/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2023 Alexander V. Chernikov
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/param.h>
#include <sys/refcount.h>
#include <sys/types.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/socket.h>
#include <sys/stdarg.h>
#include <sys/priv.h>

#include <netlink/netlink.h>
#include <netlink/netlink_ctl.h>
#include <netlink/netlink_generic.h>
#include <netlink/netlink_message_parser.h>

#include <tests/ktest.h>

struct mtx ktest_mtx;
#define KTEST_LOCK()            mtx_lock(&ktest_mtx)
#define KTEST_UNLOCK()          mtx_unlock(&ktest_mtx)
#define KTEST_LOCK_ASSERT()     mtx_assert(&ktest_mtx, MA_OWNED)

MTX_SYSINIT(ktest_mtx, &ktest_mtx, "ktest mutex", MTX_DEF);

struct ktest_module {
        struct ktest_module_info        *info;
        volatile u_int                  refcount;
        TAILQ_ENTRY(ktest_module)       entries;
};
static TAILQ_HEAD(, ktest_module) module_list = TAILQ_HEAD_INITIALIZER(module_list);

struct nl_ktest_parsed {
        char            *mod_name;
        char            *test_name;
        struct nlattr   *test_meta;
};

#define _IN(_field)     offsetof(struct genlmsghdr, _field)
#define _OUT(_field)    offsetof(struct nl_ktest_parsed, _field)

static const struct nlattr_parser nla_p_get[] = {
        { .type = KTEST_ATTR_MOD_NAME, .off = _OUT(mod_name), .cb = nlattr_get_string },
        { .type = KTEST_ATTR_TEST_NAME, .off = _OUT(test_name), .cb = nlattr_get_string },
        { .type = KTEST_ATTR_TEST_META, .off = _OUT(test_meta), .cb = nlattr_get_nla },
};
static const struct nlfield_parser nlf_p_get[] = {
};
NL_DECLARE_PARSER(ktest_parser, struct genlmsghdr, nlf_p_get, nla_p_get);
#undef _IN
#undef _OUT

static bool
create_reply(struct nl_writer *nw, struct nlmsghdr *hdr, int cmd)
{
        if (!nlmsg_reply(nw, hdr, sizeof(struct genlmsghdr)))
                return (false);

        struct genlmsghdr *ghdr_new = nlmsg_reserve_object(nw, struct genlmsghdr);
        ghdr_new->cmd = cmd;
        ghdr_new->version = 0;
        ghdr_new->reserved = 0;

        return (true);
}

static int
dump_mod_test(struct nlmsghdr *hdr, struct nl_pstate *npt,
    struct ktest_module *mod, const struct ktest_test_info *test_info)
{
        struct nl_writer *nw = npt->nw;

        if (!create_reply(nw, hdr, KTEST_CMD_NEWTEST))
                goto enomem;

        nlattr_add_string(nw, KTEST_ATTR_MOD_NAME, mod->info->name);
        nlattr_add_string(nw, KTEST_ATTR_TEST_NAME, test_info->name);
        nlattr_add_string(nw, KTEST_ATTR_TEST_DESCR, test_info->desc);

        if (nlmsg_end(nw))
                return (0);
enomem:
        nlmsg_abort(nw);
        return (ENOMEM);
}

static int
dump_mod_tests(struct nlmsghdr *hdr, struct nl_pstate *npt,
    struct ktest_module *mod, struct nl_ktest_parsed *attrs)
{
        for (int i = 0; i < mod->info->num_tests; i++) {
                const struct ktest_test_info *test_info = &mod->info->tests[i];
                if (attrs->test_name != NULL && strcmp(attrs->test_name, test_info->name))
                        continue;
                int error = dump_mod_test(hdr, npt, mod, test_info);
                if (error != 0)
                        return (error);
        }

        return (0);
}

static int
dump_tests(struct nlmsghdr *hdr, struct nl_pstate *npt)
{
        struct nl_ktest_parsed attrs = { };
        struct ktest_module *mod;
        int error;

        error = nl_parse_nlmsg(hdr, &ktest_parser, npt, &attrs);
        if (error != 0)
                return (error);

        hdr->nlmsg_flags |= NLM_F_MULTI;

