#define LOG_MODULE PacketLogModuleTelnetLayer

#include "TelnetLayer.h"
#include "Logger.h"

#include "GeneralUtils.h"
#include "SystemUtils.h"

#include <string.h>

namespace pcpp
{

bool TelnetLayer::isDataField(uint8_t *pos) const
{
	// "FF FF" means data
	return pos[0] != static_cast<int>(TelnetCommand::InterpretAsCommand) || pos[1] == static_cast<int>(TelnetCommand::InterpretAsCommand);
}

bool TelnetLayer::isCommandField(uint8_t *pos) const
{
	return !isDataField(pos);
}

size_t TelnetLayer::distanceToNextIAC(uint8_t *startPos, size_t maxLength)
{
	uint8_t *pos = nullptr;
	size_t addition = 0;
	size_t currentOffset = 0;
	do
	{
		// If it is second turn position should be adjusted to after second FF
		if (addition)
			addition += 2;

		pos = (uint8_t *)memchr(startPos + currentOffset + 1, static_cast<int>(TelnetCommand::InterpretAsCommand), maxLength - currentOffset);
		if (pos)
			addition += pos - (startPos + currentOffset);
		else
			addition += maxLength - currentOffset;
		currentOffset = currentOffset + addition;
		// "FF FF" means data continue
	} while (pos && (pos[1] == static_cast<int>(TelnetCommand::InterpretAsCommand)) && (currentOffset < maxLength));

	return addition;
}

size_t TelnetLayer::getFieldLen(uint8_t *startPos, size_t maxLength)
{
	// Check first byte is IAC
	if (startPos && (startPos[0] == static_cast<int>(TelnetCommand::InterpretAsCommand)) && (maxLength >= 2))
	{
		// If subnegotiation parse until next IAC
		if (startPos[1] == static_cast<int>(TelnetCommand::Subnegotiation))
			return distanceToNextIAC(startPos, maxLength);
		// Only WILL, WONT, DO, DONT have option. Ref http://pcmicro.com/netfoss/telnet.html
		else if (startPos[1] >= static_cast<int>(TelnetCommand::WillPerform) && startPos[1] <= static_cast<int>(TelnetCommand::DontPerform))
			return 3;
		return 2;
	}
	return distanceToNextIAC(startPos, maxLength);
}

uint8_t *TelnetLayer::getNextDataField(uint8_t *pos, size_t len)
{
	size_t offset = 0;
	while (offset < len)
	{
		// Move to next field
		size_t length = getFieldLen(pos, len - offset);
		pos += length;
		offset += length;

		if (isDataField(pos))
			return pos;
	}

	return nullptr;
}

uint8_t *TelnetLayer::getNextCommandField(uint8_t *pos, size_t len)
{
	size_t offset = 0;
	while (offset < len)
	{
		// Move to next field
		size_t length = getFieldLen(pos, len - offset);
		pos += length;
		offset += length;

		if (isCommandField(pos))
			return pos;
	}

	return nullptr;
}

int16_t TelnetLayer::getSubCommand(uint8_t *pos, size_t len)
{
	if (len < 3 || pos[1] < static_cast<int>(TelnetCommand::Subnegotiation))
		return static_cast<int>(TelnetOption::TelnetOptionNoOption);
	return pos[2];
}

uint8_t *TelnetLayer::getCommandData(uint8_t *pos, size_t &len)
{
	if (pos[1] == static_cast<int>(TelnetCommand::Subnegotiation) && len > 3)
	{
		len -= 3;
		return &pos[3];
	}
	len = 0;
	return nullptr;
}

std::string TelnetLayer::getDataAsString(bool removeEscapeCharacters)
{
	uint8_t *dataPos = nullptr;
	if (isDataField(m_Data))
		dataPos = m_Data;
	else
		dataPos = getNextDataField(m_Data, m_DataLen);

	if (!dataPos)
	{
		PCPP_LOG_DEBUG("Packet does not have a data field");
		return std::string();
	}

