/*
 * Builtin "git branch"
 *
 * Copyright (c) 2006 Kristian Høgsberg <krh@redhat.com>
 * Based on git-branch.sh by Junio C Hamano.
 */

#include "cache.h"
#include "config.h"
#include "color.h"
#include "refs.h"
#include "commit.h"
#include "builtin.h"
#include "remote.h"
#include "parse-options.h"
#include "branch.h"
#include "diff.h"
#include "revision.h"
#include "string-list.h"
#include "column.h"
#include "utf8.h"
#include "wt-status.h"
#include "ref-filter.h"
#include "worktree.h"

static const char * const builtin_branch_usage[] = {
        N_("git branch [<options>] [-r | -a] [--merged | --no-merged]"),
        N_("git branch [<options>] [-l] [-f] <branch-name> [<start-point>]"),
        N_("git branch [<options>] [-r] (-d | -D) <branch-name>..."),
        N_("git branch [<options>] (-m | -M) [<old-branch>] <new-branch>"),
        N_("git branch [<options>] [-r | -a] [--points-at]"),
        N_("git branch [<options>] [-r | -a] [--format]"),
        NULL
};

static const char *head;
static struct object_id head_oid;

static int branch_use_color = -1;
static char branch_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
        GIT_COLOR_NORMAL,       /* PLAIN */
        GIT_COLOR_RED,          /* REMOTE */
        GIT_COLOR_NORMAL,       /* LOCAL */
        GIT_COLOR_GREEN,        /* CURRENT */
        GIT_COLOR_BLUE,         /* UPSTREAM */
};
enum color_branch {
        BRANCH_COLOR_RESET = 0,
        BRANCH_COLOR_PLAIN = 1,
        BRANCH_COLOR_REMOTE = 2,
        BRANCH_COLOR_LOCAL = 3,
        BRANCH_COLOR_CURRENT = 4,
        BRANCH_COLOR_UPSTREAM = 5
};

static struct string_list output = STRING_LIST_INIT_DUP;
static unsigned int colopts;

static int parse_branch_color_slot(const char *slot)
{
        if (!strcasecmp(slot, "plain"))
                return BRANCH_COLOR_PLAIN;
        if (!strcasecmp(slot, "reset"))
                return BRANCH_COLOR_RESET;
        if (!strcasecmp(slot, "remote"))
                return BRANCH_COLOR_REMOTE;
        if (!strcasecmp(slot, "local"))
                return BRANCH_COLOR_LOCAL;
        if (!strcasecmp(slot, "current"))
                return BRANCH_COLOR_CURRENT;
        if (!strcasecmp(slot, "upstream"))
                return BRANCH_COLOR_UPSTREAM;
        return -1;
}

static int git_branch_config(const char *var, const char *value, void *cb)
{
        const char *slot_name;

        if (starts_with(var, "column."))
                return git_column_config(var, value, "branch", &colopts);
        if (!strcmp(var, "color.branch")) {
                branch_use_color = git_config_colorbool(var, value);
                return 0;
        }
        if (skip_prefix(var, "color.branch.", &slot_name)) {
                int slot = parse_branch_color_slot(slot_name);
                if (slot < 0)
                        return 0;
                if (!value)
                        return config_error_nonbool(var);
                return color_parse(value, branch_colors[slot]);
        }
        return git_default_config(var, value, cb);
}

static const char *branch_get_color(enum color_branch ix)
{
        if (want_color(branch_use_color))
                return branch_colors[ix];
        return "";
}

static int branch_merged(int kind, const char *name,
                         struct commit *rev, struct commit *head_rev)
{
        /*
         * This checks whether the merge bases of branch and HEAD (or
         * the other branch this branch builds upon) contains the
         * branch, which means that the branch has already been merged
         * safely to HEAD (or the other branch).
         */
        struct commit *reference_rev = NULL;
        const char *reference_name = NULL;
        void *reference_name_to_free = NULL;
        int merged;

        if (kind == FILTER_REFS_BRANCHES) {
                struct branch *branch = branch_get(name);
                const char *upstream = branch_get_upstream(branch, NULL);
                struct object_id oid;

                if (upstream &&
                    (reference_name = reference_name_to_free =
                     resolve_refdup(upstream, RESOLVE_REF_READING,
                                    oid.hash, NULL)) != NULL)
                        reference_rev = lookup_commit_reference(&oid);
        }
        if (!reference_rev)
                reference_rev = head_rev;

        merged = in_merge_bases(rev, reference_rev);

