/*!
 * \file
 * \brief Implementation of Selective Repeat ARQ classes
 * \author Anders Persson and Tony Ottosson
 *
 * -------------------------------------------------------------------------
 *
 * IT++ - C++ library of mathematical, signal processing, speech processing,
 *        and communications classes and functions
 *
 * Copyright (C) 1995-2008  (see AUTHORS file for a list of contributors)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * -------------------------------------------------------------------------
 */

#include <itpp/protocol/selective_repeat.h>
#include <cstdlib>

//! \cond

namespace itpp {

bool in_sequence(const int a, const int b, const int L){
  it_assert(a>=0 && a<L,"in_sequence(): ");
  it_assert(b>=0 && b<L,"in_sequence(): ");
  return ((b - a + L) % L) < L/2;
}

Selective_Repeat_ARQ_Sender::Selective_Repeat_ARQ_Sender() {
  parameters_ok = false;
  packet_input.set_name("Selective_Repeat_ARQ_Sender packet_input Slot");
  packet_input.forward(this, &Selective_Repeat_ARQ_Sender::handle_packet_input);
  ack_input.set_name("Selective_Repeat_ARQ_Sender ack_input Slot");
  ack_input.forward(this, &Selective_Repeat_ARQ_Sender::handle_ack_input);
  query_nof_ready_packets.set_name("Selective_Repeat_ARQ_Sender query_nof_ready_packets Slot");
  query_nof_ready_packets.forward(this, &Selective_Repeat_ARQ_Sender::handle_query_nof_ready_packets);
  packet_output_request.set_name("Selective_Repeat_ARQ_Sender packet_output_request Slot");
  packet_output_request.forward(this, &Selective_Repeat_ARQ_Sender::handle_packet_output_request);

}

Selective_Repeat_ARQ_Sender::Selective_Repeat_ARQ_Sender(const int Seq_no_size, const int Buffer_size_factor, const int Link_packet_size, const Ttype Time_out){
  set_parameters(Seq_no_size, Buffer_size_factor, Link_packet_size, Time_out);
  packet_input.set_name("Selective_Repeat_ARQ_Sender packet_input Slot");
  packet_input.forward(this, &Selective_Repeat_ARQ_Sender::handle_packet_input);
  ack_input.set_name("Selective_Repeat_ARQ_Sender ack_input Slot");
  ack_input.forward(this, &Selective_Repeat_ARQ_Sender::handle_ack_input);
  query_nof_ready_packets.set_name("Selective_Repeat_ARQ_Sender query_nof_ready_packets Slot");
  query_nof_ready_packets.forward(this, &Selective_Repeat_ARQ_Sender::handle_query_nof_ready_packets);
  packet_output_request.set_name("Selective_Repeat_ARQ_Sender packet_output_request Slot");
  packet_output_request.forward(this, &Selective_Repeat_ARQ_Sender::handle_packet_output_request);
}

Selective_Repeat_ARQ_Sender::~Selective_Repeat_ARQ_Sender(){
  std::cout << "no_retransmit = "<<no_retransmit << std::endl;
}

void Selective_Repeat_ARQ_Sender::set_parameters(const int Seq_no_size,
			   const int Buffer_size_factor,
			   const int Link_packet_size,
			   const Ttype Time_out){
  it_assert((0 < Seq_no_size) && (Seq_no_size <= 30),
	    "Selective_Repeat_ARQ_Sender::set_parameters(): ");
  it_assert((0 < Buffer_size_factor) && (Buffer_size_factor <= 10),
	    "Selective_Repeat_ARQ_Sender::set_parameters(): ");
  it_assert(Link_packet_size > 0,"Selective_Repeat_ARQ_Sender::set_parameters(): ");
  it_assert(Time_out>0,"Selective_Repeat_ARQ_Sender::set_parameters(): ");
  seq_no_size = Seq_no_size;
  link_packet_size = Link_packet_size;
  seq_no_max = 1<<Seq_no_size;
  input_buffer_size = seq_no_max*Buffer_size_factor;
  input_buffer.set_size(input_buffer_size);
  for(int l=0; l<input_buffer_size; input_buffer(l++) = NULL);
  input_free_space = input_buffer_size;
  input_next = 0;
  tx_next = 0;
  tx_last = 0;
  time_out = Time_out;
  timer.set_size(seq_no_max);
  for(int l=0; l<seq_no_max; timer(l++).forward(this, &Selective_Repeat_ARQ_Sender::retransmit));
  outstanding = 0;
  seq_no = 0;
  output_indexes.set_size(seq_no_max);
  output_indexes.ones();
  output_indexes *= -1;
  retransmission_indexes.set_size(seq_no_max);
  retransmission_indexes.ones();
  retransmission_indexes *= -1;
  rd_pos = 0;
  rt_pos = 0;
  scheduled_total = 0;
  scheduled_retransmissions = 0;
  no_retransmit = 0;
  parameters_ok = true;
  ip_pkt_queue.set_max_byte_size(1500*32);
  id = 0;
}

