#include "cache.h"
#include "diff.h"
#include "commit.h"
#include "tag.h"
#include "graph.h"
#include "log-tree.h"
#include "reflog-walk.h"
#include "refs.h"
#include "string-list.h"
#include "color.h"
#include "gpg-interface.h"
#include "sequencer.h"
#include "line-log.h"

struct decoration name_decoration = { "object names" };

enum decoration_type {
        DECORATION_NONE = 0,
        DECORATION_REF_LOCAL,
        DECORATION_REF_REMOTE,
        DECORATION_REF_TAG,
        DECORATION_REF_STASH,
        DECORATION_REF_HEAD,
        DECORATION_GRAFTED,
};

static char decoration_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
        GIT_COLOR_BOLD_GREEN,   /* REF_LOCAL */
        GIT_COLOR_BOLD_RED,     /* REF_REMOTE */
        GIT_COLOR_BOLD_YELLOW,  /* REF_TAG */
        GIT_COLOR_BOLD_MAGENTA, /* REF_STASH */
        GIT_COLOR_BOLD_CYAN,    /* REF_HEAD */
        GIT_COLOR_BOLD_BLUE,    /* GRAFTED */
};

static const char *decorate_get_color(int decorate_use_color, enum decoration_type ix)
{
        if (want_color(decorate_use_color))
                return decoration_colors[ix];
        return "";
}

static int parse_decorate_color_slot(const char *slot)
{
        /*
         * We're comparing with 'ignore-case' on
         * (because config.c sets them all tolower),
         * but let's match the letters in the literal
         * string values here with how they are
         * documented in Documentation/config.txt, for
         * consistency.
         *
         * We love being consistent, don't we?
         */
        if (!strcasecmp(slot, "branch"))
                return DECORATION_REF_LOCAL;
        if (!strcasecmp(slot, "remoteBranch"))
                return DECORATION_REF_REMOTE;
        if (!strcasecmp(slot, "tag"))
                return DECORATION_REF_TAG;
        if (!strcasecmp(slot, "stash"))
                return DECORATION_REF_STASH;
        if (!strcasecmp(slot, "HEAD"))
                return DECORATION_REF_HEAD;
        return -1;
}

int parse_decorate_color_config(const char *var, const int ofs, const char *value)
{
        int slot = parse_decorate_color_slot(var + ofs);
        if (slot < 0)
                return 0;
        if (!value)
                return config_error_nonbool(var);
        color_parse(value, var, decoration_colors[slot]);
        return 0;
}

/*
 * log-tree.c uses DIFF_OPT_TST for determining whether to use color
 * for showing the commit sha1, use the same check for --decorate
 */
#define decorate_get_color_opt(o, ix) \
        decorate_get_color((o)->use_color, ix)

static void add_name_decoration(enum decoration_type type, const char *name, struct object *obj)
{
        int nlen = strlen(name);
        struct name_decoration *res = xmalloc(sizeof(struct name_decoration) + nlen);
        memcpy(res->name, name, nlen + 1);
        res->type = type;
        res->next = add_decoration(&name_decoration, obj, res);
}

static int add_ref_decoration(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
{
        struct object *obj;
        enum decoration_type type = DECORATION_NONE;

        if (starts_with(refname, "refs/replace/")) {
                unsigned char original_sha1[20];
                if (!check_replace_refs)
                        return 0;
                if (get_sha1_hex(refname + 13, original_sha1)) {
                        warning("invalid replace ref %s", refname);
                        return 0;
                }
                obj = parse_object(original_sha1);
                if (obj)
                        add_name_decoration(DECORATION_GRAFTED, "replaced", obj);
                return 0;
        }

        obj = parse_object(sha1);
        if (!obj)
                return 0;

        if (starts_with(refname, "refs/heads/"))
                type = DECORATION_REF_LOCAL;
        else if (starts_with(refname, "refs/remotes/"))
                type = DECORATION_REF_REMOTE;
        else if (starts_with(refname, "refs/tags/"))
                type = DECORATION_REF_TAG;
        else if (!strcmp(refname, "refs/stash"))
                type = DECORATION_REF_STASH;
        else if (!strcmp(refname, "HEAD"))
                type = DECORATION_REF_HEAD;

