/*!
 * \file pcps_assisted_acquisition_cc.cc
 * \brief This class implements a Parallel Code Phase Search Acquisition with assistance and multi-dwells
 * \authors <ul>
 *          <li> Javier Arribas, 2013. jarribas(at)cttc.es
 *          </ul>
 *
 * -----------------------------------------------------------------------------
 *
 * GNSS-SDR is a Global Navigation Satellite System software-defined receiver.
 * This file is part of GNSS-SDR.
 *
 * Copyright (C) 2010-2020  (see AUTHORS file for a list of contributors)
 * SPDX-License-Identifier: GPL-3.0-or-later
 *
 * -----------------------------------------------------------------------------
 */

#include "pcps_assisted_acquisition_cc.h"
#include "MATH_CONSTANTS.h"
#include "concurrent_map.h"
#include "gps_acq_assist.h"
#include <gnuradio/io_signature.h>
#include <volk/volk.h>
#include <volk_gnsssdr/volk_gnsssdr.h>
#include <algorithm>
#include <array>
#include <exception>
#include <sstream>
#include <utility>

#if USE_GLOG_AND_GFLAGS
#include <glog/logging.h>
#else
#include <absl/log/log.h>
#endif

extern Concurrent_Map<Gps_Acq_Assist> global_gps_acq_assist_map;


pcps_assisted_acquisition_cc_sptr pcps_make_assisted_acquisition_cc(const Acq_Conf &conf)
{
    return pcps_assisted_acquisition_cc_sptr(new pcps_assisted_acquisition_cc(conf));
}


pcps_assisted_acquisition_cc::pcps_assisted_acquisition_cc(const Acq_Conf &conf)
    : acquisition_impl_interface("pcps_assisted_acquisition_cc",
          gr::io_signature::make(1, 1, sizeof(gr_complex)),
          gr::io_signature::make(0, 1, sizeof(Gnss_Synchro))),
      d_acq_params(conf),
      d_gnss_synchro(nullptr),
      d_sample_counter(0ULL),
      d_input_power(0.0),
      d_test_statistics(0),
      d_channel(0),
      d_code_phase(0),
      d_fft_size(conf.sampled_ms * conf.samples_per_ms),
      d_gnuradio_forecast_samples(d_fft_size * 4),
      d_doppler_max(0),
      d_doppler_min(0),
      d_num_doppler_points(0),
      d_state(0),
      d_well_count(0),
      d_active(false),
      d_disable_assist(false),
      d_fft_if(gnss_fft_fwd_make_unique(d_fft_size)),
      d_ifft(gnss_fft_rev_make_unique(d_fft_size)),
      d_fft_codes(d_fft_size)
{
    this->message_port_register_out(pmt::mp("events"));
}


pcps_assisted_acquisition_cc::~pcps_assisted_acquisition_cc()
{
    try
        {
            if (d_acq_params.dump)
                {
                    d_dump_file.close();
                }
        }
    catch (const std::ofstream::failure &e)
        {
            std::cerr << "Problem closing Acquisition dump file: " << d_acq_params.dump_filename << '\n';
        }
    catch (const std::exception &e)
        {
            std::cerr << e.what() << '\n';
        }
}


void pcps_assisted_acquisition_cc::set_local_code(std::complex<float> *code)
{
    std::copy(code, code + d_fft_size, d_fft_if->get_inbuf());
    d_fft_if->execute();  // We need the FFT of local code

    // Conjugate the local code
    volk_32fc_conjugate_32fc(d_fft_codes.data(), d_fft_if->get_outbuf(), d_fft_size);
}


void pcps_assisted_acquisition_cc::forecast(int noutput_items,
    gr_vector_int &ninput_items_required)
{
    if (noutput_items != 0)
        {
            ninput_items_required[0] = d_gnuradio_forecast_samples;  // set the required available samples in each call
        }
}