        /*
         * After the safety valve is fully redefined to "check with
         * upstream, if any, otherwise with HEAD", we should just
         * return the result of the in_merge_bases() above without
         * any of the following code, but during the transition period,
         * a gentle reminder is in order.
         */
        if ((head_rev != reference_rev) &&
            in_merge_bases(rev, head_rev) != merged) {
                if (merged)
                        warning(_("deleting branch '%s' that has been merged to\n"
                                "         '%s', but not yet merged to HEAD."),
                                name, reference_name);
                else
                        warning(_("not deleting branch '%s' that is not yet merged to\n"
                                "         '%s', even though it is merged to HEAD."),
                                name, reference_name);
        }
        free(reference_name_to_free);
        return merged;
}

static int check_branch_commit(const char *branchname, const char *refname,
                               const struct object_id *oid, struct commit *head_rev,
                               int kinds, int force)
{
        struct commit *rev = lookup_commit_reference(oid);
        if (!rev) {
                error(_("Couldn't look up commit object for '%s'"), refname);
                return -1;
        }
        if (!force && !branch_merged(kinds, branchname, rev, head_rev)) {
                error(_("The branch '%s' is not fully merged.\n"
                      "If you are sure you want to delete it, "
                      "run 'git branch -D %s'."), branchname, branchname);
                return -1;
        }
        return 0;
}

static void delete_branch_config(const char *branchname)
{
        struct strbuf buf = STRBUF_INIT;
        strbuf_addf(&buf, "branch.%s", branchname);
        if (git_config_rename_section(buf.buf, NULL) < 0)
                warning(_("Update of config-file failed"));
        strbuf_release(&buf);
}

static int delete_branches(int argc, const char **argv, int force, int kinds,
                           int quiet)
{
        struct commit *head_rev = NULL;
        struct object_id oid;
        char *name = NULL;
        const char *fmt;
        int i;
        int ret = 0;
        int remote_branch = 0;
        struct strbuf bname = STRBUF_INIT;
        unsigned allowed_interpret;

        switch (kinds) {
        case FILTER_REFS_REMOTES:
                fmt = "refs/remotes/%s";
                /* For subsequent UI messages */
                remote_branch = 1;
                allowed_interpret = INTERPRET_BRANCH_REMOTE;

                force = 1;
                break;
        case FILTER_REFS_BRANCHES:
                fmt = "refs/heads/%s";
                allowed_interpret = INTERPRET_BRANCH_LOCAL;
                break;
        default:
                die(_("cannot use -a with -d"));
        }

        if (!force) {
                head_rev = lookup_commit_reference(&head_oid);
                if (!head_rev)
                        die(_("Couldn't look up commit object for HEAD"));
        }
        for (i = 0; i < argc; i++, strbuf_reset(&bname)) {
                char *target = NULL;
                int flags = 0;

                strbuf_branchname(&bname, argv[i], allowed_interpret);
                free(name);
                name = mkpathdup(fmt, bname.buf);

                if (kinds == FILTER_REFS_BRANCHES) {
                        const struct worktree *wt =
                                find_shared_symref("HEAD", name);
                        if (wt) {
                                error(_("Cannot delete branch '%s' "
                                        "checked out at '%s'"),
                                      bname.buf, wt->path);
                                ret = 1;
                                continue;
                        }
                }

                target = resolve_refdup(name,
                                        RESOLVE_REF_READING
                                        | RESOLVE_REF_NO_RECURSE
                                        | RESOLVE_REF_ALLOW_BAD_NAME,
                                        oid.hash, &flags);
                if (!target) {
                        error(remote_branch
                              ? _("remote-tracking branch '%s' not found.")
                              : _("branch '%s' not found."), bname.buf);
                        ret = 1;
                        continue;
                }

                if (!(flags & (REF_ISSYMREF|REF_ISBROKEN)) &&
                    check_branch_commit(bname.buf, name, &oid, head_rev, kinds,
                                        force)) {
                        ret = 1;
                        goto next;
                }

