#include "cache.h"
#include "checkout.h"
#include "config.h"
#include "builtin.h"
#include "dir.h"
#include "parse-options.h"
#include "argv-array.h"
#include "branch.h"
#include "refs.h"
#include "run-command.h"
#include "sigchain.h"
#include "submodule.h"
#include "refs.h"
#include "utf8.h"
#include "worktree.h"

static const char * const worktree_usage[] = {
        N_("git worktree add [<options>] <path> [<commit-ish>]"),
        N_("git worktree list [<options>]"),
        N_("git worktree lock [<options>] <path>"),
        N_("git worktree move <worktree> <new-path>"),
        N_("git worktree prune [<options>]"),
        N_("git worktree remove [<options>] <worktree>"),
        N_("git worktree unlock <path>"),
        NULL
};

struct add_opts {
        int force;
        int detach;
        int quiet;
        int checkout;
        int keep_locked;
};

static int show_only;
static int verbose;
static int guess_remote;
static timestamp_t expire;

static int git_worktree_config(const char *var, const char *value, void *cb)
{
        if (!strcmp(var, "worktree.guessremote")) {
                guess_remote = git_config_bool(var, value);
                return 0;
        }

        return git_default_config(var, value, cb);
}

static int delete_git_dir(const char *id)
{
        struct strbuf sb = STRBUF_INIT;
        int ret;

        strbuf_addstr(&sb, git_common_path("worktrees/%s", id));
        ret = remove_dir_recursively(&sb, 0);
        if (ret < 0 && errno == ENOTDIR)
                ret = unlink(sb.buf);
        if (ret)
                error_errno(_("failed to delete '%s'"), sb.buf);
        strbuf_release(&sb);
        return ret;
}

static void delete_worktrees_dir_if_empty(void)
{
        rmdir(git_path("worktrees")); /* ignore failed removal */
}

static int prune_worktree(const char *id, struct strbuf *reason)
{
        struct stat st;
        char *path;
        int fd;
        size_t len;
        ssize_t read_result;

        if (!is_directory(git_path("worktrees/%s", id))) {
                strbuf_addf(reason, _("Removing worktrees/%s: not a valid directory"), id);
                return 1;
        }
        if (file_exists(git_path("worktrees/%s/locked", id)))
                return 0;
        if (stat(git_path("worktrees/%s/gitdir", id), &st)) {
                strbuf_addf(reason, _("Removing worktrees/%s: gitdir file does not exist"), id);
                return 1;
        }
        fd = open(git_path("worktrees/%s/gitdir", id), O_RDONLY);
        if (fd < 0) {
                strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
                            id, strerror(errno));
                return 1;
        }
        len = xsize_t(st.st_size);
        path = xmallocz(len);

        read_result = read_in_full(fd, path, len);
        if (read_result < 0) {
                strbuf_addf(reason, _("Removing worktrees/%s: unable to read gitdir file (%s)"),
                            id, strerror(errno));
                close(fd);
                free(path);
                return 1;
        }
        close(fd);

        if (read_result != len) {
                strbuf_addf(reason,
                            _("Removing worktrees/%s: short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
                            id, (uintmax_t)len, (uintmax_t)read_result);
                free(path);
                return 1;
        }
        while (len && (path[len - 1] == '\n' || path[len - 1] == '\r'))
                len--;
        if (!len) {
                strbuf_addf(reason, _("Removing worktrees/%s: invalid gitdir file"), id);
                free(path);
                return 1;
        }
        path[len] = '\0';
        if (!file_exists(path)) {
                free(path);
                if (stat(git_path("worktrees/%s/index", id), &st) ||
                    st.st_mtime <= expire) {
                        strbuf_addf(reason, _("Removing worktrees/%s: gitdir file points to non-existent location"), id);
                        return 1;
                } else {
                        return 0;
                }
        }
        free(path);
        return 0;
}

