#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"
#include "prompt.h"
#include "quote.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 GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
static GIT_PATH_FUNC(git_path_head_name, "head-name")
static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")

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>]"),
        N_("git bisect--helper --bisect-write [--no-log] <state> <revision> <good_term> <bad_term>"),
        N_("git bisect--helper --bisect-check-and-set-terms <command> <good_term> <bad_term>"),
        N_("git bisect--helper --bisect-next-check <good_term> <bad_term> [<term>]"),
        N_("git bisect--helper --bisect-terms [--term-good | --term-old | --term-bad | --term-new]"),
        N_("git bisect--helper --bisect-start [--term-{old,good}=<term> --term-{new,bad}=<term>]"
                                             "[--no-checkout] [<bad> [<good>...]] [--] [<paths>...]"),
        NULL
};

struct bisect_terms {
        char *term_good;
        char *term_bad;
};

static void free_terms(struct bisect_terms *terms)
{
        FREE_AND_NULL(terms->term_good);
        FREE_AND_NULL(terms->term_bad);
}

static void set_terms(struct bisect_terms *terms, const char *bad,
                      const char *good)
{
        free((void *)terms->term_good);
        terms->term_good = xstrdup(good);
        free((void *)terms->term_bad);
        terms->term_bad = xstrdup(bad);
}

static const char *vocab_bad = "bad|new";
static const char *vocab_good = "good|old";

/*
 * 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();
}

static void log_commit(FILE *fp, char *fmt, const char *state,
                       struct commit *commit)
{
        struct pretty_print_context pp = {0};
        struct strbuf commit_msg = STRBUF_INIT;
        char *label = xstrfmt(fmt, state);

        format_commit_message(commit, "%s", &commit_msg, &pp);

        fprintf(fp, "# %s: [%s] %s\n", label, oid_to_hex(&commit->object.oid),
                commit_msg.buf);

        strbuf_release(&commit_msg);
        free(label);
}

static int bisect_write(const char *state, const char *rev,
                        const struct bisect_terms *terms, int nolog)
{
        struct strbuf tag = STRBUF_INIT;
        struct object_id oid;
        struct commit *commit;
        FILE *fp = NULL;
        int retval = 0;

        if (!strcmp(state, terms->term_bad)) {
                strbuf_addf(&tag, "refs/bisect/%s", state);
        } else if (one_of(state, terms->term_good, "skip", NULL)) {
                strbuf_addf(&tag, "refs/bisect/%s-%s", state, rev);
        } else {
                retval = error(_("Bad bisect_write argument: %s"), state);
                goto finish;
        }

        if (get_oid(rev, &oid)) {
                retval = error(_("couldn't get the oid of the rev '%s'"), rev);
                goto finish;
        }

        if (update_ref(NULL, tag.buf, &oid, NULL, 0,
                       UPDATE_REFS_MSG_ON_ERR)) {
                retval = -1;
                goto finish;
        }

        fp = fopen(git_path_bisect_log(), "a");
        if (!fp) {
                retval = error_errno(_("couldn't open the file '%s'"), git_path_bisect_log());
                goto finish;
        }

        commit = lookup_commit_reference(the_repository, &oid);
        log_commit(fp, "%s", state, commit);

        if (!nolog)
                fprintf(fp, "git bisect %s %s\n", state, rev);

finish:
        if (fp)
                fclose(fp);
        strbuf_release(&tag);
        return retval;
}

static int check_and_set_terms(struct bisect_terms *terms, const char *cmd)
{
        int has_term_file = !is_empty_or_missing_file(git_path_bisect_terms());

        if (one_of(cmd, "skip", "start", "terms", NULL))
                return 0;

        if (has_term_file && strcmp(cmd, terms->term_bad) &&
            strcmp(cmd, terms->term_good))
                return error(_("Invalid command: you're currently in a "
                                "%s/%s bisect"), terms->term_bad,
                                terms->term_good);

        if (!has_term_file) {
                if (one_of(cmd, "bad", "good", NULL)) {
                        set_terms(terms, "bad", "good");
                        return write_terms(terms->term_bad, terms->term_good);
                }
                if (one_of(cmd, "new", "old", NULL)) {
                        set_terms(terms, "new", "old");
                        return write_terms(terms->term_bad, terms->term_good);
                }
        }

        return 0;
}

static int mark_good(const char *refname, const struct object_id *oid,
                     int flag, void *cb_data)
{
        int *m_good = (int *)cb_data;
        *m_good = 0;
        return 1;
}

