#include "builtin.h"
#include "config.h"
#include "parse-options.h"
#include "refs.h"
#include "lockfile.h"
#include "cache-tree.h"
#include "unpack-trees.h"
#include "merge-recursive.h"
#include "argv-array.h"
#include "run-command.h"
#include "dir.h"
#include "rerere.h"
#include "revision.h"
#include "log-tree.h"
#include "diffcore.h"
#include "exec-cmd.h"

#define INCLUDE_ALL_FILES 2

static const char * const git_stash_usage[] = {
        N_("git stash list [<options>]"),
        N_("git stash show [<options>] [<stash>]"),
        N_("git stash drop [-q|--quiet] [<stash>]"),
        N_("git stash ( pop | apply ) [--index] [-q|--quiet] [<stash>]"),
        N_("git stash branch <branchname> [<stash>]"),
        N_("git stash clear"),
        N_("git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
           "          [-u|--include-untracked] [-a|--all] [-m|--message <message>]\n"
           "          [--] [<pathspec>...]]"),
        N_("git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
           "          [-u|--include-untracked] [-a|--all] [<message>]"),
        NULL
};

static const char * const git_stash_list_usage[] = {
        N_("git stash list [<options>]"),
        NULL
};

static const char * const git_stash_show_usage[] = {
        N_("git stash show [<options>] [<stash>]"),
        NULL
};

static const char * const git_stash_drop_usage[] = {
        N_("git stash drop [-q|--quiet] [<stash>]"),
        NULL
};

static const char * const git_stash_pop_usage[] = {
        N_("git stash pop [--index] [-q|--quiet] [<stash>]"),
        NULL
};

static const char * const git_stash_apply_usage[] = {
        N_("git stash apply [--index] [-q|--quiet] [<stash>]"),
        NULL
};

static const char * const git_stash_branch_usage[] = {
        N_("git stash branch <branchname> [<stash>]"),
        NULL
};

static const char * const git_stash_clear_usage[] = {
        N_("git stash clear"),
        NULL
};

static const char * const git_stash_store_usage[] = {
        N_("git stash store [-m|--message <message>] [-q|--quiet] <commit>"),
        NULL
};

static const char * const git_stash_push_usage[] = {
        N_("git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
           "          [-u|--include-untracked] [-a|--all] [-m|--message <message>]\n"
           "          [--] [<pathspec>...]]"),
        NULL
};

static const char * const git_stash_save_usage[] = {
        N_("git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]\n"
           "          [-u|--include-untracked] [-a|--all] [<message>]"),
        NULL
};

static const char *ref_stash = "refs/stash";
static struct strbuf stash_index_path = STRBUF_INIT;

/*
 * w_commit is set to the commit containing the working tree
 * b_commit is set to the base commit
 * i_commit is set to the commit containing the index tree
 * u_commit is set to the commit containing the untracked files tree
 * w_tree is set to the working tree
 * b_tree is set to the base tree
 * i_tree is set to the index tree
 * u_tree is set to the untracked files tree
 */
struct stash_info {
        struct object_id w_commit;
        struct object_id b_commit;
        struct object_id i_commit;
        struct object_id u_commit;
        struct object_id w_tree;
        struct object_id b_tree;
        struct object_id i_tree;
        struct object_id u_tree;
        struct strbuf revision;
        int is_stash_ref;
        int has_u;
};

static void free_stash_info(struct stash_info *info)
{
        strbuf_release(&info->revision);
}

static void assert_stash_like(struct stash_info *info, const char *revision)
{
        if (get_oidf(&info->b_commit, "%s^1", revision) ||
            get_oidf(&info->w_tree, "%s:", revision) ||
            get_oidf(&info->b_tree, "%s^1:", revision) ||
            get_oidf(&info->i_tree, "%s^2:", revision))
                die(_("'%s' is not a stash-like commit"), revision);
}

static int get_stash_info(struct stash_info *info, int argc, const char **argv)
{
        int ret;
        char *end_of_rev;
        char *expanded_ref;
        const char *revision;
        const char *commit = NULL;
        struct object_id dummy;
        struct strbuf symbolic = STRBUF_INIT;

        if (argc > 1) {
                int i;
                struct strbuf refs_msg = STRBUF_INIT;

                for (i = 0; i < argc; i++)
                        strbuf_addf(&refs_msg, " '%s'", argv[i]);

                fprintf_ln(stderr, _("Too many revisions specified:%s"),
                           refs_msg.buf);
                strbuf_release(&refs_msg);

                return -1;
        }

        if (argc == 1)
                commit = argv[0];

        strbuf_init(&info->revision, 0);
        if (!commit) {
                if (!ref_exists(ref_stash)) {
                        free_stash_info(info);
                        fprintf_ln(stderr, _("No stash entries found."));
                        return -1;
                }

                strbuf_addf(&info->revision, "%s@{0}", ref_stash);
        } else if (strspn(commit, "0123456789") == strlen(commit)) {
                strbuf_addf(&info->revision, "%s@{%s}", ref_stash, commit);
        } else {
                strbuf_addstr(&info->revision, commit);
        }

        revision = info->revision.buf;

        if (get_oid(revision, &info->w_commit)) {
                error(_("%s is not a valid reference"), revision);
                free_stash_info(info);
                return -1;
        }

        assert_stash_like(info, revision);

        info->has_u = !get_oidf(&info->u_tree, "%s^3:", revision);

        end_of_rev = strchrnul(revision, '@');
        strbuf_add(&symbolic, revision, end_of_rev - revision);

        ret = dwim_ref(symbolic.buf, symbolic.len, &dummy, &expanded_ref);
        strbuf_release(&symbolic);
        switch (ret) {
        case 0: /* Not found, but valid ref */
                info->is_stash_ref = 0;
                break;
        case 1:
                info->is_stash_ref = !strcmp(expanded_ref, ref_stash);
                break;
        default: /* Invalid or ambiguous */
                free_stash_info(info);
        }