void pcps_assisted_acquisition_cc::get_assistance()
{
    Gps_Acq_Assist gps_acq_assisistance;
    if (global_gps_acq_assist_map.read(this->d_gnss_synchro->PRN, gps_acq_assisistance) == true)
        {
            // TODO: use the LO tolerance here
            if (gps_acq_assisistance.dopplerUncertainty >= 1000)
                {
                    d_doppler_max = gps_acq_assisistance.Doppler0 + gps_acq_assisistance.dopplerUncertainty * 2;
                    d_doppler_min = gps_acq_assisistance.Doppler0 - gps_acq_assisistance.dopplerUncertainty * 2;
                }
            else
                {
                    d_doppler_max = gps_acq_assisistance.Doppler0 + 1000;
                    d_doppler_min = gps_acq_assisistance.Doppler0 - 1000;
                }
            this->d_disable_assist = false;
            std::cout << "Acq assist ENABLED for GPS SV " << this->d_gnss_synchro->PRN << " (Doppler max,Doppler min)=("
                      << d_doppler_max << "," << d_doppler_min << ")\n";
        }
    else
        {
            this->d_disable_assist = true;
            std::cout << "Acq assist DISABLED for GPS SV " << this->d_gnss_synchro->PRN << '\n';
        }
}


void pcps_assisted_acquisition_cc::reset_grid()
{
    d_well_count = 0;
    for (int32_t i = 0; i < d_num_doppler_points; i++)
        {
            for (uint32_t j = 0; j < d_fft_size; j++)
                {
                    d_grid_data[i][j] = 0.0;
                }
        }
}


void pcps_assisted_acquisition_cc::redefine_grid()
{
    if (this->d_disable_assist == true)
        {
            d_doppler_max = d_acq_params.doppler_max;
            d_doppler_min = d_acq_params.doppler_min;
        }
    // Create the search grid array
    d_num_doppler_points = floor(std::abs(d_doppler_max - d_doppler_min) / d_acq_params.doppler_step);

    d_grid_data = std::vector<std::vector<float>>(d_num_doppler_points, std::vector<float>(d_fft_size));

    // create the carrier Doppler wipeoff signals
    int32_t doppler_hz;
    float phase_step_rad;
    d_grid_doppler_wipeoffs = std::vector<std::vector<std::complex<float>>>(d_num_doppler_points, std::vector<std::complex<float>>(d_fft_size));
    for (int32_t doppler_index = 0; doppler_index < d_num_doppler_points; doppler_index++)
        {
            doppler_hz = d_doppler_min + d_acq_params.doppler_step * doppler_index;
            // doppler search steps
            // compute the carrier doppler wipe-off signal and store it
            phase_step_rad = static_cast<float>(TWO_PI) * doppler_hz / static_cast<float>(d_acq_params.fs_in);
            std::array<float, 1> _phase{};
            volk_gnsssdr_s32f_sincos_32fc(d_grid_doppler_wipeoffs[doppler_index].data(), -phase_step_rad, _phase.data(), d_fft_size);
        }
}


float pcps_assisted_acquisition_cc::search_maximum()
{
    float magt = 0.0;
    float fft_normalization_factor;
    int32_t index_doppler = 0;
    uint32_t tmp_intex_t = 0;
    uint32_t index_time = 0;

    for (int32_t i = 0; i < d_num_doppler_points; i++)
        {
            volk_gnsssdr_32f_index_max_32u(&tmp_intex_t, d_grid_data[i].data(), d_fft_size);
            if (d_grid_data[i][tmp_intex_t] > magt)
                {
                    magt = d_grid_data[i][index_time];
                    index_doppler = i;
                    index_time = tmp_intex_t;
                }
        }

    // Normalize the maximum value to correct the scale factor introduced by FFTW
    fft_normalization_factor = static_cast<float>(d_fft_size) * static_cast<float>(d_fft_size);
    magt = magt / (fft_normalization_factor * fft_normalization_factor);

    // 5- Compute the test statistics and compare to the threshold
    d_test_statistics = 2.0F * d_fft_size * magt / (d_input_power * d_well_count);

    // 4- record the maximum peak and the associated synchronization parameters
    d_gnss_synchro->Acq_delay_samples = static_cast<double>(index_time);
    d_gnss_synchro->Acq_doppler_hz = static_cast<double>(index_doppler * d_acq_params.doppler_step + d_doppler_min);
    d_gnss_synchro->Acq_samplestamp_samples = d_sample_counter;
    d_gnss_synchro->Acq_doppler_step = d_acq_params.doppler_step;

