/*
 * Remote Laboratory FPGA Server
 *
 * 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, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * (c) 2012 Timothy Pearson
 * Raptor Engineering
 * http://www.raptorengineeringinc.com
 */

#include <stdio.h>                /* perror() */
#include <stdlib.h>               /* atoi() */
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>               /* read() */
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <sys/signal.h>
#include <sys/types.h>

#include <tqtimer.h>
#include <tqfile.h>

#include <tdelocale.h>

#include "fpga_conn.h"

#define ABORT_SOCKET(s) 		s->close();						\
					s->disconnect();					\
					delete s;						\
					s = NULL;

#define NETWORK_COMM_TIMEOUT_MS 5000

/* exception handling */
struct exit_exception {
	int c;
	exit_exception(int c):c(c) { }
};

enum connectionStates {
	StateIdle			= 0,
	StateGetFileSize		= 1,
	StateGetFileContents		= 2,
	StateStartProgramming		= 3,
	StateCheckProgrammingStatus	= 4,
	StateProgammingFinished		= 5
};

/*
  The FPGASocket class provides a socket that is connected with a client.
  For every client that connects to the server, the server creates a new
  instance of this class.
*/
FPGASocket::FPGASocket(int sock, TQObject *parent, const char *name) :
	TDEKerberosServerSocket(parent, name), m_criticalSection(0), m_loopTimer(NULL), m_config(static_cast<FPGAServer*>(parent)->m_config), m_commandLoopState(StateIdle),
	m_progpipe(NULL), m_progpipefd(-1), m_progErrorFlag(false), m_progDoneFlag(false)
{

	// Initialize timers
	m_kerberosInitTimer = new TQTimer();
	connect(m_kerberosInitTimer, SIGNAL(timeout()), this, SLOT(finishKerberosHandshake()));
	m_servClientTimeout = new TQTimer();

	setServiceName("remotefpga");

	line = 0;
	connect(this, SIGNAL(connectionClosed()), SLOT(connectionClosedHandler()));
	connect(this, SIGNAL(connectionClosed()), parent, SLOT(remoteConnectionClosed()));
	setSocket(sock);
}

FPGASocket::~FPGASocket() {
	if (m_servClientTimeout) {
		m_servClientTimeout->stop();
		delete m_servClientTimeout;
		m_servClientTimeout = NULL;
	}
	if (m_kerberosInitTimer) {
		m_kerberosInitTimer->stop();
		delete m_kerberosInitTimer;
		m_kerberosInitTimer = NULL;
	}
	if (m_loopTimer) {
		m_loopTimer->stop();
		delete m_loopTimer;
		m_loopTimer = NULL;
	}
}

void FPGASocket::close() {
	if (state() == TQSocket::Connected) {
		TDEKerberosServerSocket::close();
		connectionClosedHandler();
		TQTimer::singleShot(0, parent(), SLOT(remoteConnectionClosed()));
	}
}

void FPGASocket::connectionClosedHandler() {
	printf("[DEBUG] Connection from %s closed\n\r", m_remoteHost.ascii());

	if (m_criticalSection > 0) {
		throw exit_exception(-1);
	}
}

void FPGASocket::initiateKerberosHandshake() {
	setUsingKerberos(true);
	m_kerberosInitTimer->start(100, TRUE);
}

void FPGASocket::finishKerberosHandshake() {
	if (kerberosStatus() == TDEKerberosServerSocket::KerberosInitializing) {
		m_kerberosInitTimer->start(100, TRUE);
		return;
	}
	if (kerberosStatus() == TDEKerberosServerSocket::KerberosInUse) {
		m_config->setGroup("Security");
		TQString masterUser = m_config->readEntry("masteruser");
		TQString masterRealm = m_config->readEntry("masterrealm");
		if (masterRealm == "") {
			masterRealm = "(NULL)";
		}
		if ((m_authenticatedUserName != masterUser) || (m_authenticatedRealmName != masterRealm)) {
			printf("[DEBUG] Connection from %s closed due to authentication failure (attempted connection as user %s@%s)\n\r", m_remoteHost.ascii(), m_authenticatedUserName.ascii(), m_authenticatedRealmName.ascii());
			close();
			return;
		}

		setDataTimeout(NETWORK_COMM_TIMEOUT_MS);