        if (!cb_data || *(int *)cb_data == DECORATE_SHORT_REFS)
                refname = prettify_refname(refname);
        add_name_decoration(type, refname, obj);
        while (obj->type == OBJ_TAG) {
                obj = ((struct tag *)obj)->tagged;
                if (!obj)
                        break;
                if (!obj->parsed)
                        parse_object(obj->sha1);
                add_name_decoration(DECORATION_REF_TAG, refname, obj);
        }
        return 0;
}

static int add_graft_decoration(const struct commit_graft *graft, void *cb_data)
{
        struct commit *commit = lookup_commit(graft->sha1);
        if (!commit)
                return 0;
        add_name_decoration(DECORATION_GRAFTED, "grafted", &commit->object);
        return 0;
}

void load_ref_decorations(int flags)
{
        static int loaded;
        if (!loaded) {
                loaded = 1;
                for_each_ref(add_ref_decoration, &flags);
                head_ref(add_ref_decoration, &flags);
                for_each_commit_graft(add_graft_decoration, NULL);
        }
}

static void show_parents(struct commit *commit, int abbrev)
{
        struct commit_list *p;
        for (p = commit->parents; p ; p = p->next) {
                struct commit *parent = p->item;
                printf(" %s", find_unique_abbrev(parent->object.sha1, abbrev));
        }
}

static void show_children(struct rev_info *opt, struct commit *commit, int abbrev)
{
        struct commit_list *p = lookup_decoration(&opt->children, &commit->object);
        for ( ; p; p = p->next) {
                printf(" %s", find_unique_abbrev(p->item->object.sha1, abbrev));
        }
}

/*
 * The caller makes sure there is no funny color before
 * calling. format_decorations makes sure the same after return.
 */
void format_decorations(struct strbuf *sb,
                        const struct commit *commit,
                        int use_color)
{
        const char *prefix;
        struct name_decoration *decoration;
        const char *color_commit =
                diff_get_color(use_color, DIFF_COMMIT);
        const char *color_reset =
                decorate_get_color(use_color, DECORATION_NONE);

        decoration = lookup_decoration(&name_decoration, &commit->object);
        if (!decoration)
                return;
        prefix = " (";
        while (decoration) {
                strbuf_addstr(sb, color_commit);
                strbuf_addstr(sb, prefix);
                strbuf_addstr(sb, decorate_get_color(use_color, decoration->type));
                if (decoration->type == DECORATION_REF_TAG)
                        strbuf_addstr(sb, "tag: ");
                strbuf_addstr(sb, decoration->name);
                strbuf_addstr(sb, color_reset);
                prefix = ", ";
                decoration = decoration->next;
        }
        strbuf_addstr(sb, color_commit);
        strbuf_addch(sb, ')');
        strbuf_addstr(sb, color_reset);
}

void show_decorations(struct rev_info *opt, struct commit *commit)
{
        struct strbuf sb = STRBUF_INIT;

        if (opt->show_source && commit->util)
                printf("\t%s", (char *) commit->util);
        if (!opt->show_decorations)
                return;
        format_decorations(&sb, commit, opt->diffopt.use_color);
        fputs(sb.buf, stdout);
        strbuf_release(&sb);
}

static unsigned int digits_in_number(unsigned int number)
{
        unsigned int i = 10, result = 1;
        while (i <= number) {
                i *= 10;
                result++;
        }
        return result;
}

void fmt_output_subject(struct strbuf *filename,
                        const char *subject,
                        struct rev_info *info)
{
        const char *suffix = info->patch_suffix;
        int nr = info->nr;
        int start_len = filename->len;
        int max_len = start_len + FORMAT_PATCH_NAME_MAX - (strlen(suffix) + 1);

        if (0 < info->reroll_count)
                strbuf_addf(filename, "v%d-", info->reroll_count);
        strbuf_addf(filename, "%04d-%s", nr, subject);

