/*
 * Builtin "git commit"
 *
 * Copyright (c) 2007 Kristian Høgsberg <krh@redhat.com>
 * Based on git-commit.sh by Junio C Hamano and Linus Torvalds
 */

#include "cache.h"
#include "cache-tree.h"
#include "color.h"
#include "dir.h"
#include "builtin.h"
#include "diff.h"
#include "diffcore.h"
#include "commit.h"
#include "revision.h"
#include "wt-status.h"
#include "run-command.h"
#include "refs.h"
#include "log-tree.h"
#include "strbuf.h"
#include "utf8.h"
#include "parse-options.h"
#include "string-list.h"
#include "rerere.h"
#include "unpack-trees.h"
#include "quote.h"

static const char * const builtin_commit_usage[] = {
        "git commit [options] [--] <filepattern>...",
        NULL
};

static const char * const builtin_status_usage[] = {
        "git status [options] [--] <filepattern>...",
        NULL
};

static unsigned char head_sha1[20], merge_head_sha1[20];
static char *use_message_buffer;
static const char commit_editmsg[] = "COMMIT_EDITMSG";
static struct lock_file index_lock; /* real index */
static struct lock_file false_lock; /* used only for partial commits */
static enum {
        COMMIT_AS_IS = 1,
        COMMIT_NORMAL,
        COMMIT_PARTIAL,
} commit_style;

static const char *logfile, *force_author;
static const char *template_file;
static char *edit_message, *use_message;
static char *author_name, *author_email, *author_date;
static int all, edit_flag, also, interactive, only, amend, signoff;
static int quiet, verbose, no_verify, allow_empty, dry_run;
static char *untracked_files_arg;
/*
 * The default commit message cleanup mode will remove the lines
 * beginning with # (shell comments) and leading and trailing
 * whitespaces (empty lines or containing only whitespaces)
 * if editor is used, and only the whitespaces if the message
 * is specified explicitly.
 */
static enum {
        CLEANUP_SPACE,
        CLEANUP_NONE,
        CLEANUP_ALL,
} cleanup_mode;
static char *cleanup_arg;

static int use_editor = 1, initial_commit, in_merge;
static const char *only_include_assumed;
static struct strbuf message;

static int null_termination;
static enum {
        STATUS_FORMAT_LONG,
        STATUS_FORMAT_SHORT,
        STATUS_FORMAT_PORCELAIN,
} status_format = STATUS_FORMAT_LONG;

static int opt_parse_m(const struct option *opt, const char *arg, int unset)
{
        struct strbuf *buf = opt->value;
        if (unset)
                strbuf_setlen(buf, 0);
        else {
                strbuf_addstr(buf, arg);
                strbuf_addstr(buf, "\n\n");
        }
        return 0;
}

static struct option builtin_commit_options[] = {
        OPT__QUIET(&quiet),
        OPT__VERBOSE(&verbose),
        OPT_GROUP("Commit message options"),

        OPT_FILENAME('F', "file", &logfile, "read log from file"),
        OPT_STRING(0, "author", &force_author, "AUTHOR", "override author for commit"),
        OPT_CALLBACK('m', "message", &message, "MESSAGE", "specify commit message", opt_parse_m),
        OPT_STRING('c', "reedit-message", &edit_message, "COMMIT", "reuse and edit message from specified commit "),
        OPT_STRING('C', "reuse-message", &use_message, "COMMIT", "reuse message from specified commit"),
        OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
        OPT_FILENAME('t', "template", &template_file, "use specified template file"),
        OPT_BOOLEAN('e', "edit", &edit_flag, "force edit of commit"),

        OPT_GROUP("Commit contents options"),
        OPT_BOOLEAN('a', "all", &all, "commit all changed files"),
        OPT_BOOLEAN('i', "include", &also, "add specified files to index for commit"),
        OPT_BOOLEAN(0, "interactive", &interactive, "interactively add files"),
        OPT_BOOLEAN('o', "only", &only, "commit only specified files"),
        OPT_BOOLEAN('n', "no-verify", &no_verify, "bypass pre-commit hook"),
        OPT_BOOLEAN(0, "dry-run", &dry_run, "show what would be committed"),
        OPT_SET_INT(0, "short", &status_format, "show status concisely",
                    STATUS_FORMAT_SHORT),
        OPT_SET_INT(0, "porcelain", &status_format,
                    "show porcelain output format", STATUS_FORMAT_PORCELAIN),
        OPT_BOOLEAN('z', "null", &null_termination,
                    "terminate entries with NUL"),
        OPT_BOOLEAN(0, "amend", &amend, "amend previous commit"),
        { OPTION_STRING, 'u', "untracked-files", &untracked_files_arg, "mode", "show untracked files, optional modes: all, normal, no. (Default: all)", PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
        OPT_BOOLEAN(0, "allow-empty", &allow_empty, "ok to record an empty change"),
        OPT_STRING(0, "cleanup", &cleanup_arg, "default", "how to strip spaces and #comments from message"),

