/*
 * Copyright 2003-2006, Waldemar Kornewald <wkornew@gmx.net>
 * Distributed under the terms of the MIT License.
 */

#include <cstdio>

#include "ModemDevice.h"
#include "ACFCHandler.h"
#include "fcs.h"

#include <core_funcs.h>
#include <unistd.h>
#include <termios.h>
	// for port settings

// from libkernelppp
#include <settings_tools.h>


#if DEBUG
static char sDigits[] = "0123456789ABCDEF";
void
dump_packet(struct mbuf *packet)
{
	if(!packet)
		return;
	
	uint8 *data = mtod(packet, uint8*);
	uint8 buffer[33];
	uint8 bufferIndex = 0;
	
	TRACE("Dumping packet;len=%ld;pkthdr.len=%d\n", packet->m_len,
		packet->m_flags & M_PKTHDR ? packet->m_pkthdr.len : -1);
	
	for(uint32 index = 0; index < packet->m_len; index++) {
		buffer[bufferIndex++] = sDigits[data[index] >> 4];
		buffer[bufferIndex++] = sDigits[data[index] & 0x0F];
		if(bufferIndex == 32 || index == packet->m_len - 1) {
			buffer[bufferIndex] = 0;
			TRACE("%s\n", buffer);
			bufferIndex = 0;
		}
	}
}
#endif


status_t
modem_put_line(int32 handle, const char *string, int32 length)
{
	char line[128];
	if(length > 126)
		return -1;
	
	sprintf(line, "%s\r", string);
	return write(handle, line, length + 1);
}


status_t
modem_get_line(int32 handle, char *string, int32 length, const char *echo)
{
	if(!string || length < 40)
		return -1;
	
	int32 result, position = 0;
	
	while(position < length) {
		result = read(handle, string + position, 1);
		if(result < 0)
			return -1;
		else if(result == 1) {
			if(string[position] == '\r') {
				string[position] = 0;
				if(!strcasecmp(string, echo)) {
					position = 0;
					continue;
				}
				
				return position;
			}
			
			position++;
		}
	}
	
	return -1;
}


static
status_t
worker_thread(void *data)
{
	ModemDevice *device = (ModemDevice*) data;
	int32 handle = device->Handle();
	uint8 buffer[MODEM_MTU];
	
	// send init string
	if(modem_put_line(handle, device->InitString(), strlen(device->InitString())) < 0
			|| modem_get_line(handle, (char*) buffer, sizeof(buffer),
					device->InitString()) < 0
			|| strcmp((char*) buffer, "OK")) {
		device->FailedDialing();
		return B_ERROR;
	}
	
	// send dial string
	if(modem_put_line(handle, device->DialString(), strlen(device->DialString())) < 0
			|| modem_get_line(handle, (char*) buffer, sizeof(buffer),
					device->DialString()) < 0
			|| strncmp((char*) buffer, "CONNECT", 7)) {
		device->FailedDialing();
		return B_ERROR;
	}
	
	if(strlen((char*) buffer) > 8)
		device->SetSpeed(atoi((char*) buffer + 8));
	else
		device->SetSpeed(19200);
	
	// TODO: authenticate if needed
	
	device->FinishedDialing();
	
	// start decoding
	int32 length = 0, position = 0;
	bool inPacket = true, needsEscape = false;
	
	while(true) {
		// ignore data if buffer is full
		if(position == MODEM_MTU)
			position = 0;
		
		length = read(handle, buffer + position, MODEM_MTU - position);
		
		if(length < 0 || !device->IsUp()) {
			device->ConnectionLost();
			return B_ERROR;
		}
		
		// decode the packet
		for(int32 index = 0; index < length; ) {
			if(buffer[position] == FLAG_SEQUENCE) {
				if(inPacket && position > 0)
					device->DataReceived(buffer, position);
						// DataReceived() will check FCS
				
				length = length - index - 1;
					// remaining data length
				memmove(buffer, buffer + position + 1, length);
				position = index = 0;
				
				needsEscape = false;
				inPacket = true;
				continue;
			}
			
			if(buffer[position + index] < 0x20) {
				++index;
				continue;
			}
			
			if(needsEscape) {
				buffer[position] = buffer[position + index] ^ 0x20;
				++position;
				needsEscape = false;
			} else if(buffer[position + index] == CONTROL_ESCAPE) {
				++index;
				needsEscape = true;
			} else {
				buffer[position] = buffer[position + index];
				++position;
			}
		}
	}
}