    // Record results to file if required
    if (d_acq_params.dump)
        {
            std::stringstream filename;
            std::streamsize n = 2 * sizeof(float) * (d_fft_size);  // complex file write
            filename.str("");
            filename << "./test_statistics_" << d_gnss_synchro->System
                     << "_" << d_gnss_synchro->Signal[0] << d_gnss_synchro->Signal[1] << "_sat_"
                     << d_gnss_synchro->PRN << "_doppler_" << d_gnss_synchro->Acq_doppler_hz << ".dat";
            d_dump_file.open(filename.str().c_str(), std::ios::out | std::ios::binary);
            d_dump_file.write(reinterpret_cast<char *>(d_grid_data[index_doppler].data()), n);  // write directly |abs(x)|^2 in this Doppler bin?
            d_dump_file.close();
        }

    return d_test_statistics;
}


float pcps_assisted_acquisition_cc::estimate_input_power(gr_vector_const_void_star &input_items) const
{
    const auto *in = reinterpret_cast<const gr_complex *>(input_items[0]);  // Get the input samples pointer
    // 1- Compute the input signal power estimation
    std::vector<float> p_tmp_vector(d_fft_size);

    volk_32fc_magnitude_squared_32f(p_tmp_vector.data(), in, d_fft_size);

    float power;
    volk_32f_accumulator_s32f(&power, p_tmp_vector.data(), d_fft_size);
    return (power / static_cast<float>(d_fft_size));
}


int32_t pcps_assisted_acquisition_cc::compute_and_accumulate_grid(gr_vector_const_void_star &input_items)
{
    // initialize acquisition algorithm
    const auto *in = reinterpret_cast<const gr_complex *>(input_items[0]);  // Get the input samples pointer

    DLOG(INFO) << "Channel: " << d_channel
               << " , doing acquisition of satellite: " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN
               << " , sample stamp: " << d_sample_counter
               << ", threshold: " << d_acq_params.threshold
               << ", doppler_max: " << d_doppler_max
               << ", doppler_step: " << d_acq_params.doppler_step;

    // 2- Doppler frequency search loop
    std::vector<float> p_tmp_vector(d_fft_size);

    for (int32_t doppler_index = 0; doppler_index < d_num_doppler_points; doppler_index++)
        {
            // doppler search steps
            // Perform the carrier wipe-off
            volk_32fc_x2_multiply_32fc(d_fft_if->get_inbuf(), in, d_grid_doppler_wipeoffs[doppler_index].data(), d_fft_size);
            // 3- Perform the FFT-based convolution  (parallel time search)
            // Compute the FFT of the carrier wiped--off incoming signal
            d_fft_if->execute();

            // Multiply carrier wiped--off, Fourier transformed incoming signal
            // with the local FFT'd code reference using SIMD operations with VOLK library
            volk_32fc_x2_multiply_32fc(d_ifft->get_inbuf(), d_fft_if->get_outbuf(), d_fft_codes.data(), d_fft_size);

            // compute the inverse FFT
            d_ifft->execute();

            // save the grid matrix delay file
            volk_32fc_magnitude_squared_32f(p_tmp_vector.data(), d_ifft->get_outbuf(), d_fft_size);
            const float *old_vector = d_grid_data[doppler_index].data();
            volk_32f_x2_add_32f(d_grid_data[doppler_index].data(), old_vector, p_tmp_vector.data(), d_fft_size);
        }
    return d_fft_size;
}


int pcps_assisted_acquisition_cc::general_work(int noutput_items,
    gr_vector_int &ninput_items, gr_vector_const_void_star &input_items,
    gr_vector_void_star &output_items)
{
    /*!
     * TODO:     High sensitivity acquisition algorithm:
     *             State Machine:
     *             S0. StandBy. If d_active==1 -> S1
     *             S1. GetAssist. Define search grid with assistance information. Reset grid matrix -> S2
     *             S2. ComputeGrid. Perform the FFT acquisition doppler and delay grid.
     *                 Accumulate the search grid matrix (#doppler_bins x #fft_size)
     *                 Compare maximum to threshold and decide positive or negative
     *                 If T>=gamma -> S4 else
     *                 If d_well_count<max_dwells -> S2
     *                 else if !disable_assist -> S3
     *                 else -> S5.
     *             S3. RedefineGrid. Open the grid search to unasisted acquisition. Reset counters and grid. -> S2
     *             S4. Positive_Acq: Send message and stop acq -> S0
     *             S5. Negative_Acq: Send message and stop acq -> S0
     */