        OPT_END()
};

static void rollback_index_files(void)
{
        switch (commit_style) {
        case COMMIT_AS_IS:
                break; /* nothing to do */
        case COMMIT_NORMAL:
                rollback_lock_file(&index_lock);
                break;
        case COMMIT_PARTIAL:
                rollback_lock_file(&index_lock);
                rollback_lock_file(&false_lock);
                break;
        }
}

static int commit_index_files(void)
{
        int err = 0;

        switch (commit_style) {
        case COMMIT_AS_IS:
                break; /* nothing to do */
        case COMMIT_NORMAL:
                err = commit_lock_file(&index_lock);
                break;
        case COMMIT_PARTIAL:
                err = commit_lock_file(&index_lock);
                rollback_lock_file(&false_lock);
                break;
        }

        return err;
}

/*
 * Take a union of paths in the index and the named tree (typically, "HEAD"),
 * and return the paths that match the given pattern in list.
 */
static int list_paths(struct string_list *list, const char *with_tree,
                      const char *prefix, const char **pattern)
{
        int i;
        char *m;

        for (i = 0; pattern[i]; i++)
                ;
        m = xcalloc(1, i);

        if (with_tree)
                overlay_tree_on_cache(with_tree, prefix);

        for (i = 0; i < active_nr; i++) {
                struct cache_entry *ce = active_cache[i];
                if (ce->ce_flags & CE_UPDATE)
                        continue;
                if (!match_pathspec(pattern, ce->name, ce_namelen(ce), 0, m))
                        continue;
                string_list_insert(ce->name, list);
        }

        return report_path_error(m, pattern, prefix ? strlen(prefix) : 0);
}

static void add_remove_files(struct string_list *list)
{
        int i;
        for (i = 0; i < list->nr; i++) {
                struct stat st;
                struct string_list_item *p = &(list->items[i]);

                if (!lstat(p->string, &st)) {
                        if (add_to_cache(p->string, &st, 0))
                                die("updating files failed");
                } else
                        remove_file_from_cache(p->string);
        }
}

static void create_base_index(void)
{
        struct tree *tree;
        struct unpack_trees_options opts;
        struct tree_desc t;

        if (initial_commit) {
                discard_cache();
                return;
        }

        memset(&opts, 0, sizeof(opts));
        opts.head_idx = 1;
        opts.index_only = 1;
        opts.merge = 1;
        opts.src_index = &the_index;
        opts.dst_index = &the_index;

        opts.fn = oneway_merge;
        tree = parse_tree_indirect(head_sha1);
        if (!tree)
                die("failed to unpack HEAD tree object");
        parse_tree(tree);
        init_tree_desc(&t, tree->buffer, tree->size);
        if (unpack_trees(1, &t, &opts))
                exit(128); /* We've already reported the error, finish dying */
}

static char *prepare_index(int argc, const char **argv, const char *prefix, int is_status)
{
        int fd;
        struct string_list partial;
        const char **pathspec = NULL;
        int refresh_flags = REFRESH_QUIET;

        if (is_status)
                refresh_flags |= REFRESH_UNMERGED;
        if (interactive) {
                if (interactive_add(argc, argv, prefix) != 0)
                        die("interactive add failed");
                if (read_cache_preload(NULL) < 0)
                        die("index file corrupt");
                commit_style = COMMIT_AS_IS;
                return get_index_file();
        }

        if (*argv)
                pathspec = get_pathspec(prefix, argv);

        if (read_cache_preload(pathspec) < 0)
                die("index file corrupt");

        /*
         * Non partial, non as-is commit.
         *
         * (1) get the real index;
         * (2) update the_index as necessary;
         * (3) write the_index out to the real index (still locked);
         * (4) return the name of the locked index file.
         *
         * The caller should run hooks on the locked real index, and
         * (A) if all goes well, commit the real index;
         * (B) on failure, rollback the real index.
         */
        if (all || (also && pathspec && *pathspec)) {
                int fd = hold_locked_index(&index_lock, 1);
                add_files_to_cache(also ? prefix : NULL, pathspec, 0);
                refresh_cache(refresh_flags);
                if (write_cache(fd, active_cache, active_nr) ||
                    close_lock_file(&index_lock))
                        die("unable to write new_index file");
                commit_style = COMMIT_NORMAL;
                return index_lock.filename;
        }

        /*
         * As-is commit.
         *
         * (1) return the name of the real index file.
         *
         * The caller should run hooks on the real index, and run
         * hooks on the real index, and create commit from the_index.
         * We still need to refresh the index here.
         */
        if (!pathspec || !*pathspec) {
                fd = hold_locked_index(&index_lock, 1);
                refresh_cache(refresh_flags);
                if (write_cache(fd, active_cache, active_nr) ||
                    commit_locked_index(&index_lock))
                        die("unable to write new_index file");
                commit_style = COMMIT_AS_IS;
                return get_index_file();
        }