        free(expanded_ref);
        return !(ret == 0 || ret == 1);
}

static int do_clear_stash(void)
{
        struct object_id obj;
        if (get_oid(ref_stash, &obj))
                return 0;

        return delete_ref(NULL, ref_stash, &obj, 0);
}

static int clear_stash(int argc, const char **argv, const char *prefix)
{
        struct option options[] = {
                OPT_END()
        };

        argc = parse_options(argc, argv, prefix, options,
                             git_stash_clear_usage,
                             PARSE_OPT_STOP_AT_NON_OPTION);

        if (argc)
                return error(_("git stash clear with parameters is "
                               "unimplemented"));

        return do_clear_stash();
}

static int reset_tree(struct object_id *i_tree, int update, int reset)
{
        int nr_trees = 1;
        struct unpack_trees_options opts;
        struct tree_desc t[MAX_UNPACK_TREES];
        struct tree *tree;
        struct lock_file lock_file = LOCK_INIT;

        read_cache_preload(NULL);
        if (refresh_cache(REFRESH_QUIET))
                return -1;

        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);

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

        tree = parse_tree_indirect(i_tree);
        if (parse_tree(tree))
                return -1;

        init_tree_desc(t, tree->buffer, tree->size);

        opts.head_idx = 1;
        opts.src_index = &the_index;
        opts.dst_index = &the_index;
        opts.merge = 1;
        opts.reset = reset;
        opts.update = update;
        opts.fn = oneway_merge;

        if (unpack_trees(nr_trees, t, &opts))
                return -1;

        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
                return error(_("unable to write new index file"));

        return 0;
}

static int diff_tree_binary(struct strbuf *out, struct object_id *w_commit)
{
        struct child_process cp = CHILD_PROCESS_INIT;
        const char *w_commit_hex = oid_to_hex(w_commit);

        /*
         * Diff-tree would not be very hard to replace with a native function,
         * however it should be done together with apply_cached.
         */
        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "diff-tree", "--binary", NULL);
        argv_array_pushf(&cp.args, "%s^2^..%s^2", w_commit_hex, w_commit_hex);

        return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
}

static int apply_cached(struct strbuf *out)
{
        struct child_process cp = CHILD_PROCESS_INIT;

        /*
         * Apply currently only reads either from stdin or a file, thus
         * apply_all_patches would have to be updated to optionally take a
         * buffer.
         */
        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "apply", "--cached", NULL);
        return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
}

static int reset_head(void)
{
        struct child_process cp = CHILD_PROCESS_INIT;

        /*
         * Reset is overall quite simple, however there is no current public
         * API for resetting.
         */
        cp.git_cmd = 1;
        argv_array_push(&cp.args, "reset");

        return run_command(&cp);
}

static void add_diff_to_buf(struct diff_queue_struct *q,
                            struct diff_options *options,
                            void *data)
{
        int i;

        for (i = 0; i < q->nr; i++) {
                strbuf_addstr(data, q->queue[i]->one->path);

                /* NUL-terminate: will be fed to update-index -z */
                strbuf_addch(data, '\0');
        }
}

static int get_newly_staged(struct strbuf *out, struct object_id *c_tree)
{
        struct child_process cp = CHILD_PROCESS_INIT;
        const char *c_tree_hex = oid_to_hex(c_tree);

        /*
         * diff-index is very similar to diff-tree above, and should be
         * converted together with update_index.
         */
        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "diff-index", "--cached", "--name-only",
                         "--diff-filter=A", NULL);
        argv_array_push(&cp.args, c_tree_hex);
        return pipe_command(&cp, NULL, 0, out, 0, NULL, 0);
}

static int update_index(struct strbuf *out)
{
        struct child_process cp = CHILD_PROCESS_INIT;

        /*
         * Update-index is very complicated and may need to have a public
         * function exposed in order to remove this forking.
         */
        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "update-index", "--add", "--stdin", NULL);
        return pipe_command(&cp, out->buf, out->len, NULL, 0, NULL, 0);
}

static int restore_untracked(struct object_id *u_tree)
{
        int res;
        struct child_process cp = CHILD_PROCESS_INIT;

        /*
         * We need to run restore files from a given index, but without
         * affecting the current index, so we use GIT_INDEX_FILE with
         * run_command to fork processes that will not interfere.
         */
        cp.git_cmd = 1;
        argv_array_push(&cp.args, "read-tree");
        argv_array_push(&cp.args, oid_to_hex(u_tree));
        argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);
        if (run_command(&cp)) {
                remove_path(stash_index_path.buf);
                return -1;
        }

        child_process_init(&cp);
        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "checkout-index", "--all", NULL);
        argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);

        res = run_command(&cp);
        remove_path(stash_index_path.buf);
        return res;
}

static int do_apply_stash(const char *prefix, struct stash_info *info,
                          int index, int quiet)
{
        int ret;
        int has_index = index;
        struct merge_options o;
        struct object_id c_tree;
        struct object_id index_tree;
        struct commit *result;
        const struct object_id *bases[1];

        read_cache_preload(NULL);
        if (refresh_cache(REFRESH_QUIET))
                return -1;

        if (write_cache_as_tree(&c_tree, 0, NULL))
                return error(_("cannot apply a stash in the middle of a merge"));

        if (index) {
                if (oideq(&info->b_tree, &info->i_tree) ||
                    oideq(&c_tree, &info->i_tree)) {
                        has_index = 0;
                } else {
                        struct strbuf out = STRBUF_INIT;

                        if (diff_tree_binary(&out, &info->w_commit)) {
                                strbuf_release(&out);
                                return error(_("could not generate diff %s^!."),
                                             oid_to_hex(&info->w_commit));
                        }

                        ret = apply_cached(&out);
                        strbuf_release(&out);
                        if (ret)
                                return error(_("conflicts in index."
                                               "Try without --index."));

                        discard_cache();
                        read_cache();
                        if (write_cache_as_tree(&index_tree, 0, NULL))
                                return error(_("could not save index tree"));

