/*
 * 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 "builtin.h"
#include "notes.h"
#include "blob.h"
#include "commit.h"
#include "refs.h"
#include "exec_cmd.h"
#include "run-command.h"
#include "parse-options.h"
#include "string-list.h"
#include "notes-merge.h"

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

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

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

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

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

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

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

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

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

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

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

static const char note_template[] =
        "\n"
        "#\n"
        "# Write/edit the notes for the following object:\n"
        "#\n";

struct msg_arg {
        int given;
        int use_editor;
        struct strbuf buf;
};

static int list_each_note(const unsigned char *object_sha1,
                const unsigned char *note_sha1, char *note_path,
                void *cb_data)
{
        printf("%s %s\n", sha1_to_hex(note_sha1), sha1_to_hex(object_sha1));
        return 0;
}

static void write_note_data(int fd, const unsigned char *sha1)
{
        unsigned long size;
        enum object_type type;
        char *buf = read_sha1_file(sha1, &type, &size);
        if (buf) {
                if (size)
                        write_or_die(fd, buf, size);
                free(buf);
        }
}

static void write_commented_object(int fd, const unsigned char *object)
{
        const char *show_args[5] =
                {"show", "--stat", "--no-notes", sha1_to_hex(object), NULL};
        struct child_process show;
        struct strbuf buf = STRBUF_INIT;
        FILE *show_out;

        /* Invoke "git show --stat --no-notes $object" */
        memset(&show, 0, sizeof(show));
        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'",
                    sha1_to_hex(object));

        /* Open the output as FILE* so strbuf_getline() can be used. */
        show_out = xfdopen(show.out, "r");
        if (show_out == NULL)
                die_errno("can't fdopen 'show' output fd");

        /* Prepend "# " to each output line and write result to 'fd' */
        while (strbuf_getline(&buf, show_out, '\n') != EOF) {
                write_or_die(fd, "# ", 2);
                write_or_die(fd, buf.buf, buf.len);
                write_or_die(fd, "\n", 1);
        }
        strbuf_release(&buf);
        if (fclose(show_out))
                die_errno("failed to close pipe to 'show' for object '%s'",
                          sha1_to_hex(object));
        if (finish_command(&show))
                die("failed to finish 'show' for object '%s'",
                    sha1_to_hex(object));
}

static void create_note(const unsigned char *object, struct msg_arg *msg,
                        int append_only, const unsigned char *prev,
                        unsigned char *result)
{
        char *path = NULL;

        if (msg->use_editor || !msg->given) {
                int fd;

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

                if (msg->given)
                        write_or_die(fd, msg->buf.buf, msg->buf.len);
                else if (prev && !append_only)
                        write_note_data(fd, prev);
                write_or_die(fd, note_template, strlen(note_template));

                write_commented_object(fd, object);

                close(fd);
                strbuf_reset(&(msg->buf));

                if (launch_editor(path, &(msg->buf), NULL)) {
                        die("Please supply the note contents using either -m" \
                            " or -F option");
                }
                stripspace(&(msg->buf), 1);
        }

        if (prev && append_only) {
                /* Append buf to previous note contents */
                unsigned long size;
                enum object_type type;
                char *prev_buf = read_sha1_file(prev, &type, &size);

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

        if (!msg->buf.len) {
                fprintf(stderr, "Removing note for object %s\n",
                        sha1_to_hex(object));
                hashclr(result);
        } else {
                if (write_sha1_file(msg->buf.buf, msg->buf.len, blob_type, result)) {
                        error("unable to write note object");
                        if (path)
                                error("The note contents has been left in %s",
                                      path);
                        exit(128);
                }
        }

        if (path) {
                unlink_or_warn(path);
                free(path);
        }
}

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

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

        msg->given = 1;
        return 0;
}

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

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

        msg->given = 1;
        return 0;
}

static int parse_reuse_arg(const struct option *opt, const char *arg, int unset)
{
        struct msg_arg *msg = opt->value;
        char *buf;
        unsigned char object[20];
        enum object_type type;
        unsigned long len;