ModemDevice::ModemDevice(KPPPInterface& interface, driver_parameter *settings)
	: KPPPDevice("Modem", 0, interface, settings),
	fPortName(NULL),
	fHandle(-1),
	fWorkerThread(-1),
	fOutputBytes(0),
	fState(INITIAL)
{
#if DEBUG
	TRACE("ModemDevice: Constructor\n");
	if(!settings || !settings->parameters)
		TRACE("ModemDevice::ctor: No settings!\n");
#endif
	
	fACFC = new ACFCHandler(REQUEST_ACFC | ALLOW_ACFC, interface);
	if(!interface.LCP().AddOptionHandler(fACFC)) {
		fInitStatus = B_ERROR;
		return;
	}
	
	interface.SetPFCOptions(PPP_REQUEST_PFC | PPP_ALLOW_PFC);
	
	SetSpeed(19200);
	SetMTU(MODEM_MTU);
		// MTU size does not contain PPP header
	
	fPortName = get_parameter_value(MODEM_PORT_KEY, settings);
	fInitString = get_parameter_value(MODEM_INIT_KEY, settings);
	fDialString = get_parameter_value(MODEM_DIAL_KEY, settings);
	
	TRACE("ModemDevice::ctor: interfaceName: %s\n", fPortName);
}


ModemDevice::~ModemDevice()
{
	TRACE("ModemDevice: Destructor\n");
}


status_t
ModemDevice::InitCheck() const
{
	if(fState != INITIAL && Handle() == -1)
		return B_ERROR;
	
	return PortName() && InitString() && DialString()
		&& KPPPDevice::InitCheck() == B_OK ? B_OK : B_ERROR;
}


bool
ModemDevice::Up()
{
	TRACE("ModemDevice: Up()\n");
	
	if(InitCheck() != B_OK)
		return false;
	
	if(IsUp())
		return true;
	
	fState = INITIAL;
		// reset state
	
	// check if we are allowed to go up now (user intervention might disallow that)
	if(!UpStarted()) {
		CloseModem();
		DownEvent();
		return true;
			// there was no error
	}
	
	OpenModem();
	
	fState = DIALING;
	
	if(fWorkerThread == -1) {
		fWorkerThread = spawn_kernel_thread(worker_thread, "Modem: worker_thread",
			B_NORMAL_PRIORITY, this);
		resume_thread(fWorkerThread);
	}
	
	return true;
}


bool
ModemDevice::Down()
{
	TRACE("ModemDevice: Down()\n");
	
	if(InitCheck() != B_OK)
		return false;
	
	fState = TERMINATING;
	
	if(!IsUp()) {
		fState = INITIAL;
		CloseModem();
		DownEvent();
		return true;
	}
	
	DownStarted();
		// this tells StateMachine that DownEvent() does not mean we lost connection
	
	// worker_thread will notice that we are terminating (IsUp() == false)
	// ConnectionLost() will be called so we can terminate the connection there.
	int32 tmp;
	wait_for_thread(fWorkerThread, &tmp);
	
	DownEvent();
	
	return true;
}


void
ModemDevice::SetSpeed(uint32 bps)
{
	fInputTransferRate = bps / 8;
	fOutputTransferRate = (fInputTransferRate * 60) / 100;
		// 60% of input transfer rate
}


uint32
ModemDevice::InputTransferRate() const
{
	return fInputTransferRate;
}


uint32
ModemDevice::OutputTransferRate() const
{
	return fOutputTransferRate;
}


uint32
ModemDevice::CountOutputBytes() const
{
	return fOutputBytes;
}


void
ModemDevice::OpenModem()
{
	if(Handle() >= 0)
		return;
	
	fHandle = open(PortName(), O_RDWR);
	
	// init port
	struct termios options;
	if(ioctl(fHandle, TCGETA, &options) != B_OK) {
		ERROR("ModemDevice: Could not retrieve port options!\n");
		return;
	}
	
	// adjust options
	options.c_cflag &= ~CBAUD;
	options.c_cflag |= B115200;
	options.c_cflag |= (CLOCAL | CREAD);
	options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
	options.c_oflag &= ~OPOST;
	options.c_cc[VMIN] = 0;
	options.c_cc[VTIME] = 10;
	