                if (delete_ref(NULL, name, is_null_oid(&oid) ? NULL : oid.hash,
                               REF_NODEREF)) {
                        error(remote_branch
                              ? _("Error deleting remote-tracking branch '%s'")
                              : _("Error deleting branch '%s'"),
                              bname.buf);
                        ret = 1;
                        goto next;
                }
                if (!quiet) {
                        printf(remote_branch
                               ? _("Deleted remote-tracking branch %s (was %s).\n")
                               : _("Deleted branch %s (was %s).\n"),
                               bname.buf,
                               (flags & REF_ISBROKEN) ? "broken"
                               : (flags & REF_ISSYMREF) ? target
                               : find_unique_abbrev(oid.hash, DEFAULT_ABBREV));
                }
                delete_branch_config(bname.buf);

        next:
                free(target);
        }

        free(name);
        strbuf_release(&bname);

        return ret;
}

static int calc_maxwidth(struct ref_array *refs, int remote_bonus)
{
        int i, max = 0;
        for (i = 0; i < refs->nr; i++) {
                struct ref_array_item *it = refs->items[i];
                const char *desc = it->refname;
                int w;

                skip_prefix(it->refname, "refs/heads/", &desc);
                skip_prefix(it->refname, "refs/remotes/", &desc);
                if (it->kind == FILTER_REFS_DETACHED_HEAD) {
                        char *head_desc = get_head_description();
                        w = utf8_strwidth(head_desc);
                        free(head_desc);
                } else
                        w = utf8_strwidth(desc);

                if (it->kind == FILTER_REFS_REMOTES)
                        w += remote_bonus;
                if (w > max)
                        max = w;
        }
        return max;
}

static const char *quote_literal_for_format(const char *s)
{
        static struct strbuf buf = STRBUF_INIT;

        strbuf_reset(&buf);
        while (*s) {
                const char *ep = strchrnul(s, '%');
                if (s < ep)
                        strbuf_add(&buf, s, ep - s);
                if (*ep == '%') {
                        strbuf_addstr(&buf, "%%");
                        s = ep + 1;
                } else {
                        s = ep;
                }
        }
        return buf.buf;
}

static char *build_format(struct ref_filter *filter, int maxwidth, const char *remote_prefix)
{
        struct strbuf fmt = STRBUF_INIT;
        struct strbuf local = STRBUF_INIT;
        struct strbuf remote = STRBUF_INIT;

        strbuf_addf(&local, "%%(if)%%(HEAD)%%(then)* %s%%(else)  %s%%(end)",
                    branch_get_color(BRANCH_COLOR_CURRENT),
                    branch_get_color(BRANCH_COLOR_LOCAL));
        strbuf_addf(&remote, "  %s",
                    branch_get_color(BRANCH_COLOR_REMOTE));

        if (filter->verbose) {
                struct strbuf obname = STRBUF_INIT;

                if (filter->abbrev < 0)
                        strbuf_addf(&obname, "%%(objectname:short)");
                else if (!filter->abbrev)
                        strbuf_addf(&obname, "%%(objectname)");
                else
                        strbuf_addf(&obname, "%%(objectname:short=%d)", filter->abbrev);

                strbuf_addf(&local, "%%(align:%d,left)%%(refname:lstrip=2)%%(end)", maxwidth);
                strbuf_addf(&local, "%s", branch_get_color(BRANCH_COLOR_RESET));
                strbuf_addf(&local, " %s ", obname.buf);

                if (filter->verbose > 1)
                        strbuf_addf(&local, "%%(if)%%(upstream)%%(then)[%s%%(upstream:short)%s%%(if)%%(upstream:track)"
                                    "%%(then): %%(upstream:track,nobracket)%%(end)] %%(end)%%(contents:subject)",
                                    branch_get_color(BRANCH_COLOR_UPSTREAM), branch_get_color(BRANCH_COLOR_RESET));
                else
                        strbuf_addf(&local, "%%(if)%%(upstream:track)%%(then)%%(upstream:track) %%(end)%%(contents:subject)");