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

        if (get_sha1(arg, object))
                die("Failed to resolve '%s' as a valid ref.", arg);
        if (!(buf = read_sha1_file(object, &type, &len)) || !len) {
                free(buf);
                die("Failed to read object '%s'.", arg);;
        }
        strbuf_add(&(msg->buf), buf, len);
        free(buf);

        msg->given = 1;
        return 0;
}

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

void commit_notes(struct notes_tree *t, const char *msg)
{
        struct strbuf buf = STRBUF_INIT;
        unsigned char commit_sha1[20];

        if (!t)
                t = &default_notes_tree;
        if (!t->initialized || !t->ref || !*t->ref)
                die("Cannot commit uninitialized/unreferenced notes tree");
        if (!t->dirty)
                return; /* don't have to commit an unchanged tree */

        /* Prepare commit message and reflog message */
        strbuf_addstr(&buf, "notes: "); /* commit message starts at index 7 */
        strbuf_addstr(&buf, msg);
        if (buf.buf[buf.len - 1] != '\n')
                strbuf_addch(&buf, '\n'); /* Make sure msg ends with newline */

        create_notes_commit(t, NULL, buf.buf + 7, commit_sha1);
        update_ref(buf.buf, t->ref, commit_sha1, NULL, 0, DIE_ON_ERR);

        strbuf_release(&buf);
}

combine_notes_fn parse_combine_notes_fn(const char *v)
{
        if (!strcasecmp(v, "overwrite"))
                return combine_notes_overwrite;
        else if (!strcasecmp(v, "ignore"))
                return combine_notes_ignore;
        else if (!strcasecmp(v, "concatenate"))
                return combine_notes_concatenate;
        else if (!strcasecmp(v, "cat_sort_uniq"))
                return combine_notes_cat_sort_uniq;
        else
                return NULL;
}

static int notes_rewrite_config(const char *k, const char *v, void *cb)
{
        struct notes_rewrite_cfg *c = cb;
        if (!prefixcmp(k, "notes.rewrite.") && !strcmp(k+14, c->cmd)) {
                c->enabled = git_config_bool(k, v);
                return 0;
        } else if (!c->mode_from_env && !strcmp(k, "notes.rewritemode")) {
                if (!v)
                        config_error_nonbool(k);
                c->combine = parse_combine_notes_fn(v);
                if (!c->combine) {
                        error("Bad notes.rewriteMode value: '%s'", v);
                        return 1;
                }
                return 0;
        } else if (!c->refs_from_env && !strcmp(k, "notes.rewriteref")) {
                /* note that a refs/ prefix is implied in the
                 * underlying for_each_glob_ref */
                if (!prefixcmp(v, "refs/notes/"))
                        string_list_add_refs_by_glob(c->refs, v);
                else
                        warning("Refusing to rewrite notes in %s"
                                " (outside of refs/notes/)", v);
                return 0;
        }

        return 0;
}


struct notes_rewrite_cfg *init_copy_notes_for_rewrite(const char *cmd)
{
        struct notes_rewrite_cfg *c = xmalloc(sizeof(struct notes_rewrite_cfg));
        const char *rewrite_mode_env = getenv(GIT_NOTES_REWRITE_MODE_ENVIRONMENT);
        const char *rewrite_refs_env = getenv(GIT_NOTES_REWRITE_REF_ENVIRONMENT);
        c->cmd = cmd;
        c->enabled = 1;
        c->combine = combine_notes_concatenate;
        c->refs = xcalloc(1, sizeof(struct string_list));
        c->refs->strdup_strings = 1;
        c->refs_from_env = 0;
        c->mode_from_env = 0;
        if (rewrite_mode_env) {
                c->mode_from_env = 1;
                c->combine = parse_combine_notes_fn(rewrite_mode_env);
                if (!c->combine)
                        error("Bad " GIT_NOTES_REWRITE_MODE_ENVIRONMENT
                              " value: '%s'", rewrite_mode_env);
        }
        if (rewrite_refs_env) {
                c->refs_from_env = 1;
                string_list_add_refs_from_colon_sep(c->refs, rewrite_refs_env);
        }
        git_config(notes_rewrite_config, c);
        if (!c->enabled || !c->refs->nr) {
                string_list_clear(c->refs, 0);
                free(c->refs);
                free(c);
                return NULL;
        }
        c->trees = load_notes_trees(c->refs);
        string_list_clear(c->refs, 0);
        free(c->refs);
        return c;
}

