/*
	Copyright (C) 2019-2021 Doug McLain

	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 <https://www.gnu.org/licenses/>.
*/

#include <cstring>
#include <iostream>
#include "m17codec.h"
#define M17CHARACTERS " ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-/."

#define DEBUG

M17Codec::M17Codec(QString callsign, char module, QString hostname, QString host, int port, bool ipv6, QString modem, QString audioin, QString audioout) :
	Codec(callsign, module, hostname, host, port, ipv6, NULL, modem, audioin, audioout),
	m_txrate(1)
{
	m_modeinfo.callsign = callsign;
	m_modeinfo.host = host;
	m_modeinfo.port = port;
	m_modeinfo.count = 0;
	m_modeinfo.frame_number = 0;
	m_modeinfo.streamid = 0;
#ifdef Q_OS_WIN
	m_txtimerint = 30; // Qt timers on windows seem to be slower than desired value

#else
	m_txtimerint = 36;
#endif
}

M17Codec::~M17Codec()
{
}

void M17Codec::encode_callsign(uint8_t *callsign)
{
	const std::string m17_alphabet(M17CHARACTERS);
	char cs[10];
	memset(cs, 0, sizeof(cs));
	memcpy(cs, callsign, strlen((char *)callsign));
	uint64_t encoded = 0;
	for(int i = std::strlen((char *)callsign)-1; i >= 0; i--) {
		auto pos = m17_alphabet.find(cs[i]);
		if (pos == std::string::npos) {
			pos = 0;
		}
		encoded *= 40;
		encoded += pos;
	}
	for (int i=0; i<6; i++) {
		callsign[i] = (encoded >> (8*(5-i)) & 0xFFU);
	}
}

void M17Codec::decode_callsign(uint8_t *callsign)
{
	const std::string m17_alphabet(M17CHARACTERS);
	uint8_t code[6];
	uint64_t coded = callsign[0];
	for (int i=1; i<6; i++)
		coded = (coded << 8) | callsign[i];
	if (coded > 0xee6b27ffffffu) {
		std::cerr << "Callsign code is too large, 0x" << std::hex << coded << std::endl;
		return;
	}
	memcpy(code, callsign, 6);
	memset(callsign, 0, 10);
	int i = 0;
	while (coded) {
		if(i < 10){
			callsign[i++] = m17_alphabet[coded % 40];
		}
		coded /= 40;
	}
}

void M17Codec::decode_c2(int16_t *audio, uint8_t *c)
{
	m_c2->codec2_decode(audio, c);
}

void M17Codec::encode_c2(int16_t *audio, uint8_t *c)
{
	m_c2->codec2_encode(c, audio);
}

void M17Codec::process_udp()
{
	QByteArray buf;
	QHostAddress sender;
	quint16 senderPort;

	buf.resize(m_udp->pendingDatagramSize());
	m_udp->readDatagram(buf.data(), buf.size(), &sender, &senderPort);
#ifdef DEBUG
	fprintf(stderr, "RECV: ");
	for(int i = 0; i < buf.size(); ++i){
		fprintf(stderr, "%02x ", (unsigned char)buf.data()[i]);
	}
	fprintf(stderr, "\n");
	fflush(stderr);
#endif
	if((m_modeinfo.status != CONNECTED_RW) && (buf.size() == 4) && (::memcmp(buf.data(), "NACK", 4U) == 0)){
		m_modeinfo.status = DISCONNECTED;
	}
	if((buf.size() == 4) && (::memcmp(buf.data(), "ACKN", 4U) == 0)){
		if(m_modeinfo.status == CONNECTING){
			m_modeinfo.status = CONNECTED_RW;
			m_c2 = new CCodec2(true);
			m_txtimer = new QTimer();
			connect(m_txtimer, SIGNAL(timeout()), this, SLOT(transmit()));
			m_rxtimer = new QTimer();
			connect(m_rxtimer, SIGNAL(timeout()), this, SLOT(process_rx_data()));
			m_ping_timer = new QTimer();
			connect(m_ping_timer, SIGNAL(timeout()), this, SLOT(send_ping()));
			m_ping_timer->start(8000);
			m_audio = new AudioEngine(m_audioin, m_audioout);
			m_audio->init();
		}
		emit update(m_modeinfo);
	}
	if((buf.size() == 10) && (::memcmp(buf.data(), "PING", 4U) == 0)){
		if(m_modeinfo.streamid == 0){
			m_modeinfo.stream_state = STREAM_IDLE;
		}
		m_modeinfo.count++;
		emit update(m_modeinfo);
	}
	if((buf.size() == 54) && (::memcmp(buf.data(), "M17 ", 4U) == 0)){
		uint16_t streamid = (buf.data()[4] << 8) | (buf.data()[5] & 0xff);
		if( (m_modeinfo.streamid != 0) && (streamid != m_modeinfo.streamid) ){
			qDebug() << "New streamid received before timeout";
			m_modeinfo.streamid = 0;
			m_audio->stop_playback();
		}
		if( !m_tx && (m_modeinfo.streamid == 0) ){
			uint8_t cs[10];
			::memcpy(cs, &(buf.data()[12]), 6);
			decode_callsign(cs);
			m_modeinfo.src = QString((char *)cs);
			::memcpy(cs, &(buf.data()[6]), 6);
			decode_callsign(cs);
			m_modeinfo.dst = QString((char *)cs);
			m_modeinfo.streamid = streamid;
			m_audio->start_playback();

