/*
 * 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 "context.h"
#include "timer.h"
#include "pfcp-path.h"
#include "gtp-path.h"
#include "n4-handler.h"
#include "bearer-binding.h"
#include "sbi-path.h"

static uint8_t gtp_cause_from_pfcp(uint8_t pfcp_cause)
{
    switch (pfcp_cause) {
    case OGS_PFCP_CAUSE_REQUEST_ACCEPTED:
        return OGS_GTP_CAUSE_REQUEST_ACCEPTED;
    case OGS_PFCP_CAUSE_REQUEST_REJECTED:
        return OGS_GTP_CAUSE_REQUEST_REJECTED_REASON_NOT_SPECIFIED;
    case OGS_PFCP_CAUSE_SESSION_CONTEXT_NOT_FOUND:
        return OGS_GTP_CAUSE_CONTEXT_NOT_FOUND;
    case OGS_PFCP_CAUSE_MANDATORY_IE_MISSING:
        return OGS_GTP_CAUSE_MANDATORY_IE_MISSING;
    case OGS_PFCP_CAUSE_CONDITIONAL_IE_MISSING:
        return OGS_GTP_CAUSE_CONDITIONAL_IE_MISSING;
    case OGS_PFCP_CAUSE_INVALID_LENGTH:
        return OGS_GTP_CAUSE_INVALID_LENGTH;
    case OGS_PFCP_CAUSE_MANDATORY_IE_INCORRECT:
        return OGS_GTP_CAUSE_MANDATORY_IE_INCORRECT;
    case OGS_PFCP_CAUSE_INVALID_FORWARDING_POLICY:
    case OGS_PFCP_CAUSE_INVALID_F_TEID_ALLOCATION_OPTION:
        return OGS_GTP_CAUSE_INVALID_MESSAGE_FORMAT;
    case OGS_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOCIATION:
        return OGS_GTP_CAUSE_REMOTE_PEER_NOT_RESPONDING;
    case OGS_PFCP_CAUSE_RULE_CREATION_MODIFICATION_FAILURE:
        return OGS_GTP_CAUSE_SEMANTIC_ERROR_IN_THE_TFT_OPERATION;
    case OGS_PFCP_CAUSE_PFCP_ENTITY_IN_CONGESTION:
        return OGS_GTP_CAUSE_GTP_C_ENTITY_CONGESTION;
    case OGS_PFCP_CAUSE_NO_RESOURCES_AVAILABLE:
        return OGS_GTP_CAUSE_NO_RESOURCES_AVAILABLE;
    case OGS_PFCP_CAUSE_SERVICE_NOT_SUPPORTED:
        return OGS_GTP_CAUSE_SERVICE_NOT_SUPPORTED;
    case OGS_PFCP_CAUSE_SYSTEM_FAILURE:
        return OGS_GTP_CAUSE_SYSTEM_FAILURE;
    default:
        return OGS_GTP_CAUSE_SYSTEM_FAILURE;
    }

