/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2015 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsUE library.
 *
 * srsUE 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.
 *
 * srsUE 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 Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

#ifndef DL_HARQ_H
#define DL_HARQ_H

#define Error(fmt, ...)   log_h->error_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Warning(fmt, ...) log_h->warning_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Info(fmt, ...)    log_h->info_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)
#define Debug(fmt, ...)   log_h->debug_line(__FILE__, __LINE__, fmt, ##__VA_ARGS__)

#include "srslte/common/log.h"
#include "srslte/common/timers.h"
#include "mac/demux.h"
#include "mac/mac_common.h"
#include "mac/dl_sps.h"
#include "srslte/common/mac_pcap.h"

#include "srslte/interfaces/ue_interfaces.h"

/* Downlink HARQ entity as defined in 5.3.2 of 36.321 */


namespace srsue {

template <std::size_t N, typename Tgrant, typename Taction, typename Tphygrant>
class dl_harq_entity
{
public:

  const static uint32_t HARQ_BCCH_PID = N;
  
  dl_harq_entity() : proc(N+1)
  {
    pcap = NULL;
  }
    
  bool init(srslte::log *log_h_, srslte::timers *timers_, demux *demux_unit_)
  {
    timers_db  = timers_; 
    demux_unit = demux_unit_; 
    si_window_start = 0; 
    log_h = log_h_; 
    for (uint32_t i=0;i<N+1;i++) {
      if (!proc[i].init(i, this)) {
        return false; 
      }
    }
    return true;
  }

  /***************** PHY->MAC interface for DL processes **************************/
  void new_grant_dl(Tgrant grant, Taction *action)
  {
    if (grant.rnti_type != SRSLTE_RNTI_SPS) {
      uint32_t harq_pid; 
      // Set BCCH PID for SI RNTI 
      if (grant.rnti_type == SRSLTE_RNTI_SI) {
        harq_pid = HARQ_BCCH_PID; 
      } else {
        harq_pid = grant.pid%N;
      }
      if (grant.rnti_type == SRSLTE_RNTI_TEMP && last_temporal_crnti != grant.rnti) {
        grant.ndi = true;
        Info("Set NDI=1 for Temp-RNTI DL grant\n");
        last_temporal_crnti = grant.rnti;
      }
      if (grant.rnti_type == SRSLTE_RNTI_USER && proc[harq_pid].is_sps()) {
        grant.ndi = true;
        Info("Set NDI=1 for C-RNTI DL grant\n");
      }
      proc[harq_pid].new_grant_dl(grant, action);
    } else {
      /* This is for SPS scheduling */
      uint32_t harq_pid = get_harq_sps_pid(grant.tti)%N;
      if (grant.ndi) {
        grant.ndi = false; 
        proc[harq_pid].new_grant_dl(grant, action);
      } else {
        if (grant.is_sps_release) {
          dl_sps_assig.clear();
          if (timers_db->get(TIME_ALIGNMENT)->is_running()) {
            //phy_h->send_sps_ack();
            Warning("PHY Send SPS ACK not implemented\n");
          }
        } else {
          Error("SPS not implemented\n");
          //dl_sps_assig.reset(grant.tti, grant);
          //grant.ndi = true;
          //procs[harq_pid].save_grant();
        }
      }
    }
  }


  void tb_decoded(bool ack, srslte_rnti_type_t rnti_type, uint32_t harq_pid)
  {
    if (rnti_type == SRSLTE_RNTI_SI) {
      proc[N].tb_decoded(ack);
    } else {
      proc[harq_pid%N].tb_decoded(ack);
    }
  }


  void reset()
  {
    for (uint32_t i=0;i<N+1;i++) {
      proc[i].reset();
    }
    dl_sps_assig.clear();
  }

  void start_pcap(srslte::mac_pcap* pcap_) { pcap = pcap_; }

  int  get_current_tbs(uint32_t harq_pid) { return proc[harq_pid%N].get_current_tbs(); }

  void set_si_window_start(int si_window_start_) { si_window_start = si_window_start_; }