                        reset_head();
                }
        }

        if (info->has_u && restore_untracked(&info->u_tree))
                return error(_("could not restore untracked files from stash"));

        init_merge_options(&o);

        o.branch1 = "Updated upstream";
        o.branch2 = "Stashed changes";

        if (oideq(&info->b_tree, &c_tree))
                o.branch1 = "Version stash was based on";

        if (quiet)
                o.verbosity = 0;

        if (o.verbosity >= 3)
                printf_ln(_("Merging %s with %s"), o.branch1, o.branch2);

        bases[0] = &info->b_tree;

        ret = merge_recursive_generic(&o, &c_tree, &info->w_tree, 1, bases,
                                      &result);
        if (ret) {
                rerere(0);

                if (index)
                        fprintf_ln(stderr, _("Index was not unstashed."));

                return ret;
        }

        if (has_index) {
                if (reset_tree(&index_tree, 0, 0))
                        return -1;
        } else {
                struct strbuf out = STRBUF_INIT;

                if (get_newly_staged(&out, &c_tree)) {
                        strbuf_release(&out);
                        return -1;
                }

                if (reset_tree(&c_tree, 0, 1)) {
                        strbuf_release(&out);
                        return -1;
                }

                ret = update_index(&out);
                strbuf_release(&out);
                if (ret)
                        return -1;

                discard_cache();
        }

        if (quiet) {
                if (refresh_cache(REFRESH_QUIET))
                        warning("could not refresh index");
        } else {
                struct child_process cp = CHILD_PROCESS_INIT;

                /*
                 * Status is quite simple and could be replaced with calls to
                 * wt_status in the future, but it adds complexities which may
                 * require more tests.
                 */
                cp.git_cmd = 1;
                cp.dir = prefix;
                argv_array_push(&cp.args, "status");
                run_command(&cp);
        }

        return 0;
}

static int apply_stash(int argc, const char **argv, const char *prefix)
{
        int ret;
        int quiet = 0;
        int index = 0;
        struct stash_info info;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_BOOL(0, "index", &index,
                         N_("attempt to recreate the index")),
                OPT_END()
        };

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

        if (get_stash_info(&info, argc, argv))
                return -1;

        ret = do_apply_stash(prefix, &info, index, quiet);
        free_stash_info(&info);
        return ret;
}

static int do_drop_stash(const char *prefix, struct stash_info *info, int quiet)
{
        int ret;
        struct child_process cp_reflog = CHILD_PROCESS_INIT;
        struct child_process cp = CHILD_PROCESS_INIT;

        /*
         * reflog does not provide a simple function for deleting refs. One will
         * need to be added to avoid implementing too much reflog code here
         */

        cp_reflog.git_cmd = 1;
        argv_array_pushl(&cp_reflog.args, "reflog", "delete", "--updateref",
                         "--rewrite", NULL);
        argv_array_push(&cp_reflog.args, info->revision.buf);
        ret = run_command(&cp_reflog);
        if (!ret) {
                if (!quiet)
                        printf_ln(_("Dropped %s (%s)"), info->revision.buf,
                                  oid_to_hex(&info->w_commit));
        } else {
                return error(_("%s: Could not drop stash entry"),
                             info->revision.buf);
        }

        /*
         * This could easily be replaced by get_oid, but currently it will throw
         * a fatal error when a reflog is empty, which we can not recover from.
         */
        cp.git_cmd = 1;
        /* Even though --quiet is specified, rev-parse still outputs the hash */
        cp.no_stdout = 1;
        argv_array_pushl(&cp.args, "rev-parse", "--verify", "--quiet", NULL);
        argv_array_pushf(&cp.args, "%s@{0}", ref_stash);
        ret = run_command(&cp);

        /* do_clear_stash if we just dropped the last stash entry */
        if (ret)
                do_clear_stash();

        return 0;
}

static void assert_stash_ref(struct stash_info *info)
{
        if (!info->is_stash_ref) {
                error(_("'%s' is not a stash reference"), info->revision.buf);
                free_stash_info(info);
                exit(1);
        }
}

static int drop_stash(int argc, const char **argv, const char *prefix)
{
        int ret;
        int quiet = 0;
        struct stash_info info;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_END()
        };

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

        if (get_stash_info(&info, argc, argv))
                return -1;

        assert_stash_ref(&info);

        ret = do_drop_stash(prefix, &info, quiet);
        free_stash_info(&info);
        return ret;
}

static int pop_stash(int argc, const char **argv, const char *prefix)
{
        int ret;
        int index = 0;
        int quiet = 0;
        struct stash_info info;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet, only report errors")),
                OPT_BOOL(0, "index", &index,
                         N_("attempt to recreate the index")),
                OPT_END()
        };

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

        if (get_stash_info(&info, argc, argv))
                return -1;

        assert_stash_ref(&info);
        if ((ret = do_apply_stash(prefix, &info, index, quiet)))
                printf_ln(_("The stash entry is kept in case "
                            "you need it again."));
        else
                ret = do_drop_stash(prefix, &info, quiet);

        free_stash_info(&info);
        return ret;
}

static int branch_stash(int argc, const char **argv, const char *prefix)
{
        int ret;
        const char *branch = NULL;
        struct stash_info info;
        struct child_process cp = CHILD_PROCESS_INIT;
        struct option options[] = {
                OPT_END()
        };

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

        if (!argc) {
                fprintf_ln(stderr, _("No branch name specified"));
                return -1;
        }

        branch = argv[0];

        if (get_stash_info(&info, argc - 1, argv + 1))
                return -1;