    return OGS_GTP_CAUSE_SYSTEM_FAILURE;
}
static int sbi_status_from_pfcp(uint8_t pfcp_cause)
{
    switch (pfcp_cause) {
    case OGS_PFCP_CAUSE_REQUEST_ACCEPTED:
        return OGS_SBI_HTTP_STATUS_OK;
    case OGS_PFCP_CAUSE_REQUEST_REJECTED:
        return OGS_SBI_HTTP_STATUS_FORBIDDEN;
    case OGS_PFCP_CAUSE_SESSION_CONTEXT_NOT_FOUND:
        return OGS_SBI_HTTP_STATUS_NOT_FOUND;
    case OGS_PFCP_CAUSE_MANDATORY_IE_MISSING:
    case OGS_PFCP_CAUSE_CONDITIONAL_IE_MISSING:
    case OGS_PFCP_CAUSE_INVALID_LENGTH:
    case OGS_PFCP_CAUSE_MANDATORY_IE_INCORRECT:
    case OGS_PFCP_CAUSE_INVALID_FORWARDING_POLICY:
    case OGS_PFCP_CAUSE_INVALID_F_TEID_ALLOCATION_OPTION:
    case OGS_PFCP_CAUSE_RULE_CREATION_MODIFICATION_FAILURE:
    case OGS_PFCP_CAUSE_PFCP_ENTITY_IN_CONGESTION:
    case OGS_PFCP_CAUSE_NO_RESOURCES_AVAILABLE:
        return OGS_SBI_HTTP_STATUS_BAD_REQUEST;
    case OGS_PFCP_CAUSE_NO_ESTABLISHED_PFCP_ASSOCIATION:
        return OGS_SBI_HTTP_STATUS_GATEWAY_TIMEOUT;
    case OGS_PFCP_CAUSE_SERVICE_NOT_SUPPORTED:
        return OGS_SBI_HTTP_STATUS_SERVICE_UNAVAILABLE;
    case OGS_PFCP_CAUSE_SYSTEM_FAILURE:
        return OGS_SBI_HTTP_STATUS_INTERNAL_SERVER_ERROR;
    default:
        return OGS_SBI_HTTP_STATUS_INTERNAL_SERVER_ERROR;
    }

    return OGS_SBI_HTTP_STATUS_INTERNAL_SERVER_ERROR;
}

void smf_n4_handle_association_setup_request(
        ogs_pfcp_node_t *node, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_association_setup_request_t *req)
{
    int i;

    ogs_assert(xact);
    ogs_assert(node);
    ogs_assert(req);

    smf_pfcp_send_association_setup_response(
            xact, OGS_PFCP_CAUSE_REQUEST_ACCEPTED);

    ogs_pfcp_gtpu_resource_remove_all(&node->gtpu_resource_list);

    for (i = 0; i < OGS_MAX_NUM_OF_GTPU_RESOURCE; i++) {
        ogs_pfcp_tlv_user_plane_ip_resource_information_t *message =
            &req->user_plane_ip_resource_information[i];
        ogs_pfcp_user_plane_ip_resource_info_t info;

        if (message->presence == 0)
            break;

        ogs_pfcp_parse_user_plane_ip_resource_info(&info, message);
        ogs_pfcp_gtpu_resource_add(&node->gtpu_resource_list, &info);
    }
}

void smf_n4_handle_association_setup_response(
        ogs_pfcp_node_t *node, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_association_setup_response_t *rsp)
{
    int i;

    ogs_assert(xact);
    ogs_pfcp_xact_commit(xact);

    ogs_assert(node);
    ogs_assert(rsp);

    ogs_pfcp_gtpu_resource_remove_all(&node->gtpu_resource_list);

    for (i = 0; i < OGS_MAX_NUM_OF_GTPU_RESOURCE; i++) {
        ogs_pfcp_tlv_user_plane_ip_resource_information_t *message =
            &rsp->user_plane_ip_resource_information[i];
        ogs_pfcp_user_plane_ip_resource_info_t info;

        if (message->presence == 0)
            break;

        ogs_pfcp_parse_user_plane_ip_resource_info(&info, message);
        ogs_pfcp_gtpu_resource_add(&node->gtpu_resource_list, &info);
    }
}

void smf_n4_handle_heartbeat_request(
        ogs_pfcp_node_t *node, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_heartbeat_request_t *req)
{
    ogs_assert(xact);
    ogs_pfcp_send_heartbeat_response(xact);
}

void smf_n4_handle_heartbeat_response(
        ogs_pfcp_node_t *node, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_heartbeat_response_t *rsp)
{
    ogs_assert(xact);
    ogs_pfcp_xact_commit(xact);

    ogs_timer_start(node->t_no_heartbeat,
            ogs_config()->time.message.pfcp.no_heartbeat_duration);
}

void smf_5gc_n4_handle_session_establishment_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_establishment_response_t *rsp)
{
    ogs_pfcp_f_seid_t *up_f_seid = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    ogs_pfcp_xact_commit(xact);

    if (!sess) {
        ogs_warn("No Context");
        return;
    }

    if (rsp->up_f_seid.presence == 0) {
        ogs_error("No UP F-SEID");
        return;
    }

    if (rsp->cause.presence) {
        if (rsp->cause.u8 != OGS_PFCP_CAUSE_REQUEST_ACCEPTED) {
            ogs_error("PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
            return;
        }
    } else {
        ogs_error("No Cause");
        return;
    }

    ogs_assert(sess);

