/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2025 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software were developed by Konstantin Belousov <kib@FreeBSD.org>
 * under sponsorship from the FreeBSD Foundation.
 */

#include <sys/param.h>
#include <sys/exterr_cat.h>
#include <sys/exterrvar.h>
#include <exterr.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static const char * const cat_to_filenames[] = {
#include "exterr_cat_filenames.h"
};

static const char *
cat_to_filename(int category)
{
        if (category < 0 || category >= nitems(cat_to_filenames) ||
            cat_to_filenames[category] == NULL)
                return ("unknown");
        return (cat_to_filenames[category]);
}

static const char exterror_verbose_name[] = "EXTERROR_VERBOSE";
enum exterr_verbose_state {
        EXTERR_VERBOSE_UNKNOWN = 100,
        EXTERR_VERBOSE_DEFAULT,
        EXTERR_VERBOSE_ALLOW_BRIEF,
        EXTERR_VERBOSE_ALLOW_FULL,
};
static enum exterr_verbose_state exterror_verbose = EXTERR_VERBOSE_UNKNOWN;

static void
exterr_verbose_init(void)
{
        const char *v;

        /*
         * No need to care about thread-safety, the result is
         * idempotent.
         */
        if (exterror_verbose != EXTERR_VERBOSE_UNKNOWN)
                return;
        if (issetugid()) {
                exterror_verbose = EXTERR_VERBOSE_DEFAULT;
        } else if ((v = getenv(exterror_verbose_name)) != NULL) {
                exterror_verbose = strcmp(v, "brief") == 0 ?
                    EXTERR_VERBOSE_ALLOW_BRIEF : EXTERR_VERBOSE_ALLOW_FULL;
        } else {
                exterror_verbose = EXTERR_VERBOSE_DEFAULT;
        }
}

int
__uexterr_format(const struct uexterror *ue, char *buf, size_t bufsz)
{
        bool has_msg;

        if (bufsz > UEXTERROR_MAXLEN)
                bufsz = UEXTERROR_MAXLEN;
        if (ue->error == 0) {
                strlcpy(buf, "", bufsz);
                return (0);
        }
        exterr_verbose_init();
        has_msg = ue->msg[0] != '\0';

        if (has_msg) {
                snprintf(buf, bufsz, ue->msg, (uintmax_t)ue->p1,
                    (uintmax_t)ue->p2);
        } else {
                strlcpy(buf, "", bufsz);
        }

        if (exterror_verbose > EXTERR_VERBOSE_DEFAULT || !has_msg) {
                char lbuf[128];

#define SRC_FMT "(src sys/%s:%u)"
                if (exterror_verbose == EXTERR_VERBOSE_ALLOW_BRIEF) {
                        snprintf(lbuf, sizeof(lbuf), SRC_FMT,
                            cat_to_filename(ue->cat), ue->src_line);
                } else if (!has_msg ||
                    exterror_verbose == EXTERR_VERBOSE_ALLOW_FULL) {
                        snprintf(lbuf, sizeof(lbuf),
                            "errno %d category %u " SRC_FMT " p1 %#jx p2 %#jx",
                            ue->error, ue->cat, cat_to_filename(ue->cat),
                            ue->src_line, (uintmax_t)ue->p1, (uintmax_t)ue->p2);
                }
#undef SRC_FMT
                if (has_msg)
                        strlcat(buf, " ", bufsz);
                strlcat(buf, lbuf, bufsz);
        }
        return (0);
}