static void prune_worktrees(void)
{
        struct strbuf reason = STRBUF_INIT;
        DIR *dir = opendir(git_path("worktrees"));
        struct dirent *d;
        if (!dir)
                return;
        while ((d = readdir(dir)) != NULL) {
                if (is_dot_or_dotdot(d->d_name))
                        continue;
                strbuf_reset(&reason);
                if (!prune_worktree(d->d_name, &reason))
                        continue;
                if (show_only || verbose)
                        printf("%s\n", reason.buf);
                if (show_only)
                        continue;
                delete_git_dir(d->d_name);
        }
        closedir(dir);
        if (!show_only)
                delete_worktrees_dir_if_empty();
        strbuf_release(&reason);
}

static int prune(int ac, const char **av, const char *prefix)
{
        struct option options[] = {
                OPT__DRY_RUN(&show_only, N_("do not remove, show only")),
                OPT__VERBOSE(&verbose, N_("report pruned working trees")),
                OPT_EXPIRY_DATE(0, "expire", &expire,
                                N_("expire working trees older than <time>")),
                OPT_END()
        };

        expire = TIME_MAX;
        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac)
                usage_with_options(worktree_usage, options);
        prune_worktrees();
        return 0;
}

static char *junk_work_tree;
static char *junk_git_dir;
static int is_junk;
static pid_t junk_pid;

static void remove_junk(void)
{
        struct strbuf sb = STRBUF_INIT;
        if (!is_junk || getpid() != junk_pid)
                return;
        if (junk_git_dir) {
                strbuf_addstr(&sb, junk_git_dir);
                remove_dir_recursively(&sb, 0);
                strbuf_reset(&sb);
        }
        if (junk_work_tree) {
                strbuf_addstr(&sb, junk_work_tree);
                remove_dir_recursively(&sb, 0);
        }
        strbuf_release(&sb);
}

static void remove_junk_on_signal(int signo)
{
        remove_junk();
        sigchain_pop(signo);
        raise(signo);
}

static const char *worktree_basename(const char *path, int *olen)
{
        const char *name;
        int len;

        len = strlen(path);
        while (len && is_dir_sep(path[len - 1]))
                len--;

        for (name = path + len - 1; name > path; name--)
                if (is_dir_sep(*name)) {
                        name++;
                        break;
                }

        *olen = len;
        return name;
}

static void validate_worktree_add(const char *path, const struct add_opts *opts)
{
        struct worktree **worktrees;
        struct worktree *wt;
        int locked;

        if (file_exists(path) && !is_empty_dir(path))
                die(_("'%s' already exists"), path);

        worktrees = get_worktrees(0);
        /*
         * find_worktree()'s suffix matching may undesirably find the main
         * rather than a linked worktree (for instance, when the basenames
         * of the main worktree and the one being created are the same).
         * We're only interested in linked worktrees, so skip the main
         * worktree with +1.
         */
        wt = find_worktree(worktrees + 1, NULL, path);
        if (!wt)
                goto done;

        locked = !!worktree_lock_reason(wt);
        if ((!locked && opts->force) || (locked && opts->force > 1)) {
                if (delete_git_dir(wt->id))
                    die(_("unable to re-add worktree '%s'"), path);
                goto done;
        }

        if (locked)
                die(_("'%s' is a missing but locked worktree;\nuse 'add -f -f' to override, or 'unlock' and 'prune' or 'remove' to clear"), path);
        else
                die(_("'%s' is a missing but already registered worktree;\nuse 'add -f' to override, or 'prune' or 'remove' to clear"), path);

done:
        free_worktrees(worktrees);
}

static int add_worktree(const char *path, const char *refname,
                        const struct add_opts *opts)
{
        struct strbuf sb_git = STRBUF_INIT, sb_repo = STRBUF_INIT;
        struct strbuf sb = STRBUF_INIT;
        const char *name;
        struct stat st;
        struct child_process cp = CHILD_PROCESS_INIT;
        struct argv_array child_env = ARGV_ARRAY_INIT;
        int counter = 0, len, ret;
        struct strbuf symref = STRBUF_INIT;
        struct commit *commit = NULL;
        int is_branch = 0;

        validate_worktree_add(path, opts);