        /*
         * A partial commit.
         *
         * (0) find the set of affected paths;
         * (1) get lock on the real index file;
         * (2) update the_index with the given paths;
         * (3) write the_index out to the real index (still locked);
         * (4) get lock on the false index file;
         * (5) reset the_index from HEAD;
         * (6) update the_index the same way as (2);
         * (7) write the_index out to the false index file;
         * (8) return the name of the false index file (still locked);
         *
         * The caller should run hooks on the locked false index, and
         * create commit from it.  Then
         * (A) if all goes well, commit the real index;
         * (B) on failure, rollback the real index;
         * In either case, rollback the false index.
         */
        commit_style = COMMIT_PARTIAL;

        if (file_exists(git_path("MERGE_HEAD")))
                die("cannot do a partial commit during a merge.");

        memset(&partial, 0, sizeof(partial));
        partial.strdup_strings = 1;
        if (list_paths(&partial, initial_commit ? NULL : "HEAD", prefix, pathspec))
                exit(1);

        discard_cache();
        if (read_cache() < 0)
                die("cannot read the index");

        fd = hold_locked_index(&index_lock, 1);
        add_remove_files(&partial);
        refresh_cache(REFRESH_QUIET);
        if (write_cache(fd, active_cache, active_nr) ||
            close_lock_file(&index_lock))
                die("unable to write new_index file");

        fd = hold_lock_file_for_update(&false_lock,
                                       git_path("next-index-%"PRIuMAX,
                                                (uintmax_t) getpid()),
                                       LOCK_DIE_ON_ERROR);

        create_base_index();
        add_remove_files(&partial);
        refresh_cache(REFRESH_QUIET);

        if (write_cache(fd, active_cache, active_nr) ||
            close_lock_file(&false_lock))
                die("unable to write temporary index file");

        discard_cache();
        read_cache_from(false_lock.filename);

        return false_lock.filename;
}

static int run_status(FILE *fp, const char *index_file, const char *prefix, int nowarn,
                      struct wt_status *s)
{
        unsigned char sha1[20];

        if (s->relative_paths)
                s->prefix = prefix;

        if (amend) {
                s->amend = 1;
                s->reference = "HEAD^1";
        }
        s->verbose = verbose;
        s->index_file = index_file;
        s->fp = fp;
        s->nowarn = nowarn;
        s->is_initial = get_sha1(s->reference, sha1) ? 1 : 0;

        wt_status_collect(s);

        switch (status_format) {
        case STATUS_FORMAT_SHORT:
                wt_shortstatus_print(s, null_termination);
                break;
        case STATUS_FORMAT_PORCELAIN:
                wt_shortstatus_print(s, null_termination);
                break;
        case STATUS_FORMAT_LONG:
                wt_status_print(s);
                break;
        }

        return s->commitable;
}

static int is_a_merge(const unsigned char *sha1)
{
        struct commit *commit = lookup_commit(sha1);
        if (!commit || parse_commit(commit))
                die("could not parse HEAD commit");
        return !!(commit->parents && commit->parents->next);
}

static const char sign_off_header[] = "Signed-off-by: ";

static void determine_author_info(void)
{
        char *name, *email, *date;

        name = getenv("GIT_AUTHOR_NAME");
        email = getenv("GIT_AUTHOR_EMAIL");
        date = getenv("GIT_AUTHOR_DATE");

        if (use_message) {
                const char *a, *lb, *rb, *eol;

                a = strstr(use_message_buffer, "\nauthor ");
                if (!a)
                        die("invalid commit: %s", use_message);

                lb = strstr(a + 8, " <");
                rb = strstr(a + 8, "> ");
                eol = strchr(a + 8, '\n');
                if (!lb || !rb || !eol)
                        die("invalid commit: %s", use_message);

                name = xstrndup(a + 8, lb - (a + 8));
                email = xstrndup(lb + 2, rb - (lb + 2));
                date = xstrndup(rb + 2, eol - (rb + 2));
        }

        if (force_author) {
                const char *lb = strstr(force_author, " <");
                const char *rb = strchr(force_author, '>');

                if (!lb || !rb)
                        die("malformed --author parameter");
                name = xstrndup(force_author, lb - force_author);
                email = xstrndup(lb + 2, rb - (lb + 2));
        }

        author_name = name;
        author_email = email;
        author_date = date;
}

static int prepare_to_commit(const char *index_file, const char *prefix,
                             struct wt_status *s)
{
        struct stat statbuf;
        int commitable, saved_color_setting;
        struct strbuf sb = STRBUF_INIT;
        char *buffer;
        FILE *fp;
        const char *hook_arg1 = NULL;
        const char *hook_arg2 = NULL;
        int ident_shown = 0;

        if (!no_verify && run_hook(index_file, "pre-commit", NULL))
                return 0;

