/*
 * 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 "pfcp-path.h"
#include "gtp-path.h"
#include "n4-handler.h"

static void setup_gtp_node(ogs_pfcp_far_t *far)
{
    int rv;
    ogs_ip_t ip;
    ogs_gtp_node_t *gnode = NULL;

    ogs_assert(far);

    ogs_pfcp_outer_header_creation_to_ip(&far->outer_header_creation, &ip);

    /* No Outer Header Creation */
    if (ip.len == 0) return;

    gnode = ogs_gtp_node_find_by_ip(&upf_self()->peer_list, &ip);
    if (!gnode) {
        gnode = ogs_gtp_node_add_by_ip(
            &upf_self()->peer_list, &ip, upf_self()->gtpu_port,
            ogs_app()->parameter.no_ipv4,
            ogs_app()->parameter.no_ipv6,
            ogs_app()->parameter.prefer_ipv4);
        ogs_assert(gnode);

        rv = ogs_gtp_connect(
                upf_self()->gtpu_sock, upf_self()->gtpu_sock6, gnode);
        ogs_assert(rv == OGS_OK);
    }

    OGS_SETUP_GTP_NODE(far, gnode);

    ogs_pfcp_far_hash_set(far);
}

void upf_n4_handle_session_establishment_request(
        upf_sess_t *sess, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_session_establishment_request_t *req)
{
    ogs_pfcp_pdr_t *pdr = NULL;
    ogs_pfcp_far_t *far = NULL;
    ogs_pfcp_pdr_t *created_pdr[OGS_MAX_NUM_OF_PDR];
    int num_of_created_pdr = 0;
    uint8_t cause_value = 0;
    uint8_t offending_ie_value = 0;
    int i;

    ogs_assert(xact);
    ogs_assert(req);

    ogs_debug("Session Establishment Request");

    cause_value = OGS_PFCP_CAUSE_REQUEST_ACCEPTED;

    if (!sess) {
        ogs_error("No Context");
        ogs_pfcp_send_error_message(xact, 0,
                OGS_PFCP_SESSION_ESTABLISHMENT_RESPONSE_TYPE,
                OGS_PFCP_CAUSE_SESSION_CONTEXT_NOT_FOUND, 0);
        return;
    }

    for (i = 0; i < OGS_MAX_NUM_OF_PDR; i++) {
        created_pdr[i] = ogs_pfcp_handle_create_pdr(&sess->pfcp,
                &req->create_pdr[i], &cause_value, &offending_ie_value);
        if (created_pdr[i] == NULL)
            break;
    }
    num_of_created_pdr = i;
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_FAR; i++) {
        if (ogs_pfcp_handle_create_far(&sess->pfcp, &req->create_far[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_QER; i++) {
        if (ogs_pfcp_handle_create_qer(&sess->pfcp, &req->create_qer[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    /* Setup GTP Node */
    ogs_list_for_each(&sess->pfcp.far_list, far)
        setup_gtp_node(far);

    /* Setup UPF-N3-TEID & QFI Hash */
    for (i = 0; i < num_of_created_pdr; i++) {
        pdr = created_pdr[i];
        ogs_assert(pdr);

        if (pdr->src_if == OGS_PFCP_INTERFACE_ACCESS) { /* Uplink */
            if (pdr->f_teid_len)
                ogs_pfcp_pdr_hash_set(pdr);
        }
    }

    /* Send Buffered Packet to gNB/SGW */
    ogs_list_for_each(&sess->pfcp.pdr_list, pdr) {
        if (pdr->src_if == OGS_PFCP_INTERFACE_CORE) { /* Downlink */
            ogs_pfcp_send_buffered_packet(pdr);
        }
    }

    upf_pfcp_send_session_establishment_response(
            xact, sess, created_pdr, num_of_created_pdr);
    return;

cleanup:
    ogs_pfcp_sess_clear(&sess->pfcp);
    ogs_pfcp_send_error_message(xact, sess ? sess->smf_n4_seid : 0,
            OGS_PFCP_SESSION_ESTABLISHMENT_RESPONSE_TYPE,
            cause_value, offending_ie_value);
}

void upf_n4_handle_session_modification_request(
        upf_sess_t *sess, ogs_pfcp_xact_t *xact, 
        ogs_pfcp_session_modification_request_t *req)
{
    ogs_pfcp_pdr_t *pdr = NULL;
    ogs_pfcp_far_t *far = NULL;
    ogs_pfcp_pdr_t *created_pdr[OGS_MAX_NUM_OF_PDR];
    int num_of_created_pdr = 0;
    uint8_t cause_value = 0;
    uint8_t offending_ie_value = 0;
    int i;

    ogs_assert(xact);
    ogs_assert(req);

    ogs_debug("Session Modification Request");

