/*
 * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The OpenAirInterface Software Alliance licenses this file to You under
 * the OAI Public License, Version 1.1  (the "License"); you may not use this file
 * except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.openairinterface.org/?page_id=698
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *-------------------------------------------------------------------------------
 * For more information about the OpenAirInterface (OAI) Software Alliance:
 *      contact@openairinterface.org
 */

/*! \file       gNB_scheduler_dlsch.c
 * \brief       procedures related to gNB for the DLSCH transport channel
 * \author      Guido Casati
 * \date        2019
 * \email:      guido.casati@iis.fraunhofe.de
 * \version     1.0
 * @ingroup     _mac

 */

/*PHY*/
#include "PHY/CODING/coding_defs.h"
#include "PHY/defs_nr_common.h"
#include "PHY/NR_TRANSPORT/nr_transport_common_proto.h"
/*MAC*/
#include "NR_MAC_COMMON/nr_mac.h"
#include "NR_MAC_gNB/nr_mac_gNB.h"
#include "NR_MAC_COMMON/nr_mac_extern.h"
#include "LAYER2/MAC/mac.h"

/*NFAPI*/
#include "nfapi_nr_interface.h"
/*TAG*/
#include "NR_TAG-Id.h"

////////////////////////////////////////////////////////
/////* DLSCH MAC PDU generation (6.1.2 TS 38.321) */////
////////////////////////////////////////////////////////

int nr_generate_dlsch_pdu(module_id_t module_idP,
                          unsigned char *sdus_payload,
                          unsigned char *mac_pdu,
                          unsigned char num_sdus,
                          unsigned short *sdu_lengths,
                          unsigned char *sdu_lcids,
                          unsigned char drx_cmd,
                          unsigned char *ue_cont_res_id,
                          unsigned short post_padding){

  gNB_MAC_INST *gNB = RC.nrmac[module_idP];

  NR_MAC_SUBHEADER_FIXED *mac_pdu_ptr = (NR_MAC_SUBHEADER_FIXED *) mac_pdu;
  unsigned char * dlsch_buffer_ptr = sdus_payload;
  uint8_t last_size = 0;
  int offset = 0, mac_ce_size, i, timing_advance_cmd, tag_id = 0;
  // MAC CEs 
  uint8_t mac_header_control_elements[16], *ce_ptr;
  ce_ptr = &mac_header_control_elements[0];

  // 1) Compute MAC CE and related subheaders 

  // DRX command subheader (MAC CE size 0)
  if (drx_cmd != 255) {
    mac_pdu_ptr->R = 0;
    mac_pdu_ptr->LCID = DL_SCH_LCID_DRX;
    //last_size = 1;
    mac_pdu_ptr++;
  }

  // Timing Advance subheader
  /* This was done only when timing_advance_cmd != 31
  // now TA is always send when ta_timer resets regardless of its value
  // this is done to avoid issues with the timeAlignmentTimer which is
  // supposed to monitor if the UE received TA or not */
  if (gNB->ta_len){
    mac_pdu_ptr->R = 0;
    mac_pdu_ptr->LCID = DL_SCH_LCID_TA_COMMAND;
    //last_size = 1;
    mac_pdu_ptr++;

    // TA MAC CE (1 octet)
    timing_advance_cmd = gNB->ta_command;
    AssertFatal(timing_advance_cmd < 64,"timing_advance_cmd %d > 63\n", timing_advance_cmd);
    ((NR_MAC_CE_TA *) ce_ptr)->TA_COMMAND = timing_advance_cmd;    //(timing_advance_cmd+31)&0x3f;
    if (gNB->tag->tag_Id != 0){
       tag_id = gNB->tag->tag_Id;
      ((NR_MAC_CE_TA *) ce_ptr)->TAGID = tag_id;
    }

    LOG_D(MAC, "NR MAC CE timing advance command = %d (%d) TAG ID = %d\n", timing_advance_cmd, ((NR_MAC_CE_TA *) ce_ptr)->TA_COMMAND, tag_id);

    mac_ce_size = sizeof(NR_MAC_CE_TA);