        /* is 'refname' a branch or commit? */
        if (!opts->detach && !strbuf_check_branch_ref(&symref, refname) &&
            ref_exists(symref.buf)) {
                is_branch = 1;
                if (!opts->force)
                        die_if_checked_out(symref.buf, 0);
        }
        commit = lookup_commit_reference_by_name(refname);
        if (!commit)
                die(_("invalid reference: %s"), refname);

        name = worktree_basename(path, &len);
        git_path_buf(&sb_repo, "worktrees/%.*s", (int)(path + len - name), name);
        len = sb_repo.len;
        if (safe_create_leading_directories_const(sb_repo.buf))
                die_errno(_("could not create leading directories of '%s'"),
                          sb_repo.buf);
        while (!stat(sb_repo.buf, &st)) {
                counter++;
                strbuf_setlen(&sb_repo, len);
                strbuf_addf(&sb_repo, "%d", counter);
        }
        name = strrchr(sb_repo.buf, '/') + 1;

        junk_pid = getpid();
        atexit(remove_junk);
        sigchain_push_common(remove_junk_on_signal);

        if (mkdir(sb_repo.buf, 0777))
                die_errno(_("could not create directory of '%s'"), sb_repo.buf);
        junk_git_dir = xstrdup(sb_repo.buf);
        is_junk = 1;

        /*
         * lock the incomplete repo so prune won't delete it, unlock
         * after the preparation is over.
         */
        strbuf_addf(&sb, "%s/locked", sb_repo.buf);
        if (!opts->keep_locked)
                write_file(sb.buf, "initializing");
        else
                write_file(sb.buf, "added with --lock");

        strbuf_addf(&sb_git, "%s/.git", path);
        if (safe_create_leading_directories_const(sb_git.buf))
                die_errno(_("could not create leading directories of '%s'"),
                          sb_git.buf);
        junk_work_tree = xstrdup(path);

        strbuf_reset(&sb);
        strbuf_addf(&sb, "%s/gitdir", sb_repo.buf);
        write_file(sb.buf, "%s", real_path(sb_git.buf));
        write_file(sb_git.buf, "gitdir: %s/worktrees/%s",
                   real_path(get_git_common_dir()), name);
        /*
         * This is to keep resolve_ref() happy. We need a valid HEAD
         * or is_git_directory() will reject the directory. Any value which
         * looks like an object ID will do since it will be immediately
         * replaced by the symbolic-ref or update-ref invocation in the new
         * worktree.
         */
        strbuf_reset(&sb);
        strbuf_addf(&sb, "%s/HEAD", sb_repo.buf);
        write_file(sb.buf, "%s", sha1_to_hex(null_sha1));
        strbuf_reset(&sb);
        strbuf_addf(&sb, "%s/commondir", sb_repo.buf);
        write_file(sb.buf, "../..");

        argv_array_pushf(&child_env, "%s=%s", GIT_DIR_ENVIRONMENT, sb_git.buf);
        argv_array_pushf(&child_env, "%s=%s", GIT_WORK_TREE_ENVIRONMENT, path);
        cp.git_cmd = 1;

        if (!is_branch)
                argv_array_pushl(&cp.args, "update-ref", "HEAD",
                                 oid_to_hex(&commit->object.oid), NULL);
        else {
                argv_array_pushl(&cp.args, "symbolic-ref", "HEAD",
                                 symref.buf, NULL);
                if (opts->quiet)
                        argv_array_push(&cp.args, "--quiet");
        }

        cp.env = child_env.argv;
        ret = run_command(&cp);
        if (ret)
                goto done;

        if (opts->checkout) {
                cp.argv = NULL;
                argv_array_clear(&cp.args);
                argv_array_pushl(&cp.args, "reset", "--hard", NULL);
                if (opts->quiet)
                        argv_array_push(&cp.args, "--quiet");
                cp.env = child_env.argv;
                ret = run_command(&cp);
                if (ret)
                        goto done;
        }

        is_junk = 0;
        FREE_AND_NULL(junk_work_tree);
        FREE_AND_NULL(junk_git_dir);

done:
        if (ret || !opts->keep_locked) {
                strbuf_reset(&sb);
                strbuf_addf(&sb, "%s/locked", sb_repo.buf);
                unlink_or_warn(sb.buf);
        }

