/*
 * Builtin "git notes"
 *
 * Copyright (c) 2010 Johan Herland <johan@herland.net>
 *
 * Based on git-notes.sh by Johannes Schindelin,
 * and builtin/tag.c by Kristian Høgsberg and Carlos Rica.
 */

#include "cache.h"
#include "config.h"
#include "builtin.h"
#include "notes.h"
#include "blob.h"
#include "pretty.h"
#include "refs.h"
#include "exec-cmd.h"
#include "run-command.h"
#include "parse-options.h"
#include "string-list.h"
#include "notes-merge.h"
#include "notes-utils.h"
#include "worktree.h"

static const char * const git_notes_usage[] = {
        N_("git notes [--ref <notes-ref>] [list [<object>]]"),
        N_("git notes [--ref <notes-ref>] add [-f] [--allow-empty] [-m <msg> | -F <file> | (-c | -C) <object>] [<object>]"),
        N_("git notes [--ref <notes-ref>] copy [-f] <from-object> <to-object>"),
        N_("git notes [--ref <notes-ref>] append [--allow-empty] [-m <msg> | -F <file> | (-c | -C) <object>] [<object>]"),
        N_("git notes [--ref <notes-ref>] edit [--allow-empty] [<object>]"),
        N_("git notes [--ref <notes-ref>] show [<object>]"),
        N_("git notes [--ref <notes-ref>] merge [-v | -q] [-s <strategy>] <notes-ref>"),
        N_("git notes merge --commit [-v | -q]"),
        N_("git notes merge --abort [-v | -q]"),
        N_("git notes [--ref <notes-ref>] remove [<object>...]"),
        N_("git notes [--ref <notes-ref>] prune [-n] [-v]"),
        N_("git notes [--ref <notes-ref>] get-ref"),
        NULL
};

static const char * const git_notes_list_usage[] = {
        N_("git notes [list [<object>]]"),
        NULL
};

static const char * const git_notes_add_usage[] = {
        N_("git notes add [<options>] [<object>]"),
        NULL
};

static const char * const git_notes_copy_usage[] = {
        N_("git notes copy [<options>] <from-object> <to-object>"),
        N_("git notes copy --stdin [<from-object> <to-object>]..."),
        NULL
};

static const char * const git_notes_append_usage[] = {
        N_("git notes append [<options>] [<object>]"),
        NULL
};

static const char * const git_notes_edit_usage[] = {
        N_("git notes edit [<object>]"),
        NULL
};

static const char * const git_notes_show_usage[] = {
        N_("git notes show [<object>]"),
        NULL
};

static const char * const git_notes_merge_usage[] = {
        N_("git notes merge [<options>] <notes-ref>"),
        N_("git notes merge --commit [<options>]"),
        N_("git notes merge --abort [<options>]"),
        NULL
};

static const char * const git_notes_remove_usage[] = {
        N_("git notes remove [<object>]"),
        NULL
};

static const char * const git_notes_prune_usage[] = {
        N_("git notes prune [<options>]"),
        NULL
};

static const char * const git_notes_get_ref_usage[] = {
        N_("git notes get-ref"),
        NULL
};

static const char note_template[] =
        N_("Write/edit the notes for the following object:");

struct note_data {
        int given;
        int use_editor;
        char *edit_path;
        struct strbuf buf;
};

static void free_note_data(struct note_data *d)
{
        if (d->edit_path) {
                unlink_or_warn(d->edit_path);
                free(d->edit_path);
        }
        strbuf_release(&d->buf);
}

static int list_each_note(const struct object_id *object_oid,
                const struct object_id *note_oid, char *note_path,
                void *cb_data)
{
        printf("%s %s\n", oid_to_hex(note_oid), oid_to_hex(object_oid));
        return 0;
}

static void copy_obj_to_fd(int fd, const struct object_id *oid)
{
        unsigned long size;
        enum object_type type;
        char *buf = read_object_file(oid, &type, &size);
        if (buf) {
                if (size)
                        write_or_die(fd, buf, size);
                free(buf);
        }
}

static void write_commented_object(int fd, const struct object_id *object)
{
        const char *show_args[5] =
                {"show", "--stat", "--no-notes", oid_to_hex(object), NULL};
        struct child_process show = CHILD_PROCESS_INIT;
        struct strbuf buf = STRBUF_INIT;
        struct strbuf cbuf = STRBUF_INIT;