void Selective_Repeat_ARQ_Sender::handle_ack_input(Array<Packet*> packet_array){
  Packet *packet = packet_array(0);
  ACK *A = (ACK *) packet;

  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::handle_ack_input(): ");
  it_assert(A,"Selective_Repeat_ARQ_Sender::handle_ack_input(): ");
  it_assert(A->seq_no>=0 && A->seq_no<seq_no_max,"Selective_Repeat_ARQ_Sender::handle_ack_input(): ");
  if(outstanding){
    if(in_sequence(tx_last%seq_no_max, A->seq_no, seq_no_max))
      remove(A->seq_no);
    while(!input_buffer(tx_last)&&outstanding){
      outstanding--;
      input_free_space++;
      tx_last = (tx_last + 1) % input_buffer_size;
    }
  }
  delete A;
  fill_output();
}

void Selective_Repeat_ARQ_Sender::handle_packet_input(Packet *packet){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::handle_packet_input(): ");
  it_assert(packet,"Selective_Repeat_ARQ_Sender::handle_packet_input(): ");
  ip_pkt_queue.push(packet);

}

// The number of blocks in the ip_pkt_queue that can be scheduled to be
// transmitted (in the tx buffer)
int Selective_Repeat_ARQ_Sender::feasable_blocks(){
  div_t q = div(ip_pkt_queue.byte_size(),link_packet_size);
  int blocks_in_ip_queue = (q.rem) ? q.quot+1 : q.quot;
  return std::min(free_sequence_numbers(),
                  buffered_non_outstanding() +
                  std::min(blocks_in_ip_queue, input_free_space));
}


void Selective_Repeat_ARQ_Sender::handle_query_nof_ready_packets(void*){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::handle_query_nof_ready_packets(): ");
  nof_ready_packets(scheduled_total + feasable_blocks());
}

void Selective_Repeat_ARQ_Sender::handle_packet_output_request(const int nbr_blocks_requested){
  int nbr_blocks_to_tx;
  int feasable_blks = feasable_blocks();
  if (nbr_blocks_requested <= scheduled_total+feasable_blks) {
     nbr_blocks_to_tx = nbr_blocks_requested;
  }
  else {
     it_warning("Number of requested blocks is more than what is possible to transmitt");
     nbr_blocks_to_tx = scheduled_total+feasable_blks;
  }

  //int nbr_ip_pkts_in_q = ip_pkt_queue.size();
  while (nbr_blocks_to_tx > scheduled_total) {
    it_assert(!ip_pkt_queue.empty(),"Selective_Repeat_ARQ_Sender::handle_packet_output_request(): ");
    Packet *packet = ip_pkt_queue.front();
    ip_pkt_queue.pop();
    push_packet_on_tx_buffer(packet);
  }

  Array<Packet*> tmp;
  get_link_packets(nbr_blocks_requested, tmp);
  packet_output(tmp);
}

void Selective_Repeat_ARQ_Sender::push_packet_on_tx_buffer(Packet *packet){
  L3_Packet_Info *pkt_info = new L3_Packet_Info(packet);
  int packet_byte_size = pkt_info->pkt_pointer->bit_size()/8;
  int nbr_blocks = packet_byte_size/link_packet_size;
  if(nbr_blocks*link_packet_size!=packet_byte_size)
     nbr_blocks++;
  if(input_free_space>=nbr_blocks){
    pkt_info->timestamp = Event_Queue::now();
    for(int n=nbr_blocks-1; n>=0; n--){
      input_buffer(input_next) = new Link_Packet(-1, n, pkt_info);
      input_free_space--;
      input_next = (input_next+1)%input_buffer_size;
    }
  }
  else{
    buffer_overflow(0);
    it_error("Selective_Repeat_ARQ_Sender::push_packet_on_tx_buffer(): "
	     "Stopped due to buffer overflow");
  }
  fill_output();