                strbuf_addf(&remote, "%%(align:%d,left)%s%%(refname:lstrip=2)%%(end)%s"
                            "%%(if)%%(symref)%%(then) -> %%(symref:short)"
                            "%%(else) %s %%(contents:subject)%%(end)",
                            maxwidth, quote_literal_for_format(remote_prefix),
                            branch_get_color(BRANCH_COLOR_RESET), obname.buf);
                strbuf_release(&obname);
        } else {
                strbuf_addf(&local, "%%(refname:lstrip=2)%s%%(if)%%(symref)%%(then) -> %%(symref:short)%%(end)",
                            branch_get_color(BRANCH_COLOR_RESET));
                strbuf_addf(&remote, "%s%%(refname:lstrip=2)%s%%(if)%%(symref)%%(then) -> %%(symref:short)%%(end)",
                            quote_literal_for_format(remote_prefix),
                            branch_get_color(BRANCH_COLOR_RESET));
        }

        strbuf_addf(&fmt, "%%(if:notequals=refs/remotes)%%(refname:rstrip=-2)%%(then)%s%%(else)%s%%(end)", local.buf, remote.buf);

        strbuf_release(&local);
        strbuf_release(&remote);
        return strbuf_detach(&fmt, NULL);
}

static void print_ref_list(struct ref_filter *filter, struct ref_sorting *sorting, struct ref_format *format)
{
        int i;
        struct ref_array array;
        int maxwidth = 0;
        const char *remote_prefix = "";
        struct strbuf out = STRBUF_INIT;
        char *to_free = NULL;

        /*
         * If we are listing more than just remote branches,
         * then remote branches will have a "remotes/" prefix.
         * We need to account for this in the width.
         */
        if (filter->kind != FILTER_REFS_REMOTES)
                remote_prefix = "remotes/";

        memset(&array, 0, sizeof(array));

        filter_refs(&array, filter, filter->kind | FILTER_REFS_INCLUDE_BROKEN);

        if (filter->verbose)
                maxwidth = calc_maxwidth(&array, strlen(remote_prefix));

        if (!format->format)
                format->format = to_free = build_format(filter, maxwidth, remote_prefix);
        format->use_color = branch_use_color;

        if (verify_ref_format(format))
                die(_("unable to parse format string"));

        ref_array_sort(sorting, &array);

        for (i = 0; i < array.nr; i++) {
                format_ref_array_item(array.items[i], format, &out);
                if (column_active(colopts)) {
                        assert(!filter->verbose && "--column and --verbose are incompatible");
                         /* format to a string_list to let print_columns() do its job */
                        string_list_append(&output, out.buf);
                } else {
                        fwrite(out.buf, 1, out.len, stdout);
                        putchar('\n');
                }
                strbuf_release(&out);
        }

        ref_array_clear(&array);
        free(to_free);
}

static void reject_rebase_or_bisect_branch(const char *target)
{
        struct worktree **worktrees = get_worktrees(0);
        int i;

        for (i = 0; worktrees[i]; i++) {
                struct worktree *wt = worktrees[i];

                if (!wt->is_detached)
                        continue;

                if (is_worktree_being_rebased(wt, target))
                        die(_("Branch %s is being rebased at %s"),
                            target, wt->path);

                if (is_worktree_being_bisected(wt, target))
                        die(_("Branch %s is being bisected at %s"),
                            target, wt->path);
        }

        free_worktrees(worktrees);
}

static void rename_branch(const char *oldname, const char *newname, int force)
{
        struct strbuf oldref = STRBUF_INIT, newref = STRBUF_INIT, logmsg = STRBUF_INIT;
        struct strbuf oldsection = STRBUF_INIT, newsection = STRBUF_INIT;
        int recovery = 0;
        int clobber_head_ok;

        if (!oldname)
                die(_("cannot rename the current branch while not on any."));

        if (strbuf_check_branch_ref(&oldref, oldname)) {
                /*
                 * Bad name --- this could be an attempt to rename a
                 * ref that we used to allow to be created by accident.
                 */
                if (ref_exists(oldref.buf))
                        recovery = 1;
                else
                        die(_("Invalid branch name: '%s'"), oldname);
        }