        /* Invoke "git show --stat --no-notes $object" */
        show.argv = show_args;
        show.no_stdin = 1;
        show.out = -1;
        show.err = 0;
        show.git_cmd = 1;
        if (start_command(&show))
                die(_("unable to start 'show' for object '%s'"),
                    oid_to_hex(object));

        if (strbuf_read(&buf, show.out, 0) < 0)
                die_errno(_("could not read 'show' output"));
        strbuf_add_commented_lines(&cbuf, buf.buf, buf.len);
        write_or_die(fd, cbuf.buf, cbuf.len);

        strbuf_release(&cbuf);
        strbuf_release(&buf);

        if (finish_command(&show))
                die(_("failed to finish 'show' for object '%s'"),
                    oid_to_hex(object));
}

static void prepare_note_data(const struct object_id *object, struct note_data *d,
                const struct object_id *old_note)
{
        if (d->use_editor || !d->given) {
                int fd;
                struct strbuf buf = STRBUF_INIT;

                /* write the template message before editing: */
                d->edit_path = git_pathdup("NOTES_EDITMSG");
                fd = open(d->edit_path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
                if (fd < 0)
                        die_errno(_("could not create file '%s'"), d->edit_path);

                if (d->given)
                        write_or_die(fd, d->buf.buf, d->buf.len);
                else if (old_note)
                        copy_obj_to_fd(fd, old_note);

                strbuf_addch(&buf, '\n');
                strbuf_add_commented_lines(&buf, "\n", strlen("\n"));
                strbuf_add_commented_lines(&buf, _(note_template), strlen(_(note_template)));
                strbuf_addch(&buf, '\n');
                write_or_die(fd, buf.buf, buf.len);

                write_commented_object(fd, object);

                close(fd);
                strbuf_release(&buf);
                strbuf_reset(&d->buf);

                if (launch_editor(d->edit_path, &d->buf, NULL)) {
                        die(_("please supply the note contents using either -m or -F option"));
                }
                strbuf_stripspace(&d->buf, 1);
        }
}

static void write_note_data(struct note_data *d, struct object_id *oid)
{
        if (write_object_file(d->buf.buf, d->buf.len, blob_type, oid)) {
                error(_("unable to write note object"));
                if (d->edit_path)
                        error(_("the note contents have been left in %s"),
                                d->edit_path);
                exit(128);
        }
}

static int parse_msg_arg(const struct option *opt, const char *arg, int unset)
{
        struct note_data *d = opt->value;

        strbuf_grow(&d->buf, strlen(arg) + 2);
        if (d->buf.len)
                strbuf_addch(&d->buf, '\n');
        strbuf_addstr(&d->buf, arg);
        strbuf_stripspace(&d->buf, 0);

        d->given = 1;
        return 0;
}

static int parse_file_arg(const struct option *opt, const char *arg, int unset)
{
        struct note_data *d = opt->value;

        if (d->buf.len)
                strbuf_addch(&d->buf, '\n');
        if (!strcmp(arg, "-")) {
                if (strbuf_read(&d->buf, 0, 1024) < 0)
                        die_errno(_("cannot read '%s'"), arg);
        } else if (strbuf_read_file(&d->buf, arg, 1024) < 0)
                die_errno(_("could not open or read '%s'"), arg);
        strbuf_stripspace(&d->buf, 0);

        d->given = 1;
        return 0;
}

static int parse_reuse_arg(const struct option *opt, const char *arg, int unset)
{
        struct note_data *d = opt->value;
        char *buf;
        struct object_id object;
        enum object_type type;
        unsigned long len;

        if (d->buf.len)
                strbuf_addch(&d->buf, '\n');

        if (get_oid(arg, &object))
                die(_("failed to resolve '%s' as a valid ref."), arg);
        if (!(buf = read_object_file(&object, &type, &len))) {
                free(buf);
                die(_("failed to read object '%s'."), arg);
        }
        if (type != OBJ_BLOB) {
                free(buf);
                die(_("cannot read note data from non-blob object '%s'."), arg);
        }
        strbuf_add(&d->buf, buf, len);
        free(buf);

        d->given = 1;
        return 0;
}

static int parse_reedit_arg(const struct option *opt, const char *arg, int unset)
{
        struct note_data *d = opt->value;
        d->use_editor = 1;
        return parse_reuse_arg(opt, arg, unset);
}