        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "checkout", "-b", NULL);
        argv_array_push(&cp.args, branch);
        argv_array_push(&cp.args, oid_to_hex(&info.b_commit));
        ret = run_command(&cp);
        if (!ret)
                ret = do_apply_stash(prefix, &info, 1, 0);
        if (!ret && info.is_stash_ref)
                ret = do_drop_stash(prefix, &info, 0);

        free_stash_info(&info);

        return ret;
}

static int list_stash(int argc, const char **argv, const char *prefix)
{
        struct child_process cp = CHILD_PROCESS_INIT;
        struct option options[] = {
                OPT_END()
        };

        argc = parse_options(argc, argv, prefix, options,
                             git_stash_list_usage,
                             PARSE_OPT_KEEP_UNKNOWN);

        if (!ref_exists(ref_stash))
                return 0;

        cp.git_cmd = 1;
        argv_array_pushl(&cp.args, "log", "--format=%gd: %gs", "-g",
                         "--first-parent", "-m", NULL);
        argv_array_pushv(&cp.args, argv);
        argv_array_push(&cp.args, ref_stash);
        argv_array_push(&cp.args, "--");
        return run_command(&cp);
}

static int show_stat = 1;
static int show_patch;

static int git_stash_config(const char *var, const char *value, void *cb)
{
        if (!strcmp(var, "stash.showstat")) {
                show_stat = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp(var, "stash.showpatch")) {
                show_patch = git_config_bool(var, value);
                return 0;
        }
        return git_default_config(var, value, cb);
}

static int show_stash(int argc, const char **argv, const char *prefix)
{
        int i;
        int opts = 0;
        int ret = 0;
        struct stash_info info;
        struct rev_info rev;
        struct argv_array stash_args = ARGV_ARRAY_INIT;
        struct option options[] = {
                OPT_END()
        };

        init_diff_ui_defaults();
        git_config(git_diff_ui_config, NULL);
        init_revisions(&rev, prefix);

        for (i = 1; i < argc; i++) {
                if (argv[i][0] != '-')
                        argv_array_push(&stash_args, argv[i]);
                else
                        opts++;
        }

        ret = get_stash_info(&info, stash_args.argc, stash_args.argv);
        argv_array_clear(&stash_args);
        if (ret)
                return -1;

        /*
         * The config settings are applied only if there are not passed
         * any options.
         */
        if (!opts) {
                git_config(git_stash_config, NULL);
                if (show_stat)
                        rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT;

                if (show_patch)
                        rev.diffopt.output_format |= DIFF_FORMAT_PATCH;

                if (!show_stat && !show_patch) {
                        free_stash_info(&info);
                        return 0;
                }
        }

        argc = setup_revisions(argc, argv, &rev, NULL);
        if (argc > 1) {
                free_stash_info(&info);
                usage_with_options(git_stash_show_usage, options);
        }

        rev.diffopt.flags.recursive = 1;
        setup_diff_pager(&rev.diffopt);
        diff_tree_oid(&info.b_commit, &info.w_commit, "", &rev.diffopt);
        log_tree_diff_flush(&rev);

        free_stash_info(&info);
        return diff_result_code(&rev.diffopt, 0);
}

static int do_store_stash(const struct object_id *w_commit, const char *stash_msg,
                          int quiet)
{
        if (!stash_msg)
                stash_msg = "Created via \"git stash store\".";

        if (update_ref(stash_msg, ref_stash, w_commit, NULL,
                       REF_FORCE_CREATE_REFLOG,
                       quiet ? UPDATE_REFS_QUIET_ON_ERR :
                       UPDATE_REFS_MSG_ON_ERR)) {
                if (!quiet) {
                        fprintf_ln(stderr, _("Cannot update %s with %s"),
                                   ref_stash, oid_to_hex(w_commit));
                }
                return -1;
        }

        return 0;
}

static int store_stash(int argc, const char **argv, const char *prefix)
{
        int quiet = 0;
        const char *stash_msg = NULL;
        struct object_id obj;
        struct object_context dummy;
        struct option options[] = {
                OPT__QUIET(&quiet, N_("be quiet")),
                OPT_STRING('m', "message", &stash_msg, "message",
                           N_("stash message")),
                OPT_END()
        };

        argc = parse_options(argc, argv, prefix, options,
                             git_stash_store_usage,
                             PARSE_OPT_KEEP_UNKNOWN);

        if (argc != 1) {
                if (!quiet)
                        fprintf_ln(stderr, _("\"git stash store\" requires one "
                                             "<commit> argument"));
                return -1;
        }

        if (get_oid_with_context(argv[0], quiet ? GET_OID_QUIETLY : 0, &obj,
                                 &dummy)) {
                if (!quiet)
                        fprintf_ln(stderr, _("Cannot update %s with %s"),
                                             ref_stash, argv[0]);
                return -1;
        }

        return do_store_stash(&obj, stash_msg, quiet);
}

static void add_pathspecs(struct argv_array *args,
                          struct pathspec ps) {
        int i;

        for (i = 0; i < ps.nr; i++)
                argv_array_push(args, ps.items[i].match);
}

/*
 * `untracked_files` will be filled with the names of untracked files.
 * The return value is:
 *
 * = 0 if there are not any untracked files
 * > 0 if there are untracked files
 */
static int get_untracked_files(struct pathspec ps, int include_untracked,
                               struct strbuf *untracked_files)
{
        int i;
        int max_len;
        int found = 0;
        char *seen;
        struct dir_struct dir;

        memset(&dir, 0, sizeof(dir));
        if (include_untracked != INCLUDE_ALL_FILES)
                setup_standard_excludes(&dir);

        seen = xcalloc(ps.nr, 1);

        max_len = fill_directory(&dir, the_repository->index, &ps);
        for (i = 0; i < dir.nr; i++) {
                struct dir_entry *ent = dir.entries[i];
                if (dir_path_match(&the_index, ent, &ps, max_len, seen)) {
                        found++;
                        strbuf_addstr(untracked_files, ent->name);
                        /* NUL-terminate: will be fed to update-index -z */
                        strbuf_addch(untracked_files, '\0');
                }
                free(ent);
        }

        free(seen);
        free(dir.entries);
        free(dir.ignored);
        clear_directory(&dir);
        return found;
}

/*
 * The return value of `check_changes_tracked_files()` can be:
 *
 * < 0 if there was an error
 * = 0 if there are no changes.
 * > 0 if there are changes.
 */
static int check_changes_tracked_files(struct pathspec ps)
{
        int result;
        struct rev_info rev;
        struct object_id dummy;