        /*
         * Hook failure does not warrant worktree deletion, so run hook after
         * is_junk is cleared, but do return appropriate code when hook fails.
         */
        if (!ret && opts->checkout) {
                const char *hook = find_hook("post-checkout");
                if (hook) {
                        const char *env[] = { "GIT_DIR", "GIT_WORK_TREE", NULL };
                        cp.git_cmd = 0;
                        cp.no_stdin = 1;
                        cp.stdout_to_stderr = 1;
                        cp.dir = path;
                        cp.env = env;
                        cp.argv = NULL;
                        argv_array_pushl(&cp.args, absolute_path(hook),
                                         oid_to_hex(&null_oid),
                                         oid_to_hex(&commit->object.oid),
                                         "1", NULL);
                        ret = run_command(&cp);
                }
        }

        argv_array_clear(&child_env);
        strbuf_release(&sb);
        strbuf_release(&symref);
        strbuf_release(&sb_repo);
        strbuf_release(&sb_git);
        return ret;
}

static void print_preparing_worktree_line(int detach,
                                          const char *branch,
                                          const char *new_branch,
                                          int force_new_branch)
{
        if (force_new_branch) {
                struct commit *commit = lookup_commit_reference_by_name(new_branch);
                if (!commit)
                        printf_ln(_("Preparing worktree (new branch '%s')"), new_branch);
                else
                        printf_ln(_("Preparing worktree (resetting branch '%s'; was at %s)"),
                                  new_branch,
                                  find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
        } else if (new_branch) {
                printf_ln(_("Preparing worktree (new branch '%s')"), new_branch);
        } else {
                struct strbuf s = STRBUF_INIT;
                if (!detach && !strbuf_check_branch_ref(&s, branch) &&
                    ref_exists(s.buf))
                        printf_ln(_("Preparing worktree (checking out '%s')"),
                                  branch);
                else {
                        struct commit *commit = lookup_commit_reference_by_name(branch);
                        if (!commit)
                                die(_("invalid reference: %s"), branch);
                        printf_ln(_("Preparing worktree (detached HEAD %s)"),
                                  find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
                }
                strbuf_release(&s);
        }
}

static const char *dwim_branch(const char *path, const char **new_branch)
{
        int n;
        const char *s = worktree_basename(path, &n);
        const char *branchname = xstrndup(s, n);
        struct strbuf ref = STRBUF_INIT;

        UNLEAK(branchname);
        if (!strbuf_check_branch_ref(&ref, branchname) &&
            ref_exists(ref.buf)) {
                strbuf_release(&ref);
                return branchname;
        }

        *new_branch = branchname;
        if (guess_remote) {
                struct object_id oid;
                const char *remote =
                        unique_tracking_name(*new_branch, &oid, NULL);
                return remote;
        }
        return NULL;
}

