/*@!Encoding:1252*/

// This file contains functions that abstract the Ethernet Interaction Layer
/// It provides following methods
///   - _ModbusConnectTo()		Prepare anything that sending works. Here: Create a new packet
///   - _ModbusDisconnect()		Gracefully disconnect from the device. Here: Invalidate the existing packet
///   - _ModbusRecv()			Receive data from the device. Here: Does nothing, receiving takes place automatically
///   - _ModbusSnd()			Send data to the device. Here: Fills the packet with payload data and sends it
///   - Some function that receives packets and hands them to _OnModbusReceive()

includes
{
	#include "Common.cin"
	#include "TcpUdpEilCommon.cin"
}

variables
{
	long gPacket;						// The packet that will be send
	msTimer gtModbusArp;				// A timer waiting for the ARP response
	
	byte gLocalMac[6];					// Storage of the local  MAC address
	byte gRemoteMac[6];					// Storage of the remote MAC address (the one of the device)
	// TODO: The local IP should not have to be specified here. Where can we get it from?
	dword gLocalIP = 0xC0A80101;		// The local IP address.
}

// This method prepares anything in a way that sending with ModbusSnd() is possible.
// Here: The method will create an ARP telegram to get the MAC address of the device with the specified Remote_IP
word _ModbusConnectTo(char Remote_IP[], word remotePort)
{
	dword remoteIp;

	// Convert IP string to Number
	remoteIp = IpGetAddressAsNumber(Remote_IP);
	if (remoteIp == INVALID_IP)
	{
		writeDbg(ConnError, "EilConnectTo: invalid server Ip address!");
		OnModbusClientPanics(ConnectionError);
		return ipGetLastError();
	}

	return _ModbusConnectTo(remoteIp, remotePort);
}
// This method prepares anything in a way that sending with ModbusSnd() is possible.
// Here: The method will create an ARP telegram to get the MAC address of the device with the specified remoteIp
word _ModbusConnectTo(dword remoteIp, word remotePort)
{
	long error;
	byte broadcastMac[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

	if (EthGetMacId(gLocalMac) != 0)
	{
		gSocketState = ERROR;
		error = EthGetLastError();
		writeDbg(ConnError, "EthGetMacId: Could not get local MAC! %d", error);
		OnModbusClientPanics(ConnectionError);
		return error;
	}

	// TCP/IP API gives IP in little endian but EIL uses big endian
	gRemotePort = remotePort;
	gRemoteIP = (remoteIp >> 24) | (remoteIp >> 8) & 0x0000FF00 | (remoteIp << 8) & 0x00FF0000 | (remoteIp << 24);

	if (gPacket != 0)
		_ModbusDisconnect();
	// Try to create an ARP packet that gets the MAC from remote server
	gPacket = EthInitPacket("arp");
	if (gPacket == 0)
	{
		gSocketState = ERROR;
		error = EthGetLastError();
		writeDbg(ConnError, "EthInitPacket: Could not create ARP package! %d", error);
		OnModbusClientPanics(ConnectionError);
		return error;
	}

	gSocketState = CONNECTING;

	EthSetTokenData(gPacket,	"eth",	"source"				, elCount(gLocalMac), gLocalMac);
	EthSetTokenData(gPacket,	"eth",	"destination"			, elCount(broadcastMac), broadcastMac);
	EthSetTokenInt(gPacket,		"arp",	"hwType"				, 1);			// Ethernet
	EthSetTokenInt(gPacket,		"arp",	"protType"				, 0x0800);		// IPv4
	EthSetTokenInt(gPacket,		"arp",	"hwSize"				, 6);			// Ethernet addr size
	EthSetTokenInt(gPacket,		"arp",	"protSize"				, 4);			// IP addr size
	EthSetTokenInt(gPacket,		"arp",	"operation"				, 1);
	EthSetTokenData(gPacket,	"arp",	"hwSourceAddr"			, elCount(gLocalMac), gLocalMac);
	EthSetTokenInt(gPacket,		"arp",	"protSourceAddr"		, gLocalIP);
	EthSetTokenInt(gPacket,		"arp",	"protDestinationAddr"	, gRemoteIP);

	EthReceivePacket("OnEthReceivePacket");

	EthCompletePacket(gPacket);
	EthOutputPacket(gPacket);
	EthReleasePacket(gPacket);
	gSocketState = NULL;
	gtModbusArp.set(@sysvar::Config::Modbus::RequestTimeout);
	return 0;
}
// This method prepares anything in a way that sending with ModbusSnd() is possible.
// Here: The method will be called after an ARP telegram was received and set up the EthernetIL packet.
void _ModbusConnectTo2()
{
	gPacket = EthInitPacket("udp");
	if (gPacket == 0)
	{
		gSocketState = ERROR;
		writeDbg(ConnError, "EthInitPacket: Could not create UDP packet: %d", EthGetLastError());
		OnModbusClientPanics(ConnectionError);
		return;
	}