int copy_note_for_rewrite(struct notes_rewrite_cfg *c,
                          const unsigned char *from_obj, const unsigned char *to_obj)
{
        int ret = 0;
        int i;
        for (i = 0; c->trees[i]; i++)
                ret = copy_note(c->trees[i], from_obj, to_obj, 1, c->combine) || ret;
        return ret;
}

void finish_copy_notes_for_rewrite(struct notes_rewrite_cfg *c)
{
        int i;
        for (i = 0; c->trees[i]; i++) {
                commit_notes(c->trees[i], "Notes added by 'git notes copy'");
                free_notes(c->trees[i]);
        }
        free(c->trees);
        free(c);
}

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;

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

        while (strbuf_getline(&buf, stdin, '\n') != EOF) {
                unsigned char from_obj[20], to_obj[20];
                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_sha1(split[0]->buf, from_obj))
                        die("Failed to resolve '%s' as a valid ref.", split[0]->buf);
                if (get_sha1(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, "Notes added by 'git notes copy'");
                free_notes(t);
        } else {
                finish_copy_notes_for_rewrite(c);
        }
        return ret;
}

static struct notes_tree *init_notes_check(const char *subcommand)
{
        struct notes_tree *t;
        init_notes(NULL, NULL, NULL, 0);
        t = &default_notes_tree;

        if (prefixcmp(t->ref, "refs/notes/"))
                die("Refusing to %s notes in %s (outside of refs/notes/)",
                    subcommand, t->ref);
        return t;
}

static int list(int argc, const char **argv, const char *prefix)
{
        struct notes_tree *t;
        unsigned char object[20];
        const unsigned char *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");
        if (argc) {
                if (get_sha1(argv[0], object))
                        die("Failed to resolve '%s' as a valid ref.", argv[0]);
                note = get_note(t, object);
                if (note) {
                        puts(sha1_to_hex(note));
                        retval = 0;
                } else
                        retval = error("No note found for object %s.",
                                       sha1_to_hex(object));
        } else
                retval = for_each_note(t, 0, list_each_note, NULL);

        free_notes(t);
        return retval;
}

static int add(int argc, const char **argv, const char *prefix)
{
        int retval = 0, force = 0;
        const char *object_ref;
        struct notes_tree *t;
        unsigned char object[20], new_note[20];
        char logmsg[100];
        const unsigned char *note;
        struct msg_arg msg = { 0, 0, STRBUF_INIT };
        struct option options[] = {
                { OPTION_CALLBACK, 'm', "message", &msg, "msg",
                        "note contents as a string", PARSE_OPT_NONEG,
                        parse_msg_arg},
                { OPTION_CALLBACK, 'F', "file", &msg, "file",
                        "note contents in a file", PARSE_OPT_NONEG,
                        parse_file_arg},
                { OPTION_CALLBACK, 'c', "reedit-message", &msg, "object",
                        "reuse and edit specified note object", PARSE_OPT_NONEG,
                        parse_reedit_arg},
                { OPTION_CALLBACK, 'C', "reuse-message", &msg, "object",
                        "reuse specified note object", PARSE_OPT_NONEG,
                        parse_reuse_arg},
                OPT__FORCE(&force, "replace existing notes"),
                OPT_END()
        };

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

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

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

        if (get_sha1(object_ref, object))
                die("Failed to resolve '%s' as a valid ref.", object_ref);