static int add(int ac, const char **av, const char *prefix)
{
        struct add_opts opts;
        const char *new_branch_force = NULL;
        char *path;
        const char *branch;
        const char *new_branch = NULL;
        const char *opt_track = NULL;
        struct option options[] = {
                OPT__FORCE(&opts.force,
                           N_("checkout <branch> even if already checked out in other worktree"),
                           PARSE_OPT_NOCOMPLETE),
                OPT_STRING('b', NULL, &new_branch, N_("branch"),
                           N_("create a new branch")),
                OPT_STRING('B', NULL, &new_branch_force, N_("branch"),
                           N_("create or reset a branch")),
                OPT_BOOL(0, "detach", &opts.detach, N_("detach HEAD at named commit")),
                OPT_BOOL(0, "checkout", &opts.checkout, N_("populate the new working tree")),
                OPT_BOOL(0, "lock", &opts.keep_locked, N_("keep the new working tree locked")),
                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
                OPT_PASSTHRU(0, "track", &opt_track, NULL,
                             N_("set up tracking mode (see git-branch(1))"),
                             PARSE_OPT_NOARG | PARSE_OPT_OPTARG),
                OPT_BOOL(0, "guess-remote", &guess_remote,
                         N_("try to match the new branch name with a remote-tracking branch")),
                OPT_END()
        };

        memset(&opts, 0, sizeof(opts));
        opts.checkout = 1;
        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (!!opts.detach + !!new_branch + !!new_branch_force > 1)
                die(_("-b, -B, and --detach are mutually exclusive"));
        if (ac < 1 || ac > 2)
                usage_with_options(worktree_usage, options);

        path = prefix_filename(prefix, av[0]);
        branch = ac < 2 ? "HEAD" : av[1];

        if (!strcmp(branch, "-"))
                branch = "@{-1}";

        if (new_branch_force) {
                struct strbuf symref = STRBUF_INIT;

                new_branch = new_branch_force;

                if (!opts.force &&
                    !strbuf_check_branch_ref(&symref, new_branch) &&
                    ref_exists(symref.buf))
                        die_if_checked_out(symref.buf, 0);
                strbuf_release(&symref);
        }

        if (ac < 2 && !new_branch && !opts.detach) {
                const char *s = dwim_branch(path, &new_branch);
                if (s)
                        branch = s;
        }

        if (ac == 2 && !new_branch && !opts.detach) {
                struct object_id oid;
                struct commit *commit;
                const char *remote;

                commit = lookup_commit_reference_by_name(branch);
                if (!commit) {
                        remote = unique_tracking_name(branch, &oid, NULL);
                        if (remote) {
                                new_branch = branch;
                                branch = remote;
                        }
                }
        }
        if (!opts.quiet)
                print_preparing_worktree_line(opts.detach, branch, new_branch, !!new_branch_force);

        if (new_branch) {
                struct child_process cp = CHILD_PROCESS_INIT;
                cp.git_cmd = 1;
                argv_array_push(&cp.args, "branch");
                if (new_branch_force)
                        argv_array_push(&cp.args, "--force");
                if (opts.quiet)
                        argv_array_push(&cp.args, "--quiet");
                argv_array_push(&cp.args, new_branch);
                argv_array_push(&cp.args, branch);
                if (opt_track)
                        argv_array_push(&cp.args, opt_track);
                if (run_command(&cp))
                        return -1;
                branch = new_branch;
        } else if (opt_track) {
                die(_("--[no-]track can only be used if a new branch is created"));
        }

        UNLEAK(path);
        UNLEAK(opts);
        return add_worktree(path, branch, &opts);
}

static void show_worktree_porcelain(struct worktree *wt)
{
        printf("worktree %s\n", wt->path);
        if (wt->is_bare)
                printf("bare\n");
        else {
                printf("HEAD %s\n", oid_to_hex(&wt->head_oid));
                if (wt->is_detached)
                        printf("detached\n");
                else if (wt->head_ref)
                        printf("branch %s\n", wt->head_ref);
        }
        printf("\n");
}

static void show_worktree(struct worktree *wt, int path_maxlen, int abbrev_len)
{
        struct strbuf sb = STRBUF_INIT;
        int cur_path_len = strlen(wt->path);
        int path_adj = cur_path_len - utf8_strwidth(wt->path);