    cause_value = OGS_PFCP_CAUSE_REQUEST_ACCEPTED;

    if (!sess) {
        ogs_error("No Context");
        ogs_pfcp_send_error_message(xact, 0,
                OGS_PFCP_SESSION_MODIFICATION_RESPONSE_TYPE,
                OGS_PFCP_CAUSE_SESSION_CONTEXT_NOT_FOUND, 0);
        return;
    }

    for (i = 0; i < OGS_MAX_NUM_OF_PDR; i++) {
        created_pdr[i] = ogs_pfcp_handle_create_pdr(&sess->pfcp,
                &req->create_pdr[i], &cause_value, &offending_ie_value);
        if (created_pdr[i] == NULL)
            break;
    }
    num_of_created_pdr = i;
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_PDR; i++) {
        if (ogs_pfcp_handle_update_pdr(&sess->pfcp, &req->update_pdr[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_PDR; i++) {
        if (ogs_pfcp_handle_remove_pdr(&sess->pfcp, &req->remove_pdr[i],
                &cause_value, &offending_ie_value) == false)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_FAR; i++) {
        if (ogs_pfcp_handle_create_far(&sess->pfcp, &req->create_far[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_FAR; i++) {
        if (ogs_pfcp_handle_update_far_flags(&sess->pfcp, &req->update_far[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    /* Send End Marker to gNB */
    ogs_list_for_each(&sess->pfcp.pdr_list, pdr) {
        far = pdr->far;
        if (far && far->smreq_flags.send_end_marker_packets)
            ogs_pfcp_send_end_marker(pdr);
    }
    /* Clear PFCPSMReq-Flags */
    ogs_list_for_each(&sess->pfcp.far_list, far)
        far->smreq_flags.value = 0;

    for (i = 0; i < OGS_MAX_NUM_OF_FAR; i++) {
        if (ogs_pfcp_handle_update_far(&sess->pfcp, &req->update_far[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_FAR; i++) {
        if (ogs_pfcp_handle_remove_far(&sess->pfcp, &req->remove_far[i],
                &cause_value, &offending_ie_value) == false)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_QER; i++) {
        if (ogs_pfcp_handle_create_qer(&sess->pfcp, &req->create_qer[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_QER; i++) {
        if (ogs_pfcp_handle_update_qer(&sess->pfcp, &req->update_qer[i],
                    &cause_value, &offending_ie_value) == NULL)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    for (i = 0; i < OGS_MAX_NUM_OF_QER; i++) {
        if (ogs_pfcp_handle_remove_qer(&sess->pfcp, &req->remove_qer[i],
                &cause_value, &offending_ie_value) == false)
            break;
    }
    if (cause_value != OGS_PFCP_CAUSE_REQUEST_ACCEPTED)
        goto cleanup;

    /* Setup GTP Node */
    ogs_list_for_each(&sess->pfcp.far_list, far)
        setup_gtp_node(far);

    /* Setup UPF-N3-TEID & QFI Hash */
    for (i = 0; i < num_of_created_pdr; i++) {
        pdr = created_pdr[i];
        ogs_assert(pdr);

        if (pdr->src_if == OGS_PFCP_INTERFACE_ACCESS) { /* Uplink */
            if (pdr->f_teid_len)
                ogs_pfcp_pdr_hash_set(pdr);
        }
    }

    /* Send Buffered Packet to gNB/SGW */
    ogs_list_for_each(&sess->pfcp.pdr_list, pdr) {
        if (pdr->src_if == OGS_PFCP_INTERFACE_CORE) { /* Downlink */
            ogs_pfcp_send_buffered_packet(pdr);
        }
    }

    upf_pfcp_send_session_modification_response(
            xact, sess, created_pdr, num_of_created_pdr);
    return;

cleanup:
    ogs_pfcp_sess_clear(&sess->pfcp);
    ogs_pfcp_send_error_message(xact, sess ? sess->smf_n4_seid : 0,
            OGS_PFCP_SESSION_MODIFICATION_RESPONSE_TYPE,
            cause_value, offending_ie_value);
}

void upf_n4_handle_session_deletion_request(
        upf_sess_t *sess, ogs_pfcp_xact_t *xact,
        ogs_pfcp_session_deletion_request_t *req)
{
    ogs_assert(xact);
    ogs_assert(req);

    ogs_debug("Session Deletion Request");

    if (!sess) {
        ogs_error("No Context");
        ogs_pfcp_send_error_message(xact, 0,
                OGS_PFCP_SESSION_DELETION_RESPONSE_TYPE,
                OGS_PFCP_CAUSE_SESSION_CONTEXT_NOT_FOUND, 0);
        return;
    }

    ogs_assert(sess);

    upf_pfcp_send_session_deletion_response(xact, sess);

    upf_sess_remove(sess);
}