}

void Selective_Repeat_ARQ_Sender::fill_output(){
  int packets_2_output = std::min(free_sequence_numbers(), buffered_non_outstanding());
  while(packets_2_output){
    input_buffer(tx_next)->seq_no = seq_no;
    outstanding++;
    schedule_output(tx_next, seq_no, false);
    seq_no = (seq_no + 1) % seq_no_max;
    tx_next = (tx_next + 1) % input_buffer_size;
    packets_2_output--;
  }
}

void Selective_Repeat_ARQ_Sender::schedule_output(const int Buffer_index, const int Sequence_number, const bool Retransmission){
  it_assert(input_buffer(Buffer_index)!=NULL,"Selective_Repeat_ARQ_Sender::schedule_output(): ");
  if(output_indexes(Sequence_number) == -1)
    scheduled_total++;
  output_indexes(Sequence_number) = Buffer_index;
  if(Retransmission){
    if(retransmission_indexes(Sequence_number) != 1) // This is a new retransmission.
      scheduled_retransmissions++;
    retransmission_indexes(Sequence_number) = 1; // Mark packet (index) for retransmission.
  }
  else // Mark packet (index) for first time transmission.
    retransmission_indexes(Sequence_number) = 0;
}

void Selective_Repeat_ARQ_Sender::get_link_packets(const int K, Array<Packet*> &pa){
  int packets_2_retransmit = std::min(K, scheduled_retransmissions);
  int new_packets_2_transmit = std::min(K, scheduled_total)-packets_2_retransmit;
  scheduled_retransmissions -= packets_2_retransmit;
  scheduled_total -= packets_2_retransmit + new_packets_2_transmit;
  pa.set_size(packets_2_retransmit+new_packets_2_transmit);
  int l=0;
  while(packets_2_retransmit){ // Retransmissions have priority over ...
    if(retransmission_indexes(rt_pos) == 1){
      timer(rt_pos).set(rt_pos, time_out);
      pa(l++) = (Packet *) new Link_Packet(*input_buffer(output_indexes(rt_pos)));
      output_indexes(rt_pos) = -1;
      retransmission_indexes(rt_pos) = -1;
      packets_2_retransmit--;
    }
    rt_pos = (rt_pos + 1) % seq_no_max;
  }
  while(new_packets_2_transmit){ // new packets.
    if(output_indexes(rd_pos) != -1){
      timer(rd_pos).set(rd_pos, time_out);
      pa(l++) = (Packet *) new Link_Packet(*input_buffer(output_indexes(rd_pos)));
      output_indexes(rd_pos) = -1;
      new_packets_2_transmit--;
    }
    rd_pos = (rd_pos + 1) % seq_no_max;
  }
}

void Selective_Repeat_ARQ_Sender::remove(const int Sequence_number){
  if(output_indexes(Sequence_number)!=-1){
    output_indexes(Sequence_number)=-1;
    scheduled_total--;
    if(retransmission_indexes(Sequence_number) == 1)
      scheduled_retransmissions--;
    retransmission_indexes(Sequence_number)=-1;
  }
  const int i = sequence_number_2_buffer_index(Sequence_number);
  if(input_buffer(i)){
    timer(Sequence_number).cancel(); // Cancel the retransmission timer.
    it_assert(input_buffer(i)->seq_no==Sequence_number,"Selective_Repeat_ARQ_Sender::remove(): ");
    delete input_buffer(i);
    input_buffer(i) = NULL;
  }
}

void Selective_Repeat_ARQ_Sender::retransmit(const int Sequence_number){
  no_retransmit++;
  const int buffer_index = sequence_number_2_buffer_index(Sequence_number);
  schedule_output(buffer_index, Sequence_number, true);
}

int Selective_Repeat_ARQ_Sender::buffered_non_outstanding(){
  return input_buffer_size - input_free_space - outstanding;
}

int Selective_Repeat_ARQ_Sender::free_sequence_numbers(){
  return seq_no_max/2 - outstanding;
}

int Selective_Repeat_ARQ_Sender::sequence_number_2_buffer_index(const int Sequence_number){
  it_assert(input_buffer(tx_last),"Selective_Repeat_ARQ_Sender::sequence_number_2_buffer_index(): ");
  it_assert(input_buffer(tx_last)->seq_no!=-1,"Selective_Repeat_ARQ_Sender::sequence_number_2_buffer_index(): ");
  return (tx_last + (Sequence_number-input_buffer(tx_last)->seq_no+seq_no_max)%seq_no_max) % input_buffer_size;
}

