/*
    Copyright (C) 2014 CSP Innovazione nelle ICT s.c.a r.l. (http://www.csp.it/)
    Copyright (C) 2020 Matthias P. Braendli (http://www.opendigitalradio.org)
    Copyright (C) 2015 Data Path

    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/>.

    Authors:
         Sergio Sagliocco <sergio.sagliocco@csp.it>
         Matthias P. Braendli <matthias@mpb.li>
                   / |  |-  ')|)  |-|_ _ (|,_   .|  _  ,_ \
         Data Path \(|(||_(|/_| (||_||(a)_||||(|||.(_()|||/

*/

#include <vector>
#include <sstream>
#include "watermarkdecoder.hpp"

static std::string calc_watermark(const std::vector<bool>& bits)
{
    // First try to find the 0x55 0x55 sync in the waternark data
    size_t bit_ix;
    int alternance_count = 0;
    bool last_bit = 1;
    for (bit_ix = 0; bit_ix < bits.size(); bit_ix++) {
        if (alternance_count == 16) {
            break;
        }
        else {
            if (last_bit != bits[bit_ix]) {
                last_bit = bits[bit_ix];
                alternance_count++;
            }
            else {
                alternance_count = 0;
                last_bit = 1;
            }
        }
    }

    if (bit_ix < bits.size()) {
        fprintf(stderr, "Found SYNC at offset %zu out of %zu\n",
                bit_ix - alternance_count, bits.size());

        std::stringstream watermark_ss;

        uint8_t b = 0;
        size_t i = 0;
        while (bit_ix < bits.size()) {

            b |= bits[bit_ix] << (7 - i);

            if (i == 7) {
                watermark_ss << (char)b;

                b = 0;
                i = 0;
            }
            else {
                i++;
            }

            bit_ix += 2;
        }

        return watermark_ss.str();
    }
    else {
        return "";
    }
}

WatermarkDecoder::WatermarkDecoder() {}

void WatermarkDecoder::push_fig0_1_bit(bool bit)
{
    // The order of FIG0_1 subchannels represents the bits
    m_fig0_1_bits.push_back(bit);
}

void WatermarkDecoder::push_confind_bit(bool confind)
{
    // The ConfInd of FIG 0/10 contains the CRC-DABMUX and ODR-DabMux watermark
    m_confind_bits.push_back(confind);
}

std::string WatermarkDecoder::calculate_watermark()
{
    std::string w_old = calc_watermark(m_confind_bits);
    std::string w_new = calc_watermark(m_fig0_1_bits);
    if (not w_new.empty()) {
        return w_new;
    }
    else if (not w_old.empty()) {
        return w_old + " (old watermark)";
    }
    else {
        return "(NOT FOUND)";
    }
}