        strbuf_addf(&sb, "%-*s ", 1 + path_maxlen + path_adj, wt->path);
        if (wt->is_bare)
                strbuf_addstr(&sb, "(bare)");
        else {
                strbuf_addf(&sb, "%-*s ", abbrev_len,
                                find_unique_abbrev(&wt->head_oid, DEFAULT_ABBREV));
                if (wt->is_detached)
                        strbuf_addstr(&sb, "(detached HEAD)");
                else if (wt->head_ref) {
                        char *ref = shorten_unambiguous_ref(wt->head_ref, 0);
                        strbuf_addf(&sb, "[%s]", ref);
                        free(ref);
                } else
                        strbuf_addstr(&sb, "(error)");
        }
        printf("%s\n", sb.buf);

        strbuf_release(&sb);
}

static void measure_widths(struct worktree **wt, int *abbrev, int *maxlen)
{
        int i;

        for (i = 0; wt[i]; i++) {
                int sha1_len;
                int path_len = strlen(wt[i]->path);

                if (path_len > *maxlen)
                        *maxlen = path_len;
                sha1_len = strlen(find_unique_abbrev(&wt[i]->head_oid, *abbrev));
                if (sha1_len > *abbrev)
                        *abbrev = sha1_len;
        }
}

static int list(int ac, const char **av, const char *prefix)
{
        int porcelain = 0;

        struct option options[] = {
                OPT_BOOL(0, "porcelain", &porcelain, N_("machine-readable output")),
                OPT_END()
        };

        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac)
                usage_with_options(worktree_usage, options);
        else {
                struct worktree **worktrees = get_worktrees(GWT_SORT_LINKED);
                int path_maxlen = 0, abbrev = DEFAULT_ABBREV, i;

                if (!porcelain)
                        measure_widths(worktrees, &abbrev, &path_maxlen);

                for (i = 0; worktrees[i]; i++) {
                        if (porcelain)
                                show_worktree_porcelain(worktrees[i]);
                        else
                                show_worktree(worktrees[i], path_maxlen, abbrev);
                }
                free_worktrees(worktrees);
        }
        return 0;
}

static int lock_worktree(int ac, const char **av, const char *prefix)
{
        const char *reason = "", *old_reason;
        struct option options[] = {
                OPT_STRING(0, "reason", &reason, N_("string"),
                           N_("reason for locking")),
                OPT_END()
        };
        struct worktree **worktrees, *wt;

        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac != 1)
                usage_with_options(worktree_usage, options);

        worktrees = get_worktrees(0);
        wt = find_worktree(worktrees, prefix, av[0]);
        if (!wt)
                die(_("'%s' is not a working tree"), av[0]);
        if (is_main_worktree(wt))
                die(_("The main working tree cannot be locked or unlocked"));

        old_reason = worktree_lock_reason(wt);
        if (old_reason) {
                if (*old_reason)
                        die(_("'%s' is already locked, reason: %s"),
                            av[0], old_reason);
                die(_("'%s' is already locked"), av[0]);
        }

        write_file(git_common_path("worktrees/%s/locked", wt->id),
                   "%s", reason);
        free_worktrees(worktrees);
        return 0;
}

static int unlock_worktree(int ac, const char **av, const char *prefix)
{
        struct option options[] = {
                OPT_END()
        };
        struct worktree **worktrees, *wt;
        int ret;

        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac != 1)
                usage_with_options(worktree_usage, options);

        worktrees = get_worktrees(0);
        wt = find_worktree(worktrees, prefix, av[0]);
        if (!wt)
                die(_("'%s' is not a working tree"), av[0]);
        if (is_main_worktree(wt))
                die(_("The main working tree cannot be locked or unlocked"));
        if (!worktree_lock_reason(wt))
                die(_("'%s' is not locked"), av[0]);
        ret = unlink_or_warn(git_common_path("worktrees/%s/locked", wt->id));
        free_worktrees(worktrees);
        return ret;
}

static void validate_no_submodules(const struct worktree *wt)
{
        struct index_state istate = { NULL };
        struct strbuf path = STRBUF_INIT;
        int i, found_submodules = 0;

        if (is_directory(worktree_git_path(wt, "modules"))) {
                /*
                 * There could be false positives, e.g. the "modules"
                 * directory exists but is empty. But it's a rare case and
                 * this simpler check is probably good enough for now.
                 */
                found_submodules = 1;
        } else if (read_index_from(&istate, worktree_git_path(wt, "index"),
                                   get_worktree_git_dir(wt)) > 0) {
                for (i = 0; i < istate.cache_nr; i++) {
                        struct cache_entry *ce = istate.cache[i];
                        int err;

