/* -*- c++ -*- */
/*
 * gr-satnogs: SatNOGS GNU Radio Out-Of-Tree Module
 *
 *  Copyright (C) 2017
 *  Libre Space Foundation <http://librespacefoundation.org/>
 *
 *  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 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 <http://www.gnu.org/licenses/>.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gnuradio/io_signature.h>
#include <satnogs/log.h>
#include "cw_encoder_impl.h"

namespace gr {
namespace satnogs {

cw_encoder::sptr
cw_encoder::make(double samp_rate, double cw_freq, size_t wpm)
{
  return gnuradio::get_initial_sptr
         (new cw_encoder_impl(samp_rate, cw_freq, wpm));
}

/*
 * The private constructor
 */
cw_encoder_impl::cw_encoder_impl(double samp_rate, double cw_freq,
                                 size_t wpm)
  : gr::sync_block("cw_encoder",
                   gr::io_signature::make(0, 0, 0),
                   gr::io_signature::make(1, 1, sizeof(gr_complex))),
    d_samp_rate(samp_rate),
    d_cw_freq(cw_freq),
    d_wpm(wpm),
    d_dot_samples((1.2 / wpm) / (1.0 / samp_rate)),
    d_window_size(0),
    d_windows_remaining(0),
    d_cw_symbol(MORSE_L_SPACE),
    d_nco()
{
  message_port_register_in(pmt::mp("symbol"));

  /*
   * Try to split the CW pulses in smaller windows for dealing efficiently
   * with the available buffer size
   */
  size_t i = 10;
  d_window_size = d_dot_samples / i;
  while (d_window_size > 200) {
    i += 10;
    d_window_size = d_dot_samples / i;
  }

  /* NOTE: The dot duration should be a perfect multiple of the window */
  while (d_dot_samples % d_window_size != 0) {
    d_window_size++;
  }

  set_output_multiple(d_window_size);
  d_nco.set_freq((2 * M_PI * cw_freq) / samp_rate);
}

/*
 * Our virtual destructor.
 */
cw_encoder_impl::~cw_encoder_impl()
{
}

int
cw_encoder_impl::work(int noutput_items,
                      gr_vector_const_void_star &input_items,
                      gr_vector_void_star &output_items)
{
  size_t available;
  size_t i;
  gr_complex *out = (gr_complex *) output_items[0];

  if (noutput_items < 0) {
    return noutput_items;
  }

  if (d_windows_remaining == 0) {
    pmt::pmt_t symbol = delete_head_nowait(pmt::mp("symbol"));
    if (symbol.get() == nullptr) {
      return 0;
    }
    d_cw_symbol = (morse_symbol_t) pmt::to_long(symbol);
    /* Reset NCO so the amplitude starts from zero */
    d_nco.set_freq((2 * M_PI * d_cw_freq) / d_samp_rate);
    switch (d_cw_symbol) {
    case MORSE_DOT:
    case MORSE_INTRA_SPACE:
      d_windows_remaining = d_dot_samples / d_window_size;
      break;
    case MORSE_DASH:
    case MORSE_S_SPACE:
      d_windows_remaining = (d_dot_samples / d_window_size) * 3;
      break;
    case MORSE_L_SPACE:
      d_windows_remaining = (d_dot_samples / d_window_size) * 7;
      break;
    default:
      LOG_WARN("Unrecognized CW symbol");
      return 0;
    }
  }

  for (i = 0; i < (size_t)noutput_items / d_window_size; i++) {
    switch (d_cw_symbol) {
    case MORSE_S_SPACE:
    case MORSE_L_SPACE:
    case MORSE_INTRA_SPACE:
      memset(out + i * d_window_size, 0,
             d_window_size * sizeof(gr_complex));
      break;
    case MORSE_DOT:
    case MORSE_DASH:
      d_nco.sincos(out + i * d_window_size, d_window_size, 1.0);
      break;
    }
    d_windows_remaining--;
    if (d_windows_remaining == 0) {
      return (i + 1) * d_window_size;
    }
  }
  return i * d_window_size;
}

} /* namespace satnogs */
} /* namespace gr */