#include "builtin.h"
#include "cache.h"
#include "parse-options.h"
#include "bisect.h"
#include "refs.h"
#include "dir.h"
#include "argv-array.h"
#include "run-command.h"

static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
static GIT_PATH_FUNC(git_path_bisect_head, "BISECT_HEAD")

static const char * const git_bisect_helper_usage[] = {
        N_("git bisect--helper --next-all [--no-checkout]"),
        N_("git bisect--helper --write-terms <bad_term> <good_term>"),
        N_("git bisect--helper --bisect-clean-state"),
        N_("git bisect--helper --bisect-reset [<commit>]"),
        NULL
};

/*
 * Check whether the string `term` belongs to the set of strings
 * included in the variable arguments.
 */
LAST_ARG_MUST_BE_NULL
static int one_of(const char *term, ...)
{
        int res = 0;
        va_list matches;
        const char *match;

        va_start(matches, term);
        while (!res && (match = va_arg(matches, const char *)))
                res = !strcmp(term, match);
        va_end(matches);

        return res;
}

static int check_term_format(const char *term, const char *orig_term)
{
        int res;
        char *new_term = xstrfmt("refs/bisect/%s", term);

        res = check_refname_format(new_term, 0);
        free(new_term);

        if (res)
                return error(_("'%s' is not a valid term"), term);

        if (one_of(term, "help", "start", "skip", "next", "reset",
                        "visualize", "view", "replay", "log", "run", "terms", NULL))
                return error(_("can't use the builtin command '%s' as a term"), term);

        /*
         * In theory, nothing prevents swapping completely good and bad,
         * but this situation could be confusing and hasn't been tested
         * enough. Forbid it for now.
         */

        if ((strcmp(orig_term, "bad") && one_of(term, "bad", "new", NULL)) ||
                 (strcmp(orig_term, "good") && one_of(term, "good", "old", NULL)))
                return error(_("can't change the meaning of the term '%s'"), term);

        return 0;
}

static int write_terms(const char *bad, const char *good)
{
        FILE *fp = NULL;
        int res;

        if (!strcmp(bad, good))
                return error(_("please use two different terms"));

        if (check_term_format(bad, "bad") || check_term_format(good, "good"))
                return -1;

        fp = fopen(git_path_bisect_terms(), "w");
        if (!fp)
                return error_errno(_("could not open the file BISECT_TERMS"));

        res = fprintf(fp, "%s\n%s\n", bad, good);
        res |= fclose(fp);
        return (res < 0) ? -1 : 0;
}

static int is_expected_rev(const char *expected_hex)
{
        struct strbuf actual_hex = STRBUF_INIT;
        int res = 0;
        if (strbuf_read_file(&actual_hex, git_path_bisect_expected_rev(), 0) >= 40) {
                strbuf_trim(&actual_hex);
                res = !strcmp(actual_hex.buf, expected_hex);
        }
        strbuf_release(&actual_hex);
        return res;
}

static void check_expected_revs(const char **revs, int rev_nr)
{
        int i;

        for (i = 0; i < rev_nr; i++) {
                if (!is_expected_rev(revs[i])) {
                        unlink_or_warn(git_path_bisect_ancestors_ok());
                        unlink_or_warn(git_path_bisect_expected_rev());
                }
        }
}

static int bisect_reset(const char *commit)
{
        struct strbuf branch = STRBUF_INIT;

        if (!commit) {
                if (strbuf_read_file(&branch, git_path_bisect_start(), 0) < 1) {
                        printf(_("We are not bisecting.\n"));
                        return 0;
                }
                strbuf_rtrim(&branch);
        } else {
                struct object_id oid;

                if (get_oid_commit(commit, &oid))
                        return error(_("'%s' is not a valid commit"), commit);
                strbuf_addstr(&branch, commit);
        }

        if (!file_exists(git_path_bisect_head())) {
                struct argv_array argv = ARGV_ARRAY_INIT;

                argv_array_pushl(&argv, "checkout", branch.buf, "--", NULL);
                if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
                        strbuf_release(&branch);
                        argv_array_clear(&argv);
                        return error(_("could not check out original"
                                       " HEAD '%s'. Try 'git bisect"
                                       "reset <commit>'."), branch.buf);
                }
                argv_array_clear(&argv);
        }

        strbuf_release(&branch);
        return bisect_clean_state();
}

int cmd_bisect__helper(int argc, const char **argv, const char *prefix)
{
        enum {
                NEXT_ALL = 1,
                WRITE_TERMS,
                BISECT_CLEAN_STATE,
                CHECK_EXPECTED_REVS,
                BISECT_RESET
        } cmdmode = 0;
        int no_checkout = 0;
        struct option options[] = {
                OPT_CMDMODE(0, "next-all", &cmdmode,
                         N_("perform 'git bisect next'"), NEXT_ALL),
                OPT_CMDMODE(0, "write-terms", &cmdmode,
                         N_("write the terms to .git/BISECT_TERMS"), WRITE_TERMS),
                OPT_CMDMODE(0, "bisect-clean-state", &cmdmode,
                         N_("cleanup the bisection state"), BISECT_CLEAN_STATE),
                OPT_CMDMODE(0, "check-expected-revs", &cmdmode,
                         N_("check for expected revs"), CHECK_EXPECTED_REVS),
                OPT_CMDMODE(0, "bisect-reset", &cmdmode,
                         N_("reset the bisection state"), BISECT_RESET),
                OPT_BOOL(0, "no-checkout", &no_checkout,
                         N_("update BISECT_HEAD instead of checking out the current commit")),
                OPT_END()
        };

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

        if (!cmdmode)
                usage_with_options(git_bisect_helper_usage, options);

        switch (cmdmode) {
        case NEXT_ALL:
                return bisect_next_all(prefix, no_checkout);
        case WRITE_TERMS:
                if (argc != 2)
                        return error(_("--write-terms requires two arguments"));
                return write_terms(argv[0], argv[1]);
        case BISECT_CLEAN_STATE:
                if (argc != 0)
                        return error(_("--bisect-clean-state requires no arguments"));
                return bisect_clean_state();
        case CHECK_EXPECTED_REVS:
                check_expected_revs(argv, argc);
                return 0;
        case BISECT_RESET:
                if (argc > 1)
                        return error(_("--bisect-reset requires either no argument or a commit"));
                return !!bisect_reset(argc ? argv[0] : NULL);
        default:
                return error("BUG: unknown subcommand '%d'", cmdmode);
        }
        return 0;
}