        if (max_len < filename->len)
                strbuf_setlen(filename, max_len);
        strbuf_addstr(filename, suffix);
}

void fmt_output_commit(struct strbuf *filename,
                       struct commit *commit,
                       struct rev_info *info)
{
        struct pretty_print_context ctx = {0};
        struct strbuf subject = STRBUF_INIT;

        format_commit_message(commit, "%f", &subject, &ctx);
        fmt_output_subject(filename, subject.buf, info);
        strbuf_release(&subject);
}

void log_write_email_headers(struct rev_info *opt, struct commit *commit,
                             const char **subject_p,
                             const char **extra_headers_p,
                             int *need_8bit_cte_p)
{
        const char *subject = NULL;
        const char *extra_headers = opt->extra_headers;
        const char *name = sha1_to_hex(commit->object.sha1);

        *need_8bit_cte_p = 0; /* unknown */
        if (opt->total > 0) {
                static char buffer[64];
                snprintf(buffer, sizeof(buffer),
                         "Subject: [%s%s%0*d/%d] ",
                         opt->subject_prefix,
                         *opt->subject_prefix ? " " : "",
                         digits_in_number(opt->total),
                         opt->nr, opt->total);
                subject = buffer;
        } else if (opt->total == 0 && opt->subject_prefix && *opt->subject_prefix) {
                static char buffer[256];
                snprintf(buffer, sizeof(buffer),
                         "Subject: [%s] ",
                         opt->subject_prefix);
                subject = buffer;
        } else {
                subject = "Subject: ";
        }

        printf("From %s Mon Sep 17 00:00:00 2001\n", name);
        graph_show_oneline(opt->graph);
        if (opt->message_id) {
                printf("Message-Id: <%s>\n", opt->message_id);
                graph_show_oneline(opt->graph);
        }
        if (opt->ref_message_ids && opt->ref_message_ids->nr > 0) {
                int i, n;
                n = opt->ref_message_ids->nr;
                printf("In-Reply-To: <%s>\n", opt->ref_message_ids->items[n-1].string);
                for (i = 0; i < n; i++)
                        printf("%s<%s>\n", (i > 0 ? "\t" : "References: "),
                               opt->ref_message_ids->items[i].string);
                graph_show_oneline(opt->graph);
        }
        if (opt->mime_boundary) {
                static char subject_buffer[1024];
                static char buffer[1024];
                struct strbuf filename =  STRBUF_INIT;
                *need_8bit_cte_p = -1; /* NEVER */
                snprintf(subject_buffer, sizeof(subject_buffer) - 1,
                         "%s"
                         "MIME-Version: 1.0\n"
                         "Content-Type: multipart/mixed;"
                         " boundary=\"%s%s\"\n"
                         "\n"
                         "This is a multi-part message in MIME "
                         "format.\n"
                         "--%s%s\n"
                         "Content-Type: text/plain; "
                         "charset=UTF-8; format=fixed\n"
                         "Content-Transfer-Encoding: 8bit\n\n",
                         extra_headers ? extra_headers : "",
                         mime_boundary_leader, opt->mime_boundary,
                         mime_boundary_leader, opt->mime_boundary);
                extra_headers = subject_buffer;

                if (opt->numbered_files)
                        strbuf_addf(&filename, "%d", opt->nr);
                else
                        fmt_output_commit(&filename, commit, opt);
                snprintf(buffer, sizeof(buffer) - 1,
                         "\n--%s%s\n"
                         "Content-Type: text/x-patch;"
                         " name=\"%s\"\n"
                         "Content-Transfer-Encoding: 8bit\n"
                         "Content-Disposition: %s;"
                         " filename=\"%s\"\n\n",
                         mime_boundary_leader, opt->mime_boundary,
                         filename.buf,
                         opt->no_inline ? "attachment" : "inline",
                         filename.buf);
                opt->diffopt.stat_sep = buffer;
                strbuf_release(&filename);
        }
        *subject_p = subject;
        *extra_headers_p = extra_headers;
}