        if (message.len) {
                strbuf_addbuf(&sb, &message);
                hook_arg1 = "message";
        } else if (logfile && !strcmp(logfile, "-")) {
                if (isatty(0))
                        fprintf(stderr, "(reading log message from standard input)\n");
                if (strbuf_read(&sb, 0, 0) < 0)
                        die_errno("could not read log from standard input");
                hook_arg1 = "message";
        } else if (logfile) {
                if (strbuf_read_file(&sb, logfile, 0) < 0)
                        die_errno("could not read log file '%s'",
                                  logfile);
                hook_arg1 = "message";
        } else if (use_message) {
                buffer = strstr(use_message_buffer, "\n\n");
                if (!buffer || buffer[2] == '\0')
                        die("commit has empty message");
                strbuf_add(&sb, buffer + 2, strlen(buffer + 2));
                hook_arg1 = "commit";
                hook_arg2 = use_message;
        } else if (!stat(git_path("MERGE_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("MERGE_MSG"), 0) < 0)
                        die_errno("could not read MERGE_MSG");
                hook_arg1 = "merge";
        } else if (!stat(git_path("SQUASH_MSG"), &statbuf)) {
                if (strbuf_read_file(&sb, git_path("SQUASH_MSG"), 0) < 0)
                        die_errno("could not read SQUASH_MSG");
                hook_arg1 = "squash";
        } else if (template_file && !stat(template_file, &statbuf)) {
                if (strbuf_read_file(&sb, template_file, 0) < 0)
                        die_errno("could not read '%s'", template_file);
                hook_arg1 = "template";
        }

        /*
         * This final case does not modify the template message,
         * it just sets the argument to the prepare-commit-msg hook.
         */
        else if (in_merge)
                hook_arg1 = "merge";

        fp = fopen(git_path(commit_editmsg), "w");
        if (fp == NULL)
                die_errno("could not open '%s'", git_path(commit_editmsg));

        if (cleanup_mode != CLEANUP_NONE)
                stripspace(&sb, 0);

        if (signoff) {
                struct strbuf sob = STRBUF_INIT;
                int i;

                strbuf_addstr(&sob, sign_off_header);
                strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
                                             getenv("GIT_COMMITTER_EMAIL")));
                strbuf_addch(&sob, '\n');
                for (i = sb.len - 1; i > 0 && sb.buf[i - 1] != '\n'; i--)
                        ; /* do nothing */
                if (prefixcmp(sb.buf + i, sob.buf)) {
                        if (prefixcmp(sb.buf + i, sign_off_header))
                                strbuf_addch(&sb, '\n');
                        strbuf_addbuf(&sb, &sob);
                }
                strbuf_release(&sob);
        }

        if (fwrite(sb.buf, 1, sb.len, fp) < sb.len)
                die_errno("could not write commit template");

        strbuf_release(&sb);

        determine_author_info();

        /* This checks if committer ident is explicitly given */
        git_committer_info(0);
        if (use_editor) {
                char *author_ident;
                const char *committer_ident;

                if (in_merge)
                        fprintf(fp,
                                "#\n"
                                "# It looks like you may be committing a MERGE.\n"
                                "# If this is not correct, please remove the file\n"
                                "#      %s\n"
                                "# and try again.\n"
                                "#\n",
                                git_path("MERGE_HEAD"));

                fprintf(fp,
                        "\n"
                        "# Please enter the commit message for your changes.");
                if (cleanup_mode == CLEANUP_ALL)
                        fprintf(fp,
                                " Lines starting\n"
                                "# with '#' will be ignored, and an empty"
                                " message aborts the commit.\n");
                else /* CLEANUP_SPACE, that is. */
                        fprintf(fp,
                                " Lines starting\n"
                                "# with '#' will be kept; you may remove them"
                                " yourself if you want to.\n"
                                "# An empty message aborts the commit.\n");
                if (only_include_assumed)
                        fprintf(fp, "# %s\n", only_include_assumed);

                author_ident = xstrdup(fmt_name(author_name, author_email));
                committer_ident = fmt_name(getenv("GIT_COMMITTER_NAME"),
                                           getenv("GIT_COMMITTER_EMAIL"));
                if (strcmp(author_ident, committer_ident))
                        fprintf(fp,
                                "%s"
                                "# Author:    %s\n",
                                ident_shown++ ? "" : "#\n",
                                author_ident);
                free(author_ident);

                if (!user_ident_explicitly_given)
                        fprintf(fp,
                                "%s"
                                "# Committer: %s\n",
                                ident_shown++ ? "" : "#\n",
                                committer_ident);

                if (ident_shown)
                        fprintf(fp, "#\n");

                saved_color_setting = s->use_color;
                s->use_color = 0;
                commitable = run_status(fp, index_file, prefix, 1, s);
                s->use_color = saved_color_setting;
        } else {
                unsigned char sha1[20];
                const char *parent = "HEAD";

                if (!active_nr && read_cache() < 0)
                        die("Cannot read index");

                if (amend)
                        parent = "HEAD^1";

                if (get_sha1(parent, sha1))
                        commitable = !!active_nr;
                else
                        commitable = index_differs_from(parent, 0);
        }

        fclose(fp);

        if (!commitable && !in_merge && !allow_empty &&
            !(amend && is_a_merge(head_sha1))) {
                run_status(stdout, index_file, prefix, 0, s);
                return 0;
        }