        /* No initial commit. */
        if (get_oid("HEAD", &dummy))
                return -1;

        if (read_cache() < 0)
                return -1;

        init_revisions(&rev, NULL);
        rev.prune_data = ps;

        rev.diffopt.flags.quick = 1;
        rev.diffopt.flags.ignore_submodules = 1;
        rev.abbrev = 0;

        add_head_to_pending(&rev);
        diff_setup_done(&rev.diffopt);

        result = run_diff_index(&rev, 1);
        if (diff_result_code(&rev.diffopt, result))
                return 1;

        object_array_clear(&rev.pending);
        result = run_diff_files(&rev, 0);
        if (diff_result_code(&rev.diffopt, result))
                return 1;

        return 0;
}

/*
 * The function will fill `untracked_files` with the names of untracked files
 * It will return 1 if there were any changes and 0 if there were not.
 */
static int check_changes(struct pathspec ps, int include_untracked,
                         struct strbuf *untracked_files)
{
        int ret = 0;
        if (check_changes_tracked_files(ps))
                ret = 1;

        if (include_untracked && get_untracked_files(ps, include_untracked,
                                                     untracked_files))
                ret = 1;

        return ret;
}

static int save_untracked_files(struct stash_info *info, struct strbuf *msg,
                                struct strbuf files)
{
        int ret = 0;
        struct strbuf untracked_msg = STRBUF_INIT;
        struct child_process cp_upd_index = CHILD_PROCESS_INIT;
        struct index_state istate = { NULL };

        cp_upd_index.git_cmd = 1;
        argv_array_pushl(&cp_upd_index.args, "update-index", "-z", "--add",
                         "--remove", "--stdin", NULL);
        argv_array_pushf(&cp_upd_index.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);

        strbuf_addf(&untracked_msg, "untracked files on %s\n", msg->buf);
        if (pipe_command(&cp_upd_index, files.buf, files.len, NULL, 0,
                         NULL, 0)) {
                ret = -1;
                goto done;
        }

        if (write_index_as_tree(&info->u_tree, &istate, stash_index_path.buf, 0,
                                NULL)) {
                ret = -1;
                goto done;
        }

        if (commit_tree(untracked_msg.buf, untracked_msg.len,
                        &info->u_tree, NULL, &info->u_commit, NULL, NULL)) {
                ret = -1;
                goto done;
        }

done:
        discard_index(&istate);
        strbuf_release(&untracked_msg);
        remove_path(stash_index_path.buf);
        return ret;
}

static int stash_patch(struct stash_info *info, struct pathspec ps,
                       struct strbuf *out_patch, int quiet)
{
        int ret = 0;
        struct child_process cp_read_tree = CHILD_PROCESS_INIT;
        struct child_process cp_add_i = CHILD_PROCESS_INIT;
        struct child_process cp_diff_tree = CHILD_PROCESS_INIT;
        struct index_state istate = { NULL };

        remove_path(stash_index_path.buf);

        cp_read_tree.git_cmd = 1;
        argv_array_pushl(&cp_read_tree.args, "read-tree", "HEAD", NULL);
        argv_array_pushf(&cp_read_tree.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);
        if (run_command(&cp_read_tree)) {
                ret = -1;
                goto done;
        }

        /* Find out what the user wants. */
        cp_add_i.git_cmd = 1;
        argv_array_pushl(&cp_add_i.args, "add--interactive", "--patch=stash",
                         "--", NULL);
        add_pathspecs(&cp_add_i.args, ps);
        argv_array_pushf(&cp_add_i.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);
        if (run_command(&cp_add_i)) {
                ret = -1;
                goto done;
        }

        /* State of the working tree. */
        if (write_index_as_tree(&info->w_tree, &istate, stash_index_path.buf, 0,
                                NULL)) {
                ret = -1;
                goto done;
        }

        cp_diff_tree.git_cmd = 1;
        argv_array_pushl(&cp_diff_tree.args, "diff-tree", "-p", "HEAD",
                         oid_to_hex(&info->w_tree), "--", NULL);
        if (pipe_command(&cp_diff_tree, NULL, 0, out_patch, 0, NULL, 0)) {
                ret = -1;
                goto done;
        }

        if (!out_patch->len) {
                if (!quiet)
                        fprintf_ln(stderr, _("No changes selected"));
                ret = 1;
        }

done:
        discard_index(&istate);
        remove_path(stash_index_path.buf);
        return ret;
}

static int stash_working_tree(struct stash_info *info, struct pathspec ps)
{
        int ret = 0;
        struct rev_info rev;
        struct child_process cp_upd_index = CHILD_PROCESS_INIT;
        struct strbuf diff_output = STRBUF_INIT;
        struct index_state istate = { NULL };

        init_revisions(&rev, NULL);

        set_alternate_index_output(stash_index_path.buf);
        if (reset_tree(&info->i_tree, 0, 0)) {
                ret = -1;
                goto done;
        }
        set_alternate_index_output(NULL);

        rev.prune_data = ps;
        rev.diffopt.output_format = DIFF_FORMAT_CALLBACK;
        rev.diffopt.format_callback = add_diff_to_buf;
        rev.diffopt.format_callback_data = &diff_output;

        if (read_cache_preload(&rev.diffopt.pathspec) < 0) {
                ret = -1;
                goto done;
        }

        add_pending_object(&rev, parse_object(the_repository, &info->b_commit),
                           "");
        if (run_diff_index(&rev, 0)) {
                ret = -1;
                goto done;
        }

        cp_upd_index.git_cmd = 1;
        argv_array_pushl(&cp_upd_index.args, "update-index", "-z", "--add",
                         "--remove", "--stdin", NULL);
        argv_array_pushf(&cp_upd_index.env_array, "GIT_INDEX_FILE=%s",
                         stash_index_path.buf);

        if (pipe_command(&cp_upd_index, diff_output.buf, diff_output.len,
                         NULL, 0, NULL, 0)) {
                ret = -1;
                goto done;
        }