static int notes_copy_from_stdin(int force, const char *rewrite_cmd)
{
        struct strbuf buf = STRBUF_INIT;
        struct notes_rewrite_cfg *c = NULL;
        struct notes_tree *t = NULL;
        int ret = 0;
        const char *msg = "Notes added by 'git notes copy'";

        if (rewrite_cmd) {
                c = init_copy_notes_for_rewrite(rewrite_cmd);
                if (!c)
                        return 0;
        } else {
                init_notes(NULL, NULL, NULL, NOTES_INIT_WRITABLE);
                t = &default_notes_tree;
        }

        while (strbuf_getline_lf(&buf, stdin) != EOF) {
                struct object_id from_obj, to_obj;
                struct strbuf **split;
                int err;

                split = strbuf_split(&buf, ' ');
                if (!split[0] || !split[1])
                        die(_("malformed input line: '%s'."), buf.buf);
                strbuf_rtrim(split[0]);
                strbuf_rtrim(split[1]);
                if (get_oid(split[0]->buf, &from_obj))
                        die(_("failed to resolve '%s' as a valid ref."), split[0]->buf);
                if (get_oid(split[1]->buf, &to_obj))
                        die(_("failed to resolve '%s' as a valid ref."), split[1]->buf);

                if (rewrite_cmd)
                        err = copy_note_for_rewrite(c, &from_obj, &to_obj);
                else
                        err = copy_note(t, &from_obj, &to_obj, force,
                                        combine_notes_overwrite);

                if (err) {
                        error(_("failed to copy notes from '%s' to '%s'"),
                              split[0]->buf, split[1]->buf);
                        ret = 1;
                }

                strbuf_list_free(split);
        }

        if (!rewrite_cmd) {
                commit_notes(t, msg);
                free_notes(t);
        } else {
                finish_copy_notes_for_rewrite(c, msg);
        }
        strbuf_release(&buf);
        return ret;
}

static struct notes_tree *init_notes_check(const char *subcommand,
                                           int flags)
{
        struct notes_tree *t;
        const char *ref;
        init_notes(NULL, NULL, NULL, flags);
        t = &default_notes_tree;

        ref = (flags & NOTES_INIT_WRITABLE) ? t->update_ref : t->ref;
        if (!starts_with(ref, "refs/notes/"))
                /*
                 * TRANSLATORS: the first %s will be replaced by a git
                 * notes command: 'add', 'merge', 'remove', etc.
                 */
                die(_("refusing to %s notes in %s (outside of refs/notes/)"),
                    subcommand, ref);
        return t;
}

static int list(int argc, const char **argv, const char *prefix)
{
        struct notes_tree *t;
        struct object_id object;
        const struct object_id *note;
        int retval = -1;
        struct option options[] = {
                OPT_END()
        };

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

        if (1 < argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_list_usage, options);
        }

        t = init_notes_check("list", 0);
        if (argc) {
                if (get_oid(argv[0], &object))
                        die(_("failed to resolve '%s' as a valid ref."), argv[0]);
                note = get_note(t, &object);
                if (note) {
                        puts(oid_to_hex(note));
                        retval = 0;
                } else
                        retval = error(_("no note found for object %s."),
                                       oid_to_hex(&object));
        } else
                retval = for_each_note(t, 0, list_each_note, NULL);

        free_notes(t);
        return retval;
}

static int append_edit(int argc, const char **argv, const char *prefix);

static int add(int argc, const char **argv, const char *prefix)
{
        int force = 0, allow_empty = 0;
        const char *object_ref;
        struct notes_tree *t;
        struct object_id object, new_note;
        const struct object_id *note;
        struct note_data d = { 0, 0, NULL, STRBUF_INIT };
        struct option options[] = {
                { OPTION_CALLBACK, 'm', "message", &d, N_("message"),
                        N_("note contents as a string"), PARSE_OPT_NONEG,
                        parse_msg_arg},
                { OPTION_CALLBACK, 'F', "file", &d, N_("file"),
                        N_("note contents in a file"), PARSE_OPT_NONEG,
                        parse_file_arg},
                { OPTION_CALLBACK, 'c', "reedit-message", &d, N_("object"),
                        N_("reuse and edit specified note object"), PARSE_OPT_NONEG,
                        parse_reedit_arg},
                { OPTION_CALLBACK, 'C', "reuse-message", &d, N_("object"),
                        N_("reuse specified note object"), PARSE_OPT_NONEG,
                        parse_reuse_arg},
                OPT_BOOL(0, "allow-empty", &allow_empty,
                        N_("allow storing empty note")),
                OPT__FORCE(&force, N_("replace existing notes"), PARSE_OPT_NOCOMPLETE),
                OPT_END()
        };

