/* Gy Interface, 3GPP TS 32.299
 * Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>
 * Copyright (C) 2022 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
 *
 * 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 "gtp-path.h"
#include "pfcp-path.h"
#include "gy-handler.h"
#include "binding.h"

static void urr_update_volume(smf_sess_t *sess, ogs_pfcp_urr_t *urr, ogs_diam_gy_message_t *gy_message)
{
    if (gy_message->cca.granted.cc_total_octets_present || gy_message->cca.volume_threshold) {
        urr->meas_method |= OGS_PFCP_MEASUREMENT_METHOD_VOLUME;
        ogs_assert(sess->pfcp_node);
        if (sess->pfcp_node->up_function_features.mnop)
            urr->meas_info.mnop = 1;
    } else {
        urr->meas_method &= ~OGS_PFCP_MEASUREMENT_METHOD_VOLUME;
    }

    /* Volume Quota */
    if (gy_message->cca.granted.cc_total_octets_present) {
        ogs_debug("Adding Volume Quota total_octets=%" PRIu64, gy_message->cca.granted.cc_total_octets);
        urr->rep_triggers.volume_quota = 1;
        urr->vol_quota.tovol = 1;
        urr->vol_quota.total_volume = gy_message->cca.granted.cc_total_octets;
    } else {
        urr->rep_triggers.volume_quota = 0;
        urr->vol_quota.tovol = 0;
        urr->vol_quota.total_volume = 0;
    }

    /* Volume Threshold, requires Volume Quota for calculations */
    if (gy_message->cca.volume_threshold &&
        gy_message->cca.granted.cc_total_octets >= gy_message->cca.volume_threshold) {
        ogs_debug("Adding Volume Threshold total_octets=%" PRIu32, gy_message->cca.volume_threshold);
        urr->rep_triggers.volume_threshold = 1;
        urr->vol_threshold.tovol = 1;
        urr->vol_threshold.total_volume = (gy_message->cca.granted.cc_total_octets -
                                           gy_message->cca.volume_threshold);
    } else {
        urr->rep_triggers.volume_threshold = 0;
        urr->vol_threshold.tovol = 0;
        urr->vol_threshold.total_volume = 0;
    }
}

static void urr_update_time(smf_sess_t *sess, ogs_pfcp_urr_t *urr, ogs_diam_gy_message_t *gy_message)
{
    uint32_t time_quota;

    if (sess->pfcp_node->up_function_features.vtime) {
        if (gy_message->cca.validity_time > 0) {
            urr->rep_triggers.quota_validity_time = 1;
            urr->quota_validity_time = gy_message->cca.validity_time;
        } else {
            urr->rep_triggers.quota_validity_time = 0;
            urr->quota_validity_time = 0;
        }
        time_quota = gy_message->cca.granted.cc_time_present ? gy_message->cca.granted.cc_time : 0;
    } else {
        /* Store Validity Time as Volume Quota (if not longer than Volume Quota) */
        if (gy_message->cca.validity_time && (gy_message->cca.granted.cc_time_present && gy_message->cca.granted.cc_time > 0))
            time_quota = (gy_message->cca.validity_time <= gy_message->cca.granted.cc_time) ?
                             gy_message->cca.validity_time : gy_message->cca.granted.cc_time;
        else if (gy_message->cca.validity_time)
            time_quota = gy_message->cca.validity_time;
        else if (gy_message->cca.granted.cc_time_present && gy_message->cca.granted.cc_time > 0)
            time_quota = gy_message->cca.granted.cc_time;
        else
            time_quota = 0;
    }

    if (gy_message->cca.validity_time || time_quota || gy_message->cca.time_threshold) {
        urr->meas_method |= OGS_PFCP_MEASUREMENT_METHOD_DURATION;
        urr->meas_info.istm  = 1;
    } else {
        urr->meas_info.istm  = 0;
        urr->meas_method &= ~OGS_PFCP_MEASUREMENT_METHOD_DURATION;
    }

    /* Time Quota */
    if (time_quota) {
        ogs_debug("Adding Time Quota secs=%" PRIu32, time_quota);
        urr->rep_triggers.time_quota = 1;
        urr->time_quota = time_quota;
    } else {
        urr->rep_triggers.time_quota = 0;
        urr->time_quota = 0;
    }

