/*
 * Copyright (C) John Baier 2014 <ebusd@johnm.de>
 *
 * This file is part of ebusd.
 *
 * ebusd 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.
 *
 * ebusd 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 ebusd. If not, see http://www.gnu.org/licenses/.
 */

#include "symbol.h"
#include "result.h"
#include <iostream>
#include <iomanip>

/**
 * @brief CRC8 lookup table for the polynom 0x9b = x^8 + x^7 + x^4 + x^3 + x^1 + 1.
 */
static const unsigned char CRC_LOOKUP_TABLE[] =
{
	0x00, 0x9b, 0xad, 0x36, 0xc1, 0x5a, 0x6c, 0xf7, 0x19, 0x82, 0xb4, 0x2f, 0xd8, 0x43, 0x75, 0xee,
	0x32, 0xa9, 0x9f, 0x04, 0xf3, 0x68, 0x5e, 0xc5, 0x2b, 0xb0, 0x86, 0x1d, 0xea, 0x71, 0x47, 0xdc,
	0x64, 0xff, 0xc9, 0x52, 0xa5, 0x3e, 0x08, 0x93, 0x7d, 0xe6, 0xd0, 0x4b, 0xbc, 0x27, 0x11, 0x8a,
	0x56, 0xcd, 0xfb, 0x60, 0x97, 0x0c, 0x3a, 0xa1, 0x4f, 0xd4, 0xe2, 0x79, 0x8e, 0x15, 0x23, 0xb8,
	0xc8, 0x53, 0x65, 0xfe, 0x09, 0x92, 0xa4, 0x3f, 0xd1, 0x4a, 0x7c, 0xe7, 0x10, 0x8b, 0xbd, 0x26,
	0xfa, 0x61, 0x57, 0xcc, 0x3b, 0xa0, 0x96, 0x0d, 0xe3, 0x78, 0x4e, 0xd5, 0x22, 0xb9, 0x8f, 0x14,
	0xac, 0x37, 0x01, 0x9a, 0x6d, 0xf6, 0xc0, 0x5b, 0xb5, 0x2e, 0x18, 0x83, 0x74, 0xef, 0xd9, 0x42,
	0x9e, 0x05, 0x33, 0xa8, 0x5f, 0xc4, 0xf2, 0x69, 0x87, 0x1c, 0x2a, 0xb1, 0x46, 0xdd, 0xeb, 0x70,
	0x0b, 0x90, 0xa6, 0x3d, 0xca, 0x51, 0x67, 0xfc, 0x12, 0x89, 0xbf, 0x24, 0xd3, 0x48, 0x7e, 0xe5,
	0x39, 0xa2, 0x94, 0x0f, 0xf8, 0x63, 0x55, 0xce, 0x20, 0xbb, 0x8d, 0x16, 0xe1, 0x7a, 0x4c, 0xd7,
	0x6f, 0xf4, 0xc2, 0x59, 0xae, 0x35, 0x03, 0x98, 0x76, 0xed, 0xdb, 0x40, 0xb7, 0x2c, 0x1a, 0x81,
	0x5d, 0xc6, 0xf0, 0x6b, 0x9c, 0x07, 0x31, 0xaa, 0x44, 0xdf, 0xe9, 0x72, 0x85, 0x1e, 0x28, 0xb3,
	0xc3, 0x58, 0x6e, 0xf5, 0x02, 0x99, 0xaf, 0x34, 0xda, 0x41, 0x77, 0xec, 0x1b, 0x80, 0xb6, 0x2d,
	0xf1, 0x6a, 0x5c, 0xc7, 0x30, 0xab, 0x9d, 0x06, 0xe8, 0x73, 0x45, 0xde, 0x29, 0xb2, 0x84, 0x1f,
	0xa7, 0x3c, 0x0a, 0x91, 0x66, 0xfd, 0xcb, 0x50, 0xbe, 0x25, 0x13, 0x88, 0x7f, 0xe4, 0xd2, 0x49,
	0x95, 0x0e, 0x38, 0xa3, 0x54, 0xcf, 0xf9, 0x62, 0x8c, 0x17, 0x21, 0xba, 0x4d, 0xd6, 0xe0, 0x7b,
};