        argc = parse_options(argc, argv, prefix, options, git_notes_add_usage,
                             PARSE_OPT_KEEP_ARGV0);

        if (2 < argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_add_usage, options);
        }

        object_ref = argc > 1 ? argv[1] : "HEAD";

        if (get_oid(object_ref, &object))
                die(_("failed to resolve '%s' as a valid ref."), object_ref);

        t = init_notes_check("add", NOTES_INIT_WRITABLE);
        note = get_note(t, &object);

        if (note) {
                if (!force) {
                        free_notes(t);
                        if (d.given) {
                                free_note_data(&d);
                                return error(_("Cannot add notes. "
                                        "Found existing notes for object %s. "
                                        "Use '-f' to overwrite existing notes"),
                                        oid_to_hex(&object));
                        }
                        /*
                         * Redirect to "edit" subcommand.
                         *
                         * We only end up here if none of -m/-F/-c/-C or -f are
                         * given. The original args are therefore still in
                         * argv[0-1].
                         */
                        argv[0] = "edit";
                        return append_edit(argc, argv, prefix);
                }
                fprintf(stderr, _("Overwriting existing notes for object %s\n"),
                        oid_to_hex(&object));
        }

        prepare_note_data(&object, &d, note);
        if (d.buf.len || allow_empty) {
                write_note_data(&d, &new_note);
                if (add_note(t, &object, &new_note, combine_notes_overwrite))
                        BUG("combine_notes_overwrite failed");
                commit_notes(t, "Notes added by 'git notes add'");
        } else {
                fprintf(stderr, _("Removing note for object %s\n"),
                        oid_to_hex(&object));
                remove_note(t, object.hash);
                commit_notes(t, "Notes removed by 'git notes add'");
        }

        free_note_data(&d);
        free_notes(t);
        return 0;
}

static int copy(int argc, const char **argv, const char *prefix)
{
        int retval = 0, force = 0, from_stdin = 0;
        const struct object_id *from_note, *note;
        const char *object_ref;
        struct object_id object, from_obj;
        struct notes_tree *t;
        const char *rewrite_cmd = NULL;
        struct option options[] = {
                OPT__FORCE(&force, N_("replace existing notes"), PARSE_OPT_NOCOMPLETE),
                OPT_BOOL(0, "stdin", &from_stdin, N_("read objects from stdin")),
                OPT_STRING(0, "for-rewrite", &rewrite_cmd, N_("command"),
                           N_("load rewriting config for <command> (implies "
                              "--stdin)")),
                OPT_END()
        };

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

        if (from_stdin || rewrite_cmd) {
                if (argc) {
                        error(_("too many parameters"));
                        usage_with_options(git_notes_copy_usage, options);
                } else {
                        return notes_copy_from_stdin(force, rewrite_cmd);
                }
        }

        if (argc < 2) {
                error(_("too few parameters"));
                usage_with_options(git_notes_copy_usage, options);
        }
        if (2 < argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_copy_usage, options);
        }

        if (get_oid(argv[0], &from_obj))
                die(_("failed to resolve '%s' as a valid ref."), argv[0]);

        object_ref = 1 < argc ? argv[1] : "HEAD";

        if (get_oid(object_ref, &object))
                die(_("failed to resolve '%s' as a valid ref."), object_ref);

        t = init_notes_check("copy", NOTES_INIT_WRITABLE);
        note = get_note(t, &object);

        if (note) {
                if (!force) {
                        retval = error(_("Cannot copy notes. Found existing "
                                       "notes for object %s. Use '-f' to "
                                       "overwrite existing notes"),
                                       oid_to_hex(&object));
                        goto out;
                }
                fprintf(stderr, _("Overwriting existing notes for object %s\n"),
                        oid_to_hex(&object));
        }

