contents"))
                        v->s = xstrdup(subpos);
        }
}

/* We want to have empty print-string for field requests
 * that do not apply (e.g. "authordate" for a tag object)
 */
static void fill_missing_values(struct atom_value *val)
{
        int i;
        for (i = 0; i < used_atom_cnt; i++) {
                struct atom_value *v = &val[i];
                if (v->s == NULL)
                        v->s = "";
        }
}

/*
 * val is a list of atom_value to hold returned values.  Extract
 * the values for atoms in used_atom array out of (obj, buf, sz).
 * when deref is false, (obj, buf, sz) is the object that is
 * pointed at by the ref itself; otherwise it is the object the
 * ref (which is a tag) refers to.
 */
static void grab_values(struct atom_value *val, int deref, struct object *obj, void *buf, unsigned long sz)
{
        grab_common_values(val, deref, obj, buf, sz);
        switch (obj->type) {
        case OBJ_TAG:
                grab_tag_values(val, deref, obj, buf, sz);
                grab_sub_body_contents(val, deref, obj, buf, sz);
                grab_person("tagger", val, deref, obj, buf, sz);
                break;
        case OBJ_COMMIT:
                grab_commit_values(val, deref, obj, buf, sz);
                grab_sub_body_contents(val, deref, obj, buf, sz);
                grab_person("author", val, deref, obj, buf, sz);
                grab_person("committer", val, deref, obj, buf, sz);
                break;
        case OBJ_TREE:
                // grab_tree_values(val, deref, obj, buf, sz);
                break;
        case OBJ_BLOB:
                // grab_blob_values(val, deref, obj, buf, sz);
                break;
        default:
                die("Eh?  Object of type %d?", obj->type);
        }
}

/*
 * Parse the object referred by ref, and grab needed value.
 */
static void populate_value(struct refinfo *ref)
{
        void *buf;
        struct object *obj;
        int eaten, i;
        unsigned long size;
        const unsigned char *tagged;

        ref->value = xcalloc(sizeof(struct atom_value), used_atom_cnt);

        buf = get_obj(ref->objectname, &obj, &size, &eaten);
        if (!buf)
                die("missing object %s for %s",
                    sha1_to_hex(ref->objectname), ref->refname);
        if (!obj)
                die("parse_object_buffer failed on %s for %s",
                    sha1_to_hex(ref->objectname), ref->refname);

        /* Fill in specials first */
        for (i = 0; i < used_atom_cnt; i++) {
                const char *name = used_atom[i];
                struct atom_value *v = &ref->value[i];
                int deref = 0;
                const char *refname;
                const char *formatp;

                if (*name == '*') {
                        deref = 1;
                        name++;
                }

                if (!prefixcmp(name, "refname"))
                        refname = ref->refname;
                else if(!prefixcmp(name, "upstream")) {
                        struct branch *branch;
                        /* only local branches may have an upstream */
                        if (prefixcmp(ref->refname, "refs/heads/"))
                                continue;
                        branch = branch_get(ref->refname + 11);

                        if (!branch || !branch->merge || !branch->merge[0] ||
                            !branch->merge[0]->dst)
                                continue;
                        refname = branch->merge[0]->dst;
                }
                else
                        continue;

                formatp = strchr(name, ':');
                /* look for "short" refname format */
                if (formatp) {
                        formatp++;
                        if (!strcmp(formatp, "short"))
                                refname = shorten_unambiguous_ref(refname,
                                                      warn_ambiguous_refs);
                        else
                                die("unknown %.*s format %s",
                                    (int)(formatp - name), name, formatp);
                }

                if (!deref)
                        v->s = refname;
                else {
                        int len = strlen(refname);
                        char *s = xmalloc(len + 4);
                        sprintf(s, "%s^{}", refname);
                        v->s = s;
                }
        }

        grab_values(ref->value, 0, obj, buf, size);
        if (!eaten)
                free(buf);

        /* If there is no atom that wants to know about tagged
         * object, we are done.
         */
        if (!need_tagged || (obj->type != OBJ_TAG))
                return;

        /* If it is a tag object, see if we use a value that derefs
         * the object, and if we do grab the object it refers to.
         */
        tagged = ((struct tag *)obj)->tagged->sha1;