static const char *need_bad_and_good_revision_warning =
        N_("You need to give me at least one %s and %s revision.\n"
           "You can use \"git bisect %s\" and \"git bisect %s\" for that.");

static const char *need_bisect_start_warning =
        N_("You need to start by \"git bisect start\".\n"
           "You then need to give me at least one %s and %s revision.\n"
           "You can use \"git bisect %s\" and \"git bisect %s\" for that.");

static int bisect_next_check(const struct bisect_terms *terms,
                             const char *current_term)
{
        int missing_good = 1, missing_bad = 1, retval = 0;
        const char *bad_ref = xstrfmt("refs/bisect/%s", terms->term_bad);
        const char *good_glob = xstrfmt("%s-*", terms->term_good);

        if (ref_exists(bad_ref))
                missing_bad = 0;

        for_each_glob_ref_in(mark_good, good_glob, "refs/bisect/",
                             (void *) &missing_good);

        if (!missing_good && !missing_bad)
                goto finish;

        if (!current_term) {
                retval = -1;
                goto finish;
        }

        if (missing_good && !missing_bad &&
            !strcmp(current_term, terms->term_good)) {
                char *yesno;
                /*
                 * have bad (or new) but not good (or old). We could bisect
                 * although this is less optimum.
                 */
                warning(_("bisecting only with a %s commit"), terms->term_bad);
                if (!isatty(0))
                        goto finish;
                /*
                 * TRANSLATORS: Make sure to include [Y] and [n] in your
                 * translation. The program will only accept English input
                 * at this point.
                 */
                yesno = git_prompt(_("Are you sure [Y/n]? "), PROMPT_ECHO);
                if (starts_with(yesno, "N") || starts_with(yesno, "n"))
                        retval = -1;
                goto finish;
        }
        if (!is_empty_or_missing_file(git_path_bisect_start())) {
                retval = error(_(need_bad_and_good_revision_warning),
                               vocab_bad, vocab_good, vocab_bad, vocab_good);
        } else {
                retval = error(_(need_bisect_start_warning),
                               vocab_good, vocab_bad, vocab_good, vocab_bad);
        }

finish:
        free((void *) good_glob);
        free((void *) bad_ref);
        return retval;
}

static int get_terms(struct bisect_terms *terms)
{
        struct strbuf str = STRBUF_INIT;
        FILE *fp = NULL;
        int res = 0;

        fp = fopen(git_path_bisect_terms(), "r");
        if (!fp) {
                res = -1;
                goto finish;
        }

        free_terms(terms);
        strbuf_getline_lf(&str, fp);
        terms->term_bad = strbuf_detach(&str, NULL);
        strbuf_getline_lf(&str, fp);
        terms->term_good = strbuf_detach(&str, NULL);

finish:
        if (fp)
                fclose(fp);
        strbuf_release(&str);
        return res;
}

static int bisect_terms(struct bisect_terms *terms, const char *option)
{
        if (get_terms(terms))
                return error(_("no terms defined"));

        if (option == NULL) {
                printf(_("Your current terms are %s for the old state\n"
                         "and %s for the new state.\n"),
                       terms->term_good, terms->term_bad);
                return 0;
        }
        if (one_of(option, "--term-good", "--term-old", NULL))
                printf("%s\n", terms->term_good);
        else if (one_of(option, "--term-bad", "--term-new", NULL))
                printf("%s\n", terms->term_bad);
        else
                return error(_("invalid argument %s for 'git bisect terms'.\n"
                               "Supported options are: "
                               "--term-good|--term-old and "
                               "--term-bad|--term-new."), option);

        return 0;
}

static int bisect_append_log_quoted(const char **argv)
{
        int retval = 0;
        FILE *fp = fopen(git_path_bisect_log(), "a");
        struct strbuf orig_args = STRBUF_INIT;

        if (!fp)
                return -1;

        if (fprintf(fp, "git bisect start") < 1) {
                retval = -1;
                goto finish;
        }

        sq_quote_argv(&orig_args, argv);
        if (fprintf(fp, "%s\n", orig_args.buf) < 1)
                retval = -1;

finish:
        fclose(fp);
        strbuf_release(&orig_args);
        return retval;
}

static int bisect_start(struct bisect_terms *terms, int no_checkout,
                        const char **argv, int argc)
{
        int i, has_double_dash = 0, must_write_terms = 0, bad_seen = 0;
        int flags, pathspec_pos, retval = 0;
        struct string_list revs = STRING_LIST_INIT_DUP;
        struct string_list states = STRING_LIST_INIT_DUP;
        struct strbuf start_head = STRBUF_INIT;
        struct strbuf bisect_names = STRBUF_INIT;
        struct object_id head_oid;
        struct object_id oid;
        const char *head;

        if (is_bare_repository())
                no_checkout = 1;