        KTEST_LOCK();
        TAILQ_FOREACH(mod, &module_list, entries) {
                if (attrs.mod_name && strcmp(attrs.mod_name, mod->info->name))
                        continue;
                error = dump_mod_tests(hdr, npt, mod, &attrs);
                if (error != 0)
                        break;
        }
        KTEST_UNLOCK();

        if (!nlmsg_end_dump(npt->nw, error, hdr)) {
                //NL_LOG(LOG_DEBUG, "Unable to finalize the dump");
                return (ENOMEM);
        }

        return (error);
}

static int
run_test(struct nlmsghdr *hdr, struct nl_pstate *npt)
{
        struct nl_ktest_parsed attrs = { };
        struct ktest_module *mod;
        int error;

        error = nl_parse_nlmsg(hdr, &ktest_parser, npt, &attrs);
        if (error != 0)
                return (error);

        if (attrs.mod_name == NULL) {
                nlmsg_report_err_msg(npt, "KTEST_ATTR_MOD_NAME not set");
                return (EINVAL);
        }

        if (attrs.test_name == NULL) {
                nlmsg_report_err_msg(npt, "KTEST_ATTR_TEST_NAME not set");
                return (EINVAL);
        }

        const struct ktest_test_info *test = NULL;

        KTEST_LOCK();
        TAILQ_FOREACH(mod, &module_list, entries) {
                if (strcmp(attrs.mod_name, mod->info->name))
                        continue;

                const struct ktest_module_info *info = mod->info;

                for (int i = 0; i < info->num_tests; i++) {
                        const struct ktest_test_info *test_info = &info->tests[i];

                        if (!strcmp(attrs.test_name, test_info->name)) {
                                test = test_info;
                                break;
                        }
                }
                break;
        }
        if (test != NULL)
                refcount_acquire(&mod->refcount);
        KTEST_UNLOCK();

        if (test == NULL)
                return (ESRCH);

        /* Run the test */
        struct ktest_test_context ctx = {
                .npt = npt,
                .hdr = hdr,
                .buf = npt_alloc(npt, KTEST_MAX_BUF),
                .bufsize = KTEST_MAX_BUF,
        };

        if (ctx.buf == NULL) {
                //NL_LOG(LOG_DEBUG, "unable to allocate temporary buffer");
                return (ENOMEM);
        }

        if (test->parse != NULL && attrs.test_meta != NULL) {
                error = test->parse(&ctx, attrs.test_meta);
                if (error != 0)
                        return (error);
        }

        hdr->nlmsg_flags |= NLM_F_MULTI;

        KTEST_LOG_LEVEL(&ctx, LOG_INFO, "start running %s", test->name);
        error = test->func(&ctx);
        KTEST_LOG_LEVEL(&ctx, LOG_INFO, "end running %s", test->name);

        refcount_release(&mod->refcount);

        if (!nlmsg_end_dump(npt->nw, error, hdr)) {
                //NL_LOG(LOG_DEBUG, "Unable to finalize the dump");
                return (ENOMEM);
        }

        return (error);
}


/* USER API */
static void
register_test_module(struct ktest_module_info *info)
{
        struct ktest_module *mod = malloc(sizeof(*mod), M_TEMP, M_WAITOK | M_ZERO);

        mod->info = info;
        info->module_ptr = mod;
        KTEST_LOCK();
        TAILQ_INSERT_TAIL(&module_list, mod, entries);
        KTEST_UNLOCK();
}

static void
unregister_test_module(struct ktest_module_info *info)
{
        struct ktest_module *mod = info->module_ptr;

        info->module_ptr = NULL;