                        if (!S_ISGITLINK(ce->ce_mode))
                                continue;

                        strbuf_reset(&path);
                        strbuf_addf(&path, "%s/%s", wt->path, ce->name);
                        if (!is_submodule_populated_gently(path.buf, &err))
                                continue;

                        found_submodules = 1;
                        break;
                }
        }
        discard_index(&istate);
        strbuf_release(&path);

        if (found_submodules)
                die(_("working trees containing submodules cannot be moved or removed"));
}

static int move_worktree(int ac, const char **av, const char *prefix)
{
        int force = 0;
        struct option options[] = {
                OPT__FORCE(&force,
                         N_("force move even if worktree is dirty or locked"),
                         PARSE_OPT_NOCOMPLETE),
                OPT_END()
        };
        struct worktree **worktrees, *wt;
        struct strbuf dst = STRBUF_INIT;
        struct strbuf errmsg = STRBUF_INIT;
        const char *reason = NULL;
        char *path;

        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac != 2)
                usage_with_options(worktree_usage, options);

        path = prefix_filename(prefix, av[1]);
        strbuf_addstr(&dst, path);
        free(path);

        worktrees = get_worktrees(0);
        wt = find_worktree(worktrees, prefix, av[0]);
        if (!wt)
                die(_("'%s' is not a working tree"), av[0]);
        if (is_main_worktree(wt))
                die(_("'%s' is a main working tree"), av[0]);
        if (is_directory(dst.buf)) {
                const char *sep = find_last_dir_sep(wt->path);

                if (!sep)
                        die(_("could not figure out destination name from '%s'"),
                            wt->path);
                strbuf_trim_trailing_dir_sep(&dst);
                strbuf_addstr(&dst, sep);
        }
        if (file_exists(dst.buf))
                die(_("target '%s' already exists"), dst.buf);

        validate_no_submodules(wt);

        if (force < 2)
                reason = worktree_lock_reason(wt);
        if (reason) {
                if (*reason)
                        die(_("cannot move a locked working tree, lock reason: %s\nuse 'move -f -f' to override or unlock first"),
                            reason);
                die(_("cannot move a locked working tree;\nuse 'move -f -f' to override or unlock first"));
        }
        if (validate_worktree(wt, &errmsg, 0))
                die(_("validation failed, cannot move working tree: %s"),
                    errmsg.buf);
        strbuf_release(&errmsg);

        if (rename(wt->path, dst.buf) == -1)
                die_errno(_("failed to move '%s' to '%s'"), wt->path, dst.buf);

        update_worktree_location(wt, dst.buf);

        strbuf_release(&dst);
        free_worktrees(worktrees);
        return 0;
}

/*
 * Note, "git status --porcelain" is used to determine if it's safe to
 * delete a whole worktree. "git status" does not ignore user
 * configuration, so if a normal "git status" shows "clean" for the
 * user, then it's ok to remove it.
 *
 * This assumption may be a bad one. We may want to ignore
 * (potentially bad) user settings and only delete a worktree when
 * it's absolutely safe to do so from _our_ point of view because we
 * know better.
 */
static void check_clean_worktree(struct worktree *wt,
                                 const char *original_path)
{
        struct argv_array child_env = ARGV_ARRAY_INIT;
        struct child_process cp;
        char buf[1];
        int ret;

