#include "cache.h"
#include "commit.h"
#include "diff.h"
#include "revision.h"
#include "list-objects.h"
#include "builtin.h"
#include "log-tree.h"
#include "graph.h"
#include "bisect.h"

static const char rev_list_usage[] =
"git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
"  limiting output:\n"
"    --max-count=nr\n"
"    --max-age=epoch\n"
"    --min-age=epoch\n"
"    --sparse\n"
"    --no-merges\n"
"    --remove-empty\n"
"    --all\n"
"    --branches\n"
"    --tags\n"
"    --remotes\n"
"    --stdin\n"
"    --quiet\n"
"  ordering output:\n"
"    --topo-order\n"
"    --date-order\n"
"    --reverse\n"
"  formatting output:\n"
"    --parents\n"
"    --children\n"
"    --objects | --objects-edge\n"
"    --unpacked\n"
"    --header | --pretty\n"
"    --abbrev=nr | --no-abbrev\n"
"    --abbrev-commit\n"
"    --left-right\n"
"  special purpose:\n"
"    --bisect\n"
"    --bisect-vars\n"
"    --bisect-all"
;

static void finish_commit(struct commit *commit, void *data);
static void show_commit(struct commit *commit, void *data)
{
        struct rev_list_info *info = data;
        struct rev_info *revs = info->revs;

        graph_show_commit(revs->graph);

        if (info->show_timestamp)
                printf("%lu ", commit->date);
        if (info->header_prefix)
                fputs(info->header_prefix, stdout);

        if (!revs->graph) {
                if (commit->object.flags & BOUNDARY)
                        putchar('-');
                else if (commit->object.flags & UNINTERESTING)
                        putchar('^');
                else if (revs->left_right) {
                        if (commit->object.flags & SYMMETRIC_LEFT)
                                putchar('<');
                        else
                                putchar('>');
                }
        }
        if (revs->abbrev_commit && revs->abbrev)
                fputs(find_unique_abbrev(commit->object.sha1, revs->abbrev),
                      stdout);
        else
                fputs(sha1_to_hex(commit->object.sha1), stdout);
        if (revs->print_parents) {
                struct commit_list *parents = commit->parents;
                while (parents) {
                        printf(" %s", sha1_to_hex(parents->item->object.sha1));
                        parents = parents->next;
                }
        }
        if (revs->children.name) {
                struct commit_list *children;

                children = lookup_decoration(&revs->children, &commit->object);
                while (children) {
                        printf(" %s", sha1_to_hex(children->item->object.sha1));
                        children = children->next;
                }
        }
        show_decorations(revs, commit);
        if (revs->commit_format == CMIT_FMT_ONELINE)
                putchar(' ');
        else
                putchar('\n');

        if (revs->verbose_header && commit->buffer) {
                struct strbuf buf = STRBUF_INIT;
                struct pretty_print_context ctx = {0};
                ctx.abbrev = revs->abbrev;
                ctx.date_mode = revs->date_mode;
                pretty_print_commit(revs->commit_format, commit, &buf, &ctx);
                if (revs->graph) {
                        if (buf.len) {
                                if (revs->commit_format != CMIT_FMT_ONELINE)
                                        graph_show_oneline(revs->graph);

                                graph_show_commit_msg(revs->graph, &buf);