			if((buf.data()[19] & 0x06U) == 0x04U){
				m_modeinfo.type = 1;//"3200 Voice";
				set_mode(true);
			}
			else{
				m_modeinfo.type = 0;//"1600 V/D";
				set_mode(false);
			}

			if(!m_rxtimer->isActive()){
#ifdef Q_OS_WIN
				m_rxtimer->start(m_modeinfo.type ? m_rxtimerint : 32);
#else
				m_rxtimer->start(m_modeinfo.type ? m_rxtimerint : m_rxtimerint*2);
#endif
			}

			m_modeinfo.stream_state = STREAM_NEW;
			m_modeinfo.ts = QDateTime::currentMSecsSinceEpoch();
			qDebug() << "New stream from " << m_modeinfo.src << " to " << m_modeinfo.dst << " id == " << QString::number(m_modeinfo.streamid, 16);
		}
		else{
			m_modeinfo.stream_state = STREAMING;
		}

		m_modeinfo.frame_number = (buf.data()[34] << 8) | (buf.data()[35] & 0xff);
		m_rxwatchdog = 0;
		int s = 8;
		if(get_mode()){
			s = 16;
		}

		for(int i = 0; i < s; ++i){
			m_rxcodecq.append((uint8_t )buf.data()[36+i]);
		}

		if(m_modeinfo.frame_number & 0x8000){ // EOT
			qDebug() << "M17 stream ended";
			m_rxwatchdog = 0;
			m_modeinfo.stream_state = STREAM_END;
			m_modeinfo.ts = QDateTime::currentMSecsSinceEpoch();
			emit update(m_modeinfo);
			m_modeinfo.streamid = 0;
		}
		else{
			emit update(m_modeinfo);
		}
	}
	//emit update(m_modeinfo);
}

void M17Codec::hostname_lookup(QHostInfo i)
{
	if (!i.addresses().isEmpty()) {
		QByteArray out;
		uint8_t cs[10];
		memset(cs, ' ', 9);
		memcpy(cs, m_modeinfo.callsign.toLocal8Bit(), m_modeinfo.callsign.size());
		cs[8] = 'D';
		cs[9] = 0x00;
		M17Codec::encode_callsign(cs);
		out.append('C');
		out.append('O');
		out.append('N');
		out.append('N');
		out.append((char *)cs, 6);
		out.append(m_module);
		m_address = i.addresses().first();
		m_udp = new QUdpSocket(this);
		connect(m_udp, SIGNAL(readyRead()), this, SLOT(process_udp()));
		m_udp->writeDatagram(out, m_address, m_modeinfo.port);
#ifdef DEBUG
		fprintf(stderr, "CONN: ");
		for(int i = 0; i < out.size(); ++i){
			fprintf(stderr, "%02x ", (unsigned char)out.data()[i]);
		}
		fprintf(stderr, "\n");
		fflush(stderr);
#endif
	}
}

void M17Codec::send_ping()
{
	QByteArray out;
	uint8_t cs[10];
	memset(cs, ' ', 9);
	memcpy(cs, m_modeinfo.callsign.toLocal8Bit(), m_modeinfo.callsign.size());
	cs[8] = 'D';
	cs[9] = 0x00;
	encode_callsign(cs);
	out.append('P');
	out.append('O');
	out.append('N');
	out.append('G');
	out.append((char *)cs, 6);
	m_udp->writeDatagram(out, m_address, m_modeinfo.port);
#ifdef DEBUG
	fprintf(stderr, "PING: ");
	for(int i = 0; i < out.size(); ++i){
		fprintf(stderr, "%02x ", (unsigned char)out.data()[i]);
	}
	fprintf(stderr, "\n");
	fflush(stderr);
#endif
}