        /*
         * A command like "git branch -M currentbranch currentbranch" cannot
         * cause the worktree to become inconsistent with HEAD, so allow it.
         */
        clobber_head_ok = !strcmp(oldname, newname);

        validate_new_branchname(newname, &newref, force, clobber_head_ok);

        reject_rebase_or_bisect_branch(oldref.buf);

        strbuf_addf(&logmsg, "Branch: renamed %s to %s",
                 oldref.buf, newref.buf);

        if (rename_ref(oldref.buf, newref.buf, logmsg.buf))
                die(_("Branch rename failed"));

        if (recovery)
                warning(_("Renamed a misnamed branch '%s' away"), oldref.buf + 11);

        if (replace_each_worktree_head_symref(oldref.buf, newref.buf, logmsg.buf))
                die(_("Branch renamed to %s, but HEAD is not updated!"), newname);

        strbuf_release(&logmsg);

        strbuf_addf(&oldsection, "branch.%s", oldref.buf + 11);
        strbuf_release(&oldref);
        strbuf_addf(&newsection, "branch.%s", newref.buf + 11);
        strbuf_release(&newref);
        if (git_config_rename_section(oldsection.buf, newsection.buf) < 0)
                die(_("Branch is renamed, but update of config-file failed"));
        strbuf_release(&oldsection);
        strbuf_release(&newsection);
}

static GIT_PATH_FUNC(edit_description, "EDIT_DESCRIPTION")

static int edit_branch_description(const char *branch_name)
{
        struct strbuf buf = STRBUF_INIT;
        struct strbuf name = STRBUF_INIT;

        read_branch_desc(&buf, branch_name);
        if (!buf.len || buf.buf[buf.len-1] != '\n')
                strbuf_addch(&buf, '\n');
        strbuf_commented_addf(&buf,
                    _("Please edit the description for the branch\n"
                      "  %s\n"
                      "Lines starting with '%c' will be stripped.\n"),
                    branch_name, comment_line_char);
        write_file_buf(edit_description(), buf.buf, buf.len);
        strbuf_reset(&buf);
        if (launch_editor(edit_description(), &buf, NULL)) {
                strbuf_release(&buf);
                return -1;
        }
        strbuf_stripspace(&buf, 1);

        strbuf_addf(&name, "branch.%s.description", branch_name);
        git_config_set(name.buf, buf.len ? buf.buf : NULL);
        strbuf_release(&name);
        strbuf_release(&buf);

        return 0;
}

int cmd_branch(int argc, const char **argv, const char *prefix)
{
        int delete = 0, rename = 0, force = 0, list = 0;
        int reflog = 0, edit_description = 0;
        int quiet = 0, unset_upstream = 0;
        const char *new_upstream = NULL;
        enum branch_track track;
        struct ref_filter filter;
        int icase = 0;
        static struct ref_sorting *sorting = NULL, **sorting_tail = &sorting;
        struct ref_format format = REF_FORMAT_INIT;

        struct option options[] = {
                OPT_GROUP(N_("Generic options")),
                OPT__VERBOSE(&filter.verbose,
                        N_("show hash and subject, give twice for upstream branch")),
                OPT__QUIET(&quiet, N_("suppress informational messages")),
                OPT_SET_INT('t', "track",  &track, N_("set up tracking mode (see git-pull(1))"),
                        BRANCH_TRACK_EXPLICIT),
                OPT_SET_INT( 0, "set-upstream",  &track, N_("change upstream info"),
                        BRANCH_TRACK_OVERRIDE),
                OPT_STRING('u', "set-upstream-to", &new_upstream, N_("upstream"), N_("change the upstream info")),
                OPT_BOOL(0, "unset-upstream", &unset_upstream, N_("Unset the upstream info")),
                OPT__COLOR(&branch_use_color, N_("use colored output")),
                OPT_SET_INT('r', "remotes",     &filter.kind, N_("act on remote-tracking branches"),
                        FILTER_REFS_REMOTES),
                OPT_CONTAINS(&filter.with_commit, N_("print only branches that contain the commit")),
                OPT_NO_CONTAINS(&filter.no_commit, N_("print only branches that don't contain the commit")),
                OPT_WITH(&filter.with_commit, N_("print only branches that contain the commit")),
                OPT_WITHOUT(&filter.no_commit, N_("print only branches that don't contain the commit")),
                OPT__ABBREV(&filter.abbrev),

