/**
* Digital Voice Modem - Host Software
* GPLv2 Open Source. Use is subject to license terms.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* @package DVM / Host Software
*
*/
/*
*   Copyright (C) 2022 by Bryan Biedenkapp N2PLL
*
*   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "Defines.h"
#include "dmr/lc/csbk/CSBKFactory.h"
#include "edac/BPTC19696.h"
#include "edac/CRC.h"
#include "Log.h"
#include "Utils.h"

using namespace dmr::lc::csbk;
using namespace dmr::lc;
using namespace dmr;

#include <cassert>

// ---------------------------------------------------------------------------
//  Public Class Members
// ---------------------------------------------------------------------------

/// <summary>
/// Initializes a new instance of the CSBKFactory class.
/// </summary>
CSBKFactory::CSBKFactory()
{
    /* stub */
}

/// <summary>
/// Finalizes a instance of CSBKFactory class.
/// </summary>
CSBKFactory::~CSBKFactory()
{
    /* stub */
}

/// <summary>
/// Create an instance of a CSBK.
/// </summary>
/// <param name="data"></param>
/// <returns>True, if CSBK was decoded, otherwise false.</returns>
std::unique_ptr<CSBK> CSBKFactory::createCSBK(const uint8_t* data)
{
    assert(data != nullptr);

    uint8_t csbk[DMR_CSBK_LENGTH_BYTES];

    // decode BPTC (196,96) FEC
    edac::BPTC19696 bptc;
    bptc.decode(data, csbk);

    // validate the CRC-CCITT 16
    csbk[10U] ^= CSBK_CRC_MASK[0U];
    csbk[11U] ^= CSBK_CRC_MASK[1U];

    bool valid = edac::CRC::checkCCITT162(csbk, DMR_CSBK_LENGTH_BYTES);
    if (!valid) {
        LogError(LOG_DMR, "CSBK::decode(), failed CRC CCITT-162 check");
        return nullptr;
    }

    // restore the checksum
    csbk[10U] ^= CSBK_CRC_MASK[0U];
    csbk[11U] ^= CSBK_CRC_MASK[1U];

    uint8_t CSBKO = csbk[0U] & 0x3FU;                                               // CSBKO
    uint8_t FID = csbk[1U];                                                         // Feature ID

    switch (CSBKO) {
    case CSBKO_BSDWNACT:
        return decode(new CSBK_BSDWNACT(), data);
    case CSBKO_UU_V_REQ:
        return decode(new CSBK_UU_V_REQ(), data);
    case CSBKO_UU_ANS_RSP:
        return decode(new CSBK_UU_ANS_RSP(), data);
    case CSBKO_PRECCSBK:
        return decode(new CSBK_PRECCSBK(), data);
    case CSBKO_RAND: // CSBKO_CALL_ALRT when FID == FID_DMRA
        switch (FID)
        {
        case FID_DMRA:
            return decode(new CSBK_CALL_ALRT(), data);
        case FID_ETSI:
        default:
            return decode(new CSBK_RAND(), data);
        }
    case CSBKO_EXT_FNCT:
        return decode(new CSBK_EXT_FNCT(), data);
    case CSBKO_NACK_RSP:
        return decode(new CSBK_NACK_RSP(), data);

    /** Tier 3 */
    case CSBKO_ACK_RSP:
        return decode(new CSBK_ACK_RSP(), data);

    default:
        LogError(LOG_DMR, "CSBKFactory::create(), unknown CSBK type, csbko = $%02X", CSBKO);
        break;
    }

    return nullptr;    
}

// ---------------------------------------------------------------------------
//  Private Class Members
// ---------------------------------------------------------------------------

/// <summary>
/// 
/// </summary>
/// <param name="csbk"></param>
/// <param name="data"></param>
/// <returns></returns>
std::unique_ptr<CSBK> CSBKFactory::decode(CSBK* csbk, const uint8_t* data)
{
    assert(csbk != nullptr);
    assert(data != nullptr);

    if (!csbk->decode(data)) {
        return nullptr;
    }

    return std::unique_ptr<CSBK>(csbk);
}