static void show_sig_lines(struct rev_info *opt, int status, const char *bol)
{
        const char *color, *reset, *eol;

        color = diff_get_color_opt(&opt->diffopt,
                                   status ? DIFF_WHITESPACE : DIFF_FRAGINFO);
        reset = diff_get_color_opt(&opt->diffopt, DIFF_RESET);
        while (*bol) {
                eol = strchrnul(bol, '\n');
                printf("%s%.*s%s%s", color, (int)(eol - bol), bol, reset,
                       *eol ? "\n" : "");
                graph_show_oneline(opt->graph);
                bol = (*eol) ? (eol + 1) : eol;
        }
}

static void show_signature(struct rev_info *opt, struct commit *commit)
{
        struct strbuf payload = STRBUF_INIT;
        struct strbuf signature = STRBUF_INIT;
        struct strbuf gpg_output = STRBUF_INIT;
        int status;

        if (parse_signed_commit(commit, &payload, &signature) <= 0)
                goto out;

        status = verify_signed_buffer(payload.buf, payload.len,
                                      signature.buf, signature.len,
                                      &gpg_output, NULL);
        if (status && !gpg_output.len)
                strbuf_addstr(&gpg_output, "No signature\n");

        show_sig_lines(opt, status, gpg_output.buf);

 out:
        strbuf_release(&gpg_output);
        strbuf_release(&payload);
        strbuf_release(&signature);
}

static int which_parent(const unsigned char *sha1, const struct commit *commit)
{
        int nth;
        const struct commit_list *parent;

        for (nth = 0, parent = commit->parents; parent; parent = parent->next) {
                if (!hashcmp(parent->item->object.sha1, sha1))
                        return nth;
                nth++;
        }
        return -1;
}

static int is_common_merge(const struct commit *commit)
{
        return (commit->parents
                && commit->parents->next
                && !commit->parents->next->next);
}

static void show_one_mergetag(struct rev_info *opt,
                              struct commit_extra_header *extra,
                              struct commit *commit)
{
        unsigned char sha1[20];
        struct tag *tag;
        struct strbuf verify_message;
        int status, nth;
        size_t payload_size, gpg_message_offset;

        hash_sha1_file(extra->value, extra->len, typename(OBJ_TAG), sha1);
        tag = lookup_tag(sha1);
        if (!tag)
                return; /* error message already given */

        strbuf_init(&verify_message, 256);
        if (parse_tag_buffer(tag, extra->value, extra->len))
                strbuf_addstr(&verify_message, "malformed mergetag\n");
        else if (is_common_merge(commit) &&
                 !hashcmp(tag->tagged->sha1,
                          commit->parents->next->item->object.sha1))
                strbuf_addf(&verify_message,
                            "merged tag '%s'\n", tag->tag);
        else if ((nth = which_parent(tag->tagged->sha1, commit)) < 0)
                strbuf_addf(&verify_message, "tag %s names a non-parent %s\n",
                                    tag->tag, tag->tagged->sha1);
        else
                strbuf_addf(&verify_message,
                            "parent #%d, tagged '%s'\n", nth + 1, tag->tag);
        gpg_message_offset = verify_message.len;

        payload_size = parse_signature(extra->value, extra->len);
        status = -1;
        if (extra->len > payload_size) {
                /* could have a good signature */
                if (!verify_signed_buffer(extra->value, payload_size,
                                          extra->value + payload_size,
                                          extra->len - payload_size,
                                          &verify_message, NULL))
                        status = 0; /* good */
                else if (verify_message.len <= gpg_message_offset)
                        strbuf_addstr(&verify_message, "No signature\n");
                /* otherwise we couldn't verify, which is shown as bad */
        }

        show_sig_lines(opt, status, verify_message.buf);
        strbuf_release(&verify_message);
}

static void show_mergetag(struct rev_info *opt, struct commit *commit)
{
        struct commit_extra_header *extra, *to_free;