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

        if (note) {
                if (!force) {
                        retval = error("Cannot add notes. Found existing notes "
                                       "for object %s. Use '-f' to overwrite "
                                       "existing notes", sha1_to_hex(object));
                        goto out;
                }
                fprintf(stderr, "Overwriting existing notes for object %s\n",
                        sha1_to_hex(object));
        }

        create_note(object, &msg, 0, note, new_note);

        if (is_null_sha1(new_note))
                remove_note(t, object);
        else if (add_note(t, object, new_note, combine_notes_overwrite))
                die("BUG: combine_notes_overwrite failed");

        snprintf(logmsg, sizeof(logmsg), "Notes %s by 'git notes %s'",
                 is_null_sha1(new_note) ? "removed" : "added", "add");
        commit_notes(t, logmsg);
out:
        free_notes(t);
        strbuf_release(&(msg.buf));
        return retval;
}

static int copy(int argc, const char **argv, const char *prefix)
{
        int retval = 0, force = 0, from_stdin = 0;
        const unsigned char *from_note, *note;
        const char *object_ref;
        unsigned char object[20], from_obj[20];
        struct notes_tree *t;
        const char *rewrite_cmd = NULL;
        struct option options[] = {
                OPT__FORCE(&force, "replace existing notes"),
                OPT_BOOLEAN(0, "stdin", &from_stdin, "read objects from stdin"),
                OPT_STRING(0, "for-rewrite", &rewrite_cmd, "command",
                           "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_sha1(argv[0], from_obj))
                die("Failed to resolve '%s' as a valid ref.", argv[0]);

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

        if (get_sha1(object_ref, object))
                die("Failed to resolve '%s' as a valid ref.", object_ref);

        t = init_notes_check("copy");
        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",
                                       sha1_to_hex(object));
                        goto out;
                }
                fprintf(stderr, "Overwriting existing notes for object %s\n",
                        sha1_to_hex(object));
        }

        from_note = get_note(t, from_obj);
        if (!from_note) {
                retval = error("Missing notes on source object %s. Cannot "
                               "copy.", sha1_to_hex(from_obj));
                goto out;
        }

        if (add_note(t, object, from_note, combine_notes_overwrite))
                die("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)
{
        const char *object_ref;
        struct notes_tree *t;
        unsigned char object[20], new_note[20];
        const unsigned char *note;
        char logmsg[100];
        const char * const *usage;
        struct msg_arg msg = { 0, 0, STRBUF_INIT };
        struct option options[] = {
                { OPTION_CALLBACK, 'm', "message", &msg, "msg",
                        "note contents as a string", PARSE_OPT_NONEG,
                        parse_msg_arg},
                { OPTION_CALLBACK, 'F', "file", &msg, "file",
                        "note contents in a file", PARSE_OPT_NONEG,
                        parse_file_arg},
                { OPTION_CALLBACK, 'c', "reedit-message", &msg, "object",
                        "reuse and edit specified note object", PARSE_OPT_NONEG,
                        parse_reedit_arg},
                { OPTION_CALLBACK, 'C', "reuse-message", &msg, "object",
                        "reuse specified note object", PARSE_OPT_NONEG,
                        parse_reuse_arg},
                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 (msg.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_sha1(object_ref, object))
                die("Failed to resolve '%s' as a valid ref.", object_ref);

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

        create_note(object, &msg, !edit, note, new_note);

        if (is_null_sha1(new_note))
                remove_note(t, object);
        else if (add_note(t, object, new_note, combine_notes_overwrite))
                die("BUG: combine_notes_overwrite failed");

        snprintf(logmsg, sizeof(logmsg), "Notes %s by 'git notes %s'",
                 is_null_sha1(new_note) ? "removed" : "added", argv[0]);
        commit_notes(t, logmsg);
        free_notes(t);
        strbuf_release(&(msg.buf));
        return 0;
}

static int show(int argc, const char **argv, const char *prefix)
{
        const char *object_ref;
        struct notes_tree *t;
        unsigned char object[20];
        const unsigned char *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_sha1(object_ref, object))
                die("Failed to resolve '%s' as a valid ref.", object_ref);

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

        if (!note)
                retval = error("No note found for object %s.",
                               sha1_to_hex(object));
        else {
                const char *show_args[3] = {"show", sha1_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("NOTES_MERGE_PARTIAL", NULL, 0))
                ret += error("Failed to delete ref NOTES_MERGE_PARTIAL");
        if (delete_ref("NOTES_MERGE_REF", NULL, REF_NODEREF))
                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;
        unsigned char sha1[20], parent_sha1[20];
        struct notes_tree *t;
        struct commit *partial;
        struct pretty_print_context pretty_ctx;