int Selective_Repeat_ARQ_Sender::link_packets_buffered(){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::link_packets_buffered(): ");
  return input_buffer_size - input_free_space;
}

int Selective_Repeat_ARQ_Sender::nof_ready_link_packets(){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::nof_ready_link_packets(): ");
  return scheduled_total + feasable_blocks();
}

int Selective_Repeat_ARQ_Sender::link_packets_queued_waiting_for_transmission(){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::link_packets_queued_waiting_for_transmission(): ");
  div_t q = div(ip_pkt_queue.byte_size(),link_packet_size);
  int blocks_in_ip_queue = (q.rem) ? q.quot+1 : q.quot;
  return buffered_non_outstanding() + scheduled_total + blocks_in_ip_queue;
}

// int Selective_Repeat_ARQ_Sender::time_stamp_HOL_packet(){
//   assert(parameters_ok);
//   return buffered_non_outstanding()+feasable_blocks();
// }

int Selective_Repeat_ARQ_Sender::buffer_size(){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::buffer_size(): ");
  return input_buffer_size;
}

Ttype Selective_Repeat_ARQ_Sender::link_packets_max_queuing_time(){
  it_assert(parameters_ok,"Selective_Repeat_ARQ_Sender::link_packets_max_queuing_time(): ");
  it_assert(input_buffer(tx_last),"Selective_Repeat_ARQ_Sender::link_packets_max_queuing_time(): ");
  return Event_Queue::now()-input_buffer(tx_last)->l3_pkt_info_p->timestamp;
}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
Selective_Repeat_ARQ_Receiver::Selective_Repeat_ARQ_Receiver(){
  parameters_ok = false;
  packet_input.forward(this, &Selective_Repeat_ARQ_Receiver::handle_packet_input);
  packet_input.set_name("Selective_Repeat_ARQ_Receiver packet_input Slot");
}

Selective_Repeat_ARQ_Receiver::Selective_Repeat_ARQ_Receiver(const int Seq_no_size){
  set_parameters(Seq_no_size);
  packet_input.forward(this, &Selective_Repeat_ARQ_Receiver::handle_packet_input);
  packet_input.set_name("Selective_Repeat_ARQ_Receiver packet_input Slot");
}

Selective_Repeat_ARQ_Receiver::~Selective_Repeat_ARQ_Receiver(){}

void Selective_Repeat_ARQ_Receiver::set_parameters(const int Seq_no_size){
  seq_no_size = Seq_no_size;
  seq_no_max = 1<<seq_no_size;
  rx_buffer.set_size(seq_no_max);
  for(int l=0; l<seq_no_max; rx_buffer(l++) = NULL);
  Rnext = 0;
  id = 0;
  parameters_ok = true;
}

void Selective_Repeat_ARQ_Receiver::handle_packet_input(Array<Packet*> packet_array){
   it_assert(parameters_ok,"Selective_Repeat_ARQ_Receiver::handle_packet_input(): ");

   int nbr_pkts = packet_array.length();
   Link_Packet *packet;
   for (int i=0;i<nbr_pkts;i++) {
      packet = (Link_Packet *) packet_array(i);
      it_assert(packet,"Selective_Repeat_ARQ_Receiver::handle_packet_input(): ");
      it_assert(packet->seq_no>=0 && packet->seq_no<seq_no_max,"Selective_Repeat_ARQ_Receiver::handle_packet_input(): ");
      Array<Packet*> ack_pkt;
      ack_pkt.set_size(1);
      ack_pkt(0) = (Packet *) new ACK(packet->seq_no, id++);
      ack_output(ack_pkt); // Acknowledge the receipt of this packet.
      if(in_sequence(Rnext, packet->seq_no, seq_no_max)&&!rx_buffer(packet->seq_no)) // Is this a new packet in-sequence packet?
         rx_buffer(packet->seq_no) = packet; // This is a new in-sequence packet.
      else // This either is a duplicate packet or an out-of-sequence packet.
         delete packet;
      while(rx_buffer(Rnext)){ // Is there an unbroken sequence of packets that we can output?

         if(rx_buffer(Rnext)->link_packet_id==0){
            packet_output(rx_buffer(Rnext)->l3_pkt_info_p->pkt_pointer);
            delete rx_buffer(Rnext)->l3_pkt_info_p;
         }
         delete rx_buffer(Rnext);
         rx_buffer(Rnext) = NULL;
         Rnext = (Rnext + 1) % seq_no_max;
      }
   }
}


} //namespace itpp

//! \endcond