    /* UP F-SEID */
    up_f_seid = rsp->up_f_seid.data;
    ogs_assert(up_f_seid);
    sess->upf_n4_seid = be64toh(up_f_seid->seid);

    /* UPDATE_UpCnxState - ACTIVATING */
    sess->ueUpCnxState = OpenAPI_up_cnx_state_ACTIVATING;
    sess->smfUpCnxState = OpenAPI_up_cnx_state_ACTIVATING;

    smf_sbi_discover_and_send(OpenAPI_nf_type_AMF, sess, NULL,
            smf_namf_comm_build_n1_n2_message_transfer);

#if 0
    smf_bearer_binding(sess);
#endif
}

void smf_5gc_n4_handle_session_modification_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_modification_response_t *rsp)
{
    int status = 0;
    ogs_sbi_session_t *session = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    session = xact->assoc_session;
    ogs_assert(session);

    ogs_pfcp_xact_commit(xact);

    status = OGS_SBI_HTTP_STATUS_OK;

    if (!sess) {
        ogs_warn("No Context");
        status = OGS_SBI_HTTP_STATUS_NOT_FOUND;
    }

    if (rsp->cause.presence) {
        if (rsp->cause.u8 != OGS_PFCP_CAUSE_REQUEST_ACCEPTED) {
            ogs_warn("PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
            status = sbi_status_from_pfcp(rsp->cause.u8);
        }
    } else {
        ogs_error("No Cause");
        status = OGS_SBI_HTTP_STATUS_BAD_REQUEST;
    }

    if (status != OGS_SBI_HTTP_STATUS_OK) {
        char *strerror = ogs_msprintf(
                "PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
        smf_sbi_send_sm_context_update_error(session, status, strerror,
                NULL, NULL, NULL);
        ogs_free(strerror);
        return;
    }

    ogs_assert(sess);

    /* UPDATE_UpCnxState - SYNC */
    sess->smfUpCnxState = sess->ueUpCnxState;

    smf_sbi_send_sm_context_updated_data(sess, session);
}

void smf_5gc_n4_handle_session_deletion_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_deletion_response_t *rsp)
{
    int status = 0;
    int trigger;

    ogs_sbi_session_t *session = NULL;

    ogs_sbi_message_t sendmsg;
    ogs_sbi_response_t *response = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    session = xact->assoc_session;
    ogs_assert(session);
    trigger = xact->trigger;
    ogs_assert(trigger);

    ogs_pfcp_xact_commit(xact);

    status = OGS_SBI_HTTP_STATUS_OK;

    if (!sess) {
        ogs_warn("No Context");
        status = OGS_SBI_HTTP_STATUS_NOT_FOUND;
    }

    if (rsp->cause.presence) {
        if (rsp->cause.u8 != OGS_PFCP_CAUSE_REQUEST_ACCEPTED) {
            ogs_warn("PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
            status = sbi_status_from_pfcp(rsp->cause.u8);
        }
    } else {
        ogs_error("No Cause");
        status = OGS_SBI_HTTP_STATUS_BAD_REQUEST;
    }

    if (status != OGS_SBI_HTTP_STATUS_OK) {
        char *strerror = ogs_msprintf(
                "PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
        ogs_sbi_server_send_error(session, status, NULL, NULL, NULL);
        ogs_free(strerror);
        return;
    }

    ogs_assert(sess);

    if (trigger == OGS_PFCP_5GC_DELETE_TRIGGER_UE_REQUESTED) {

        smf_sbi_send_sm_context_updated_data_in_session_deletion(sess, session);

    } else {

        memset(&sendmsg, 0, sizeof(sendmsg));

        response = ogs_sbi_build_response(
                &sendmsg, OGS_SBI_HTTP_STATUS_NO_CONTENT);
        ogs_assert(response);
        ogs_sbi_server_send_response(session, response);