        to_free = read_commit_extra_headers(commit, NULL);
        for (extra = to_free; extra; extra = extra->next) {
                if (strcmp(extra->key, "mergetag"))
                        continue; /* not a merge tag */
                show_one_mergetag(opt, extra, commit);
        }
        free_commit_extra_headers(to_free);
}

void show_log(struct rev_info *opt)
{
        struct strbuf msgbuf = STRBUF_INIT;
        struct log_info *log = opt->loginfo;
        struct commit *commit = log->commit, *parent = log->parent;
        int abbrev_commit = opt->abbrev_commit ? opt->abbrev : 40;
        const char *extra_headers = opt->extra_headers;
        struct pretty_print_context ctx = {0};

        opt->loginfo = NULL;
        if (!opt->verbose_header) {
                graph_show_commit(opt->graph);

                if (!opt->graph)
                        put_revision_mark(opt, commit);
                fputs(find_unique_abbrev(commit->object.sha1, abbrev_commit), stdout);
                if (opt->print_parents)
                        show_parents(commit, abbrev_commit);
                if (opt->children.name)
                        show_children(opt, commit, abbrev_commit);
                show_decorations(opt, commit);
                if (opt->graph && !graph_is_commit_finished(opt->graph)) {
                        putchar('\n');
                        graph_show_remainder(opt->graph);
                }
                putchar(opt->diffopt.line_termination);
                return;
        }

        /*
         * If use_terminator is set, we already handled any record termination
         * at the end of the last record.
         * Otherwise, add a diffopt.line_termination character before all
         * entries but the first.  (IOW, as a separator between entries)
         */
        if (opt->shown_one && !opt->use_terminator) {
                /*
                 * If entries are separated by a newline, the output
                 * should look human-readable.  If the last entry ended
                 * with a newline, print the graph output before this
                 * newline.  Otherwise it will end up as a completely blank
                 * line and will look like a gap in the graph.
                 *
                 * If the entry separator is not a newline, the output is
                 * primarily intended for programmatic consumption, and we
                 * never want the extra graph output before the entry
                 * separator.
                 */
                if (opt->diffopt.line_termination == '\n' &&
                    !opt->missing_newline)
                        graph_show_padding(opt->graph);
                putchar(opt->diffopt.line_termination);
        }
        opt->shown_one = 1;

        /*
         * If the history graph was requested,
         * print the graph, up to this commit's line
         */
        graph_show_commit(opt->graph);

        /*
         * Print header line of header..
         */

        if (opt->commit_format == CMIT_FMT_EMAIL) {
                log_write_email_headers(opt, commit, &ctx.subject, &extra_headers,
                                        &ctx.need_8bit_cte);
        } else if (opt->commit_format != CMIT_FMT_USERFORMAT) {
                fputs(diff_get_color_opt(&opt->diffopt, DIFF_COMMIT), stdout);
                if (opt->commit_format != CMIT_FMT_ONELINE)
                        fputs("commit ", stdout);

                if (!opt->graph)
                        put_revision_mark(opt, commit);
                fputs(find_unique_abbrev(commit->object.sha1, abbrev_commit),
                      stdout);
                if (opt->print_parents)
                        show_parents(commit, abbrev_commit);
                if (opt->children.name)
                        show_children(opt, commit, abbrev_commit);
                if (parent)
                        printf(" (from %s)",
                               find_unique_abbrev(parent->object.sha1,
                                                  abbrev_commit));
                fputs(diff_get_color_opt(&opt->diffopt, DIFF_RESET), stdout);
                show_decorations(opt, commit);
                if (opt->commit_format == CMIT_FMT_ONELINE) {
                        putchar(' ');
                } else {
                        putchar('\n');
                        graph_show_oneline(opt->graph);
                }
                if (opt->reflog_info) {
                        /*
                         * setup_revisions() ensures that opt->reflog_info
                         * and opt->graph cannot both be set,
                         * so we don't need to worry about printing the
                         * graph info here.
                         */
                        show_reflog_message(opt->reflog_info,
                                            opt->commit_format == CMIT_FMT_ONELINE,
                                            opt->date_mode,
                                            opt->date_mode_explicit);
                        if (opt->commit_format == CMIT_FMT_ONELINE)
                                return;
                }
        }