    if (!d_active)
        {
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            return 0;
        }

    switch (d_state)
        {
        case 0:  // S0. StandBy
            d_state = 1;
            break;
        case 1:  // S1. GetAssist
            get_assistance();
            redefine_grid();
            reset_grid();
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            d_state = 2;
            break;
        case 2:  // S2. ComputeGrid
            int32_t consumed_samples;
            consumed_samples = compute_and_accumulate_grid(input_items);
            d_well_count++;
            if (d_well_count >= static_cast<int32_t>(d_acq_params.max_dwells))
                {
                    d_state = 3;
                }
            d_sample_counter += static_cast<uint64_t>(consumed_samples);
            consume_each(consumed_samples);
            break;
        case 3:  // Compute test statistics and decide
            d_input_power = estimate_input_power(input_items);
            d_test_statistics = search_maximum();
            if (d_test_statistics > d_acq_params.threshold)
                {
                    d_state = 5;
                }
            else
                {
                    if (d_disable_assist == false)
                        {
                            d_disable_assist = true;
                            std::cout << "Acq assist DISABLED for GPS SV " << this->d_gnss_synchro->PRN << '\n';
                            d_state = 4;
                        }
                    else
                        {
                            d_state = 6;
                        }
                }
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            break;
        case 4:  // RedefineGrid
            redefine_grid();
            reset_grid();
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            d_state = 2;
            break;
        case 5:  // Positive_Acq
            DLOG(INFO) << "positive acquisition";
            DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
            DLOG(INFO) << "sample_stamp " << d_sample_counter;
            DLOG(INFO) << "test statistics value " << d_test_statistics;
            DLOG(INFO) << "test statistics threshold " << d_acq_params.threshold;
            DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
            DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
            DLOG(INFO) << "input signal power " << d_input_power;
            d_active = false;
            // Send message to channel port //0=STOP_CHANNEL 1=ACQ_SUCCESS 2=ACQ_FAIL
            this->message_port_pub(pmt::mp("events"), pmt::from_long(1));
            LOG(INFO) << "Successful acquisition in channel " << d_channel
                      << " for satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
            // consume samples to not block the GNU Radio flowgraph
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            d_state = 0;
            // Copy and push current Gnss_Synchro to monitor queue
            if (d_acq_params.enable_monitor_output)
                {
                    auto **out = reinterpret_cast<Gnss_Synchro **>(&output_items[0]);
                    Gnss_Synchro current_synchro_data = Gnss_Synchro();
                    current_synchro_data = *d_gnss_synchro;
                    *out[0] = std::move(current_synchro_data);
                    noutput_items = 1;  // Number of Gnss_Synchro objects produced
                }
            break;
        case 6:  // Negative_Acq
            DLOG(INFO) << "negative acquisition";
            DLOG(INFO) << "satellite " << d_gnss_synchro->System << " " << d_gnss_synchro->PRN;
            DLOG(INFO) << "sample_stamp " << d_sample_counter;
            DLOG(INFO) << "test statistics value " << d_test_statistics;
            DLOG(INFO) << "test statistics threshold " << d_acq_params.threshold;
            DLOG(INFO) << "code phase " << d_gnss_synchro->Acq_delay_samples;
            DLOG(INFO) << "doppler " << d_gnss_synchro->Acq_doppler_hz;
            DLOG(INFO) << "input signal power " << d_input_power;
            d_active = false;
            // Send message to channel port //0=STOP_CHANNEL 1=ACQ_SUCCESS 2=ACQ_FAIL
            this->message_port_pub(pmt::mp("events"), pmt::from_long(2));
            // consume samples to not block the GNU Radio flowgraph
            d_sample_counter += static_cast<uint64_t>(ninput_items[0]);  // sample counter
            consume_each(ninput_items[0]);
            d_state = 0;
            break;
        default:
            d_state = 0;
            break;
        }

    return noutput_items;
}