		TQDataStream ds(this);
		ds.setPrintableData(true);
		ds << TQString("OK");
		writeEndOfFrame();

		enterCommandLoop();
		return;
	}
	else {
		printf("[DEBUG] Connection from %s closed due to Kerberos failure\n\r", m_remoteHost.ascii()); fflush(stdout);
		close();
		return;
	}
}

void FPGASocket::commandLoop() {
	bool transferred_data;

	m_criticalSection++;
	try {
		transferred_data = false;
		if (state() == TQSocket::Connected) {
			if ((m_commandLoopState == StateIdle) || (m_commandLoopState == StateStartProgramming) || (m_commandLoopState == StateCheckProgrammingStatus) || (m_commandLoopState == StateProgammingFinished)) {
				// Certain commands can come in at any time during some operations
				if (canReadLine()) {
					processPendingData();
				}
				if (canReadFrame()) {
					TQDataStream ds(this);
					ds.setPrintableData(true);
					TQString command;
					ds >> command;
					clearFrameTail();
					if (command == "STATUS") {
						if (m_logMessages != "") {
							ds << TQString("LOGMESSAGES");
							writeEndOfFrame();
							ds << m_logMessages;
							writeEndOfFrame();
							m_logMessages = "";
						}
						else if (m_progErrorFlag) {
							ds << TQString("ERROR");
							m_progErrorFlag = false;
							writeEndOfFrame();
						}
						else if (m_progDoneFlag) {
							ds << TQString("DONE");
							ds << m_progRetCode;
							m_progDoneFlag = false;
							writeEndOfFrame();
						}
						else if (m_commandLoopState == StateIdle) {
							ds << TQString("IDLE");
							writeEndOfFrame();
						}
						else if ((m_commandLoopState == StateStartProgramming) || (m_commandLoopState == StateCheckProgrammingStatus) || (m_commandLoopState == StateProgammingFinished)) {
							ds << TQString("PROGRAMMING");
							writeEndOfFrame();
						}
						else {
							ds << TQString("UNKNOWN");
							writeEndOfFrame();
						}
					}
					else if (m_commandLoopState == StateIdle) {
						if (command == "FILE") {
							m_commandLoopState = StateGetFileSize;
						}
						else if (command == "PROGRAM") {
							m_commandLoopState = StateStartProgramming;
						}
						else {
							printf("[WARNING] Received unknown command '%s'\n\r", command.ascii());
						}
					}
					transferred_data = true;
				}
			}
			if (m_commandLoopState == StateGetFileSize) {
				if (canReadLine()) {
					processPendingData();
				}
				if (canReadFrame()) {
					TQDataStream ds(this);
					ds.setPrintableData(true);
					ds >> m_programmingFileSize;
					clearFrameTail();
					m_servClientTimeout->start(NETWORK_COMM_TIMEOUT_MS, TRUE);
					m_commandLoopState = StateGetFileContents;
				}
			}
			else if (m_commandLoopState == StateGetFileContents) {
				if (canReadLine()) {
					m_servClientTimeout->start(NETWORK_COMM_TIMEOUT_MS, TRUE);
					processPendingData();
				}
				if (bytesAvailable() >= m_programmingFileSize) {
					TQByteArray fileContents(m_programmingFileSize);
					readBlock(fileContents.data(), fileContents.size());
					m_programmingFileName = TQString("/tmp/%1#%2.dat").arg(m_remoteHost).arg(port());
					TQFile outputFile(m_programmingFileName);
					if (outputFile.open(IO_ReadWrite)) {
						outputFile.writeBlock(fileContents);
						outputFile.flush();
						outputFile.close();
					}
					transferred_data = true;
					m_commandLoopState = StateIdle;
				}
				else {
					if (!m_servClientTimeout->isActive()) {
						m_progErrorFlag = true;
						transferred_data = true;
						m_commandLoopState = StateIdle;
					}
				}
			}
			else if (m_commandLoopState == StateStartProgramming) {
				// Start programming!