        SMF_SESS_CLEAR(sess);
    }
}

void smf_epc_n4_handle_session_establishment_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_establishment_response_t *rsp)
{
    uint8_t cause_value = 0;
    ogs_gtp_xact_t *gtp_xact = NULL;
    ogs_pfcp_f_seid_t *up_f_seid = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    gtp_xact = xact->assoc_xact;
    ogs_assert(gtp_xact);

    ogs_pfcp_xact_commit(xact);

    cause_value = OGS_GTP_CAUSE_REQUEST_ACCEPTED;

    if (!sess) {
        ogs_warn("No Context");
        cause_value = OGS_GTP_CAUSE_CONTEXT_NOT_FOUND;
    }

    if (rsp->up_f_seid.presence == 0) {
        ogs_error("No UP F-SEID");
        cause_value = OGS_GTP_CAUSE_MANDATORY_IE_MISSING;
    }

    if (rsp->cause.presence) {
        if (rsp->cause.u8 != OGS_PFCP_CAUSE_REQUEST_ACCEPTED) {
            ogs_warn("PFCP Cause [%d] : Not Accepted", rsp->cause.u8);
            cause_value = gtp_cause_from_pfcp(rsp->cause.u8);
        }
    } else {
        ogs_error("No Cause");
        cause_value = OGS_GTP_CAUSE_MANDATORY_IE_MISSING;
    }

    if (cause_value != OGS_GTP_CAUSE_REQUEST_ACCEPTED) {
        ogs_gtp_send_error_message(gtp_xact, sess ? sess->sgw_s5c_teid : 0,
                OGS_GTP_CREATE_SESSION_RESPONSE_TYPE, cause_value);
        return;
    }

    ogs_assert(sess);

    /* UP F-SEID */
    up_f_seid = rsp->up_f_seid.data;
    ogs_assert(up_f_seid);
    sess->upf_n4_seid = be64toh(up_f_seid->seid);

    smf_gtp_send_create_session_response(sess, gtp_xact);

    smf_bearer_binding(sess);
}

void smf_epc_n4_handle_session_modification_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_modification_response_t *rsp)
{
    smf_bearer_t *bearer = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    bearer = xact->data;
    ogs_assert(bearer);

    ogs_pfcp_xact_commit(xact);

    if (bearer->pfcp_epc_modify.remove)
        smf_bearer_remove(bearer);
}

void smf_epc_n4_handle_session_deletion_response(
        smf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_deletion_response_t *rsp)
{
    uint8_t cause_value = 0;
    ogs_gtp_xact_t *gtp_xact = NULL;

    ogs_assert(xact);
    ogs_assert(rsp);

    gtp_xact = xact->assoc_xact;
    ogs_assert(gtp_xact);

    ogs_pfcp_xact_commit(xact);

    cause_value = OGS_GTP_CAUSE_REQUEST_ACCEPTED;

    if (!sess) {
        ogs_warn("No Context");
        cause_value = OGS_GTP_CAUSE_CONTEXT_NOT_FOUND;
    }

    if (rsp->cause.presence) {
        if (rsp->cause.u8 != OGS_PFCP_CAUSE_REQUEST_ACCEPTED) {
            ogs_warn("PFCP Cause[%d] : Not Accepted", rsp->cause.u8);
            cause_value = gtp_cause_from_pfcp(rsp->cause.u8);
        }
    } else {
        ogs_error("No Cause");
        cause_value = OGS_GTP_CAUSE_MANDATORY_IE_MISSING;
    }

    if (cause_value != OGS_GTP_CAUSE_REQUEST_ACCEPTED) {
        ogs_gtp_send_error_message(gtp_xact, sess ? sess->sgw_s5c_teid : 0,
                OGS_GTP_DELETE_SESSION_RESPONSE_TYPE, cause_value);
        return;
    }

    ogs_assert(sess);

    smf_gtp_send_delete_session_response(sess, gtp_xact);

    SMF_SESS_CLEAR(sess);
}