                OPT_GROUP(N_("Specific git-branch actions:")),
                OPT_SET_INT('a', "all", &filter.kind, N_("list both remote-tracking and local branches"),
                        FILTER_REFS_REMOTES | FILTER_REFS_BRANCHES),
                OPT_BIT('d', "delete", &delete, N_("delete fully merged branch"), 1),
                OPT_BIT('D', NULL, &delete, N_("delete branch (even if not merged)"), 2),
                OPT_BIT('m', "move", &rename, N_("move/rename a branch and its reflog"), 1),
                OPT_BIT('M', NULL, &rename, N_("move/rename a branch, even if target exists"), 2),
                OPT_BOOL(0, "list", &list, N_("list branch names")),
                OPT_BOOL('l', "create-reflog", &reflog, N_("create the branch's reflog")),
                OPT_BOOL(0, "edit-description", &edit_description,
                         N_("edit the description for the branch")),
                OPT__FORCE(&force, N_("force creation, move/rename, deletion")),
                OPT_MERGED(&filter, N_("print only branches that are merged")),
                OPT_NO_MERGED(&filter, N_("print only branches that are not merged")),
                OPT_COLUMN(0, "column", &colopts, N_("list branches in columns")),
                OPT_CALLBACK(0 , "sort", sorting_tail, N_("key"),
                             N_("field name to sort on"), &parse_opt_ref_sorting),
                {
                        OPTION_CALLBACK, 0, "points-at", &filter.points_at, N_("object"),
                        N_("print only branches of the object"), 0, parse_opt_object_name
                },
                OPT_BOOL('i', "ignore-case", &icase, N_("sorting and filtering are case insensitive")),
                OPT_STRING(  0 , "format", &format.format, N_("format"), N_("format to use for the output")),
                OPT_END(),
        };

        setup_ref_filter_porcelain_msg();

        memset(&filter, 0, sizeof(filter));
        filter.kind = FILTER_REFS_BRANCHES;
        filter.abbrev = -1;

        if (argc == 2 && !strcmp(argv[1], "-h"))
                usage_with_options(builtin_branch_usage, options);

        git_config(git_branch_config, NULL);

        track = git_branch_track;

        head = resolve_refdup("HEAD", 0, head_oid.hash, NULL);
        if (!head)
                die(_("Failed to resolve HEAD as a valid ref."));
        if (!strcmp(head, "HEAD"))
                filter.detached = 1;
        else if (!skip_prefix(head, "refs/heads/", &head))
                die(_("HEAD not found below refs/heads!"));

        argc = parse_options(argc, argv, prefix, options, builtin_branch_usage,
                             0);

        if (!delete && !rename && !edit_description && !new_upstream && !unset_upstream && argc == 0)
                list = 1;

        if (filter.with_commit || filter.merge != REF_FILTER_MERGED_NONE || filter.points_at.nr ||
            filter.no_commit)
                list = 1;

        if (!!delete + !!rename + !!new_upstream +
            list + unset_upstream > 1)
                usage_with_options(builtin_branch_usage, options);

        if (filter.abbrev == -1)
                filter.abbrev = DEFAULT_ABBREV;
        filter.ignore_case = icase;

        finalize_colopts(&colopts, -1);
        if (filter.verbose) {
                if (explicitly_enable_column(colopts))
                        die(_("--column and --verbose are incompatible"));
                colopts = 0;
        }

        if (force) {
                delete *= 2;
                rename *= 2;
        }

        if (delete) {
                if (!argc)
                        die(_("branch name required"));
                return delete_branches(argc, argv, delete > 1, filter.kind, quiet);
        } else if (list) {
                /*  git branch --local also shows HEAD when it is detached */
                if ((filter.kind & FILTER_REFS_BRANCHES) && filter.detached)
                        filter.kind |= FILTER_REFS_DETACHED_HEAD;
                filter.name_patterns = argv;
                /*
                 * If no sorting parameter is given then we default to sorting
                 * by 'refname'. This would give us an alphabetically sorted
                 * array with the 'HEAD' ref at the beginning followed by
                 * local branches 'refs/heads/...' and finally remote-tacking
                 * branches 'refs/remotes/...'.
                 */
                if (!sorting)
                        sorting = ref_default_sorting();
                sorting->ignore_case = icase;
                print_ref_list(&filter, sorting, &format);
                print_columns(&output, colopts, NULL);
                string_list_clear(&output, 0);
                return 0;
        }
        else if (edit_description) {
                const char *branch_name;
                struct strbuf branch_ref = STRBUF_INIT;

                if (!argc) {
                        if (filter.detached)
                                die(_("Cannot give description to detached HEAD"));
                        branch_name = head;
                } else if (argc == 1)
                        branch_name = argv[0];
                else
                        die(_("cannot edit description of more than one branch"));

                strbuf_addf(&branch_ref, "refs/heads/%s", branch_name);
                if (!ref_exists(branch_ref.buf)) {
                        strbuf_release(&branch_ref);

