/* Copyright (C) 2025 Open Information Security Foundation

 *

 * You can copy, redistribute or modify this Program under the terms of

 * the GNU General Public License version 2 as published by the Free

 * Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * version 2 along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

 * 02110-1301, USA.

 */

#include "suricata-common.h"

#include "app-layer-protos.h"

#include "flow-var.h"

#include "lauxlib.h"

#include "util-debug.h"

#include "util-lua-common.h"

#include "util-lua-flowvarlib.h"

#include "util-lua.h"

#include "util-var-name.h"

#include "detect-lua.h"

#include "detect-lua-extensions.h"

static const char suricata_flowvar_mt[] = "suricata:flowvar:mt";

static DetectLuaData *GetLuaData(lua_State *luastate)

{

    DetectLuaData *ld;

    lua_pushlightuserdata(luastate, (void *)&luaext_key_ld);

    lua_gettable(luastate, LUA_REGISTRYINDEX);

    ld = lua_touserdata(luastate, -1);

    return ld;

}

/**

 * \brief Register a flowvar.

 *

 * Ensures that a flowvar exists for the provided name, will be

 * created if needed.

 *

 * The flowvar ID is returned, however as this is most likely to be

 * used in the scripts "init" method, this ID is unlikely to be used.

 */

static int LuaFlowvarRegister(lua_State *L)

{

    DetectLuaData *ld = GetLuaData(L);

    const char *name = luaL_checkstring(L, 1);

    uint32_t *flowvar_id = lua_newuserdata(L, sizeof(*flowvar_id));

    *flowvar_id = VarNameStoreRegister(name, VAR_TYPE_FLOW_VAR);

    if (*flowvar_id == 0) {

        return luaL_error(L, "failed to register flowvar");

    }

    if (ld->flowvars >= DETECT_LUA_MAX_FLOWVARS) {

        return luaL_error(L, "too many flowvars registered");

    }

    ld->flowvar[ld->flowvars++] = *flowvar_id;

    luaL_getmetatable(L, suricata_flowvar_mt);

    lua_setmetatable(L, -2);

    return 1;

}

static int LuaFlowvarGet(lua_State *L)

{

    const char *name = luaL_checkstring(L, 1);

    uint32_t *flowvar_id = lua_newuserdata(L, sizeof(*flowvar_id));

    *flowvar_id = VarNameStoreLookupByName(name, VAR_TYPE_FLOW_VAR);

    if (*flowvar_id == 0) {

        return luaL_error(L, "flowvar does not exist");

    }

    luaL_getmetatable(L, suricata_flowvar_mt);

    lua_setmetatable(L, -2);

    return 1;

}

static int LuaFlowvarValue(lua_State *L)

{

    uint32_t *flowvar_id = luaL_checkudata(L, 1, suricata_flowvar_mt);

    Flow *f = LuaStateGetFlow(L);

    if (f == NULL) {

        return LuaCallbackError(L, "flow is NULL");

    }

    FlowVar *fv = FlowVarGet(f, *flowvar_id);

    if (fv == NULL) {

        lua_pushnil(L);

    } else {

        LuaPushStringBuffer(

                L, (const uint8_t *)fv->data.fv_str.value, (size_t)fv->data.fv_str.value_len);

    }

    return 1;

}

static int LuaFlowvarSet(lua_State *L)

{

    size_t slen = 0;

    const char *value = luaL_checklstring(L, 2, &slen);

    lua_Integer req = luaL_optinteger(L, 3, (lua_Integer)slen);

    if (req < 0 || ((size_t)req > slen) || (size_t)req > UINT16_MAX) {

        return luaL_error(L, "length out of range");

    }

    const size_t len = (size_t)req;

    uint32_t *flowvar_id = luaL_checkudata(L, 1, suricata_flowvar_mt);

    Flow *f = LuaStateGetFlow(L);

    if (f == NULL) {

        return luaL_error(L, "no flow");

    }

    uint8_t *buf = SCMalloc(len + 1);

    if (buf == NULL) {

        return luaL_error(L, "alloc failure");

    }

    memcpy(buf, value, len);

    buf[len] = '\0';

    FlowVarAddIdValue(f, *flowvar_id, buf, (uint16_t)len);

    return 1;

}

static const luaL_Reg flowvarlib[] = {

    // clang-format off

    { "register", LuaFlowvarRegister, },

    { "get", LuaFlowvarGet },

    { NULL, NULL, },

    // clang-format on

};

static const luaL_Reg flowvarmt[] = {

    // clang-format off

    { "value", LuaFlowvarValue, },

    { "set", LuaFlowvarSet, },

    { NULL, NULL, },

    // clang-format on

};

int LuaLoadFlowvarLib(lua_State *L)

{

    luaL_newmetatable(L, suricata_flowvar_mt);

    lua_pushvalue(L, -1);

    lua_setfield(L, -2, "__index");

    luaL_setfuncs(L, flowvarmt, 0);

    luaL_newlib(L, flowvarlib);

    return 1;

}