        from_note = get_note(t, &from_obj);
        if (!from_note) {
                retval = error(_("missing notes on source object %s. Cannot "
                               "copy."), oid_to_hex(&from_obj));
                goto out;
        }

        if (add_note(t, &object, from_note, combine_notes_overwrite))
                BUG("combine_notes_overwrite failed");
        commit_notes(t, "Notes added by 'git notes copy'");
out:
        free_notes(t);
        return retval;
}

static int append_edit(int argc, const char **argv, const char *prefix)
{
        int allow_empty = 0;
        const char *object_ref;
        struct notes_tree *t;
        struct object_id object, new_note;
        const struct object_id *note;
        char *logmsg;
        const char * const *usage;
        struct note_data d = { 0, 0, NULL, STRBUF_INIT };
        struct option options[] = {
                { OPTION_CALLBACK, 'm', "message", &d, N_("message"),
                        N_("note contents as a string"), PARSE_OPT_NONEG,
                        parse_msg_arg},
                { OPTION_CALLBACK, 'F', "file", &d, N_("file"),
                        N_("note contents in a file"), PARSE_OPT_NONEG,
                        parse_file_arg},
                { OPTION_CALLBACK, 'c', "reedit-message", &d, N_("object"),
                        N_("reuse and edit specified note object"), PARSE_OPT_NONEG,
                        parse_reedit_arg},
                { OPTION_CALLBACK, 'C', "reuse-message", &d, N_("object"),
                        N_("reuse specified note object"), PARSE_OPT_NONEG,
                        parse_reuse_arg},
                OPT_BOOL(0, "allow-empty", &allow_empty,
                        N_("allow storing empty note")),
                OPT_END()
        };
        int edit = !strcmp(argv[0], "edit");

        usage = edit ? git_notes_edit_usage : git_notes_append_usage;
        argc = parse_options(argc, argv, prefix, options, usage,
                             PARSE_OPT_KEEP_ARGV0);

        if (2 < argc) {
                error(_("too many parameters"));
                usage_with_options(usage, options);
        }

        if (d.given && edit)
                fprintf(stderr, _("The -m/-F/-c/-C options have been deprecated "
                        "for the 'edit' subcommand.\n"
                        "Please use 'git notes add -f -m/-F/-c/-C' instead.\n"));

        object_ref = 1 < argc ? argv[1] : "HEAD";

        if (get_oid(object_ref, &object))
                die(_("failed to resolve '%s' as a valid ref."), object_ref);

        t = init_notes_check(argv[0], NOTES_INIT_WRITABLE);
        note = get_note(t, &object);

        prepare_note_data(&object, &d, edit && note ? note : NULL);

        if (note && !edit) {
                /* Append buf to previous note contents */
                unsigned long size;
                enum object_type type;
                char *prev_buf = read_object_file(note, &type, &size);

                strbuf_grow(&d.buf, size + 1);
                if (d.buf.len && prev_buf && size)
                        strbuf_insert(&d.buf, 0, "\n", 1);
                if (prev_buf && size)
                        strbuf_insert(&d.buf, 0, prev_buf, size);
                free(prev_buf);
        }

        if (d.buf.len || allow_empty) {
                write_note_data(&d, &new_note);
                if (add_note(t, &object, &new_note, combine_notes_overwrite))
                        BUG("combine_notes_overwrite failed");
                logmsg = xstrfmt("Notes added by 'git notes %s'", argv[0]);
        } else {
                fprintf(stderr, _("Removing note for object %s\n"),
                        oid_to_hex(&object));
                remove_note(t, object.hash);
                logmsg = xstrfmt("Notes removed by 'git notes %s'", argv[0]);
        }
        commit_notes(t, logmsg);

        free(logmsg);
        free_note_data(&d);
        free_notes(t);
        return 0;
}

static int show(int argc, const char **argv, const char *prefix)
{
        const char *object_ref;
        struct notes_tree *t;
        struct object_id object;
        const struct object_id *note;
        int retval;
        struct option options[] = {
                OPT_END()
        };

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

        if (1 < argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_show_usage, options);
        }

        object_ref = argc ? argv[0] : "HEAD";

        if (get_oid(object_ref, &object))
                die(_("failed to resolve '%s' as a valid ref."), object_ref);

        t = init_notes_check("show", 0);
        note = get_note(t, &object);

        if (!note)
                retval = error(_("no note found for object %s."),
                               oid_to_hex(&object));
        else {
                const char *show_args[3] = {"show", oid_to_hex(note), NULL};
                retval = execv_git_cmd(show_args);
        }
        free_notes(t);
        return retval;
}

static int merge_abort(struct notes_merge_options *o)
{
        int ret = 0;