				// Open programming process
				m_config->setGroup("Programming");
				TQString programmingScript = m_config->readEntry("script");
				programmingScript.replace("%f", m_programmingFileName);
				if (!programmingScript.contains("2>&1")) {
					programmingScript.append(" 2>&1");
				}
				if ((m_progpipe = popen(programmingScript.ascii(), "r")) == NULL) {
					m_logMessages.append(TQString("The system was unable to execute '%1'\nPlease contact your system administrator with this information").arg(programmingScript));
					m_progErrorFlag = true;
					transferred_data = true;
					m_commandLoopState = StateIdle;
				}
				else {
					m_progpipefd = fileno(m_progpipe);
					fcntl(m_progpipefd, F_SETFL, O_NONBLOCK);
				}
				m_commandLoopState = StateCheckProgrammingStatus;
			}
			else if (m_commandLoopState == StateCheckProgrammingStatus) {
				// Check programming status
				TQCString buf;
				buf.resize(8192);
				ssize_t r = read(m_progpipefd, buf.data(), buf.size());
				if ((r == -1) && (errno == EAGAIN)) {
					// No data available yet
				}
				else if (r > 0) {
					// Data was received
					buf.data()[r] = 0;
					m_logMessages.append(buf);
				}
				else {
					// Process terminated
					m_commandLoopState = StateProgammingFinished;
				}
			}
			else if (m_commandLoopState == StateProgammingFinished) {
				// Programming process terminated; get exit code and clean up
				if (m_progpipe) {
					m_progRetCode = pclose(m_progpipe);
				}
				else {
					m_progRetCode = -1;
				}
				m_progpipe = NULL;
				m_progpipefd = -1;

				m_progDoneFlag = true;
				m_commandLoopState = StateIdle;
			}
		}
		m_criticalSection--;
		if (transferred_data) {
			if (m_loopTimer) m_loopTimer->start(0, TRUE);
		}
		else {
			if (m_loopTimer) m_loopTimer->start(100, TRUE);
		}
		return;
	}
	catch (...) {
		m_criticalSection--;
		return;
	}
}

int FPGASocket::enterCommandLoop() {
	m_commandLoopState = StateIdle;
	if (!m_loopTimer) {
		m_loopTimer = new TQTimer();
		connect(m_loopTimer, SIGNAL(timeout()), this, SLOT(commandLoop()));
	}
	if (m_loopTimer) m_loopTimer->start(0, TRUE);
	return 0;
}

/*
  The FPGAServer class handles new connections to the server. For every
  client that connects, it creates a new FPGASocket -- that instance is now
  responsible for the communication with that client.
*/
FPGAServer::FPGAServer(TQObject* parent, int port, KSimpleConfig* config) :
	TQServerSocket( port, 1, parent ), m_config(config), m_numberOfConnections(0) {

	if ( !ok() ) {
		printf("[ERROR] Failed to bind to port %d\n\r", port);
		exit(1);
	}

	printf("[INFO] Server started on port %d\n\r", port); fflush(stdout);
}

FPGAServer::~FPGAServer() {
	//
}

void FPGAServer::newConnection(int socket) {
	FPGASocket *s = new FPGASocket(socket, this);
	s->m_remoteHost = s->peerAddress().toString();
	printf("[DEBUG] New connection from %s\n\r", s->m_remoteHost.ascii());
	if (m_numberOfConnections > 0) {
		printf("[DEBUG] Connection from %s closed due to multiple access attempt\n\r", s->m_remoteHost.ascii());
		ABORT_SOCKET(s)
		return;
	}
	connect(s, SIGNAL(connectionClosed()), s, SLOT(deleteLater()));
	s->initiateKerberosHandshake();
	emit newConnect(s);
}

void FPGAServer::remoteConnectionClosed() {
	m_numberOfConnections--;
}