        /*
         * Check for one bad and then some good revisions
         */
        for (i = 0; i < argc; i++) {
                if (!strcmp(argv[i], "--")) {
                        has_double_dash = 1;
                        break;
                }
        }

        for (i = 0; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(argv[i], "--")) {
                        break;
                } else if (!strcmp(arg, "--no-checkout")) {
                        no_checkout = 1;
                } else if (!strcmp(arg, "--term-good") ||
                         !strcmp(arg, "--term-old")) {
                        must_write_terms = 1;
                        free((void *) terms->term_good);
                        terms->term_good = xstrdup(argv[++i]);
                } else if (skip_prefix(arg, "--term-good=", &arg) ||
                           skip_prefix(arg, "--term-old=", &arg)) {
                        must_write_terms = 1;
                        free((void *) terms->term_good);
                        terms->term_good = xstrdup(arg);
                } else if (!strcmp(arg, "--term-bad") ||
                         !strcmp(arg, "--term-new")) {
                        must_write_terms = 1;
                        free((void *) terms->term_bad);
                        terms->term_bad = xstrdup(argv[++i]);
                } else if (skip_prefix(arg, "--term-bad=", &arg) ||
                           skip_prefix(arg, "--term-new=", &arg)) {
                        must_write_terms = 1;
                        free((void *) terms->term_bad);
                        terms->term_bad = xstrdup(arg);
                } else if (starts_with(arg, "--") &&
                         !one_of(arg, "--term-good", "--term-bad", NULL)) {
                        return error(_("unrecognized option: '%s'"), arg);
                } else {
                        char *commit_id = xstrfmt("%s^{commit}", arg);
                        if (get_oid(commit_id, &oid) && has_double_dash)
                                die(_("'%s' does not appear to be a valid "
                                      "revision"), arg);

                        string_list_append(&revs, oid_to_hex(&oid));
                        free(commit_id);
                }
        }
        pathspec_pos = i;

        /*
         * The user ran "git bisect start <sha1> <sha1>", hence did not
         * explicitly specify the terms, but we are already starting to
         * set references named with the default terms, and won't be able
         * to change afterwards.
         */
        if (revs.nr)
                must_write_terms = 1;
        for (i = 0; i < revs.nr; i++) {
                if (bad_seen) {
                        string_list_append(&states, terms->term_good);
                } else {
                        bad_seen = 1;
                        string_list_append(&states, terms->term_bad);
                }
        }

        /*
         * Verify HEAD
         */
        head = resolve_ref_unsafe("HEAD", 0, &head_oid, &flags);
        if (!head)
                if (get_oid("HEAD", &head_oid))
                        return error(_("bad HEAD - I need a HEAD"));

        /*
         * Check if we are bisecting
         */
        if (!is_empty_or_missing_file(git_path_bisect_start())) {
                /* Reset to the rev from where we started */
                strbuf_read_file(&start_head, git_path_bisect_start(), 0);
                strbuf_trim(&start_head);
                if (!no_checkout) {
                        struct argv_array argv = ARGV_ARRAY_INIT;

                        argv_array_pushl(&argv, "checkout", start_head.buf,
                                         "--", NULL);
                        if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
                                retval = error(_("checking out '%s' failed."
                                                 " Try 'git bisect start "
                                                 "<valid-branch>'."),
                                               start_head.buf);
                                goto finish;
                        }
                }
        } else {
                /* Get the rev from where we start. */
                if (!get_oid(head, &head_oid) &&
                    !starts_with(head, "refs/heads/")) {
                        strbuf_reset(&start_head);
                        strbuf_addstr(&start_head, oid_to_hex(&head_oid));
                } else if (!get_oid(head, &head_oid) &&
                           skip_prefix(head, "refs/heads/", &head)) {
                        /*
                         * This error message should only be triggered by
                         * cogito usage, and cogito users should understand
                         * it relates to cg-seek.
                         */
                        if (!is_empty_or_missing_file(git_path_head_name()))
                                return error(_("won't bisect on cg-seek'ed tree"));
                        strbuf_addstr(&start_head, head);
                } else {
                        return error(_("bad HEAD - strange symbolic ref"));
                }
        }

        /*
         * Get rid of any old bisect state.
         */
        if (bisect_clean_state())
                return -1;