        /*
         * Remove .git/NOTES_MERGE_PARTIAL and .git/NOTES_MERGE_REF, and call
         * notes_merge_abort() to remove .git/NOTES_MERGE_WORKTREE.
         */

        if (delete_ref(NULL, "NOTES_MERGE_PARTIAL", NULL, 0))
                ret += error(_("failed to delete ref NOTES_MERGE_PARTIAL"));
        if (delete_ref(NULL, "NOTES_MERGE_REF", NULL, REF_NO_DEREF))
                ret += error(_("failed to delete ref NOTES_MERGE_REF"));
        if (notes_merge_abort(o))
                ret += error(_("failed to remove 'git notes merge' worktree"));
        return ret;
}

static int merge_commit(struct notes_merge_options *o)
{
        struct strbuf msg = STRBUF_INIT;
        struct object_id oid, parent_oid;
        struct notes_tree *t;
        struct commit *partial;
        struct pretty_print_context pretty_ctx;
        void *local_ref_to_free;
        int ret;

        /*
         * Read partial merge result from .git/NOTES_MERGE_PARTIAL,
         * and target notes ref from .git/NOTES_MERGE_REF.
         */

        if (get_oid("NOTES_MERGE_PARTIAL", &oid))
                die(_("failed to read ref NOTES_MERGE_PARTIAL"));
        else if (!(partial = lookup_commit_reference(&oid)))
                die(_("could not find commit from NOTES_MERGE_PARTIAL."));
        else if (parse_commit(partial))
                die(_("could not parse commit from NOTES_MERGE_PARTIAL."));

        if (partial->parents)
                oidcpy(&parent_oid, &partial->parents->item->object.oid);
        else
                oidclr(&parent_oid);

        t = xcalloc(1, sizeof(struct notes_tree));
        init_notes(t, "NOTES_MERGE_PARTIAL", combine_notes_overwrite, 0);

        o->local_ref = local_ref_to_free =
                resolve_refdup("NOTES_MERGE_REF", 0, &oid, NULL);
        if (!o->local_ref)
                die(_("failed to resolve NOTES_MERGE_REF"));

        if (notes_merge_commit(o, t, partial, &oid))
                die(_("failed to finalize notes merge"));

        /* Reuse existing commit message in reflog message */
        memset(&pretty_ctx, 0, sizeof(pretty_ctx));
        format_commit_message(partial, "%s", &msg, &pretty_ctx);
        strbuf_trim(&msg);
        strbuf_insert(&msg, 0, "notes: ", 7);
        update_ref(msg.buf, o->local_ref, &oid,
                   is_null_oid(&parent_oid) ? NULL : &parent_oid,
                   0, UPDATE_REFS_DIE_ON_ERR);

        free_notes(t);
        strbuf_release(&msg);
        ret = merge_abort(o);
        free(local_ref_to_free);
        return ret;
}

static int git_config_get_notes_strategy(const char *key,
                                         enum notes_merge_strategy *strategy)
{
        char *value;

        if (git_config_get_string(key, &value))
                return 1;
        if (parse_notes_merge_strategy(value, strategy))
                git_die_config(key, _("unknown notes merge strategy %s"), value);

        free(value);
        return 0;
}

static int merge(int argc, const char **argv, const char *prefix)
{
        struct strbuf remote_ref = STRBUF_INIT, msg = STRBUF_INIT;
        struct object_id result_oid;
        struct notes_tree *t;
        struct notes_merge_options o;
        int do_merge = 0, do_commit = 0, do_abort = 0;
        int verbosity = 0, result;
        const char *strategy = NULL;
        struct option options[] = {
                OPT_GROUP(N_("General options")),
                OPT__VERBOSITY(&verbosity),
                OPT_GROUP(N_("Merge options")),
                OPT_STRING('s', "strategy", &strategy, N_("strategy"),
                           N_("resolve notes conflicts using the given strategy "
                              "(manual/ours/theirs/union/cat_sort_uniq)")),
                OPT_GROUP(N_("Committing unmerged notes")),
                OPT_SET_INT_F(0, "commit", &do_commit,
                              N_("finalize notes merge by committing unmerged notes"),
                              1, PARSE_OPT_NONEG),
                OPT_GROUP(N_("Aborting notes merge resolution")),
                OPT_SET_INT_F(0, "abort", &do_abort,
                              N_("abort notes merge"),
                              1, PARSE_OPT_NONEG),
                OPT_END()
        };