	EthSetTokenData(gPacket,	"eth",	"source"				, elCount(gLocalMac), gLocalMac);
	EthSetTokenData(gPacket,	"eth",	"destination"			, elCount(gRemoteMac), gRemoteMac);
	EthSetTokenInt(gPacket,		"ipv4",	"source"				, gLocalIP);
	EthSetTokenInt(gPacket,		"ipv4",	"destination"			, gRemoteIP);
	EthSetTokenInt(gPacket,		"udp",	"source"				, 23456);
	EthSetTokenInt(gPacket,		"udp",	"destination"			, 502);

	gSocketState = OK;
}

// This method will gracefully disconnect from the remote device.
// Here: The method will invalidate the packet 'gPacket'
void _ModbusDisconnect()
{
	if (gPacket != 0)
	{
		EthReleasePacket(gPacket);
		gPacket = 0;
	}
	gSocketState = CLOSED;
}

// This method will wait for data from the remote device.
// Here: Nothing has to be done, EthernetIL is waiting for packets all the time
void _ModbusRecv()
{
}

// This method will send the payload 'buffer' to the device.
// Here: It fills the packet 'gPacket' and sends it
byte _ModbusSnd(byte buffer[], word length)
{
	char str[20*3];

	switch (gSocketState)
	{
		case CLOSED:
			_ModbusConnectTo(gRemoteIP, gRemotePort);
			if (gSocketState != OK)
			{
				writeDbg(ConnWarning, "_ModbusSnd: Reconnecting failed!");
				return 1;
			}
		case OK:
			break;
		case NULL:										// Delay
		case CONNECTING:
			return 1;
		case ERROR:
			writeDbg(ConnError, "_ModbusSnd: Socket status is not OK!");
			OnModbusClientPanics(ConnectionError);
			return 1;
		default:
			writeDbg(ConnError, "_ModbusSnd: Unknown socket status: %d", gSocketState);
			OnModbusClientPanics(SwitchArgumentInvalid);
			return 1;
	}

	bin_to_strhex(buffer, str);
	writeDbg(ConnDebug, "_ModbusSnd: %s (Länge: %d)", str, length);

	EthResizeToken(gPacket,		"udp",	"data"	, length*8);
	EthSetTokenData(gPacket,	"udp",	"data"	, length, buffer);

	EthCompletePacket(gPacket);
	EthOutputPacket(gPacket);

	return 0;
}

// This Method simply combines the two EthGetLastError functions
long _ModbusGetLastConnectionError(char string[])
{
	EthGetLastErrorText(elCount(string), string);
	return EthGetLastError();
}

// When the ARP times out the "connection" could not be opened and we have to throw an error
on timer gtModbusArp
{
	gSocketState = ERROR;
	writeDbg(ConnError, "No (valid) ARP response detected. The host seems to be offline!");
	OnModbusClientPanics(ConnectionError);
}

// This function will handle incoming packets and give them to the Modbus layer
void OnEthReceivePacket(long channel, long dir, long packet)
{
	byte buffer[gModbusMaxTelegramSize];
	long size;

	if (dir == TX)
		return;

	if (EthGetTokenInt(packet, "arp", "protSourceAddr") == gRemoteIP)								// this was our ARP package
	{
		if (EthGetTokenData(packet, "arp", "hwSourceAddr", elCount(gRemoteMac), gRemoteMac) == 6)	// save it
		{
			gtModbusArp.Cancel();
			writeDbg(ConnDebug, "Remote Mac: %02X:%02X:%02X:%02X:%02X:%02X", gRemoteMac[0], gRemoteMac[1], gRemoteMac[2], gRemoteMac[3], gRemoteMac[4], gRemoteMac[5]);
			_ModbusConnectTo2();		// create the UDP package
			_ModbusStartQueue();
		}
		return;
	}

	if (EthGetTokenInt(packet, "ipv4", "protocol") == 0x11 && EthGetTokenInt(packet, "ipv4", "source") == gRemoteIP)	// if this is a UDP package from our server
	{
		size = EthGetThisData(0, gModbusMaxTelegramSize, buffer);
		_OnModbusReceive(0, 0, EthGetTokenInt(packet, "ipv4", "source"), gRemoteIP, buffer, size);	// Hand to Modbus Layer
	}
}