                                /*
                                 * Add a newline after the commit message.
                                 *
                                 * Usually, this newline produces a blank
                                 * padding line between entries, in which case
                                 * we need to add graph padding on this line.
                                 *
                                 * However, the commit message may not end in a
                                 * newline.  In this case the newline simply
                                 * ends the last line of the commit message,
                                 * and we don't need any graph output.  (This
                                 * always happens with CMIT_FMT_ONELINE, and it
                                 * happens with CMIT_FMT_USERFORMAT when the
                                 * format doesn't explicitly end in a newline.)
                                 */
                                if (buf.len && buf.buf[buf.len - 1] == '\n')
                                        graph_show_padding(revs->graph);
                                putchar('\n');
                        } else {
                                /*
                                 * If the message buffer is empty, just show
                                 * the rest of the graph output for this
                                 * commit.
                                 */
                                if (graph_show_remainder(revs->graph))
                                        putchar('\n');
                        }
                } else {
                        if (buf.len)
                                printf("%s%c", buf.buf, info->hdr_termination);
                }
                strbuf_release(&buf);
        } else {
                if (graph_show_remainder(revs->graph))
                        putchar('\n');
        }
        maybe_flush_or_die(stdout, "stdout");
        finish_commit(commit, data);
}

static void finish_commit(struct commit *commit, void *data)
{
        if (commit->parents) {
                free_commit_list(commit->parents);
                commit->parents = NULL;
        }
        free(commit->buffer);
        commit->buffer = NULL;
}

static void finish_object(struct object *obj, const struct name_path *path, const char *name)
{
        if (obj->type == OBJ_BLOB && !has_sha1_file(obj->sha1))
                die("missing blob object '%s'", sha1_to_hex(obj->sha1));
}

static void show_object(struct object *obj, const struct name_path *path, const char *component)
{
        char *name = path_name(path, component);
        /* An object with name "foo\n0000000..." can be used to
         * confuse downstream "git pack-objects" very badly.
         */
        const char *ep = strchr(name, '\n');

        finish_object(obj, path, name);
        if (ep) {
                printf("%s %.*s\n", sha1_to_hex(obj->sha1),
                       (int) (ep - name),
                       name);
        }
        else
                printf("%s %s\n", sha1_to_hex(obj->sha1), name);
        free(name);
}

static void show_edge(struct commit *commit)
{
        printf("-%s\n", sha1_to_hex(commit->object.sha1));
}

static inline int log2i(int n)
{
        int log2 = 0;

        for (; n > 1; n >>= 1)
                log2++;

        return log2;
}

static inline int exp2i(int n)
{
        return 1 << n;
}

/*
 * Estimate the number of bisect steps left (after the current step)
 *
 * For any x between 0 included and 2^n excluded, the probability for
 * n - 1 steps left looks like:
 *
 * P(2^n + x) == (2^n - x) / (2^n + x)
 *
 * and P(2^n + x) < 0.5 means 2^n < 3x
 */
int estimate_bisect_steps(int all)
{
        int n, x, e;

        if (all < 3)
                return 0;

        n = log2i(all);
        e = exp2i(n);
        x = all - e;

        return (e < 3 * x) ? n : n - 1;
}

void print_commit_list(struct commit_list *list,
                       const char *format_cur,
                       const char *format_last)
{
        for ( ; list; list = list->next) {
                const char *format = list->next ? format_cur : format_last;
                printf(format, sha1_to_hex(list->item->object.sha1));
        }
}

static void show_tried_revs(struct commit_list *tried)
{
        printf("bisect_tried='");
        print_commit_list(tried, "%s|", "%s");
        printf("'\n");
}

static void print_var_str(const char *var, const char *val)
{
        printf("%s='%s'\n", var, val);
}

static void print_var_int(const char *var, int val)
{
        printf("%s=%d\n", var, val);
}

int show_bisect_vars(struct rev_list_info *info, int reaches, int all)
{
        int cnt, flags = info->bisect_show_flags;
        char hex[41] = "";
        struct commit_list *tried;
        struct rev_info *revs = info->revs;

        if (!revs->commits && !(flags & BISECT_SHOW_TRIED))
                return 1;

        revs->commits = filter_skipped(revs->commits, &tried,
                                       flags & BISECT_SHOW_ALL,
                                       NULL, NULL);