  float get_average_retx() { return average_retx; }

private:  
  class dl_harq_process {
  public:
    dl_harq_process()
    {
      is_initiated = false; 
      ack = false; 
      bzero(&cur_grant, sizeof(Tgrant));
    }

    bool init(uint32_t pid_, dl_harq_entity *parent)
    {
      if (srslte_softbuffer_rx_init(&softbuffer, 110)) {
        Error("Error initiating soft buffer\n");
        return false; 
      } else {
        pid = pid_;
        is_initiated = true; 
        harq_entity = parent; 
        log_h = harq_entity->log_h; 
        return true;
      }
    }

    void reset()
    {
      ack = false; 
      payload_buffer_ptr = NULL; 
      bzero(&cur_grant, sizeof(Tgrant));
      if (is_initiated) {
        srslte_softbuffer_rx_reset(&softbuffer);
      }
    }
    
    void new_grant_dl(Tgrant grant, Taction *action)
    {
      // Compute RV for BCCH when not specified in PDCCH format
      if (pid == HARQ_BCCH_PID && grant.rv == -1) {
        uint32_t k; 
        if ((grant.tti/10)%2 == 0 && grant.tti%10 == 5) { // This is SIB1, k is different
          k = (grant.tti/20)%4; 
          grant.rv = ((uint32_t) ceilf((float)1.5*k))%4;
        } else if (grant.rv == -1) {      
          k = (grant.tti-harq_entity->si_window_start)%4; 
          grant.rv = ((uint32_t) ceilf((float)1.5*k))%4;
        }
      }
      calc_is_new_transmission(grant);
      if (is_new_transmission) {
        ack = false; 
        srslte_softbuffer_rx_reset_tbs(&softbuffer, cur_grant.n_bytes*8);
        n_retx = 0; 
      }
      
      // Save grant 
      grant.last_ndi = cur_grant.ndi; 
      grant.last_tti = cur_grant.tti; 
      memcpy(&cur_grant, &grant, sizeof(Tgrant));
      
      // Fill action structure 
      bzero(action, sizeof(Taction));
      action->default_ack = ack; 
      action->generate_ack = true; 
      action->decode_enabled = false; 
      
      // If data has not yet been successfully decoded
      if (ack == false) {
        
        // Instruct the PHY To combine the received data and attempt to decode it
        payload_buffer_ptr = harq_entity->demux_unit->request_buffer(pid, cur_grant.n_bytes);
        action->payload_ptr = payload_buffer_ptr;
        if (!action->payload_ptr) {
          action->decode_enabled = false; 
          Error("Can't get a buffer for TBS=%d\n", cur_grant.n_bytes);
          return;       
        }    
        action->decode_enabled = true;     
        action->rv = cur_grant.rv; 
        action->rnti = cur_grant.rnti; 
        action->softbuffer = &softbuffer;     
        memcpy(&action->phy_grant, &cur_grant.phy_grant, sizeof(Tphygrant));
        n_retx++; 
        
      } else {
        Warning("DL PID %d: Received duplicate TB. Discarting and retransmitting ACK\n", pid);
      }
        
      if (pid == HARQ_BCCH_PID || harq_entity->timers_db->get(TIME_ALIGNMENT)->is_expired()) {
        // Do not generate ACK
        Debug("Not generating ACK\n");
        action->generate_ack = false;    
      } else {
        if (cur_grant.rnti_type == SRSLTE_RNTI_TEMP && ack == false) {
          // Postpone ACK after contention resolution is resolved
          action->generate_ack_callback = harq_entity->generate_ack_callback; 
          action->generate_ack_callback_arg = harq_entity->demux_unit;
          Debug("ACK pending contention resolution\n");
        } else {
          Debug("Generating ACK\n");
        }
      }
    }
    