        /*
         * Re-read the index as pre-commit hook could have updated it,
         * and write it out as a tree.  We must do this before we invoke
         * the editor and after we invoke run_status above.
         */
        discard_cache();
        read_cache_from(index_file);
        if (!active_cache_tree)
                active_cache_tree = cache_tree();
        if (cache_tree_update(active_cache_tree,
                              active_cache, active_nr, 0, 0) < 0) {
                error("Error building trees");
                return 0;
        }

        if (run_hook(index_file, "prepare-commit-msg",
                     git_path(commit_editmsg), hook_arg1, hook_arg2, NULL))
                return 0;

        if (use_editor) {
                char index[PATH_MAX];
                const char *env[2] = { index, NULL };
                snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", index_file);
                if (launch_editor(git_path(commit_editmsg), NULL, env)) {
                        fprintf(stderr,
                        "Please supply the message using either -m or -F option.\n");
                        exit(1);
                }
        }

        if (!no_verify &&
            run_hook(index_file, "commit-msg", git_path(commit_editmsg), NULL)) {
                return 0;
        }

        return 1;
}

/*
 * Find out if the message in the strbuf contains only whitespace and
 * Signed-off-by lines.
 */
static int message_is_empty(struct strbuf *sb)
{
        struct strbuf tmpl = STRBUF_INIT;
        const char *nl;
        int eol, i, start = 0;

        if (cleanup_mode == CLEANUP_NONE && sb->len)
                return 0;

        /* See if the template is just a prefix of the message. */
        if (template_file && strbuf_read_file(&tmpl, template_file, 0) > 0) {
                stripspace(&tmpl, cleanup_mode == CLEANUP_ALL);
                if (start + tmpl.len <= sb->len &&
                    memcmp(tmpl.buf, sb->buf + start, tmpl.len) == 0)
                        start += tmpl.len;
        }
        strbuf_release(&tmpl);

        /* Check if the rest is just whitespace and Signed-of-by's. */
        for (i = start; i < sb->len; i++) {
                nl = memchr(sb->buf + i, '\n', sb->len - i);
                if (nl)
                        eol = nl - sb->buf;
                else
                        eol = sb->len;

                if (strlen(sign_off_header) <= eol - i &&
                    !prefixcmp(sb->buf + i, sign_off_header)) {
                        i = eol;
                        continue;
                }
                while (i < eol)
                        if (!isspace(sb->buf[i++]))
                                return 0;
        }

        return 1;
}

static const char *find_author_by_nickname(const char *name)
{
        struct rev_info revs;
        struct commit *commit;
        struct strbuf buf = STRBUF_INIT;
        const char *av[20];
        int ac = 0;

        init_revisions(&revs, NULL);
        strbuf_addf(&buf, "--author=%s", name);
        av[++ac] = "--all";
        av[++ac] = "-i";
        av[++ac] = buf.buf;
        av[++ac] = NULL;
        setup_revisions(ac, av, &revs, NULL);
        prepare_revision_walk(&revs);
        commit = get_revision(&revs);
        if (commit) {
                strbuf_release(&buf);
                format_commit_message(commit, "%an <%ae>", &buf, DATE_NORMAL);
                return strbuf_detach(&buf, NULL);
        }
        die("No existing author found with '%s'", name);
}


static void handle_untracked_files_arg(struct wt_status *s)
{
        if (!untracked_files_arg)
                ; /* default already initialized */
        else if (!strcmp(untracked_files_arg, "no"))
                s->show_untracked_files = SHOW_NO_UNTRACKED_FILES;
        else if (!strcmp(untracked_files_arg, "normal"))
                s->show_untracked_files = SHOW_NORMAL_UNTRACKED_FILES;
        else if (!strcmp(untracked_files_arg, "all"))
                s->show_untracked_files = SHOW_ALL_UNTRACKED_FILES;
        else
                die("Invalid untracked files mode '%s'", untracked_files_arg);
}

static int parse_and_validate_options(int argc, const char *argv[],
                                      const char * const usage[],
                                      const char *prefix,
                                      struct wt_status *s)
{
        int f = 0;

        argc = parse_options(argc, argv, prefix, builtin_commit_options, usage,
                             0);

        if (force_author && !strchr(force_author, '>'))
                force_author = find_author_by_nickname(force_author);

        if (logfile || message.len || use_message)
                use_editor = 0;
        if (edit_flag)
                use_editor = 1;
        if (!use_editor)
                setenv("GIT_EDITOR", ":", 1);

        if (get_sha1("HEAD", head_sha1))
                initial_commit = 1;

        if (!get_sha1("MERGE_HEAD", merge_head_sha1))
                in_merge = 1;