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

        if (get_sha1("NOTES_MERGE_PARTIAL", sha1))
                die("Failed to read ref NOTES_MERGE_PARTIAL");
        else if (!(partial = lookup_commit_reference(sha1)))
                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)
                hashcpy(parent_sha1, partial->parents->item->object.sha1);
        else
                hashclr(parent_sha1);

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

        o->local_ref = resolve_ref("NOTES_MERGE_REF", sha1, 0, NULL);
        if (!o->local_ref)
                die("Failed to resolve NOTES_MERGE_REF");

        if (notes_merge_commit(o, t, partial, sha1))
                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, sha1,
                   is_null_sha1(parent_sha1) ? NULL : parent_sha1,
                   0, DIE_ON_ERR);

        free_notes(t);
        strbuf_release(&msg);
        return merge_abort(o);
}

static int merge(int argc, const char **argv, const char *prefix)
{
        struct strbuf remote_ref = STRBUF_INIT, msg = STRBUF_INIT;
        unsigned char result_sha1[20];
        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("General options"),
                OPT__VERBOSITY(&verbosity),
                OPT_GROUP("Merge options"),
                OPT_STRING('s', "strategy", &strategy, "strategy",
                           "resolve notes conflicts using the given strategy "
                           "(manual/ours/theirs/union/cat_sort_uniq)"),
                OPT_GROUP("Committing unmerged notes"),
                { OPTION_BOOLEAN, 0, "commit", &do_commit, NULL,
                        "finalize notes merge by committing unmerged notes",
                        PARSE_OPT_NOARG | PARSE_OPT_NONEG },
                OPT_GROUP("Aborting notes merge resolution"),
                { OPTION_BOOLEAN, 0, "abort", &do_abort, NULL,
                        "abort notes merge",
                        PARSE_OPT_NOARG | 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_notes_ref(&remote_ref);
        o.remote_ref = remote_ref.buf;

        if (strategy) {
                if (!strcmp(strategy, "manual"))
                        o.strategy = NOTES_MERGE_RESOLVE_MANUAL;
                else if (!strcmp(strategy, "ours"))
                        o.strategy = NOTES_MERGE_RESOLVE_OURS;
                else if (!strcmp(strategy, "theirs"))
                        o.strategy = NOTES_MERGE_RESOLVE_THEIRS;
                else if (!strcmp(strategy, "union"))
                        o.strategy = NOTES_MERGE_RESOLVE_UNION;
                else if (!strcmp(strategy, "cat_sort_uniq"))
                        o.strategy = NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ;
                else {
                        error("Unknown -s/--strategy: %s", strategy);
                        usage_with_options(git_notes_merge_usage, options);
                }
        }

        t = init_notes_check("merge");

        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_sha1);

        if (result >= 0) /* Merge resulted (trivially) in result_sha1 */
                /* Update default notes ref with new commit */
                update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
                           0, DIE_ON_ERR);
        else { /* Merge has unresolved conflicts */
                /* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
                update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
                           0, DIE_ON_ERR);
                /* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
                if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
                        die("Failed to store link to current notes ref (%s)",
                            default_notes_ref());
                printf("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 */
}

static int remove_cmd(int argc, const char **argv, const char *prefix)
{
        struct option options[] = {
                OPT_END()
        };
        const char *object_ref;
        struct notes_tree *t;
        unsigned char object[20];
        int retval;

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

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

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

        if (get_sha1(object_ref, object))
                die("Failed to resolve '%s' as a valid ref.", object_ref);

        t = init_notes_check("remove");

        retval = remove_note(t, object);
        if (retval)
                fprintf(stderr, "Object %s has no note\n", sha1_to_hex(object));
        else {
                fprintf(stderr, "Removing note for object %s\n",
                        sha1_to_hex(object));

                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, "do not remove, show only"),
                OPT__VERBOSE(&verbose, "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");

        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, "notes_ref",
                           "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;
}