        /*
         * revs->commits can reach "reaches" commits among
         * "all" commits.  If it is good, then there are
         * (all-reaches) commits left to be bisected.
         * On the other hand, if it is bad, then the set
         * to bisect is "reaches".
         * A bisect set of size N has (N-1) commits further
         * to test, as we already know one bad one.
         */
        cnt = all - reaches;
        if (cnt < reaches)
                cnt = reaches;

        if (revs->commits)
                strcpy(hex, sha1_to_hex(revs->commits->item->object.sha1));

        if (flags & BISECT_SHOW_ALL) {
                traverse_commit_list(revs, show_commit, show_object, info);
                printf("------\n");
        }

        if (flags & BISECT_SHOW_TRIED)
                show_tried_revs(tried);

        print_var_str("bisect_rev", hex);
        print_var_int("bisect_nr", cnt - 1);
        print_var_int("bisect_good", all - reaches - 1);
        print_var_int("bisect_bad", reaches - 1);
        print_var_int("bisect_all", all);
        print_var_int("bisect_steps", estimate_bisect_steps(all));

        return 0;
}

int cmd_rev_list(int argc, const char **argv, const char *prefix)
{
        struct rev_info revs;
        struct rev_list_info info;
        int i;
        int bisect_list = 0;
        int bisect_show_vars = 0;
        int bisect_find_all = 0;
        int quiet = 0;

        git_config(git_default_config, NULL);
        init_revisions(&revs, prefix);
        revs.abbrev = 0;
        revs.commit_format = CMIT_FMT_UNSPECIFIED;
        argc = setup_revisions(argc, argv, &revs, NULL);

        memset(&info, 0, sizeof(info));
        info.revs = &revs;
        if (revs.bisect)
                bisect_list = 1;

        quiet = DIFF_OPT_TST(&revs.diffopt, QUICK);
        for (i = 1 ; i < argc; i++) {
                const char *arg = argv[i];

                if (!strcmp(arg, "--header")) {
                        revs.verbose_header = 1;
                        continue;
                }
                if (!strcmp(arg, "--timestamp")) {
                        info.show_timestamp = 1;
                        continue;
                }
                if (!strcmp(arg, "--bisect")) {
                        bisect_list = 1;
                        continue;
                }
                if (!strcmp(arg, "--bisect-all")) {
                        bisect_list = 1;
                        bisect_find_all = 1;
                        info.bisect_show_flags = BISECT_SHOW_ALL;
                        revs.show_decorations = 1;
                        continue;
                }
                if (!strcmp(arg, "--bisect-vars")) {
                        bisect_list = 1;
                        bisect_show_vars = 1;
                        continue;
                }
                usage(rev_list_usage);

        }
        if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
                /* The command line has a --pretty  */
                info.hdr_termination = '\n';
                if (revs.commit_format == CMIT_FMT_ONELINE)
                        info.header_prefix = "";
                else
                        info.header_prefix = "commit ";
        }
        else if (revs.verbose_header)
                /* Only --header was specified */
                revs.commit_format = CMIT_FMT_RAW;

        if ((!revs.commits &&
             (!(revs.tag_objects||revs.tree_objects||revs.blob_objects) &&
              !revs.pending.nr)) ||
            revs.diff)
                usage(rev_list_usage);

        save_commit_buffer = revs.verbose_header ||
                revs.grep_filter.pattern_list;
        if (bisect_list)
                revs.limited = 1;

        if (prepare_revision_walk(&revs))
                die("revision walk setup failed");
        if (revs.tree_objects)
                mark_edges_uninteresting(revs.commits, &revs, show_edge);

        if (bisect_list) {
                int reaches = reaches, all = all;

                revs.commits = find_bisection(revs.commits, &reaches, &all,
                                              bisect_find_all);

                if (bisect_show_vars)
                        return show_bisect_vars(&info, reaches, all);
        }

        traverse_commit_list(&revs,
                             quiet ? finish_commit : show_commit,
                             quiet ? finish_object : show_object,
                             &info);

        return 0;
}