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

        if (strategy || do_commit + do_abort == 0)
                do_merge = 1;
        if (do_merge + do_commit + do_abort != 1) {
                error(_("cannot mix --commit, --abort or -s/--strategy"));
                usage_with_options(git_notes_merge_usage, options);
        }

        if (do_merge && argc != 1) {
                error(_("must specify a notes ref to merge"));
                usage_with_options(git_notes_merge_usage, options);
        } else if (!do_merge && argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_merge_usage, options);
        }

        init_notes_merge_options(&o);
        o.verbosity = verbosity + NOTES_MERGE_VERBOSITY_DEFAULT;

        if (do_abort)
                return merge_abort(&o);
        if (do_commit)
                return merge_commit(&o);

        o.local_ref = default_notes_ref();
        strbuf_addstr(&remote_ref, argv[0]);
        expand_loose_notes_ref(&remote_ref);
        o.remote_ref = remote_ref.buf;

        t = init_notes_check("merge", NOTES_INIT_WRITABLE);

        if (strategy) {
                if (parse_notes_merge_strategy(strategy, &o.strategy)) {
                        error(_("unknown -s/--strategy: %s"), strategy);
                        usage_with_options(git_notes_merge_usage, options);
                }
        } else {
                struct strbuf merge_key = STRBUF_INIT;
                const char *short_ref = NULL;

                if (!skip_prefix(o.local_ref, "refs/notes/", &short_ref))
                        BUG("local ref %s is outside of refs/notes/",
                            o.local_ref);

                strbuf_addf(&merge_key, "notes.%s.mergeStrategy", short_ref);

                if (git_config_get_notes_strategy(merge_key.buf, &o.strategy))
                        git_config_get_notes_strategy("notes.mergeStrategy", &o.strategy);

                strbuf_release(&merge_key);
        }

        strbuf_addf(&msg, "notes: Merged notes from %s into %s",
                    remote_ref.buf, default_notes_ref());
        strbuf_add(&(o.commit_msg), msg.buf + 7, msg.len - 7); /* skip "notes: " */

        result = notes_merge(&o, t, &result_oid);

        if (result >= 0) /* Merge resulted (trivially) in result_oid */
                /* Update default notes ref with new commit */
                update_ref(msg.buf, default_notes_ref(), &result_oid, NULL, 0,
                           UPDATE_REFS_DIE_ON_ERR);
        else { /* Merge has unresolved conflicts */
                const struct worktree *wt;
                /* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
                update_ref(msg.buf, "NOTES_MERGE_PARTIAL", &result_oid, NULL,
                           0, UPDATE_REFS_DIE_ON_ERR);
                /* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
                wt = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
                if (wt)
                        die(_("a notes merge into %s is already in-progress at %s"),
                            default_notes_ref(), wt->path);
                if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
                        die(_("failed to store link to current notes ref (%s)"),
                            default_notes_ref());
                fprintf(stderr, _("Automatic notes merge failed. Fix conflicts in %s "
                                  "and commit the result with 'git notes merge --commit', "
                                  "or abort the merge with 'git notes merge --abort'.\n"),
                        git_path(NOTES_MERGE_WORKTREE));
        }

        free_notes(t);
        strbuf_release(&remote_ref);
        strbuf_release(&msg);
        return result < 0; /* return non-zero on conflicts */
}

#define IGNORE_MISSING 1

static int remove_one_note(struct notes_tree *t, const char *name, unsigned flag)
{
        int status;
        struct object_id oid;
        if (get_oid(name, &oid))
                return error(_("Failed to resolve '%s' as a valid ref."), name);
        status = remove_note(t, oid.hash);
        if (status)
                fprintf(stderr, _("Object %s has no note\n"), name);
        else
                fprintf(stderr, _("Removing note for object %s\n"), name);
        return (flag & IGNORE_MISSING) ? 0 : status;
}

static int remove_cmd(int argc, const char **argv, const char *prefix)
{
        unsigned flag = 0;
        int from_stdin = 0;
        struct option options[] = {
                OPT_BIT(0, "ignore-missing", &flag,
                        N_("attempt to remove non-existent note is not an error"),
                        IGNORE_MISSING),
                OPT_BOOL(0, "stdin", &from_stdin,
                            N_("read object names from the standard input")),
                OPT_END()
        };
        struct notes_tree *t;
        int retval = 0;