        /*
         * Until we sort this out, all submodules are "dirty" and
         * will abort this function.
         */
        validate_no_submodules(wt);

        argv_array_pushf(&child_env, "%s=%s/.git",
                         GIT_DIR_ENVIRONMENT, wt->path);
        argv_array_pushf(&child_env, "%s=%s",
                         GIT_WORK_TREE_ENVIRONMENT, wt->path);
        memset(&cp, 0, sizeof(cp));
        argv_array_pushl(&cp.args, "status",
                         "--porcelain", "--ignore-submodules=none",
                         NULL);
        cp.env = child_env.argv;
        cp.git_cmd = 1;
        cp.dir = wt->path;
        cp.out = -1;
        ret = start_command(&cp);
        if (ret)
                die_errno(_("failed to run 'git status' on '%s'"),
                          original_path);
        ret = xread(cp.out, buf, sizeof(buf));
        if (ret)
                die(_("'%s' is dirty, use --force to delete it"),
                    original_path);
        close(cp.out);
        ret = finish_command(&cp);
        if (ret)
                die_errno(_("failed to run 'git status' on '%s', code %d"),
                          original_path, ret);
}

static int delete_git_work_tree(struct worktree *wt)
{
        struct strbuf sb = STRBUF_INIT;
        int ret = 0;

        strbuf_addstr(&sb, wt->path);
        if (remove_dir_recursively(&sb, 0)) {
                error_errno(_("failed to delete '%s'"), sb.buf);
                ret = -1;
        }
        strbuf_release(&sb);
        return ret;
}

static int remove_worktree(int ac, const char **av, const char *prefix)
{
        int force = 0;
        struct option options[] = {
                OPT__FORCE(&force,
                         N_("force removal even if worktree is dirty or locked"),
                         PARSE_OPT_NOCOMPLETE),
                OPT_END()
        };
        struct worktree **worktrees, *wt;
        struct strbuf errmsg = STRBUF_INIT;
        const char *reason = NULL;
        int ret = 0;

        ac = parse_options(ac, av, prefix, options, worktree_usage, 0);
        if (ac != 1)
                usage_with_options(worktree_usage, options);

        worktrees = get_worktrees(0);
        wt = find_worktree(worktrees, prefix, av[0]);
        if (!wt)
                die(_("'%s' is not a working tree"), av[0]);
        if (is_main_worktree(wt))
                die(_("'%s' is a main working tree"), av[0]);
        if (force < 2)
                reason = worktree_lock_reason(wt);
        if (reason) {
                if (*reason)
                        die(_("cannot remove a locked working tree, lock reason: %s\nuse 'remove -f -f' to override or unlock first"),
                            reason);
                die(_("cannot remove a locked working tree;\nuse 'remove -f -f' to override or unlock first"));
        }
        if (validate_worktree(wt, &errmsg, WT_VALIDATE_WORKTREE_MISSING_OK))
                die(_("validation failed, cannot remove working tree: %s"),
                    errmsg.buf);
        strbuf_release(&errmsg);

        if (file_exists(wt->path)) {
                if (!force)
                        check_clean_worktree(wt, av[0]);

                ret |= delete_git_work_tree(wt);
        }
        /*
         * continue on even if ret is non-zero, there's no going back
         * from here.
         */
        ret |= delete_git_dir(wt->id);
        delete_worktrees_dir_if_empty();

        free_worktrees(worktrees);
        return ret;
}

int cmd_worktree(int ac, const char **av, const char *prefix)
{
        struct option options[] = {
                OPT_END()
        };

        git_config(git_worktree_config, NULL);

        if (ac < 2)
                usage_with_options(worktree_usage, options);
        if (!prefix)
                prefix = "";
        if (!strcmp(av[1], "add"))
                return add(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "prune"))
                return prune(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "list"))
                return list(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "lock"))
                return lock_worktree(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "unlock"))
                return unlock_worktree(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "move"))
                return move_worktree(ac - 1, av + 1, prefix);
        if (!strcmp(av[1], "remove"))
                return remove_worktree(ac - 1, av + 1, prefix);
        usage_with_options(worktree_usage, options);
}