        /* Sanity check options */
        if (amend && initial_commit)
                die("You have nothing to amend.");
        if (amend && in_merge)
                die("You are in the middle of a merge -- cannot amend.");

        if (use_message)
                f++;
        if (edit_message)
                f++;
        if (logfile)
                f++;
        if (f > 1)
                die("Only one of -c/-C/-F can be used.");
        if (message.len && f > 0)
                die("Option -m cannot be combined with -c/-C/-F.");
        if (edit_message)
                use_message = edit_message;
        if (amend && !use_message)
                use_message = "HEAD";
        if (use_message) {
                unsigned char sha1[20];
                static char utf8[] = "UTF-8";
                const char *out_enc;
                char *enc, *end;
                struct commit *commit;

                if (get_sha1(use_message, sha1))
                        die("could not lookup commit %s", use_message);
                commit = lookup_commit_reference(sha1);
                if (!commit || parse_commit(commit))
                        die("could not parse commit %s", use_message);

                enc = strstr(commit->buffer, "\nencoding");
                if (enc) {
                        end = strchr(enc + 10, '\n');
                        enc = xstrndup(enc + 10, end - (enc + 10));
                } else {
                        enc = utf8;
                }
                out_enc = git_commit_encoding ? git_commit_encoding : utf8;

                if (strcmp(out_enc, enc))
                        use_message_buffer =
                                reencode_string(commit->buffer, out_enc, enc);

                /*
                 * If we failed to reencode the buffer, just copy it
                 * byte for byte so the user can try to fix it up.
                 * This also handles the case where input and output
                 * encodings are identical.
                 */
                if (use_message_buffer == NULL)
                        use_message_buffer = xstrdup(commit->buffer);
                if (enc != utf8)
                        free(enc);
        }

        if (!!also + !!only + !!all + !!interactive > 1)
                die("Only one of --include/--only/--all/--interactive can be used.");
        if (argc == 0 && (also || (only && !amend)))
                die("No paths with --include/--only does not make sense.");
        if (argc == 0 && only && amend)
                only_include_assumed = "Clever... amending the last one with dirty index.";
        if (argc > 0 && !also && !only)
                only_include_assumed = "Explicit paths specified without -i nor -o; assuming --only paths...";
        if (!cleanup_arg || !strcmp(cleanup_arg, "default"))
                cleanup_mode = use_editor ? CLEANUP_ALL : CLEANUP_SPACE;
        else if (!strcmp(cleanup_arg, "verbatim"))
                cleanup_mode = CLEANUP_NONE;
        else if (!strcmp(cleanup_arg, "whitespace"))
                cleanup_mode = CLEANUP_SPACE;
        else if (!strcmp(cleanup_arg, "strip"))
                cleanup_mode = CLEANUP_ALL;
        else
                die("Invalid cleanup mode %s", cleanup_arg);

        handle_untracked_files_arg(s);

        if (all && argc > 0)
                die("Paths with -a does not make sense.");
        else if (interactive && argc > 0)
                die("Paths with --interactive does not make sense.");

        if (null_termination && status_format == STATUS_FORMAT_LONG)
                status_format = STATUS_FORMAT_PORCELAIN;
        if (status_format != STATUS_FORMAT_LONG)
                dry_run = 1;

        return argc;
}

static int dry_run_commit(int argc, const char **argv, const char *prefix,
                          struct wt_status *s)
{
        int commitable;
        const char *index_file;

        index_file = prepare_index(argc, argv, prefix, 1);
        commitable = run_status(stdout, index_file, prefix, 0, s);
        rollback_index_files();

        return commitable ? 0 : 1;
}

static int parse_status_slot(const char *var, int offset)
{
        if (!strcasecmp(var+offset, "header"))
                return WT_STATUS_HEADER;
        if (!strcasecmp(var+offset, "updated")
                || !strcasecmp(var+offset, "added"))
                return WT_STATUS_UPDATED;
        if (!strcasecmp(var+offset, "changed"))
                return WT_STATUS_CHANGED;
        if (!strcasecmp(var+offset, "untracked"))
                return WT_STATUS_UNTRACKED;
        if (!strcasecmp(var+offset, "nobranch"))
                return WT_STATUS_NOBRANCH;
        if (!strcasecmp(var+offset, "unmerged"))
                return WT_STATUS_UNMERGED;
        die("bad config variable '%s'", var);
}

static int git_status_config(const char *k, const char *v, void *cb)
{
        struct wt_status *s = cb;

        if (!strcmp(k, "status.submodulesummary")) {
                int is_bool;
                s->submodule_summary = git_config_bool_or_int(k, v, &is_bool);
                if (is_bool && s->submodule_summary)
                        s->submodule_summary = -1;
                return 0;
        }
        if (!strcmp(k, "status.color") || !strcmp(k, "color.status")) {
                s->use_color = git_config_colorbool(k, v, -1);
                return 0;
        }
        if (!prefixcmp(k, "status.color.") || !prefixcmp(k, "color.status.")) {
                int slot = parse_status_slot(k, 13);
                if (!v)
                        return config_error_nonbool(k);
                color_parse(v, k, s->color_palette[slot]);
                return 0;
        }
        if (!strcmp(k, "status.relativepaths")) {
                s->relative_paths = git_config_bool(k, v);
                return 0;
        }
        if (!strcmp(k, "status.showuntrackedfiles")) {
                if (!v)
                        return config_error_nonbool(k);
                else if (!strcmp(v, "no"))
                        s->show_untracked_files = SHOW_NO_UNTRACKED_FILES;
                else if (!strcmp(v, "normal"))
                        s->show_untracked_files = SHOW_NORMAL_UNTRACKED_FILES;
                else if (!strcmp(v, "all"))
                        s->show_untracked_files = SHOW_ALL_UNTRACKED_FILES;
                else
                        return error("Invalid untracked files mode '%s'", v);
                return 0;
        }
        return git_diff_ui_config(k, v, NULL);
}