        /* NEEDSWORK: This derefs tag only once, which
         * is good to deal with chains of trust, but
         * is not consistent with what deref_tag() does
         * which peels the onion to the core.
         */
        buf = get_obj(tagged, &obj, &size, &eaten);
        if (!buf)
                die("missing object %s for %s",
                    sha1_to_hex(tagged), ref->refname);
        if (!obj)
                die("parse_object_buffer failed on %s for %s",
                    sha1_to_hex(tagged), ref->refname);
        grab_values(ref->value, 1, obj, buf, size);
        if (!eaten)
                free(buf);
}

/*
 * Given a ref, return the value for the atom.  This lazily gets value
 * out of the object by calling populate value.
 */
static void get_value(struct refinfo *ref, int atom, struct atom_value **v)
{
        if (!ref->value) {
                populate_value(ref);
                fill_missing_values(ref->value);
        }
        *v = &ref->value[atom];
}

struct grab_ref_cbdata {
        struct refinfo **grab_array;
        const char **grab_pattern;
        int grab_cnt;
};

/*
 * A call-back given to for_each_ref().  It is unfortunate that we
 * need to use global variables to pass extra information to this
 * function.
 */
static int grab_single_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
{
        struct grab_ref_cbdata *cb = cb_data;
        struct refinfo *ref;
        int cnt;

        if (*cb->grab_pattern) {
                const char **pattern;
                int namelen = strlen(refname);
                for (pattern = cb->grab_pattern; *pattern; pattern++) {
                        const char *p = *pattern;
                        int plen = strlen(p);

                        if ((plen <= namelen) &&
                            !strncmp(refname, p, plen) &&
                            (refname[plen] == '\0' ||
                             refname[plen] == '/' ||
                             p[plen-1] == '/'))
                                break;
                        if (!fnmatch(p, refname, FNM_PATHNAME))
                                break;
                }
                if (!*pattern)
                        return 0;
        }

        /* We do not open the object yet; sort may only need refname
         * to do its job and the resulting list may yet to be pruned
         * by maxcount logic.
         */
        ref = xcalloc(1, sizeof(*ref));
        ref->refname = xstrdup(refname);
        hashcpy(ref->objectname, sha1);

        cnt = cb->grab_cnt;
        cb->grab_array = xrealloc(cb->grab_array,
                                  sizeof(*cb->grab_array) * (cnt + 1));
        cb->grab_array[cnt++] = ref;
        cb->grab_cnt = cnt;
        return 0;
}

static int cmp_ref_sort(struct ref_sort *s, struct refinfo *a, struct refinfo *b)
{
        struct atom_value *va, *vb;
        int cmp;
        cmp_type cmp_type = used_atom_type[s->atom];

        get_value(a, s->atom, &va);
        get_value(b, s->atom, &vb);
        switch (cmp_type) {
        case FIELD_STR:
                cmp = strcmp(va->s, vb->s);
                break;
        default:
                if (va->ul < vb->ul)
                        cmp = -1;
                else if (va->ul == vb->ul)
                        cmp = 0;
                else
                        cmp = 1;
                break;
        }
        return (s->reverse) ? -cmp : cmp;
}

static struct ref_sort *ref_sort;
static int compare_refs(const void *a_, const void *b_)
{
        struct refinfo *a = *((struct refinfo **)a_);
        struct refinfo *b = *((struct refinfo **)b_);
        struct ref_sort *s;

        for (s = ref_sort; s; s = s->next) {
                int cmp = cmp_ref_sort(s, a, b);
                if (cmp)
                        return cmp;
        }
        return 0;
}

static void sort_refs(struct ref_sort *sort, struct refinfo **refs, int num_refs)
{
        ref_sort = sort;
        qsort(refs, num_refs, sizeof(struct refinfo *), compare_refs);
}

static void print_value(struct refinfo *ref, int atom, int quote_style)
{
        struct atom_value *v;
        get_value(ref, atom, &v);
        switch (quote_style) {
        case QUOTE_NONE:
                fputs(v->s, stdout);
                break;
        case QUOTE_SHELL:
                sq_quote_print(stdout, v->s);
                break;
        case QUOTE_PERL:
                perl_quote_print(stdout, v->s);
                break;
        case QUOTE_PYTHON:
                python_quote_print(stdout, v->s);
                break;
        case QUOTE_TCL:
                tcl_quote_print(stdout, v->s);
                break;
        }
}

static int hex1(char ch)
{
        if ('0' <= ch && ch <= '9')
                return ch - '0';
        else if ('a' <= ch && ch <= 'f')
                return ch - 'a' + 10;
        else if ('A' <= ch && ch <= 'F')
                return ch - 'A' + 10;
        return -1;
}
static int hex2(const char *cp)
{
        if (cp[0] && cp[1])
                return (hex1(cp[0]) << 4) | hex1(cp[1]);
        else
                return -1;
}

