/*
 * Remote Laboratory User Management 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) 2013 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 <klocale.h>

#include "admin_sys_ctl.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
};

/*
  The SysCtlSocket 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.
*/
SysCtlSocket::SysCtlSocket(int sock, TQObject *parent, const char *name) :
	TDEKerberosServerSocket(parent, name), m_criticalSection(0), m_loopTimer(NULL), m_config(static_cast<UserMgmtServer*>(parent)->m_config), m_terminals_database(NULL), m_workspaces_database(NULL), m_commandLoopState(StateIdle)
{

	// 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);

	if (connectToDatabase() != 0) {
		exit(1);
	}
}

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

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

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

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

void SysCtlSocket::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 SysCtlSocket::commandLoop() {
	bool transferred_data;

	m_criticalSection++;
	try {
		transferred_data = false;
		if (state() == TQSocket::Connected) {
			if (m_commandLoopState == StateIdle) {
				// 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;
					if (command == "USERS") {
						TQString subCommand;
						ds >> subCommand;
						if (subCommand == "TERMINALS") {
							clearFrameTail();
							ds << TQString("OK");
							TerminalServiceStatusList list;
							TQSqlCursor databaseActivityCursor("sessions", TRUE, m_terminals_database);
							databaseActivityCursor.select();
							while (databaseActivityCursor.next()) {
								TerminalServiceStatusType status;

								status.protocolVersion = 1;
								status.sessionID = databaseActivityCursor.value("pk").toInt();
								status.username = databaseActivityCursor.value("username").toString();
								status.serverName = databaseActivityCursor.value("servername").toString();
								status.serverPID = databaseActivityCursor.value("server_pid").toInt();
								status.wmPID = databaseActivityCursor.value("wm_pid").toInt();
								status.state = databaseActivityCursor.value("state").toInt();
								status.display = databaseActivityCursor.value("display").toInt();
								status.loginStamp.setTime_t(databaseActivityCursor.value("stamp_start").toLongLong());
								status.activityStamp.setTime_t(databaseActivityCursor.value("stamp_statechange").toLongLong());

								list.append(status);
							}
							ds << list;
							writeEndOfFrame();
						}
						else if (subCommand == "WORKSPACES") {
							clearFrameTail();
							ds << TQString("OK");
							WorkspaceServiceStatusList list;
							TQSqlCursor databaseActivityCursor("activity", TRUE, m_workspaces_database);
							databaseActivityCursor.select();
							while (databaseActivityCursor.next()) {
								WorkspaceServiceStatusType status;

								status.protocolVersion = 1;
								status.sessionID = databaseActivityCursor.value("pk").toInt();
								status.stationID = databaseActivityCursor.value("station").toInt();
								status.username = databaseActivityCursor.value("username").toString();
								status.realmname = databaseActivityCursor.value("realmname").toString();
								status.serverID = databaseActivityCursor.value("serverid").toInt();
								status.serviceID = databaseActivityCursor.value("serviceid").toInt();
								status.stationID = databaseActivityCursor.value("station").toInt();
								TQSqlCursor databaseStationsCursor("stations", TRUE, m_workspaces_database);
								databaseStationsCursor.select(TQString("pk=%1").arg(status.stationID));
								if (databaseStationsCursor.next()) {
									status.stationName = databaseStationsCursor.value("name").toString();
								}
								status.loginStamp.setTime_t(databaseActivityCursor.value("logontime").toLongLong());
								status.terminateStamp.setTime_t(databaseActivityCursor.value("terminate").toLongLong());

								list.append(status);
							}
							ds << list;
							writeEndOfFrame();
						}
						else {
							clearFrameTail();
							ds << TQString("ERRINVCMD");
							writeEndOfFrame();
						}
					}
					else if (command == "SESSION") {
						TQString subCommand;
						TQString sessionID;
						ds >> subCommand;
						ds >> sessionID;
						if (subCommand == "LOGOFF_TERMINAL") {
							TQ_UINT32 delay;
							ds >> delay;
							clearFrameTail();
							// FIXME UNIMPLEMENTED
							ds << TQString("ERRINVCMD");
							writeEndOfFrame();
						}
						else if (subCommand == "CANCEL_LOGOFF_TERMINAL") {
							clearFrameTail();
							// FIXME UNIMPLEMENTED
							ds << TQString("ERRINVCMD");
							writeEndOfFrame();
						}
						else if (subCommand == "KILL_TERMINAL") {
							clearFrameTail();
							TQSqlCursor databaseActivityCursor("sessions", TRUE, m_terminals_database);
							databaseActivityCursor.select(TQString("pk=%1").arg(sessionID));
							if (databaseActivityCursor.next()) {
								// Gather server information
								TQString server_name = databaseActivityCursor.value("servername").toString();
								int server_pid = databaseActivityCursor.value("server_pid").toInt();
								// Kill server process
								TQString command = TQString("ssh root@%1 'kill -9 %2'").arg(server_name).arg(server_pid);
								if (system(command.ascii()) == 0) {
									// Remove database entry
									databaseActivityCursor.select(TQString("pk=%1").arg(sessionID));
									if (databaseActivityCursor.next()) {
										databaseActivityCursor.primeDelete();
										databaseActivityCursor.del(true);
									}
									ds << TQString("OK");
								}
								else {
									ds << TQString("ERRFAILED");
								}
								writeEndOfFrame();
							}
							else {
								ds << TQString("ERRINVCMD");
							}
							writeEndOfFrame();
						}
						else if (subCommand == "KILL_WORKSPACE") {
							TQ_INT32 terminationOffset;
							ds >> terminationOffset;
							clearFrameTail();
							TQDateTime terminationTime = TQDateTime::currentDateTime();
							terminationTime = terminationTime.addSecs(terminationOffset*60);
							TQSqlCursor databaseActivityCursor("activity", TRUE, m_workspaces_database);
							databaseActivityCursor.select(TQString("pk=%1").arg(sessionID));
							if (databaseActivityCursor.next()) {
								TQSqlRecord *buffer = databaseActivityCursor.primeUpdate();
								if (terminationOffset > -2) {
									buffer->setValue("terminate", terminationTime.toTime_t());
								}
								else {
									buffer->setValue("terminate", 0);
								}
								databaseActivityCursor.update();