        if (write_index_as_tree(&info->w_tree, &istate, stash_index_path.buf, 0,
                                NULL)) {
                ret = -1;
                goto done;
        }

done:
        discard_index(&istate);
        UNLEAK(rev);
        object_array_clear(&rev.pending);
        strbuf_release(&diff_output);
        remove_path(stash_index_path.buf);
        return ret;
}

static int do_create_stash(struct pathspec ps, struct strbuf *stash_msg_buf,
                           int include_untracked, int patch_mode,
                           struct stash_info *info, struct strbuf *patch,
                           int quiet)
{
        int ret = 0;
        int flags = 0;
        int untracked_commit_option = 0;
        const char *head_short_sha1 = NULL;
        const char *branch_ref = NULL;
        const char *branch_name = "(no branch)";
        struct commit *head_commit = NULL;
        struct commit_list *parents = NULL;
        struct strbuf msg = STRBUF_INIT;
        struct strbuf commit_tree_label = STRBUF_INIT;
        struct strbuf untracked_files = STRBUF_INIT;

        prepare_fallback_ident("git stash", "git@stash");

        read_cache_preload(NULL);
        refresh_cache(REFRESH_QUIET);

        if (get_oid("HEAD", &info->b_commit)) {
                if (!quiet)
                        fprintf_ln(stderr, _("You do not have "
                                             "the initial commit yet"));
                ret = -1;
                goto done;
        } else {
                head_commit = lookup_commit(the_repository, &info->b_commit);
        }

        if (!check_changes(ps, include_untracked, &untracked_files)) {
                ret = 1;
                goto done;
        }

        branch_ref = resolve_ref_unsafe("HEAD", 0, NULL, &flags);
        if (flags & REF_ISSYMREF)
                branch_name = strrchr(branch_ref, '/') + 1;
        head_short_sha1 = find_unique_abbrev(&head_commit->object.oid,
                                             DEFAULT_ABBREV);
        strbuf_addf(&msg, "%s: %s ", branch_name, head_short_sha1);
        pp_commit_easy(CMIT_FMT_ONELINE, head_commit, &msg);

        strbuf_addf(&commit_tree_label, "index on %s\n", msg.buf);
        commit_list_insert(head_commit, &parents);
        if (write_cache_as_tree(&info->i_tree, 0, NULL) ||
            commit_tree(commit_tree_label.buf, commit_tree_label.len,
                        &info->i_tree, parents, &info->i_commit, NULL, NULL)) {
                if (!quiet)
                        fprintf_ln(stderr, _("Cannot save the current "
                                             "index state"));
                ret = -1;
                goto done;
        }

        if (include_untracked) {
                if (save_untracked_files(info, &msg, untracked_files)) {
                        if (!quiet)
                                fprintf_ln(stderr, _("Cannot save "
                                                     "the untracked files"));
                        ret = -1;
                        goto done;
                }
                untracked_commit_option = 1;
        }
        if (patch_mode) {
                ret = stash_patch(info, ps, patch, quiet);
                if (ret < 0) {
                        if (!quiet)
                                fprintf_ln(stderr, _("Cannot save the current "
                                                     "worktree state"));
                        goto done;
                } else if (ret > 0) {
                        goto done;
                }
        } else {
                if (stash_working_tree(info, ps)) {
                        if (!quiet)
                                fprintf_ln(stderr, _("Cannot save the current "
                                                     "worktree state"));
                        ret = -1;
                        goto done;
                }
        }

        if (!stash_msg_buf->len)
                strbuf_addf(stash_msg_buf, "WIP on %s", msg.buf);
        else
                strbuf_insertf(stash_msg_buf, 0, "On %s: ", branch_name);

        /*
         * `parents` will be empty after calling `commit_tree()`, so there is
         * no need to call `free_commit_list()`
         */
        parents = NULL;
        if (untracked_commit_option)
                commit_list_insert(lookup_commit(the_repository,
                                                 &info->u_commit),
                                   &parents);
        commit_list_insert(lookup_commit(the_repository, &info->i_commit),
                           &parents);
        commit_list_insert(head_commit, &parents);

        if (commit_tree(stash_msg_buf->buf, stash_msg_buf->len, &info->w_tree,
                        parents, &info->w_commit, NULL, NULL)) {
                if (!quiet)
                        fprintf_ln(stderr, _("Cannot record "
                                             "working tree state"));
                ret = -1;
                goto done;
        }

done:
        strbuf_release(&commit_tree_label);
        strbuf_release(&msg);
        strbuf_release(&untracked_files);
        return ret;
}

static int create_stash(int argc, const char **argv, const char *prefix)
{
        int ret = 0;
        struct strbuf stash_msg_buf = STRBUF_INIT;
        struct stash_info info;
        struct pathspec ps;

        /* Starting with argv[1], since argv[0] is "create" */
        strbuf_join_argv(&stash_msg_buf, argc - 1, ++argv, ' ');

        memset(&ps, 0, sizeof(ps));
        if (!check_changes_tracked_files(ps))
                return 0;

        ret = do_create_stash(ps, &stash_msg_buf, 0, 0, &info,
                              NULL, 0);
        if (!ret)
                printf_ln("%s", oid_to_hex(&info.w_commit));

        strbuf_release(&stash_msg_buf);
        return ret;
}

static int do_push_stash(struct pathspec ps, const char *stash_msg, int quiet,
                         int keep_index, int patch_mode, int include_untracked)
{
        int ret = 0;
        struct stash_info info;
        struct strbuf patch = STRBUF_INIT;
        struct strbuf stash_msg_buf = STRBUF_INIT;
        struct strbuf untracked_files = STRBUF_INIT;

        if (patch_mode && keep_index == -1)
                keep_index = 1;

        if (patch_mode && include_untracked) {
                fprintf_ln(stderr, _("Can't use --patch and --include-untracked"
                                     " or --all at the same time"));
                ret = -1;
                goto done;
        }

        read_cache_preload(NULL);
        if (!include_untracked && ps.nr) {
                int i;
                char *ps_matched = xcalloc(ps.nr, 1);