	// set new options
	if(ioctl(fHandle, TCSETA, &options) != B_OK) {
		ERROR("ModemDevice: Could not init port!\n");
		return;
	}
}


void
ModemDevice::CloseModem()
{
	if(Handle() >= 0)
		close(Handle());
	
	fHandle = -1;
}


void
ModemDevice::FinishedDialing()
{
	fOutputBytes = 0;
	fState = OPENED;
	UpEvent();
}


void
ModemDevice::FailedDialing()
{
	fWorkerThread = -1;
	fState = INITIAL;
	CloseModem();
	UpFailedEvent();
}


void
ModemDevice::ConnectionLost()
{
	// switch to command mode and disconnect
	fWorkerThread = -1;
	fOutputBytes = 0;
	snooze(ESCAPE_DELAY);
	if(write(Handle(), ESCAPE_SEQUENCE, strlen(ESCAPE_SEQUENCE)) < 0)
		return;
	snooze(ESCAPE_DELAY);
	
	modem_put_line(Handle(), AT_HANG_UP, strlen(AT_HANG_UP));
	CloseModem();
}


status_t
ModemDevice::Send(struct mbuf *packet, uint16 protocolNumber)
{
#if DEBUG
	TRACE("ModemDevice: Send()\n");
	dump_packet(packet);
#endif
	
	if(!packet)
		return B_ERROR;
	else if(InitCheck() != B_OK || protocolNumber != 0) {
		m_freem(packet);
		return B_ERROR;
	} else if(!IsUp()) {
		m_freem(packet);
		return PPP_NO_CONNECTION;
	}
	
	// we might need room for our header
	if(fACFC->LocalState() != ACFC_ACCEPTED) {
		M_PREPEND(packet, 2);
		if(!packet)
			return B_ERROR;
	}
	
	int32 position = 0, length;
	if(packet->m_flags & M_PKTHDR)
		length = packet->m_pkthdr.len;
	else
		length = packet->m_len;
	
	// we need a contiguous chunk of memory
	packet = m_pullup(packet, length);
	if(!packet)
		return B_ERROR;
	
	uint8 buffer[2 * (MODEM_MTU + PACKET_OVERHEAD)], *data = mtod(packet, uint8*);
	
	// add header
	if(fACFC->LocalState() != ACFC_ACCEPTED) {
		data[0] = ALL_STATIONS;
		data[1] = UI;
	}
	
	// add FCS
	uint16 fcs = 0xffff;
	fcs = pppfcs16(fcs, data, length);
	fcs ^= 0xffff;
	data[length++] = fcs & 0x00ff;
	data[length++] = (fcs & 0xff00) >> 8;
	
	// encode packet
	buffer[position++] = FLAG_SEQUENCE;
		// mark beginning of packet
	for(int32 index = 0; index < length; index++) {
		if(data[index] < 0x20 || data[index] == FLAG_SEQUENCE
				|| data[index] == CONTROL_ESCAPE) {
			buffer[position++] = CONTROL_ESCAPE;
			buffer[position++] = data[index] ^ 0x20;
		} else
			buffer[position++] = data[index];
	}
	buffer[position++] = FLAG_SEQUENCE;
		// mark end of packet
	
	m_freem(packet);
	
	// send to modem
	atomic_add((int32*) &fOutputBytes, position);
	if(write(Handle(), buffer, position) < 0)
		return PPP_NO_CONNECTION;
	atomic_add((int32*) &fOutputBytes, -position);
	
	return B_OK;
}


status_t
ModemDevice::DataReceived(uint8 *buffer, uint32 length)
{
	// TODO: report corrupted packets to KPPPInterface
	
	if(length < 3)
		return B_ERROR;
	
	// check FCS
	uint16 fcs = 0xffff;
	fcs = pppfcs16(fcs, buffer, length - 2);
	fcs ^= 0xffff;
	if(buffer[length - 2] != fcs & 0x00ff || buffer[length - 1] != (fcs & 0xff00) >> 8)
		return B_ERROR;
	
	if(buffer[0] == ALL_STATIONS && buffer[1] == UI)
		buffer += 2;
	
	mbuf *packet = m_gethdr(MT_DATA);
	packet->m_len = packet->m_pkthdr.len = length - 2;
	uint8 *data = mtod(packet, uint8*);
	memcpy(data, buffer, length - 2);
	
	return Receive(packet);
}


status_t
ModemDevice::Receive(struct mbuf *packet, uint16 protocolNumber)
{
	// we do not need to lock because only the worker_thread calls this method
	
	if(!packet)
		return B_ERROR;
	else if(InitCheck() != B_OK || !IsUp()) {
		m_freem(packet);
		return B_ERROR;
	}
	
	return Interface().ReceiveFromDevice(packet);
}