    // Copying  bytes for MAC CEs to the mac pdu pointer
    memcpy((void *) mac_pdu_ptr, (void *) ce_ptr, mac_ce_size);
    ce_ptr += mac_ce_size;
    mac_pdu_ptr += (unsigned char) mac_ce_size;
  }

  // Contention resolution fixed subheader and MAC CE
  if (ue_cont_res_id) {
    mac_pdu_ptr->R = 0;
  	mac_pdu_ptr->LCID = DL_SCH_LCID_CON_RES_ID;
    mac_pdu_ptr++;
    //last_size = 1;

    // contention resolution identity MAC ce has a fixed 48 bit size
    // this contains the UL CCCH SDU. If UL CCCH SDU is longer than 48 bits, 
    // it contains the first 48 bits of the UL CCCH SDU
    LOG_T(MAC, "[gNB ][RAPROC] Generate contention resolution msg: %x.%x.%x.%x.%x.%x\n",
        ue_cont_res_id[0], ue_cont_res_id[1], ue_cont_res_id[2],
        ue_cont_res_id[3], ue_cont_res_id[4], ue_cont_res_id[5]);

    // Copying bytes (6 octects) to CEs pointer
    mac_ce_size = 6;
    memcpy(ce_ptr, ue_cont_res_id, mac_ce_size);
    
    // Copying bytes for MAC CEs to mac pdu pointer
    memcpy((void *) mac_pdu_ptr, (void *) ce_ptr, mac_ce_size);
    ce_ptr += mac_ce_size;
    mac_pdu_ptr += (unsigned char) mac_ce_size;
  }

  // 2) Generation of DLSCH MAC subPDUs including subheaders and MAC SDUs
  for (i = 0; i < num_sdus; i++) {
    LOG_D(MAC, "[gNB] Generate DLSCH header num sdu %d len sdu %d\n", num_sdus, sdu_lengths[i]);

    if (sdu_lengths[i] < 128) {
      ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->R = 0;
      ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->F = 0;
      ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->LCID = sdu_lcids[i];
      ((NR_MAC_SUBHEADER_SHORT *) mac_pdu_ptr)->L = (unsigned char) sdu_lengths[i];
      last_size = 2;
    } else {
      ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->R = 0;
      ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->F = 1;
      ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->LCID = sdu_lcids[i];
      ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->L1 = ((unsigned short) sdu_lengths[i] >> 8) & 0x7f;
      ((NR_MAC_SUBHEADER_LONG *) mac_pdu_ptr)->L2 = (unsigned short) sdu_lengths[i] & 0xff;
      last_size = 3;
    }

    mac_pdu_ptr += last_size;

    // 3) cycle through SDUs, compute each relevant and place dlsch_buffer in
    memcpy((void *) mac_pdu_ptr, (void *) dlsch_buffer_ptr, sdu_lengths[i]);
    dlsch_buffer_ptr+= sdu_lengths[i]; 
    mac_pdu_ptr += sdu_lengths[i];
  }

  // 4) Compute final offset for padding
  if (post_padding > 0) {
    ((NR_MAC_SUBHEADER_FIXED *) mac_pdu_ptr)->R = 0;
    ((NR_MAC_SUBHEADER_FIXED *) mac_pdu_ptr)->LCID = DL_SCH_LCID_PADDING;
    mac_pdu_ptr++;

  } else {            
    // no MAC subPDU with padding
  }

  // compute final offset
  offset = ((unsigned char *) mac_pdu_ptr - mac_pdu);

  //printf("Offset %d \n", ((unsigned char *) mac_pdu_ptr - mac_pdu));

  return offset;
}

/* functionalities of this function have been moved to nr_schedule_uss_dlsch_phytest */
void nr_schedule_ue_spec(module_id_t module_idP, frame_t frameP, sub_frame_t slotP){
}