void M17Codec::send_disconnect()
{
	qDebug() << "send_disconnect()";
	QByteArray out;
	uint8_t cs[10];
	memset(cs, ' ', 9);
	memcpy(cs, m_modeinfo.callsign.toLocal8Bit(), m_modeinfo.callsign.size());
	cs[8] = 'D';
	cs[9] = 0x00;
	encode_callsign(cs);
	out.append('D');
	out.append('I');
	out.append('S');
	out.append('C');
	out.append((char *)cs, 6);
	m_udp->writeDatagram(out, m_address, m_modeinfo.port);
#ifdef DEBUG
	fprintf(stderr, "SEND: ");
	for(int i = 0; i < out.size(); ++i){
		fprintf(stderr, "%02x ", (unsigned char)out.data()[i]);
	}
	fprintf(stderr, "\n");
	fflush(stderr);
#endif
}

void M17Codec::toggle_tx(bool tx)
{
	qDebug() << "M17Codec::toggle_tx(bool tx) == " << tx;
	tx ? start_tx() : stop_tx();
}

void M17Codec::start_tx()
{
	m_c2->codec2_set_mode(m_txrate);
	Codec::start_tx();
}

void M17Codec::transmit()
{
	QByteArray txframe;
	static uint16_t txstreamid = 0;
	static uint16_t tx_cnt = 0;
	int16_t pcm[320];
	uint8_t c2[16];
#ifdef USE_FLITE
	static uint16_t ttscnt = 0;
	if(m_ttsid > 0){
		for(int i = 0; i < 320; ++i){
			if(ttscnt >= tts_audio->num_samples/2){
				//audiotx_cnt = 0;
				pcm[i] = 0;
			}
			else{
				pcm[i] = tts_audio->samples[ttscnt*2] / 2;
				ttscnt++;
			}
		}
		m_c2->codec2_encode(c2, pcm);
		if(get_mode()){
			m_c2->codec2_encode(c2+8, pcm+160);
		}
	}
#endif
	if(m_ttsid == 0){
		if(m_audio->read(pcm, 320)){
			m_c2->codec2_encode(c2, pcm);
			if(get_mode()){
				m_c2->codec2_encode(c2+8, pcm+160);
			}
		}
		else{
			return;
		}
	}

	txframe.clear();
	emit update_output_level(m_audio->level());
	int r = get_mode() ? 0x05 : 0x07;
	if(m_tx){
		if(txstreamid == 0){
		   txstreamid = static_cast<uint16_t>((::rand() & 0xFFFF));
		   //std::cerr << "txstreamid == " << txstreamid << std::endl;
		}
		uint8_t src[10];
		uint8_t dst[10];
		memset(dst, ' ', 9);
		memcpy(dst, m_hostname.toLocal8Bit(), m_hostname.size());
		dst[8] =  m_module;
		dst[9] = 0x00;
		encode_callsign(dst);
		memset(src, ' ', 9);
		memcpy(src, m_modeinfo.callsign.toLocal8Bit(), m_modeinfo.callsign.size());
		src[8] = 'D';
		src[9] = 0x00;
		encode_callsign(src);

		txframe.append('M');
		txframe.append('1');
		txframe.append('7');
		txframe.append(' ');
		txframe.append(txstreamid >> 8);
		txframe.append(txstreamid & 0xff);
		txframe.append((char *)dst, 6);
		txframe.append((char *)src, 6);
		txframe.append('\x00');
		txframe.append(r); // Frame type voice only
		txframe.append(14, 0x00); //Blank nonce
		txframe.append((char)(tx_cnt >> 8));
		txframe.append((char)tx_cnt & 0xff);
		txframe.append((char *)c2, 16);
		txframe.append(2, 0x00);