	// Convert to string
	if (removeEscapeCharacters)
	{
		std::stringstream ss;
		for (size_t idx = 0; idx < m_DataLen - (dataPos - m_Data) + 1; ++idx)
		{
			if (int(dataPos[idx]) < 127 && int(dataPos[idx]) > 31) // From SPACE to ~
				ss << dataPos[idx];
		}
		return ss.str();
	}
	return std::string((char *)m_Data, m_DataLen);
}

size_t TelnetLayer::getTotalNumberOfCommands()
{
	size_t ctr = 0;
	if (isCommandField(m_Data))
		++ctr;

	uint8_t *pos = m_Data;
	while (pos != nullptr)
	{
		size_t offset = pos - m_Data;
		pos = getNextCommandField(pos, m_DataLen - offset);
		if (pos)
			++ctr;
	}

	return ctr;
}

size_t TelnetLayer::getNumberOfCommands(TelnetCommand command)
{
	if (static_cast<int>(command) < 0)
		return 0;

	size_t ctr = 0;
	if (isCommandField(m_Data) && m_Data[1] == static_cast<int>(command))
		++ctr;

	uint8_t *pos = m_Data;
	while (pos != nullptr)
	{
		size_t offset = pos - m_Data;
		pos = getNextCommandField(pos, m_DataLen - offset);
		if (pos && pos[1] == static_cast<int>(command))
			++ctr;
	}

	return ctr;
}

TelnetLayer::TelnetCommand TelnetLayer::getFirstCommand()
{
	// If starts with command
	if (isCommandField(m_Data))
		return static_cast<TelnetCommand>(m_Data[1]);

	// Check is there any command
	uint8_t *pos = getNextCommandField(m_Data, m_DataLen);
	if (pos)
		return static_cast<TelnetCommand>(pos[1]);
	return TelnetCommand::TelnetCommandEndOfPacket;
}

TelnetLayer::TelnetCommand TelnetLayer::getNextCommand()
{
	if (lastPositionOffset == SIZE_MAX)
	{
		lastPositionOffset = 0;
		if (isCommandField(m_Data))
			return static_cast<TelnetLayer::TelnetCommand>(m_Data[1]);
	}

	uint8_t *pos = getNextCommandField(&m_Data[lastPositionOffset], m_DataLen - lastPositionOffset);
	if (pos)
	{
		lastPositionOffset = pos - m_Data;
		return static_cast<TelnetLayer::TelnetCommand>(pos[1]);
	}
	lastPositionOffset = SIZE_MAX;
	return TelnetCommand::TelnetCommandEndOfPacket;
}

TelnetLayer::TelnetOption TelnetLayer::getOption()
{
	if (lastPositionOffset < m_DataLen)
		return static_cast<TelnetOption>(getSubCommand(
			&m_Data[lastPositionOffset], getFieldLen(&m_Data[lastPositionOffset], m_DataLen - lastPositionOffset)));
	return TelnetOption::TelnetOptionNoOption;
}

TelnetLayer::TelnetOption TelnetLayer::getOption(TelnetCommand command)
{
	// Check input
	if (static_cast<int>(command) < 0)
	{
		PCPP_LOG_ERROR("Command type can't be negative");
		return TelnetOption::TelnetOptionNoOption;
	}

	if (isCommandField(m_Data) && m_Data[1] == static_cast<int>(command))
		return static_cast<TelnetOption>(getSubCommand(m_Data, getFieldLen(m_Data, m_DataLen)));

	uint8_t *pos = m_Data;
	while (pos != nullptr)
	{
		size_t offset = pos - m_Data;
		pos = getNextCommandField(pos, m_DataLen - offset);

		if (pos && pos[1] == static_cast<int>(command))
			return static_cast<TelnetOption>(getSubCommand(pos, getFieldLen(pos, m_DataLen - offset)));
	}