                        if (!argc)
                                return error(_("No commit on branch '%s' yet."),
                                             branch_name);
                        else
                                return error(_("No branch named '%s'."),
                                             branch_name);
                }
                strbuf_release(&branch_ref);

                if (edit_branch_description(branch_name))
                        return 1;
        } else if (rename) {
                if (!argc)
                        die(_("branch name required"));
                else if (argc == 1)
                        rename_branch(head, argv[0], rename > 1);
                else if (argc == 2)
                        rename_branch(argv[0], argv[1], rename > 1);
                else
                        die(_("too many branches for a rename operation"));
        } else if (new_upstream) {
                struct branch *branch = branch_get(argv[0]);

                if (argc > 1)
                        die(_("too many branches to set new upstream"));

                if (!branch) {
                        if (!argc || !strcmp(argv[0], "HEAD"))
                                die(_("could not set upstream of HEAD to %s when "
                                      "it does not point to any branch."),
                                    new_upstream);
                        die(_("no such branch '%s'"), argv[0]);
                }

                if (!ref_exists(branch->refname))
                        die(_("branch '%s' does not exist"), branch->name);

                /*
                 * create_branch takes care of setting up the tracking
                 * info and making sure new_upstream is correct
                 */
                create_branch(branch->name, new_upstream, 0, 0, 0, quiet, BRANCH_TRACK_OVERRIDE);
        } else if (unset_upstream) {
                struct branch *branch = branch_get(argv[0]);
                struct strbuf buf = STRBUF_INIT;

                if (argc > 1)
                        die(_("too many branches to unset upstream"));

                if (!branch) {
                        if (!argc || !strcmp(argv[0], "HEAD"))
                                die(_("could not unset upstream of HEAD when "
                                      "it does not point to any branch."));
                        die(_("no such branch '%s'"), argv[0]);
                }

                if (!branch_has_merge_config(branch))
                        die(_("Branch '%s' has no upstream information"), branch->name);

                strbuf_addf(&buf, "branch.%s.remote", branch->name);
                git_config_set_multivar(buf.buf, NULL, NULL, 1);
                strbuf_reset(&buf);
                strbuf_addf(&buf, "branch.%s.merge", branch->name);
                git_config_set_multivar(buf.buf, NULL, NULL, 1);
                strbuf_release(&buf);
        } else if (argc > 0 && argc <= 2) {
                struct branch *branch = branch_get(argv[0]);
                int branch_existed = 0, remote_tracking = 0;
                struct strbuf buf = STRBUF_INIT;

                if (!strcmp(argv[0], "HEAD"))
                        die(_("it does not make sense to create 'HEAD' manually"));

                if (!branch)
                        die(_("no such branch '%s'"), argv[0]);

                if (filter.kind != FILTER_REFS_BRANCHES)
                        die(_("-a and -r options to 'git branch' do not make sense with a branch name"));

                if (track == BRANCH_TRACK_OVERRIDE)
                        fprintf(stderr, _("The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to\n"));

                strbuf_addf(&buf, "refs/remotes/%s", branch->name);
                remote_tracking = ref_exists(buf.buf);
                strbuf_release(&buf);

                branch_existed = ref_exists(branch->refname);
                create_branch(argv[0], (argc == 2) ? argv[1] : head,
                              force, reflog, 0, quiet, track);

                /*
                 * We only show the instructions if the user gave us
                 * one branch which doesn't exist locally, but is the
                 * name of a remote-tracking branch.
                 */
                if (argc == 1 && track == BRANCH_TRACK_OVERRIDE &&
                    !branch_existed && remote_tracking) {
                        fprintf(stderr, _("\nIf you wanted to make '%s' track '%s', do this:\n\n"), head, branch->name);
                        fprintf(stderr, "    git branch -d %s\n", branch->name);
                        fprintf(stderr, "    git branch --set-upstream-to %s\n", branch->name);
                }

        } else
                usage_with_options(builtin_branch_usage, options);

        return 0;
}