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

        t = init_notes_check("remove", NOTES_INIT_WRITABLE);

        if (!argc && !from_stdin) {
                retval = remove_one_note(t, "HEAD", flag);
        } else {
                while (*argv) {
                        retval |= remove_one_note(t, *argv, flag);
                        argv++;
                }
        }
        if (from_stdin) {
                struct strbuf sb = STRBUF_INIT;
                while (strbuf_getwholeline(&sb, stdin, '\n') != EOF) {
                        strbuf_rtrim(&sb);
                        retval |= remove_one_note(t, sb.buf, flag);
                }
                strbuf_release(&sb);
        }
        if (!retval)
                commit_notes(t, "Notes removed by 'git notes remove'");
        free_notes(t);
        return retval;
}

static int prune(int argc, const char **argv, const char *prefix)
{
        struct notes_tree *t;
        int show_only = 0, verbose = 0;
        struct option options[] = {
                OPT__DRY_RUN(&show_only, N_("do not remove, show only")),
                OPT__VERBOSE(&verbose, N_("report pruned notes")),
                OPT_END()
        };

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

        if (argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_prune_usage, options);
        }

        t = init_notes_check("prune", NOTES_INIT_WRITABLE);

        prune_notes(t, (verbose ? NOTES_PRUNE_VERBOSE : 0) |
                (show_only ? NOTES_PRUNE_VERBOSE|NOTES_PRUNE_DRYRUN : 0) );
        if (!show_only)
                commit_notes(t, "Notes removed by 'git notes prune'");
        free_notes(t);
        return 0;
}

static int get_ref(int argc, const char **argv, const char *prefix)
{
        struct option options[] = { OPT_END() };
        argc = parse_options(argc, argv, prefix, options,
                             git_notes_get_ref_usage, 0);

        if (argc) {
                error(_("too many parameters"));
                usage_with_options(git_notes_get_ref_usage, options);
        }

        puts(default_notes_ref());
        return 0;
}

int cmd_notes(int argc, const char **argv, const char *prefix)
{
        int result;
        const char *override_notes_ref = NULL;
        struct option options[] = {
                OPT_STRING(0, "ref", &override_notes_ref, N_("notes-ref"),
                           N_("use notes from <notes-ref>")),
                OPT_END()
        };

        git_config(git_default_config, NULL);
        argc = parse_options(argc, argv, prefix, options, git_notes_usage,
                             PARSE_OPT_STOP_AT_NON_OPTION);

        if (override_notes_ref) {
                struct strbuf sb = STRBUF_INIT;
                strbuf_addstr(&sb, override_notes_ref);
                expand_notes_ref(&sb);
                setenv("GIT_NOTES_REF", sb.buf, 1);
                strbuf_release(&sb);
        }

        if (argc < 1 || !strcmp(argv[0], "list"))
                result = list(argc, argv, prefix);
        else if (!strcmp(argv[0], "add"))
                result = add(argc, argv, prefix);
        else if (!strcmp(argv[0], "copy"))
                result = copy(argc, argv, prefix);
        else if (!strcmp(argv[0], "append") || !strcmp(argv[0], "edit"))
                result = append_edit(argc, argv, prefix);
        else if (!strcmp(argv[0], "show"))
                result = show(argc, argv, prefix);
        else if (!strcmp(argv[0], "merge"))
                result = merge(argc, argv, prefix);
        else if (!strcmp(argv[0], "remove"))
                result = remove_cmd(argc, argv, prefix);
        else if (!strcmp(argv[0], "prune"))
                result = prune(argc, argv, prefix);
        else if (!strcmp(argv[0], "get-ref"))
                result = get_ref(argc, argv, prefix);
        else {
                result = error(_("unknown subcommand: %s"), argv[0]);
                usage_with_options(git_notes_usage, options);
        }

        return result ? 1 : 0;
}