static void emit(const char *cp, const char *ep)
{
        while (*cp && (!ep || cp < ep)) {
                if (*cp == '%') {
                        if (cp[1] == '%')
                                cp++;
                        else {
                                int ch = hex2(cp + 1);
                                if (0 <= ch) {
                                        putchar(ch);
                                        cp += 3;
                                        continue;
                                }
                        }
                }
                putchar(*cp);
                cp++;
        }
}

static void show_ref(struct refinfo *info, const char *format, int quote_style)
{
        const char *cp, *sp, *ep;

        for (cp = format; *cp && (sp = find_next(cp)); cp = ep + 1) {
                ep = strchr(sp, ')');
                if (cp < sp)
                        emit(cp, sp);
                print_value(info, parse_atom(sp + 2, ep), quote_style);
        }
        if (*cp) {
                sp = cp + strlen(cp);
                emit(cp, sp);
        }
        putchar('\n');
}

static struct ref_sort *default_sort(void)
{
        static const char cstr_name[] = "refname";

        struct ref_sort *sort = xcalloc(1, sizeof(*sort));

        sort->next = NULL;
        sort->atom = parse_atom(cstr_name, cstr_name + strlen(cstr_name));
        return sort;
}

static int opt_parse_sort(const struct option *opt, const char *arg, int unset)
{
        struct ref_sort **sort_tail = opt->value;
        struct ref_sort *s;
        int len;

        if (!arg) /* should --no-sort void the list ? */
                return -1;

        *sort_tail = s = xcalloc(1, sizeof(*s));

        if (*arg == '-') {
                s->reverse = 1;
                arg++;
        }
        len = strlen(arg);
        s->atom = parse_atom(arg, arg+len);
        return 0;
}

static char const * const for_each_ref_usage[] = {
        "git for-each-ref [options] [<pattern>]",
        NULL
};

int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
{
        int i, num_refs;
        const char *format = "%(objectname) %(objecttype)\t%(refname)";
        struct ref_sort *sort = NULL, **sort_tail = &sort;
        int maxcount = 0, quote_style = 0;
        struct refinfo **refs;
        struct grab_ref_cbdata cbdata;

        struct option opts[] = {
                OPT_BIT('s', "shell", &quote_style,
                        "quote placeholders suitably for shells", QUOTE_SHELL),
                OPT_BIT('p', "perl",  &quote_style,
                        "quote placeholders suitably for perl", QUOTE_PERL),
                OPT_BIT(0 , "python", &quote_style,
                        "quote placeholders suitably for python", QUOTE_PYTHON),
                OPT_BIT(0 , "tcl",  &quote_style,
                        "quote placeholders suitably for tcl", QUOTE_TCL),

                OPT_GROUP(""),
                OPT_INTEGER( 0 , "count", &maxcount, "show only <n> matched refs"),
                OPT_STRING(  0 , "format", &format, "format", "format to use for the output"),
                OPT_CALLBACK(0 , "sort", sort_tail, "key",
                            "field name to sort on", &opt_parse_sort),
                OPT_END(),
        };

        parse_options(argc, argv, prefix, opts, for_each_ref_usage, 0);
        if (maxcount < 0) {
                error("invalid --count argument: `%d'", maxcount);
                usage_with_options(for_each_ref_usage, opts);
        }
        if (HAS_MULTI_BITS(quote_style)) {
                error("more than one quoting style?");
                usage_with_options(for_each_ref_usage, opts);
        }
        if (verify_format(format))
                usage_with_options(for_each_ref_usage, opts);

        if (!sort)
                sort = default_sort();
        sort_atom_limit = used_atom_cnt;

        /* for warn_ambiguous_refs */
        git_config(git_default_config, NULL);

        memset(&cbdata, 0, sizeof(cbdata));
        cbdata.grab_pattern = argv;
        for_each_ref(grab_single_ref, &cbdata);
        refs = cbdata.grab_array;
        num_refs = cbdata.grab_cnt;

        for (i = 0; i < used_atom_cnt; i++) {
                if (used_atom[i][0] == '*') {
                        need_tagged = 1;
                        break;
                }
        }

        sort_refs(sort, refs, num_refs);

        if (!maxcount || num_refs < maxcount)
                maxcount = num_refs;
        for (i = 0; i < maxcount; i++)
                show_ref(refs[i], format, quote_style);
        return 0;
}