    /* Time Threshold, requires Time Quota for calculations */
    if (gy_message->cca.time_threshold &&
        time_quota >= gy_message->cca.time_threshold) {
        ogs_debug("Adding Time Threshold secs=%" PRIu32, gy_message->cca.time_threshold);
        urr->rep_triggers.time_threshold = 1;
        urr->time_threshold = (time_quota - gy_message->cca.time_threshold);
    } else {
        urr->rep_triggers.time_threshold = 0;
        urr->time_threshold = 0;
    }
}

/* Returns ER_DIAMETER_SUCCESS on success, Diameter error code on failue.
 * Upon failure, CCR-Terminate is needed based on "need_termination" value (this
 * may happen eg. if messaged RC is successful but MSCC RC is rejected). */
uint32_t smf_gy_handle_cca_initial_request(
        smf_sess_t *sess, ogs_diam_gy_message_t *gy_message,
        ogs_gtp_xact_t *gtp_xact,
        bool *need_termination)
{
    smf_bearer_t *bearer;

    ogs_assert(sess);
    ogs_assert(gy_message);
    ogs_assert(gtp_xact);
    ogs_assert(need_termination);

    ogs_debug("[Gy CCA Initial]");
    ogs_debug("    SGW_S5C_TEID[0x%x] PGW_S5C_TEID[0x%x]",
            sess->sgw_s5c_teid, sess->smf_n4_teid);

    *need_termination = false;
    if (gy_message->result_code != ER_DIAMETER_SUCCESS) {
        ogs_warn("Gy CCA Initial Diameter failure: res=%u",
            gy_message->result_code);
        return gy_message->err ? *gy_message->err :
                                 ER_DIAMETER_AUTHENTICATION_REJECTED;
    }
    if (gy_message->cca.result_code != ER_DIAMETER_SUCCESS) {
        ogs_warn("Gy CCA Initial Diameter Multiple-Services-Credit-Control Result-Code=%u",
            gy_message->cca.result_code);
        /* Message RC was successful but MSCC was rejected. The session needs to
         * be tear down through CCR-T: */
        *need_termination = true;
        return gy_message->cca.err ? *gy_message->cca.err :
                                     ER_DIAMETER_AUTHENTICATION_REJECTED;
    }

    bearer = smf_default_bearer_in_sess(sess);
    ogs_assert(bearer);

    if (!bearer->urr)
        bearer->urr = ogs_pfcp_urr_add(&sess->pfcp);
    ogs_assert(bearer->urr);

    /* Configure based on what we received from OCS: */
    urr_update_time(sess, bearer->urr, gy_message);
    urr_update_volume(sess, bearer->urr, gy_message);
    sess->gy.final_unit = gy_message->cca.final.cc_final_action_present;

    /* Associate acconting URR each direction PDR: */
    ogs_pfcp_pdr_associate_urr(bearer->ul_pdr, bearer->urr);
    ogs_pfcp_pdr_associate_urr(bearer->dl_pdr, bearer->urr);
    return ER_DIAMETER_SUCCESS;
}

uint32_t smf_gy_handle_cca_update_request(
        smf_sess_t *sess, ogs_diam_gy_message_t *gy_message,
        ogs_pfcp_xact_t *pfcp_xact)
{
    ogs_pfcp_urr_t *urr = NULL;
    smf_bearer_t *bearer;
    int rv;
    uint64_t modify_flags = 0;
    ogs_pfcp_measurement_method_t prev_meas_method;
    ogs_pfcp_reporting_triggers_t prev_rep_triggers;
    ogs_pfcp_quota_validity_time_t prev_quota_validity_time;
    ogs_pfcp_time_quota_t prev_time_quota;
    ogs_pfcp_volume_threshold_t prev_vol_threshold;
    ogs_pfcp_time_threshold_t prev_time_threshold;

    ogs_assert(sess);
    ogs_assert(gy_message);
    ogs_assert(pfcp_xact);

    ogs_debug("[Gy CCA Update]");
    ogs_debug("    SGW_S5C_TEID[0x%x] PGW_S5C_TEID[0x%x]",
            sess->sgw_s5c_teid, sess->smf_n4_teid);