        /*
         * In case of mistaken revs or checkout error, or signals received,
         * "bisect_auto_next" below may exit or misbehave.
         * We have to trap this to be able to clean up using
         * "bisect_clean_state".
         */

        /*
         * Write new start state
         */
        write_file(git_path_bisect_start(), "%s\n", start_head.buf);

        if (no_checkout) {
                get_oid(start_head.buf, &oid);
                if (update_ref(NULL, "BISECT_HEAD", &oid, NULL, 0,
                               UPDATE_REFS_MSG_ON_ERR)) {
                        retval = -1;
                        goto finish;
                }
        }

        if (pathspec_pos < argc - 1)
                sq_quote_argv(&bisect_names, argv + pathspec_pos);
        write_file(git_path_bisect_names(), "%s\n", bisect_names.buf);

        for (i = 0; i < states.nr; i++)
                if (bisect_write(states.items[i].string,
                                 revs.items[i].string, terms, 1)) {
                        retval = -1;
                        goto finish;
                }

        if (must_write_terms && write_terms(terms->term_bad,
                                            terms->term_good)) {
                retval = -1;
                goto finish;
        }

        retval = bisect_append_log_quoted(argv);
        if (retval)
                retval = -1;

finish:
        string_list_clear(&revs, 0);
        string_list_clear(&states, 0);
        strbuf_release(&start_head);
        strbuf_release(&bisect_names);
        return retval;
}

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,
                BISECT_WRITE,
                CHECK_AND_SET_TERMS,
                BISECT_NEXT_CHECK,
                BISECT_TERMS,
                BISECT_START
        } cmdmode = 0;
        int no_checkout = 0, res = 0, nolog = 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_CMDMODE(0, "bisect-write", &cmdmode,
                         N_("write out the bisection state in BISECT_LOG"), BISECT_WRITE),
                OPT_CMDMODE(0, "check-and-set-terms", &cmdmode,
                         N_("check and set terms in a bisection state"), CHECK_AND_SET_TERMS),
                OPT_CMDMODE(0, "bisect-next-check", &cmdmode,
                         N_("check whether bad or good terms exist"), BISECT_NEXT_CHECK),
                OPT_CMDMODE(0, "bisect-terms", &cmdmode,
                         N_("print out the bisect terms"), BISECT_TERMS),
                OPT_CMDMODE(0, "bisect-start", &cmdmode,
                         N_("start the bisect session"), BISECT_START),
                OPT_BOOL(0, "no-checkout", &no_checkout,
                         N_("update BISECT_HEAD instead of checking out the current commit")),
                OPT_BOOL(0, "no-log", &nolog,
                         N_("no log for BISECT_WRITE")),
                OPT_END()
        };
        struct bisect_terms terms = { .term_good = NULL, .term_bad = NULL };

        argc = parse_options(argc, argv, prefix, options,
                             git_bisect_helper_usage,
                             PARSE_OPT_KEEP_DASHDASH | PARSE_OPT_KEEP_UNKNOWN);

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

        switch (cmdmode) {
        case NEXT_ALL:
                return bisect_next_all(the_repository, 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);
        case BISECT_WRITE:
                if (argc != 4 && argc != 5)
                        return error(_("--bisect-write requires either 4 or 5 arguments"));
                set_terms(&terms, argv[3], argv[2]);
                res = bisect_write(argv[0], argv[1], &terms, nolog);
                break;
        case CHECK_AND_SET_TERMS:
                if (argc != 3)
                        return error(_("--check-and-set-terms requires 3 arguments"));
                set_terms(&terms, argv[2], argv[1]);
                res = check_and_set_terms(&terms, argv[0]);
                break;
        case BISECT_NEXT_CHECK:
                if (argc != 2 && argc != 3)
                        return error(_("--bisect-next-check requires 2 or 3 arguments"));
                set_terms(&terms, argv[1], argv[0]);
                res = bisect_next_check(&terms, argc == 3 ? argv[2] : NULL);
                break;
        case BISECT_TERMS:
                if (argc > 1)
                        return error(_("--bisect-terms requires 0 or 1 argument"));
                res = bisect_terms(&terms, argc == 1 ? argv[0] : NULL);
                break;
        case BISECT_START:
                set_terms(&terms, "bad", "good");
                res = bisect_start(&terms, no_checkout, argv, argc);
                break;
        default:
                return error("BUG: unknown subcommand '%d'", cmdmode);
        }
        free_terms(&terms);
        return !!res;
}