                for (i = 0; i < active_nr; i++)
                        ce_path_match(&the_index, active_cache[i], &ps,
                                      ps_matched);

                if (report_path_error(ps_matched, &ps, NULL)) {
                        fprintf_ln(stderr, _("Did you forget to 'git add'?"));
                        ret = -1;
                        free(ps_matched);
                        goto done;
                }
                free(ps_matched);
        }

        if (refresh_cache(REFRESH_QUIET)) {
                ret = -1;
                goto done;
        }

        if (!check_changes(ps, include_untracked, &untracked_files)) {
                if (!quiet)
                        printf_ln(_("No local changes to save"));
                goto done;
        }

        if (!reflog_exists(ref_stash) && do_clear_stash()) {
                ret = -1;
                if (!quiet)
                        fprintf_ln(stderr, _("Cannot initialize stash"));
                goto done;
        }

        if (stash_msg)
                strbuf_addstr(&stash_msg_buf, stash_msg);
        if (do_create_stash(ps, &stash_msg_buf, include_untracked, patch_mode,
                            &info, &patch, quiet)) {
                ret = -1;
                goto done;
        }

        if (do_store_stash(&info.w_commit, stash_msg_buf.buf, 1)) {
                ret = -1;
                if (!quiet)
                        fprintf_ln(stderr, _("Cannot save the current status"));
                goto done;
        }

        if (!quiet)
                printf_ln(_("Saved working directory and index state %s"),
                          stash_msg_buf.buf);

        if (!patch_mode) {
                if (include_untracked && !ps.nr) {
                        struct child_process cp = CHILD_PROCESS_INIT;

                        cp.git_cmd = 1;
                        argv_array_pushl(&cp.args, "clean", "--force",
                                         "--quiet", "-d", NULL);
                        if (include_untracked == INCLUDE_ALL_FILES)
                                argv_array_push(&cp.args, "-x");
                        if (run_command(&cp)) {
                                ret = -1;
                                goto done;
                        }
                }
                discard_cache();
                if (ps.nr) {
                        struct child_process cp_add = CHILD_PROCESS_INIT;
                        struct child_process cp_diff = CHILD_PROCESS_INIT;
                        struct child_process cp_apply = CHILD_PROCESS_INIT;
                        struct strbuf out = STRBUF_INIT;

                        cp_add.git_cmd = 1;
                        argv_array_push(&cp_add.args, "add");
                        if (!include_untracked)
                                argv_array_push(&cp_add.args, "-u");
                        if (include_untracked == INCLUDE_ALL_FILES)
                                argv_array_push(&cp_add.args, "--force");
                        argv_array_push(&cp_add.args, "--");
                        add_pathspecs(&cp_add.args, ps);
                        if (run_command(&cp_add)) {
                                ret = -1;
                                goto done;
                        }

                        cp_diff.git_cmd = 1;
                        argv_array_pushl(&cp_diff.args, "diff-index", "-p",
                                         "--cached", "--binary", "HEAD", "--",
                                         NULL);
                        add_pathspecs(&cp_diff.args, ps);
                        if (pipe_command(&cp_diff, NULL, 0, &out, 0, NULL, 0)) {
                                ret = -1;
                                goto done;
                        }

                        cp_apply.git_cmd = 1;
                        argv_array_pushl(&cp_apply.args, "apply", "--index",
                                         "-R", NULL);
                        if (pipe_command(&cp_apply, out.buf, out.len, NULL, 0,
                                         NULL, 0)) {
                                ret = -1;
                                goto done;
                        }
                } else {
                        struct child_process cp = CHILD_PROCESS_INIT;
                        cp.git_cmd = 1;
                        argv_array_pushl(&cp.args, "reset", "--hard", "-q",
                                         NULL);
                        if (run_command(&cp)) {
                                ret = -1;
                                goto done;
                        }
                }

                if (keep_index == 1 && !is_null_oid(&info.i_tree)) {
                        struct child_process cp_ls = CHILD_PROCESS_INIT;
                        struct child_process cp_checkout = CHILD_PROCESS_INIT;
                        struct strbuf out = STRBUF_INIT;

                        if (reset_tree(&info.i_tree, 0, 1)) {
                                ret = -1;
                                goto done;
                        }

                        cp_ls.git_cmd = 1;
                        argv_array_pushl(&cp_ls.args, "ls-files", "-z",
                                         "--modified", "--", NULL);

                        add_pathspecs(&cp_ls.args, ps);
                        if (pipe_command(&cp_ls, NULL, 0, &out, 0, NULL, 0)) {
                                ret = -1;
                                goto done;
                        }

                        cp_checkout.git_cmd = 1;
                        argv_array_pushl(&cp_checkout.args, "checkout-index",
                                         "-z", "--force", "--stdin", NULL);
                        if (pipe_command(&cp_checkout, out.buf, out.len, NULL,
                                         0, NULL, 0)) {
                                ret = -1;
                                goto done;
                        }
                }
                goto done;
        } else {
                struct child_process cp = CHILD_PROCESS_INIT;

                cp.git_cmd = 1;
                argv_array_pushl(&cp.args, "apply", "-R", NULL);

                if (pipe_command(&cp, patch.buf, patch.len, NULL, 0, NULL, 0)) {
                        if (!quiet)
                                fprintf_ln(stderr, _("Cannot remove "
                                                     "worktree changes"));
                        ret = -1;
                        goto done;
                }

                if (keep_index < 1) {
                        struct child_process cp = CHILD_PROCESS_INIT;