    if (gy_message->result_code != ER_DIAMETER_SUCCESS) {
        ogs_warn("Gy CCA Update Diameter failure: Result-Code=%u",
            gy_message->result_code);
        return gy_message->err ? *gy_message->err :
                                 ER_DIAMETER_AUTHENTICATION_REJECTED;
    }
    if (gy_message->cca.result_code != ER_DIAMETER_SUCCESS) {
        ogs_warn("Gy CCA Update Diameter Multiple-Services-Credit-Control Result-Code=%u",
            gy_message->cca.result_code);
        return gy_message->cca.err ? *gy_message->cca.err :
                                     ER_DIAMETER_AUTHENTICATION_REJECTED;
    }

    bearer = smf_default_bearer_in_sess(sess);
    ogs_assert(bearer);

    urr = bearer->urr;
    ogs_assert(urr);
    prev_meas_method = urr->meas_method;
    prev_rep_triggers = urr->rep_triggers;
    prev_quota_validity_time = urr->quota_validity_time;
    prev_time_quota = urr->time_quota;
    prev_vol_threshold = urr->vol_threshold;
    prev_time_threshold = urr->time_threshold;

    urr_update_time(sess, urr, gy_message);
    urr_update_volume(sess, urr, gy_message);
    sess->gy.final_unit = gy_message->cca.final.cc_final_action_present;
    /* Associate accounting URR each direction PDR: */
    ogs_pfcp_pdr_associate_urr(bearer->ul_pdr, urr);
    ogs_pfcp_pdr_associate_urr(bearer->dl_pdr, urr);

    if (urr->meas_method != prev_meas_method)
        modify_flags |= OGS_PFCP_MODIFY_URR_MEAS_METHOD;

    if (urr->rep_triggers.quota_validity_time != prev_rep_triggers.quota_validity_time ||
        urr->rep_triggers.time_quota != prev_rep_triggers.time_quota ||
        urr->rep_triggers.volume_quota != prev_rep_triggers.volume_quota ||
        urr->rep_triggers.time_threshold != prev_rep_triggers.time_threshold ||
        urr->rep_triggers.volume_threshold != prev_rep_triggers.volume_threshold)
        modify_flags |= OGS_PFCP_MODIFY_URR_REPORT_TRIGGER;

    if (urr->quota_validity_time != prev_quota_validity_time)
        modify_flags |= OGS_PFCP_MODIFY_URR_QUOTA_VALIDITY_TIME;

    if (urr->time_quota != prev_time_quota)
        modify_flags |= OGS_PFCP_MODIFY_URR_TIME_QUOTA;

    if (urr->vol_quota.tovol || urr->vol_quota.total_volume)
        modify_flags |= OGS_PFCP_MODIFY_URR_VOLUME_QUOTA;

    if (urr->time_threshold != prev_time_threshold)
        modify_flags |= OGS_PFCP_MODIFY_URR_TIME_THRESH;

    if (urr->vol_threshold.tovol != prev_vol_threshold.tovol ||
        urr->vol_threshold.total_volume != prev_vol_threshold.total_volume)
        modify_flags |= OGS_PFCP_MODIFY_URR_VOLUME_THRESH;

    /* Send PFCP Session Modification Request if we need to update the params. */
    if (modify_flags) {
        modify_flags |= OGS_PFCP_MODIFY_URR|OGS_PFCP_MODIFY_UL_ONLY;
        rv = smf_epc_pfcp_send_all_pdr_modification_request(
                sess, pfcp_xact, NULL, modify_flags,
                OGS_NAS_PROCEDURE_TRANSACTION_IDENTITY_UNASSIGNED,
                OGS_GTP1_CAUSE_REACTIACTION_REQUESTED);
        ogs_assert(rv == OGS_OK);
    }
    return ER_DIAMETER_SUCCESS;
}

uint32_t smf_gy_handle_cca_termination_request(
        smf_sess_t *sess, ogs_diam_gy_message_t *gy_message,
        ogs_gtp_xact_t *gtp_xact)
{
    ogs_assert(sess);
    ogs_assert(gy_message);

    ogs_debug("[SMF] Delete Session Response");
    ogs_debug("    SGW_S5C_TEID[0x%x] SMF_N4_TEID[0x%x]",
            sess->sgw_s5c_teid, sess->smf_n4_teid);

     return ER_DIAMETER_SUCCESS;
}

void smf_gy_handle_re_auth_request(
        smf_sess_t *sess, ogs_diam_gy_message_t *gy_message)
{
    /* TODO: find out what to do here */
}