        KTEST_LOCK();
        TAILQ_REMOVE(&module_list, mod, entries);
        KTEST_UNLOCK();

        free(mod, M_TEMP);
}

static bool
can_unregister(struct ktest_module_info *info)
{
        struct ktest_module *mod = info->module_ptr;

        return (refcount_load(&mod->refcount) == 0);
}

int
ktest_default_modevent(module_t mod, int type, void *arg)
{
        struct ktest_module_info *info = (struct ktest_module_info *)arg;
        int error = 0;

        switch (type) {
        case MOD_LOAD:
                register_test_module(info);
                break;
        case MOD_UNLOAD:
                if (!can_unregister(info))
                        return (EBUSY);
                unregister_test_module(info);
                break;
        default:
                error = EOPNOTSUPP;
                break;
        }
        return (error);
}

bool
ktest_start_msg(struct ktest_test_context *ctx)
{
        return (create_reply(ctx->npt->nw, ctx->hdr, KTEST_CMD_NEWMESSAGE));
}

void
ktest_add_msg_meta(struct ktest_test_context *ctx, const char *func,
    const char *fname, int line)
{
        struct nl_writer *nw = ctx->npt->nw;
        struct timespec ts;

        nanouptime(&ts);
        nlattr_add(nw, KTEST_MSG_ATTR_TS, sizeof(ts), &ts);

        nlattr_add_string(nw, KTEST_MSG_ATTR_FUNC, func);
        nlattr_add_string(nw, KTEST_MSG_ATTR_FILE, fname);
        nlattr_add_u32(nw, KTEST_MSG_ATTR_LINE, line);
}

void
ktest_add_msg_text(struct ktest_test_context *ctx, int msg_level,
    const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        vsnprintf(ctx->buf, ctx->bufsize, fmt, ap);
        va_end(ap);

        nlattr_add_u8(ctx->npt->nw, KTEST_MSG_ATTR_LEVEL, msg_level);
        nlattr_add_string(ctx->npt->nw, KTEST_MSG_ATTR_TEXT, ctx->buf);
}

void
ktest_end_msg(struct ktest_test_context *ctx)
{
        nlmsg_end(ctx->npt->nw);
}

/* Module glue */

static const struct nlhdr_parser *all_parsers[] = { &ktest_parser };

static const struct genl_cmd ktest_cmds[] = {
        {
                .cmd_num = KTEST_CMD_LIST,
                .cmd_name = "KTEST_CMD_LIST",
                .cmd_cb = dump_tests,
                .cmd_flags = GENL_CMD_CAP_DO | GENL_CMD_CAP_DUMP | GENL_CMD_CAP_HASPOL,
        },
        {
                .cmd_num = KTEST_CMD_RUN,
                .cmd_name = "KTEST_CMD_RUN",
                .cmd_cb = run_test,
                .cmd_flags = GENL_CMD_CAP_DO | GENL_CMD_CAP_HASPOL,
                .cmd_priv = PRIV_KLD_LOAD,
        },
};

static int family_id;
static void
ktest_nl_register(void)
{
        bool ret __diagused;

        NL_VERIFY_PARSERS(all_parsers);
        family_id = genl_register_family(KTEST_FAMILY_NAME, 0, 1, KTEST_CMD_MAX);
        MPASS(family_id != 0);

        ret = genl_register_cmds(family_id, ktest_cmds, nitems(ktest_cmds));
        MPASS(ret);
}

static void
ktest_nl_unregister(void)
{
        MPASS(TAILQ_EMPTY(&module_list));

        genl_unregister_family(family_id);
}

static int
ktest_modevent(module_t mod, int type, void *unused)
{
        int error = 0;

        switch (type) {
        case MOD_LOAD:
                ktest_nl_register();
                break;
        case MOD_UNLOAD:
                ktest_nl_unregister();
                break;
        default:
                error = EOPNOTSUPP;
                break;
        }
        return (error);
}

static moduledata_t ktestmod = {
        "ktest",
        ktest_modevent,
        0
};

DECLARE_MODULE(ktestmod, ktestmod, SI_SUB_PSEUDO, SI_ORDER_ANY);
MODULE_VERSION(ktestmod, 1);
MODULE_DEPEND(ktestmod, netlink, 1, 1, 1);