                        cp.git_cmd = 1;
                        argv_array_pushl(&cp.args, "reset", "-q", "--", NULL);
                        add_pathspecs(&cp.args, ps);
                        if (run_command(&cp)) {
                                ret = -1;
                                goto done;
                        }
                }
                goto done;
        }

done:
        strbuf_release(&stash_msg_buf);
        return ret;
}

static int push_stash(int argc, const char **argv, const char *prefix)
{
        int keep_index = -1;
        int patch_mode = 0;
        int include_untracked = 0;
        int quiet = 0;
        const char *stash_msg = NULL;
        struct pathspec ps;
        struct option options[] = {
                OPT_BOOL('k', "keep-index", &keep_index,
                         N_("keep index")),
                OPT_BOOL('p', "patch", &patch_mode,
                         N_("stash in patch mode")),
                OPT__QUIET(&quiet, N_("quiet mode")),
                OPT_BOOL('u', "include-untracked", &include_untracked,
                         N_("include untracked files in stash")),
                OPT_SET_INT('a', "all", &include_untracked,
                            N_("include ignore files"), 2),
                OPT_STRING('m', "message", &stash_msg, N_("message"),
                           N_("stash message")),
                OPT_END()
        };

        if (argc)
                argc = parse_options(argc, argv, prefix, options,
                                     git_stash_push_usage,
                                     0);

        parse_pathspec(&ps, 0, PATHSPEC_PREFER_FULL, prefix, argv);
        return do_push_stash(ps, stash_msg, quiet, keep_index, patch_mode,
                             include_untracked);
}

static int save_stash(int argc, const char **argv, const char *prefix)
{
        int keep_index = -1;
        int patch_mode = 0;
        int include_untracked = 0;
        int quiet = 0;
        int ret = 0;
        const char *stash_msg = NULL;
        struct pathspec ps;
        struct strbuf stash_msg_buf = STRBUF_INIT;
        struct option options[] = {
                OPT_BOOL('k', "keep-index", &keep_index,
                         N_("keep index")),
                OPT_BOOL('p', "patch", &patch_mode,
                         N_("stash in patch mode")),
                OPT__QUIET(&quiet, N_("quiet mode")),
                OPT_BOOL('u', "include-untracked", &include_untracked,
                         N_("include untracked files in stash")),
                OPT_SET_INT('a', "all", &include_untracked,
                            N_("include ignore files"), 2),
                OPT_STRING('m', "message", &stash_msg, "message",
                           N_("stash message")),
                OPT_END()
        };

        argc = parse_options(argc, argv, prefix, options,
                             git_stash_save_usage,
                             PARSE_OPT_KEEP_DASHDASH);

        if (argc)
                stash_msg = strbuf_join_argv(&stash_msg_buf, argc, argv, ' ');

        memset(&ps, 0, sizeof(ps));
        ret = do_push_stash(ps, stash_msg, quiet, keep_index,
                            patch_mode, include_untracked);

        strbuf_release(&stash_msg_buf);
        return ret;
}

static int use_builtin_stash(void)
{
        struct child_process cp = CHILD_PROCESS_INIT;
        struct strbuf out = STRBUF_INIT;
        int ret;

        argv_array_pushl(&cp.args,
                         "config", "--bool", "stash.usebuiltin", NULL);
        cp.git_cmd = 1;
        if (capture_command(&cp, &out, 6)) {
                strbuf_release(&out);
                return 1;
        }

        strbuf_trim(&out);
        ret = !strcmp("true", out.buf);
        strbuf_release(&out);
        return ret;
}

int cmd_stash(int argc, const char **argv, const char *prefix)
{
        int i = -1;
        pid_t pid = getpid();
        const char *index_file;
        struct argv_array args = ARGV_ARRAY_INIT;

        struct option options[] = {
                OPT_END()
        };

        if (!use_builtin_stash()) {
                const char *path = mkpath("%s/git-legacy-stash",
                                          git_exec_path());

                if (sane_execvp(path, (char **)argv) < 0)
                        die_errno(_("could not exec %s"), path);
                else
                        BUG("sane_execvp() returned???");
        }

        prefix = setup_git_directory();
        trace_repo_setup(prefix);
        setup_work_tree();

        git_config(git_diff_basic_config, NULL);

        argc = parse_options(argc, argv, prefix, options, git_stash_usage,
                             PARSE_OPT_KEEP_UNKNOWN | PARSE_OPT_KEEP_DASHDASH);

        index_file = get_index_file();
        strbuf_addf(&stash_index_path, "%s.stash.%" PRIuMAX, index_file,
                    (uintmax_t)pid);

        if (!argc)
                return !!push_stash(0, NULL, prefix);
        else if (!strcmp(argv[0], "apply"))
                return !!apply_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "clear"))
                return !!clear_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "drop"))
                return !!drop_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "pop"))
                return !!pop_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "branch"))
                return !!branch_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "list"))
                return !!list_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "show"))
                return !!show_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "store"))
                return !!store_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "create"))
                return !!create_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "push"))
                return !!push_stash(argc, argv, prefix);
        else if (!strcmp(argv[0], "save"))
                return !!save_stash(argc, argv, prefix);
        else if (*argv[0] != '-')
                usage_msg_opt(xstrfmt(_("unknown subcommand: %s"), argv[0]),
                              git_stash_usage, options);

        if (strcmp(argv[0], "-p")) {
                while (++i < argc && strcmp(argv[i], "--")) {
                        /*
                         * `akpqu` is a string which contains all short options,
                         * except `-m` which is verified separately.
                         */
                        if ((strlen(argv[i]) == 2) && *argv[i] == '-' &&
                            strchr("akpqu", argv[i][1]))
                                continue;

                        if (!strcmp(argv[i], "--all") ||
                            !strcmp(argv[i], "--keep-index") ||
                            !strcmp(argv[i], "--no-keep-index") ||
                            !strcmp(argv[i], "--patch") ||
                            !strcmp(argv[i], "--quiet") ||
                            !strcmp(argv[i], "--include-untracked"))
                                continue;

                        /*
                         * `-m` and `--message=` are verified separately because
                         * they need to be immediately followed by a string
                         * (i.e.`-m"foobar"` or `--message="foobar"`).
                         */
                        if (starts_with(argv[i], "-m") ||
                            starts_with(argv[i], "--message="))
                                continue;

                        usage_with_options(git_stash_usage, options);
                }
        }

        argv_array_push(&args, "push");
        argv_array_pushv(&args, argv);
        return !!push_stash(args.argc, args.argv, prefix);
}