								ds << TQString("OK");
							}
							else {
								ds << TQString("ERRINVCMD");
							}
							writeEndOfFrame();
						}
						else if (subCommand == "CANCEL_KILL_WORKSPACE") {
							clearFrameTail();
							TQSqlCursor databaseActivityCursor("activity", TRUE, m_workspaces_database);
							databaseActivityCursor.select(TQString("pk=%1").arg(sessionID));
							if (databaseActivityCursor.next()) {
								TQSqlRecord *buffer = databaseActivityCursor.primeUpdate();
								buffer->setValue("terminate", 0);
								databaseActivityCursor.update();

								ds << TQString("OK");
							}
							else {
								ds << TQString("ERRINVCMD");
							}
							writeEndOfFrame();
						}
						else {
							clearFrameTail();
							ds << TQString("ERRINVCMD");
							writeEndOfFrame();
						}
					}
					else {
						clearFrameTail();
					}
					transferred_data = true;
				}
			}
		}
		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 SysCtlSocket::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;
}

int SysCtlSocket::connectToDatabase() {
	if ((m_terminals_database) && (m_workspaces_database)) {
		return -2;
	}

	m_terminals_database = TQSqlDatabase::database("terminals");
	m_workspaces_database = TQSqlDatabase::database("workspaces");
	if ((!m_terminals_database) || (!m_workspaces_database)) {
		printf("[ERROR] Databases were not constructed by the application\n\r"); fflush(stdout);
		return -1;
	}

	return 0;
}

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

	if (connectToDatabase() != 0) {
		exit(1);
	}

	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);
}

UserMgmtServer::~UserMgmtServer() {
	if (m_sqlPingTimer) {
		m_sqlPingTimer->stop();
		delete m_sqlPingTimer;
		m_sqlPingTimer = NULL;
	}
	if (m_terminals_database) {
		TQSqlDatabase::removeDatabase(m_terminals_database);
		m_terminals_database = NULL;
	}
	if (m_workspaces_database) {
		TQSqlDatabase::removeDatabase(m_workspaces_database);
		m_workspaces_database = NULL;
	}
}

int UserMgmtServer::connectToDatabase() {
	m_config->setGroup("Terminals Database");

	m_terminals_database = TQSqlDatabase::addDatabase(m_config->readEntry("driver"), "terminals");
	m_terminals_database->setDatabaseName(m_config->readEntry("database"));
	m_terminals_database->setUserName(m_config->readEntry("username"));
	m_terminals_database->setPassword(m_config->readEntry("password"));
	m_terminals_database->setHostName(m_config->readEntry("server"));

	if(!m_terminals_database->open()) {
		printf("[ERROR] Failed to connect to control database on server '%s' [%s]\n\r", m_terminals_database->hostName().ascii(), m_terminals_database->lastError().text().ascii()); fflush(stdout);
		TQSqlDatabase::removeDatabase(m_terminals_database);
		m_terminals_database = NULL;
		return -1;
	}

	m_config->setGroup("Workspaces Database");

	m_workspaces_database = TQSqlDatabase::addDatabase(m_config->readEntry("driver"), "workspaces");
	m_workspaces_database->setDatabaseName(m_config->readEntry("database"));
	m_workspaces_database->setUserName(m_config->readEntry("username"));
	m_workspaces_database->setPassword(m_config->readEntry("password"));
	m_workspaces_database->setHostName(m_config->readEntry("server"));

	if(!m_workspaces_database->open()) {
		printf("[ERROR] Failed to connect to control database on server '%s' [%s]\n\r", m_workspaces_database->hostName().ascii(), m_workspaces_database->lastError().text().ascii()); fflush(stdout);
		TQSqlDatabase::removeDatabase(m_workspaces_database);
		m_workspaces_database = NULL;
		return -1;
	}

	// FIXME
	// We currently have no way to handle something as simple as the database server going offline!

	// Start database ping process
	m_sqlPingTimer = new TQTimer();
	connect(m_sqlPingTimer, SIGNAL(timeout()), this, SLOT(pingSQLServer()));
	m_sqlPingTimer->start(60*1000);

	return 0;
}

void UserMgmtServer::pingSQLServer() {
	TQSqlQuery terminals_query(TQString::null, m_terminals_database);
	terminals_query.exec("SELECT * FROM sessions");
	TQSqlQuery workspaces_query(TQString::null, m_workspaces_database);
	workspaces_query.exec("SELECT * FROM activity");
}

void UserMgmtServer::newConnection(int socket) {
	SysCtlSocket *s = new SysCtlSocket(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 UserMgmtServer::remoteConnectionClosed() {
	m_numberOfConnections--;
}