        if (opt->show_signature) {
                show_signature(opt, commit);
                show_mergetag(opt, commit);
        }

        if (!get_cached_commit_buffer(commit, NULL))
                return;

        if (opt->show_notes) {
                int raw;
                struct strbuf notebuf = STRBUF_INIT;

                raw = (opt->commit_format == CMIT_FMT_USERFORMAT);
                format_display_notes(commit->object.sha1, &notebuf,
                                     get_log_output_encoding(), raw);
                ctx.notes_message = notebuf.len
                        ? strbuf_detach(&notebuf, NULL)
                        : xcalloc(1, 1);
        }

        /*
         * And then the pretty-printed message itself
         */
        if (ctx.need_8bit_cte >= 0 && opt->add_signoff)
                ctx.need_8bit_cte =
                        has_non_ascii(fmt_name(getenv("GIT_COMMITTER_NAME"),
                                               getenv("GIT_COMMITTER_EMAIL")));
        ctx.date_mode = opt->date_mode;
        ctx.date_mode_explicit = opt->date_mode_explicit;
        ctx.abbrev = opt->diffopt.abbrev;
        ctx.after_subject = extra_headers;
        ctx.preserve_subject = opt->preserve_subject;
        ctx.reflog_info = opt->reflog_info;
        ctx.fmt = opt->commit_format;
        ctx.mailmap = opt->mailmap;
        ctx.color = opt->diffopt.use_color;
        ctx.output_encoding = get_log_output_encoding();
        if (opt->from_ident.mail_begin && opt->from_ident.name_begin)
                ctx.from_ident = &opt->from_ident;
        pretty_print_commit(&ctx, commit, &msgbuf);

        if (opt->add_signoff)
                append_signoff(&msgbuf, 0, APPEND_SIGNOFF_DEDUP);

        if ((ctx.fmt != CMIT_FMT_USERFORMAT) &&
            ctx.notes_message && *ctx.notes_message) {
                if (ctx.fmt == CMIT_FMT_EMAIL) {
                        strbuf_addstr(&msgbuf, "---\n");
                        opt->shown_dashes = 1;
                }
                strbuf_addstr(&msgbuf, ctx.notes_message);
        }

        if (opt->show_log_size) {
                printf("log size %i\n", (int)msgbuf.len);
                graph_show_oneline(opt->graph);
        }

        /*
         * Set opt->missing_newline if msgbuf doesn't
         * end in a newline (including if it is empty)
         */
        if (!msgbuf.len || msgbuf.buf[msgbuf.len - 1] != '\n')
                opt->missing_newline = 1;
        else
                opt->missing_newline = 0;

        if (opt->graph)
                graph_show_commit_msg(opt->graph, &msgbuf);
        else
                fwrite(msgbuf.buf, sizeof(char), msgbuf.len, stdout);
        if (opt->use_terminator) {
                if (!opt->missing_newline)
                        graph_show_padding(opt->graph);
                putchar(opt->diffopt.line_termination);
        }

        strbuf_release(&msgbuf);
        free(ctx.notes_message);
}

int log_tree_diff_flush(struct rev_info *opt)
{
        opt->shown_dashes = 0;
        diffcore_std(&opt->diffopt);

        if (diff_queue_is_empty()) {
                int saved_fmt = opt->diffopt.output_format;
                opt->diffopt.output_format = DIFF_FORMAT_NO_OUTPUT;
                diff_flush(&opt->diffopt);
                opt->diffopt.output_format = saved_fmt;
                return 0;
        }

        if (opt->loginfo && !opt->no_commit_id) {
                show_log(opt);
                if ((opt->diffopt.output_format & ~DIFF_FORMAT_NO_OUTPUT) &&
                    opt->verbose_header &&
                    opt->commit_format != CMIT_FMT_ONELINE) {
                        /*
                         * When showing a verbose header (i.e. log message),
                         * and not in --pretty=oneline format, we would want
                         * an extra newline between the end of log and the
                         * diff/diffstat output for readability.
                         */
                        int pch = DIFF_FORMAT_DIFFSTAT | DIFF_FORMAT_PATCH;
                        if (opt->diffopt.output_prefix) {
                                struct strbuf *msg = NULL;
                                msg = opt->diffopt.output_prefix(&opt->diffopt,
                                        opt->diffopt.output_prefix_data);
                                fwrite(msg->buf, msg->len, 1, stdout);
                        }