int cmd_status(int argc, const char **argv, const char *prefix)
{
        struct wt_status s;
        unsigned char sha1[20];
        static struct option builtin_status_options[] = {
                OPT__VERBOSE(&verbose),
                OPT_SET_INT('s', "short", &status_format,
                            "show status concisely", STATUS_FORMAT_SHORT),
                OPT_SET_INT(0, "porcelain", &status_format,
                            "show porcelain output format",
                            STATUS_FORMAT_PORCELAIN),
                OPT_BOOLEAN('z', "null", &null_termination,
                            "terminate entries with NUL"),
                { OPTION_STRING, 'u', "untracked-files", &untracked_files_arg,
                  "mode",
                  "show untracked files, optional modes: all, normal, no. (Default: all)",
                  PARSE_OPT_OPTARG, NULL, (intptr_t)"all" },
                OPT_END(),
        };

        if (null_termination && status_format == STATUS_FORMAT_LONG)
                status_format = STATUS_FORMAT_PORCELAIN;

        wt_status_prepare(&s);
        git_config(git_status_config, &s);
        argc = parse_options(argc, argv, prefix,
                             builtin_status_options,
                             builtin_status_usage, 0);
        handle_untracked_files_arg(&s);

        if (*argv)
                s.pathspec = get_pathspec(prefix, argv);

        read_cache();
        refresh_cache(REFRESH_QUIET|REFRESH_UNMERGED);
        s.is_initial = get_sha1(s.reference, sha1) ? 1 : 0;
        wt_status_collect(&s);

        switch (status_format) {
        case STATUS_FORMAT_SHORT:
                if (s.relative_paths)
                        s.prefix = prefix;
                if (s.use_color == -1)
                        s.use_color = git_use_color_default;
                if (diff_use_color_default == -1)
                        diff_use_color_default = git_use_color_default;
                wt_shortstatus_print(&s, null_termination);
                break;
        case STATUS_FORMAT_PORCELAIN:
                wt_shortstatus_print(&s, null_termination);
                break;
        case STATUS_FORMAT_LONG:
                s.verbose = verbose;
                if (s.relative_paths)
                        s.prefix = prefix;
                if (s.use_color == -1)
                        s.use_color = git_use_color_default;
                if (diff_use_color_default == -1)
                        diff_use_color_default = git_use_color_default;
                wt_status_print(&s);
                break;
        }
        return 0;
}

static void print_summary(const char *prefix, const unsigned char *sha1)
{
        struct rev_info rev;
        struct commit *commit;
        static const char *format = "format:%h] %s";
        unsigned char junk_sha1[20];
        const char *head = resolve_ref("HEAD", junk_sha1, 0, NULL);

        commit = lookup_commit(sha1);
        if (!commit)
                die("couldn't look up newly created commit");
        if (!commit || parse_commit(commit))
                die("could not parse newly created commit");

        init_revisions(&rev, prefix);
        setup_revisions(0, NULL, &rev, NULL);

        rev.abbrev = 0;
        rev.diff = 1;
        rev.diffopt.output_format =
                DIFF_FORMAT_SHORTSTAT | DIFF_FORMAT_SUMMARY;

        rev.verbose_header = 1;
        rev.show_root_diff = 1;
        get_commit_format(format, &rev);
        rev.always_show_header = 0;
        rev.diffopt.detect_rename = 1;
        rev.diffopt.rename_limit = 100;
        rev.diffopt.break_opt = 0;
        diff_setup_done(&rev.diffopt);

        printf("[%s%s ",
                !prefixcmp(head, "refs/heads/") ?
                        head + 11 :
                        !strcmp(head, "HEAD") ?
                                "detached HEAD" :
                                head,
                initial_commit ? " (root-commit)" : "");

        if (!log_tree_commit(&rev, commit)) {
                struct strbuf buf = STRBUF_INIT;
                format_commit_message(commit, format + 7, &buf, DATE_NORMAL);
                printf("%s\n", buf.buf);
                strbuf_release(&buf);
        }
}

static int git_commit_config(const char *k, const char *v, void *cb)
{
        struct wt_status *s = cb;

        if (!strcmp(k, "commit.template"))
                return git_config_string(&template_file, k, v);

        return git_status_config(k, v, s);
}

int cmd_commit(int argc, const char **argv, const char *prefix)
{
        struct strbuf sb = STRBUF_INIT;
        const char *index_file, *reflog_msg;
        char *nl, *p;
        unsigned char commit_sha1[20];
        struct ref_lock *ref_lock;
        struct commit_list *parents = NULL, **pptr = &parents;
        struct stat statbuf;
        int allow_fast_forward = 1;
        struct wt_status s;

        wt_status_prepare(&s);
        git_config(git_commit_config, &s);

        if (s.use_color == -1)
                s.use_color = git_use_color_default;

        argc = parse_and_validate_options(argc, argv, builtin_commit_usage,
                                          prefix, &s);
        if (dry_run) {
                if (diff_use_color_default == -1)
                        diff_use_color_default = git_use_color_default;
                return dry_run_commit(argc, argv, prefix, &s);
        }
        index_file = prepare_index(argc, argv, prefix, 0);