	PCPP_LOG_DEBUG("Can't find requested command");
	return TelnetOption::TelnetOptionNoOption;
}

uint8_t *TelnetLayer::getOptionData(size_t &length)
{
	if (lastPositionOffset < m_DataLen)
	{
		size_t lenBuffer = getFieldLen(&m_Data[lastPositionOffset], m_DataLen - lastPositionOffset);
		uint8_t *posBuffer = getCommandData(&m_Data[lastPositionOffset], lenBuffer);

		length = lenBuffer;
		return posBuffer;
	}
	return nullptr;
}

uint8_t *TelnetLayer::getOptionData(TelnetCommand command, size_t &length)
{
	// Check input
	if (static_cast<int>(command) < 0)
	{
		PCPP_LOG_ERROR("Command type can't be negative");
		length = 0;
		return nullptr;
	}

	if (isCommandField(m_Data) && m_Data[1] == static_cast<int>(command))
	{
		size_t lenBuffer = getFieldLen(m_Data, m_DataLen);
		uint8_t *posBuffer = getCommandData(m_Data, lenBuffer);

		length = lenBuffer;
		return posBuffer;
	}

	uint8_t *pos = m_Data;
	while (pos != nullptr)
	{
		size_t offset = pos - m_Data;
		pos = getNextCommandField(pos, m_DataLen - offset);

		if (pos && pos[1] == static_cast<int>(command))
		{
			size_t lenBuffer = getFieldLen(m_Data, m_DataLen);
			uint8_t *posBuffer = getCommandData(m_Data, lenBuffer);

			length = lenBuffer;
			return posBuffer;
		}
	}

	PCPP_LOG_DEBUG("Can't find requested command");
	length = 0;
	return nullptr;
}

std::string TelnetLayer::getTelnetCommandAsString(TelnetCommand val)
{
	switch (val)
	{
	case TelnetCommand::TelnetCommandEndOfPacket:
		return "Reached end of packet while parsing";
	case TelnetCommand::EndOfFile:
		return "End of File";
	case TelnetCommand::Suspend:
		return "Suspend current process";
	case TelnetCommand::Abort:
		return "Abort Process";
	case TelnetCommand::EndOfRecordCommand:
		return "End of Record";
	case TelnetCommand::SubnegotiationEnd:
		return "Subnegotiation End";
	case TelnetCommand::NoOperation:
		return "No Operation";
	case TelnetCommand::DataMark:
		return "Data Mark";
	case TelnetCommand::Break:
		return "Break";
	case TelnetCommand::InterruptProcess:
		return "Interrupt Process";
	case TelnetCommand::AbortOutput:
		return "Abort Output";
	case TelnetCommand::AreYouThere:
		return "Are You There";
	case TelnetCommand::EraseCharacter:
		return "Erase Character";
	case TelnetCommand::EraseLine:
		return "Erase Line";
	case TelnetCommand::GoAhead:
		return "Go Ahead";
	case TelnetCommand::Subnegotiation:
		return "Subnegotiation";
	case TelnetCommand::WillPerform:
		return "Will Perform";
	case TelnetCommand::WontPerform:
		return "Wont Perform";
	case TelnetCommand::DoPerform:
		return "Do Perform";
	case TelnetCommand::DontPerform:
		return "Dont Perform";
	case TelnetCommand::InterpretAsCommand:
		return "Interpret As Command";
	default:
		return "Unknown Command";
	}
}