                        /*
                         * We may have shown three-dashes line early
                         * between notes and the log message, in which
                         * case we only want a blank line after the
                         * notes without (an extra) three-dashes line.
                         * Otherwise, we show the three-dashes line if
                         * we are showing the patch with diffstat, but
                         * in that case, there is no extra blank line
                         * after the three-dashes line.
                         */
                        if (!opt->shown_dashes &&
                            (pch & opt->diffopt.output_format) == pch)
                                printf("---");
                        putchar('\n');
                }
        }
        diff_flush(&opt->diffopt);
        return 1;
}

static int do_diff_combined(struct rev_info *opt, struct commit *commit)
{
        diff_tree_combined_merge(commit, opt->dense_combined_merges, opt);
        return !opt->loginfo;
}

/*
 * Show the diff of a commit.
 *
 * Return true if we printed any log info messages
 */
static int log_tree_diff(struct rev_info *opt, struct commit *commit, struct log_info *log)
{
        int showed_log;
        struct commit_list *parents;
        unsigned const char *sha1;

        if (!opt->diff && !DIFF_OPT_TST(&opt->diffopt, EXIT_WITH_STATUS))
                return 0;

        parse_commit_or_die(commit);
        sha1 = commit->tree->object.sha1;

        /* Root commit? */
        parents = get_saved_parents(opt, commit);
        if (!parents) {
                if (opt->show_root_diff) {
                        diff_root_tree_sha1(sha1, "", &opt->diffopt);
                        log_tree_diff_flush(opt);
                }
                return !opt->loginfo;
        }

        /* More than one parent? */
        if (parents && parents->next) {
                if (opt->ignore_merges)
                        return 0;
                else if (opt->combine_merges)
                        return do_diff_combined(opt, commit);
                else if (opt->first_parent_only) {
                        /*
                         * Generate merge log entry only for the first
                         * parent, showing summary diff of the others
                         * we merged _in_.
                         */
                        parse_commit_or_die(parents->item);
                        diff_tree_sha1(parents->item->tree->object.sha1,
                                       sha1, "", &opt->diffopt);
                        log_tree_diff_flush(opt);
                        return !opt->loginfo;
                }

                /* If we show individual diffs, show the parent info */
                log->parent = parents->item;
        }

        showed_log = 0;
        for (;;) {
                struct commit *parent = parents->item;

                parse_commit_or_die(parent);
                diff_tree_sha1(parent->tree->object.sha1,
                               sha1, "", &opt->diffopt);
                log_tree_diff_flush(opt);

                showed_log |= !opt->loginfo;

                /* Set up the log info for the next parent, if any.. */
                parents = parents->next;
                if (!parents)
                        break;
                log->parent = parents->item;
                opt->loginfo = log;
        }
        return showed_log;
}

int log_tree_commit(struct rev_info *opt, struct commit *commit)
{
        struct log_info log;
        int shown;

        log.commit = commit;
        log.parent = NULL;
        opt->loginfo = &log;

        if (opt->line_level_traverse)
                return line_log_print(opt, commit);

        if (opt->track_linear && !opt->linear && !opt->reverse_output_stage)
                printf("\n%s\n", opt->break_bar);
        shown = log_tree_diff(opt, commit, &log);
        if (!shown && opt->loginfo && opt->always_show_header) {
                log.parent = NULL;
                show_log(opt);
                shown = 1;
        }
        if (opt->track_linear && !opt->linear && opt->reverse_output_stage)
                printf("\n%s\n", opt->break_bar);
        opt->loginfo = NULL;
        maybe_flush_or_die(stdout, "stdout");
        return shown;
}