        /* Set up everything for writing the commit object.  This includes
           running hooks, writing the trees, and interacting with the user.  */
        if (!prepare_to_commit(index_file, prefix, &s)) {
                rollback_index_files();
                return 1;
        }

        /* Determine parents */
        if (initial_commit) {
                reflog_msg = "commit (initial)";
        } else if (amend) {
                struct commit_list *c;
                struct commit *commit;

                reflog_msg = "commit (amend)";
                commit = lookup_commit(head_sha1);
                if (!commit || parse_commit(commit))
                        die("could not parse HEAD commit");

                for (c = commit->parents; c; c = c->next)
                        pptr = &commit_list_insert(c->item, pptr)->next;
        } else if (in_merge) {
                struct strbuf m = STRBUF_INIT;
                FILE *fp;

                reflog_msg = "commit (merge)";
                pptr = &commit_list_insert(lookup_commit(head_sha1), pptr)->next;
                fp = fopen(git_path("MERGE_HEAD"), "r");
                if (fp == NULL)
                        die_errno("could not open '%s' for reading",
                                  git_path("MERGE_HEAD"));
                while (strbuf_getline(&m, fp, '\n') != EOF) {
                        unsigned char sha1[20];
                        if (get_sha1_hex(m.buf, sha1) < 0)
                                die("Corrupt MERGE_HEAD file (%s)", m.buf);
                        pptr = &commit_list_insert(lookup_commit(sha1), pptr)->next;
                }
                fclose(fp);
                strbuf_release(&m);
                if (!stat(git_path("MERGE_MODE"), &statbuf)) {
                        if (strbuf_read_file(&sb, git_path("MERGE_MODE"), 0) < 0)
                                die_errno("could not read MERGE_MODE");
                        if (!strcmp(sb.buf, "no-ff"))
                                allow_fast_forward = 0;
                }
                if (allow_fast_forward)
                        parents = reduce_heads(parents);
        } else {
                reflog_msg = "commit";
                pptr = &commit_list_insert(lookup_commit(head_sha1), pptr)->next;
        }

        /* Finally, get the commit message */
        strbuf_reset(&sb);
        if (strbuf_read_file(&sb, git_path(commit_editmsg), 0) < 0) {
                int saved_errno = errno;
                rollback_index_files();
                die("could not read commit message: %s", strerror(saved_errno));
        }

        /* Truncate the message just before the diff, if any. */
        if (verbose) {
                p = strstr(sb.buf, "\ndiff --git ");
                if (p != NULL)
                        strbuf_setlen(&sb, p - sb.buf + 1);
        }

        if (cleanup_mode != CLEANUP_NONE)
                stripspace(&sb, cleanup_mode == CLEANUP_ALL);
        if (message_is_empty(&sb)) {
                rollback_index_files();
                fprintf(stderr, "Aborting commit due to empty commit message.\n");
                exit(1);
        }

        if (commit_tree(sb.buf, active_cache_tree->sha1, parents, commit_sha1,
                        fmt_ident(author_name, author_email, author_date,
                                IDENT_ERROR_ON_NO_NAME))) {
                rollback_index_files();
                die("failed to write commit object");
        }

        ref_lock = lock_any_ref_for_update("HEAD",
                                           initial_commit ? NULL : head_sha1,
                                           0);

        nl = strchr(sb.buf, '\n');
        if (nl)
                strbuf_setlen(&sb, nl + 1 - sb.buf);
        else
                strbuf_addch(&sb, '\n');
        strbuf_insert(&sb, 0, reflog_msg, strlen(reflog_msg));
        strbuf_insert(&sb, strlen(reflog_msg), ": ", 2);

        if (!ref_lock) {
                rollback_index_files();
                die("cannot lock HEAD ref");
        }
        if (write_ref_sha1(ref_lock, commit_sha1, sb.buf) < 0) {
                rollback_index_files();
                die("cannot update HEAD ref");
        }

        unlink(git_path("MERGE_HEAD"));
        unlink(git_path("MERGE_MSG"));
        unlink(git_path("MERGE_MODE"));
        unlink(git_path("SQUASH_MSG"));

        if (commit_index_files())
                die ("Repository has been updated, but unable to write\n"
                     "new_index file. Check that disk is not full or quota is\n"
                     "not exceeded, and then \"git reset HEAD\" to recover.");

        rerere();
        run_hook(get_index_file(), "post-commit", NULL);
        if (!quiet)
                print_summary(prefix, commit_sha1);

        return 0;
}