/*

 * Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>

 *

 * This file is part of Open5GS.

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Affero General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * 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

 * along with this program.  If not, see <https://www.gnu.org/licenses/>.

 */

#include "ogs-core.h"

typedef struct fsm_event_s {

    int id;

} fsm_event_t;

static fsm_event_t entry_event = {

    OGS_FSM_ENTRY_SIG,

};

static fsm_event_t exit_event = {

    OGS_FSM_EXIT_SIG,

};

const char *OGS_FSM_NAME_INIT_SIG = "INIT";

const char *OGS_FSM_NAME_ENTRY_SIG = "ENTRY";

const char *OGS_FSM_NAME_EXIT_SIG = "EXIT";

static void fsm_entry(ogs_fsm_t *sm, ogs_fsm_handler_t state, fsm_event_t *e)

{

    ogs_assert(sm);

    ogs_assert(state);

    if (e) {

        e->id = OGS_FSM_ENTRY_SIG;

        (*state)(sm, e);

    } else {

        (*state)(sm, &entry_event);

    }

}

static void fsm_exit(ogs_fsm_t *sm, ogs_fsm_handler_t state, fsm_event_t *e)

{

    ogs_assert(sm);

    ogs_assert(state);

    if (e) {

        e->id = OGS_FSM_EXIT_SIG;

        (*state)(sm, e);

    } else {

        (*state)(sm, &exit_event);

    }

}

static void fsm_change(

        ogs_fsm_t *sm,

        ogs_fsm_handler_t oldstate,

        ogs_fsm_handler_t newstate,

        fsm_event_t *e)

{

    ogs_assert(sm);

    ogs_assert(oldstate);

    ogs_assert(newstate);

    fsm_exit(sm, oldstate, e);

    fsm_entry(sm, newstate, e);

}

void ogs_fsm_init(void *fsm, void *init, void *fini, void *event)

{

    ogs_fsm_t *sm = fsm;

    fsm_event_t *e = event;

    ogs_assert(sm);

    sm->init = sm->state = init;

    sm->fini = fini;

    if (sm->init) {

        (*sm->init)(sm, e);

        if (sm->init != sm->state) {

            ogs_assert(sm->state);

            fsm_entry(sm, sm->state, e);

        }

    }

}

void ogs_fsm_tran(void *fsm, void *state, void *event)

{

    ogs_fsm_t *sm = fsm;

    fsm_event_t *e = event;

    ogs_fsm_handler_t tmp = NULL;

    ogs_assert(sm);

    tmp = sm->state;

    ogs_assert(tmp);

    sm->state = state;

    ogs_assert(sm->state);

    if (sm->state != tmp)

        fsm_change(fsm, tmp, sm->state, e);

}

void ogs_fsm_dispatch(void *fsm, void *event)

{

    ogs_fsm_t *sm = fsm;

    fsm_event_t *e = event;

    ogs_fsm_handler_t tmp = NULL;

    ogs_assert(sm);

    tmp = sm->state;

    ogs_assert(tmp);

    if (e)

        (*tmp)(sm, e);

    if (sm->state != tmp)

        fsm_change(fsm, tmp, sm->state, e);

}

void ogs_fsm_fini(void *fsm, void *event)

{

    ogs_fsm_t *sm = fsm;

    fsm_event_t *e = event;

    ogs_assert(sm);

    if (sm->fini != sm->state) {

        ogs_assert(sm->state);

        fsm_exit(sm, sm->state, e);

        if (sm->fini)

            (*sm->fini)(sm, e);

    }

    sm->init = sm->state = sm->fini = NULL;

}