		//QString ss = QString("%1").arg(txstreamid, 4, 16, QChar('0'));
		//QString n = QString("TX %1").arg(tx_cnt, 4, 16, QChar('0'));

		m_udp->writeDatagram(txframe, m_address, m_modeinfo.port);
		++tx_cnt;
		m_modeinfo.src = m_modeinfo.callsign;
		m_modeinfo.dst = m_hostname;
		m_modeinfo.type = get_mode();// ? "3200 Voice" : "1600 V/D";
		m_modeinfo.frame_number = tx_cnt;
		m_modeinfo.streamid = txstreamid;
		emit update(m_modeinfo);

		fprintf(stderr, "SEND:%d: ", txframe.size());
		for(int i = 0; i < txframe.size(); ++i){
			fprintf(stderr, "%02x ", (unsigned char)txframe.data()[i]);
		}
		fprintf(stderr, "\n");
		fflush(stderr);
	}
	else{
		const uint8_t quiet3200[] = { 0x00, 0x01, 0x43, 0x09, 0xe4, 0x9c, 0x08, 0x21 };
		const uint8_t quiet1600[] = { 0x01, 0x00, 0x04, 0x00, 0x25, 0x75, 0xdd, 0xf2 };
		const uint8_t *quiet = (get_mode()) ? quiet3200 : quiet1600;
		uint8_t src[10];
		uint8_t dst[10];
		memset(dst, ' ', 9);
		memcpy(dst, m_hostname.toLocal8Bit(), m_hostname.size());
		dst[8] =  m_module;
		dst[9] = 0x00;
		encode_callsign(dst);
		memset(src, ' ', 9);
		memcpy(src, m_modeinfo.callsign.toLocal8Bit(), m_modeinfo.callsign.size());
		src[8] = 'D';
		src[9] = 0x00;
		M17Codec::encode_callsign(src);
		tx_cnt |= 0x8000u;

		txframe.append('M');
		txframe.append('1');
		txframe.append('7');
		txframe.append(' ');
		txframe.append(txstreamid >> 8);
		txframe.append(txstreamid & 0xff);
		txframe.append((char *)dst, 6);
		txframe.append((char *)src, 6);
		txframe.append('\x00');
		txframe.append(r); // Frame type voice only
		txframe.append(14, 0x00); //Blank nonce
		txframe.append((char)(tx_cnt >> 8));
		txframe.append((char)tx_cnt & 0xff);
		txframe.append((char *)quiet, 8);
		txframe.append((char *)quiet, 8);
		txframe.append(2, 0x00);

		//QString n = QString("%1").arg(tx_cnt, 4, 16, QChar('0'));
		m_udp->writeDatagram(txframe, m_address, m_modeinfo.port);
		txstreamid = 0;
		tx_cnt = 0;
#ifdef USE_FLITE
		ttscnt = 0;
#endif
		m_txtimer->stop();
		if(m_ttsid == 0){
			m_audio->stop_capture();
		}
		m_modeinfo.src = m_modeinfo.callsign;
		m_modeinfo.dst = m_hostname;
		m_modeinfo.type = get_mode();// ? "3200 Voice" : "1600 V/D";
		m_modeinfo.frame_number = tx_cnt;
		m_modeinfo.streamid = txstreamid;
		emit update(m_modeinfo);
		fprintf(stderr, "LAST:%d: ", txframe.size());
		for(int i = 0; i < txframe.size(); ++i){
			fprintf(stderr, "%02x ", (unsigned char)txframe.data()[i]);
		}
		fprintf(stderr, "\n");
		fflush(stderr);
	}
}

void M17Codec::process_rx_data()
{
	int16_t pcm[320];
	uint8_t codec2[8];

	if(m_rxwatchdog++ > 50){
		qDebug() << "RX stream timeout ";
		m_rxwatchdog = 0;
		m_modeinfo.stream_state = STREAM_LOST;
		m_modeinfo.ts = QDateTime::currentMSecsSinceEpoch();
		emit update(m_modeinfo);
		m_modeinfo.streamid = 0;
	}

	if((!m_tx) && (m_rxcodecq.size() > 7) ){
		for(int i = 0; i < 8; ++i){
			codec2[i] = m_rxcodecq.dequeue();
		}
		m_c2->codec2_decode(pcm, codec2);
		int s = get_mode() ? 160 : 320;
		m_audio->write(pcm, s);
		emit update_output_level(m_audio->level());
	}
	else if ( (m_modeinfo.stream_state == STREAM_END) || (m_modeinfo.stream_state == STREAM_LOST) ){
		m_rxtimer->stop();
		m_audio->stop_playback();
		m_rxwatchdog = 0;
		m_modeinfo.streamid = 0;
		m_rxcodecq.clear();
		qDebug() << "M17 playback stopped";
		return;
	}
}