std::string TelnetLayer::getTelnetOptionAsString(TelnetOption val)
{
	switch (val)
	{
	case TelnetOption::TelnetOptionNoOption:
		return "No option for this command";
	case TelnetOption::TransmitBinary:
		return "Binary Transmission";
	case TelnetOption::Echo:
		return "Echo";
	case TelnetOption::Reconnection:
		return "Reconnection";
	case TelnetOption::SuppressGoAhead:
		return "Suppress Go Ahead";
	case TelnetOption::ApproxMsgSizeNegotiation:
		return "Negotiate approximate message size";
	case TelnetOption::Status:
		return "Status";
	case TelnetOption::TimingMark:
		return "Timing Mark";
	case TelnetOption::RemoteControlledTransAndEcho:
		return "Remote Controlled Transmission and Echo";
	case TelnetOption::OutputLineWidth:
		return "Output Line Width";
	case TelnetOption::OutputPageSize:
		return "Output Page Size";
	case TelnetOption::OutputCarriageReturnDisposition:
		return "Negotiate About Output Carriage-Return Disposition";
	case TelnetOption::OutputHorizontalTabStops:
		return "Negotiate About Output Horizontal Tabstops";
	case TelnetOption::OutputHorizontalTabDisposition:
		return "Negotiate About Output Horizontal Tab Disposition";
	case TelnetOption::OutputFormfeedDisposition:
		return "Negotiate About Output Formfeed Disposition";
	case TelnetOption::OutputVerticalTabStops:
		return "Negotiate About Vertical Tabstops";
	case TelnetOption::OutputVerticalTabDisposition:
		return "Negotiate About Output Vertcial Tab Disposition";
	case TelnetOption::OutputLinefeedDisposition:
		return "Negotiate About Output Linefeed Disposition";
	case TelnetOption::ExtendedASCII:
		return "Extended ASCII";
	case TelnetOption::Logout:
		return "Logout";
	case TelnetOption::ByteMacro:
		return "Byte Macro";
	case TelnetOption::DataEntryTerminal:
		return "Data Entry Terminal";
	case TelnetOption::SUPDUP:
		return "SUPDUP";
	case TelnetOption::SUPDUPOutput:
		return "SUPDUP Output";
	case TelnetOption::SendLocation:
		return "Send Location";
	case TelnetOption::TerminalType:
		return "Terminal Type";
	case TelnetOption::EndOfRecordOption:
		return "End Of Record";
	case TelnetOption::TACACSUserIdentification:
		return "TACACS User Identification";
	case TelnetOption::OutputMarking:
		return "Output Marking";
	case TelnetOption::TerminalLocationNumber:
		return "Terminal Location Number";
	case TelnetOption::Telnet3270Regime:
		return "Telnet 3270 Regime";
	case TelnetOption::X3Pad:
		return "X3 Pad";
	case TelnetOption::NegotiateAboutWindowSize:
		return "Negotiate About Window Size";
	case TelnetOption::TerminalSpeed:
		return "Terminal Speed";
	case TelnetOption::RemoteFlowControl:
		return "Remote Flow Control";
	case TelnetOption::Linemode:
		return "Line mode";
	case TelnetOption::XDisplayLocation:
		return "X Display Location";
	case TelnetOption::EnvironmentOption:
		return "Environment Option";
	case TelnetOption::AuthenticationOption:
		return "Authentication Option";
	case TelnetOption::EncryptionOption:
		return "Encryption Option";
	case TelnetOption::NewEnvironmentOption:
		return "New Environment Option";
	case TelnetOption::TN3270E:
		return "TN3270E";
	case TelnetOption::XAuth:
		return "X Server Authentication";
	case TelnetOption::Charset:
		return "Charset";
	case TelnetOption::TelnetRemoteSerialPort:
		return "Telnet Remote Serial Port";
	case TelnetOption::ComPortControlOption:
		return "Com Port Control Option";
	case TelnetOption::TelnetSuppressLocalEcho:
		return "Telnet Suppress Local Echo";
	case TelnetOption::TelnetStartTLS:
		return "Telnet Start TLS";
	case TelnetOption::Kermit:
		return "Kermit";
	case TelnetOption::SendURL:
		return "Send URL";
	case TelnetOption::ForwardX:
		return "Forward X Server";
	case TelnetOption::TelOptPragmaLogon:
		return "Telnet Option Pragma Logon";
	case TelnetOption::TelOptSSPILogon:
		return "Telnet Option SSPI Logon";
	case TelnetOption::TelOptPragmaHeartbeat:
		return "Telnet Option Pragma Heartbeat";
	case TelnetOption::ExtendedOptions:
		return "Extended option list";
	default:
		return "Unknown Option";
	}
}

std::string TelnetLayer::toString() const
{
	if (isDataField(m_Data))
		return "Telnet Data";
	return "Telnet Control";
}

} // namespace pcpp