/*
 * 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 "sgsap-types.h"

#include "mme-context.h"
#include "mme-path.h"
#include "nas-conv.h"
#include "nas-path.h"

void sgsap_handler_location_update_accept(mme_vlr_t *vlr, ogs_pkbuf_t *pkbuf)
{
    ogs_tlv_t *root = NULL, *iter = NULL;
    mme_ue_t *mme_ue = NULL;
    enb_ue_t *enb_ue = NULL;

    nas_mobile_identity_imsi_t *nas_mobile_identity_imsi = NULL;
    int nas_mobile_identity_imsi_len = 0;
    nas_lai_t *lai = NULL;
    nas_mobile_identity_tmsi_t *nas_mobile_identity_tmsi = NULL;

    ogs_assert(vlr);
    ogs_assert(pkbuf);

    ogs_debug("[SGSAP] LOCATION-UPDATE-ACCEPT");

    ogs_pkbuf_pull(pkbuf, 1);

    root = ogs_tlv_parse_block(pkbuf->len, pkbuf->data, OGS_TLV_MODE_T1_L1);
    ogs_assert(root);

    iter = root;
    while (iter) {
        switch (iter->type) {
        case SGSAP_IE_IMSI_TYPE:
            nas_mobile_identity_imsi = iter->value;
            nas_mobile_identity_imsi_len = iter->length;
            break;
        case SGSAP_IE_LAI_TYPE:
            lai = iter->value;
            break;
        case SGSAP_IE_MOBILE_IDENTITY_TYPE:
            nas_mobile_identity_tmsi = iter->value;
            break;
        default:
            ogs_warn("Invalid Type [%d]", iter->type);
            break;
        }
        iter = iter->next;
    }

    ogs_tlv_free_all(root);

    ogs_assert(nas_mobile_identity_imsi && lai);
    ogs_assert(nas_mobile_identity_imsi_len == SGSAP_IE_IMSI_LEN);

    if (nas_mobile_identity_imsi->type == NAS_MOBILE_IDENTITY_IMSI) {
        char imsi_bcd[MAX_IMSI_BCD_LEN+1];

        nas_imsi_to_bcd(nas_mobile_identity_imsi,
                nas_mobile_identity_imsi_len, imsi_bcd);
        mme_ue = mme_ue_find_by_imsi_bcd(imsi_bcd);
    } else
        ogs_assert_if_reached();

    ogs_assert(mme_ue);

    ogs_debug("    IMSI[%s]", mme_ue->imsi_bcd);

    if (nas_mobile_identity_tmsi) {
        if (nas_mobile_identity_tmsi->type == NAS_MOBILE_IDENTITY_TMSI) {
            mme_ue->p_tmsi = ntohl(nas_mobile_identity_tmsi->tmsi);
        } else {
            ogs_error("Not supported Identity type[%d]",
                    nas_mobile_identity_tmsi->type);
            goto error;
        }
        ogs_debug("    P-TMSI[0x%08x]", mme_ue->p_tmsi);
    }

    nas_send_attach_accept(mme_ue);

    return;

error:
    enb_ue = mme_ue->enb_ue;
    ogs_assert(enb_ue);

    nas_send_attach_reject(mme_ue,
            EMM_CAUSE_EPS_SERVICES_AND_NON_EPS_SERVICES_NOT_ALLOWED,
            ESM_CAUSE_PROTOCOL_ERROR_UNSPECIFIED);
    mme_send_delete_session_or_ue_context_release(mme_ue, enb_ue);
}

void sgsap_handler_location_update_reject(mme_vlr_t *vlr, ogs_pkbuf_t *pkbuf)
{
    ogs_tlv_t *root = NULL, *iter = NULL;
    mme_ue_t *mme_ue = NULL;
    enb_ue_t *enb_ue = NULL;

    nas_mobile_identity_imsi_t *nas_mobile_identity_imsi = NULL;
    int nas_mobile_identity_imsi_len = 0;
    nas_emm_cause_t emm_cause = 0;

    ogs_assert(vlr);
    ogs_assert(pkbuf);

    ogs_warn("[SGSAP] LOCATION-UPDATE-REJECT");

    ogs_pkbuf_pull(pkbuf, 1);

    root = ogs_tlv_parse_block(pkbuf->len, pkbuf->data, OGS_TLV_MODE_T1_L1);
    ogs_assert(root);

    iter = root;
    while (iter) {
        switch (iter->type) {
        case SGSAP_IE_IMSI_TYPE:
            nas_mobile_identity_imsi = iter->value;
            nas_mobile_identity_imsi_len = iter->length;
            break;
        case SGSAP_IE_LAI_TYPE:
            break;
        case SGSAP_IE_REJECT_CAUSE_TYPE:
            emm_cause = *((uint8_t*)(iter->value));
            break;
        default:
            ogs_warn("Invalid Type [%d]", iter->type);
            break;
        }
        iter = iter->next;
    }

    ogs_tlv_free_all(root);

    ogs_assert(nas_mobile_identity_imsi && emm_cause);
    ogs_assert(nas_mobile_identity_imsi_len == SGSAP_IE_IMSI_LEN);

    if (nas_mobile_identity_imsi->type == NAS_MOBILE_IDENTITY_IMSI) {
        char imsi_bcd[MAX_IMSI_BCD_LEN+1];

        nas_imsi_to_bcd(nas_mobile_identity_imsi,
                nas_mobile_identity_imsi_len, imsi_bcd);
        mme_ue = mme_ue_find_by_imsi_bcd(imsi_bcd);
    } else 
        ogs_assert_if_reached();

    ogs_assert(mme_ue);

    ogs_debug("    IMSI[%s] CAUSE[%d]", mme_ue->imsi_bcd, emm_cause);

    enb_ue = mme_ue->enb_ue;
    ogs_assert(enb_ue);

    nas_send_attach_reject(mme_ue,
            emm_cause, ESM_CAUSE_PROTOCOL_ERROR_UNSPECIFIED);
    mme_send_delete_session_or_ue_context_release(mme_ue, enb_ue);
}