    void tb_decoded(bool ack_)
    {
      ack = ack_;
      if (ack == true) {
        if (pid == HARQ_BCCH_PID) {
          if (harq_entity->pcap) {
            harq_entity->pcap->write_dl_sirnti(payload_buffer_ptr, cur_grant.n_bytes, ack, cur_grant.tti);
          }
          Debug("Delivering PDU=%d bytes to Dissassemble and Demux unit (BCCH)\n", cur_grant.n_bytes);
          harq_entity->demux_unit->push_pdu(pid, payload_buffer_ptr, cur_grant.n_bytes, cur_grant.tti);
        } else {      
          if (harq_entity->pcap) {
            harq_entity->pcap->write_dl_crnti(payload_buffer_ptr, cur_grant.n_bytes, cur_grant.rnti, ack, cur_grant.tti);            
          }
          if (ack) {
            if (cur_grant.rnti_type == SRSLTE_RNTI_TEMP) {
              Debug("Delivering PDU=%d bytes to Dissassemble and Demux unit (Temporal C-RNTI)\n", cur_grant.n_bytes);
              harq_entity->demux_unit->push_pdu_temp_crnti(payload_buffer_ptr, cur_grant.n_bytes);
            } else {
              Debug("Delivering PDU=%d bytes to Dissassemble and Demux unit\n", cur_grant.n_bytes);
              harq_entity->demux_unit->push_pdu(pid, payload_buffer_ptr, cur_grant.n_bytes, cur_grant.tti);

              // Compute average number of retransmissions per packet 
              harq_entity->average_retx = SRSLTE_VEC_CMA((float) n_retx, harq_entity->average_retx, harq_entity->nof_pkts++); 
            }
          }
        }
      } else {
        harq_entity->demux_unit->deallocate(payload_buffer_ptr);
      }
      
      Info("DL %d:  %s tbs=%d, rv=%d, ack=%s, ndi=%d (%d), tti=%d (%d)\n", 
           pid, is_new_transmission?"newTX":"reTX ", 
           cur_grant.n_bytes, cur_grant.rv, ack?"OK":"KO", 
           cur_grant.ndi, cur_grant.last_ndi, cur_grant.tti, cur_grant.last_tti);
      
      if (ack && pid == HARQ_BCCH_PID) {
        reset();
      }
    }

    bool is_sps() { return false; }

    int get_current_tbs() { return cur_grant.n_bytes*8; }
    
  private: 
    bool calc_is_new_transmission(Tgrant grant)
    {
      bool is_new_tb = true; 
      if ((srslte_tti_interval(grant.tti, cur_grant.tti) <= 8 && (grant.n_bytes == cur_grant.n_bytes)) ||
          pid == HARQ_BCCH_PID) 
      {
        is_new_tb = false; 
      }
      
      if ((grant.ndi != cur_grant.ndi && !is_new_tb) || // NDI toggled for same TB
          is_new_tb                                  || // is new TB
          (pid == HARQ_BCCH_PID && grant.rv == 0))      // Broadcast PID and 1st TX (RV=0)
      {
        is_new_transmission = true; 
        Debug("Set HARQ for new transmission\n");
      } else {
        is_new_transmission = false; 
        Debug("Set HARQ for retransmission\n");
      }

      return is_new_transmission;
    }

    bool            is_initiated; 
    dl_harq_entity *harq_entity; 
    srslte::log    *log_h;
    
    bool            is_new_transmission; 
    
    uint32_t        pid;    
    uint8_t        *payload_buffer_ptr; 
    bool            ack;
    
    uint32_t        n_retx; 
    
    Tgrant                         cur_grant;
    srslte_softbuffer_rx_t         softbuffer; 
  };
  
  // Private members of dl_harq_entity
  
  static bool      generate_ack_callback(void *arg)
  {
    demux *demux_unit = (demux*) arg;
    return demux_unit->get_uecrid_successful();
  }

  uint32_t         get_harq_sps_pid(uint32_t tti) { return 0; }
  
  dl_sps           dl_sps_assig;
  

  std::vector<dl_harq_process> proc;
  srslte::timers   *timers_db;
  demux           *demux_unit; 
  srslte::log     *log_h;
  srslte::mac_pcap *pcap; 
  uint16_t         last_temporal_crnti;
  int              si_window_start;

  float            average_retx;   
  uint64_t         nof_pkts; 
};

} // namespace srsue

#endif // DL_HARQ_H