SymbolString::SymbolString(const std::string str)
	: m_unescapeState(0), m_crc(0)
{
	// parse + escape
	for (size_t i = 0; i+1 < str.size(); i += 2) {
		unsigned long value = strtoul(str.substr(i, 2).c_str(), NULL, 16); // TODO check
		push_back((unsigned char)value, false, true);
	}
	// add CRC + escape
	push_back(m_crc, false, false);
}

SymbolString::SymbolString(const std::string str, bool isEscaped)
	: m_unescapeState(1), m_crc(0)
{
	// parse + optionally unescape
	for (size_t i = 0; i+1 < str.size(); i += 2) {
		unsigned long value = strtoul(str.substr(i, 2).c_str(), NULL, 16); // TODO check
		push_back((unsigned char)value, isEscaped, false);
	}
}

const std::string SymbolString::getDataStr(const bool unescape)
{
	std::stringstream sstr;
	bool previousEscape = false;

	for (size_t i = 0; i < m_data.size(); i++) {
		unsigned char value = m_data[i];
		if (m_unescapeState == 0 && unescape == true && previousEscape == true) {
			if (value == 0x00)
				sstr << "a9"; // ESC
			else if (value == 0x01)
				sstr << "aa"; // SYN
			else
				sstr << "XX"; // invalid escape sequence

			previousEscape = false;
		}
		else if (m_unescapeState == 0 && unescape == true && value == ESC) {
			previousEscape = true; // escape sequence not yet finished
		}
		else {
			sstr << std::nouppercase << std::setw(2) << std::hex
				 << std::setfill('0') << static_cast<unsigned>(value);
		}
	}

	return sstr.str();
}

int SymbolString::push_back(const unsigned char value, const bool isEscaped, const bool updateCRC)
{
	if (m_unescapeState == 0) { // store escaped data
		if (isEscaped == false && value == ESC) {
			m_data.push_back(ESC);
			m_data.push_back(0x00);
			if (updateCRC) {
				addCRC(ESC);
				addCRC(0x00);
			}
		}
		else if (isEscaped == false && value == SYN) {
			m_data.push_back(ESC);
			m_data.push_back(0x01);
			if (updateCRC) {
				addCRC(ESC);
				addCRC(0x01);
			}
		}
		else {
			m_data.push_back(value);
			if (updateCRC)
				addCRC(value);

		}
		return RESULT_OK;
	}
	else if (isEscaped == false) {
		if (m_unescapeState != 1)
			return RESULT_ERR_ESC; // invalid unescape state
		m_data.push_back(value);
		if (updateCRC) {
			if (value == ESC) {
				addCRC(ESC);
				addCRC(0x00);
			}
			else if (value == SYN) {
				addCRC(ESC);
				addCRC(0x01);
			}
			else {
				addCRC(value);
			}
		}
		return RESULT_OK;
	}
	else if (m_unescapeState != 1) {
		if (updateCRC)
			addCRC(value);

		if (value == 0x00) {
			m_data.push_back(ESC);
			m_unescapeState = 1;
			return RESULT_OK;
		}
		if (value == 0x01) {
			m_data.push_back(SYN);
			m_unescapeState = 1;
			return RESULT_OK;
		}
		return RESULT_ERR_ESC; // invalid escape sequence
	}
	else if (value == ESC) {
		if (updateCRC)
			addCRC(value);

		m_unescapeState = 2;
		return RESULT_IN_ESC;
	}
	if (updateCRC)
		addCRC(value);

	m_data.push_back(value);
	return RESULT_OK;
}

void SymbolString::addCRC(const unsigned char value) {
	m_crc = CRC_LOOKUP_TABLE[m_crc]^value;
}



bool isMaster(unsigned char addr) {
	unsigned char addrHi = (addr & 0xF0) >> 4;
	unsigned char addrLo = (addr & 0x0F);

	return ((addrHi == 0x0) || (addrHi == 0x1) || (addrHi == 0x3) || (addrHi == 0x7) || (addrHi == 0xF))
	    && ((addrLo == 0x0) || (addrLo == 0x1) || (addrLo == 0x3) || (addrLo == 0x7) || (addrLo == 0xF));
}