/*
*   Copyright (C) 2016-2020 by Jonathan Naylor G4KLX
*
*   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 2 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "P25Gateway.h"
#include "Reflectors.h"
#include "StopWatch.h"
#include "DMRLookup.h"
#include "Network.h"
#include "Version.h"
#include "Thread.h"
#include "Voice.h"
#include "Timer.h"
#include "Utils.h"
#include "Log.h"

#if defined(_WIN32) || defined(_WIN64)
#include <WS2tcpip.h>
#include <Windows.h>
#else
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <pwd.h>
#endif

#if defined(_WIN32) || defined(_WIN64)
const char* DEFAULT_INI_FILE = "P25Gateway.ini";
#else
const char* DEFAULT_INI_FILE = "/etc/P25Gateway.ini";
#endif

const unsigned P25_VOICE_ID = 10999U;

#include <cstdio>
#include <cstdlib>
#include <cstdarg>
#include <ctime>
#include <cstring>

class CStaticTG {
public:
	unsigned int     m_tg;
	sockaddr_storage m_addr;
	unsigned int     m_addrLen;
};

int main(int argc, char** argv)
{
	const char* iniFile = DEFAULT_INI_FILE;
	if (argc > 1) {
		for (int currentArg = 1; currentArg < argc; ++currentArg) {
			std::string arg = argv[currentArg];
			if ((arg == "-v") || (arg == "--version")) {
				::fprintf(stdout, "P25Gateway version %s\n", VERSION);
				return 0;
			} else if (arg.substr(0, 1) == "-") {
				::fprintf(stderr, "Usage: P25Gateway [-v|--version] [filename]\n");
				return 1;
			} else {
				iniFile = argv[currentArg];
			}
		}
	}

	CP25Gateway* gateway = new CP25Gateway(std::string(iniFile));
	gateway->run();
	delete gateway;

	return 0;
}

CP25Gateway::CP25Gateway(const std::string& file) :
m_conf(file)
{
	CUDPSocket::startup();
}

CP25Gateway::~CP25Gateway()
{
	CUDPSocket::shutdown();
}

void CP25Gateway::run()
{
	bool ret = m_conf.read();
	if (!ret) {
		::fprintf(stderr, "P25Gateway: cannot read the .ini file\n");
		return;
	}

#if !defined(_WIN32) && !defined(_WIN64)
	bool m_daemon = m_conf.getDaemon();
	if (m_daemon) {
		// Create new process
		pid_t pid = ::fork();
		if (pid == -1) {
			::fprintf(stderr, "Couldn't fork() , exiting\n");
			return;
		} else if (pid != 0) {
			exit(EXIT_SUCCESS);
		}

		// Create new session and process group
		if (::setsid() == -1) {
			::fprintf(stderr, "Couldn't setsid(), exiting\n");
			return;
		}

		// Set the working directory to the root directory
		if (::chdir("/") == -1) {
			::fprintf(stderr, "Couldn't cd /, exiting\n");
			return;
		}

		// If we are currently root...
		if (getuid() == 0) {
			struct passwd* user = ::getpwnam("mmdvm");
			if (user == NULL) {
				::fprintf(stderr, "Could not get the mmdvm user, exiting\n");
				return;
			}

			uid_t mmdvm_uid = user->pw_uid;
			gid_t mmdvm_gid = user->pw_gid;

			// Set user and group ID's to mmdvm:mmdvm
			if (setgid(mmdvm_gid) != 0) {
				::fprintf(stderr, "Could not set mmdvm GID, exiting\n");
				return;
			}

			if (setuid(mmdvm_uid) != 0) {
				::fprintf(stderr, "Could not set mmdvm UID, exiting\n");
				return;
			}

			// Double check it worked (AKA Paranoia) 
			if (setuid(0) != -1) {
				::fprintf(stderr, "It's possible to regain root - something is wrong!, exiting\n");
				return;
			}
		}
	}
#endif

#if !defined(_WIN32) && !defined(_WIN64)
        ret = ::LogInitialise(m_daemon, m_conf.getLogFilePath(), m_conf.getLogFileRoot(), m_conf.getLogFileLevel(), m_conf.getLogDisplayLevel(), m_conf.getLogFileRotate());
#else
        ret = ::LogInitialise(false, m_conf.getLogFilePath(), m_conf.getLogFileRoot(), m_conf.getLogFileLevel(), m_conf.getLogDisplayLevel(), m_conf.getLogFileRotate());
#endif
	if (!ret) {
		::fprintf(stderr, "P25Gateway: unable to open the log file\n");
		return;
	}

#if !defined(_WIN32) && !defined(_WIN64)
	if (m_daemon) {
		::close(STDIN_FILENO);
		::close(STDOUT_FILENO);
		::close(STDERR_FILENO);
	}
#endif

	sockaddr_storage rptAddr;
	unsigned int rptAddrLen;
	if (CUDPSocket::lookup(m_conf.getRptAddress(), m_conf.getRptPort(), rptAddr, rptAddrLen) != 0) {
		LogError("Unable to resolve the address of the host");
		return;
	}

	CNetwork localNetwork(m_conf.getMyPort(), m_conf.getCallsign(), m_conf.getDebug());
	ret = localNetwork.open();
	if (!ret) {
		::LogFinalise();
		return;
	}

	CNetwork remoteNetwork(m_conf.getNetworkPort(), m_conf.getCallsign(), m_conf.getNetworkDebug());
	ret = remoteNetwork.open();
	if (!ret) {
		localNetwork.close();
		::LogFinalise();
		return;
	}

	CUDPSocket* remoteSocket = NULL;
	if (m_conf.getRemoteCommandsEnabled()) {
		remoteSocket = new CUDPSocket(m_conf.getRemoteCommandsPort());
		ret = remoteSocket->open();
		if (!ret) {
			delete remoteSocket;
			remoteSocket = NULL;
		}
	}

	CReflectors reflectors(m_conf.getNetworkHosts1(), m_conf.getNetworkHosts2(), m_conf.getNetworkReloadTime());
	if (m_conf.getNetworkParrotPort() > 0U)
		reflectors.setParrot(m_conf.getNetworkParrotAddress(), m_conf.getNetworkParrotPort());
	if (m_conf.getNetworkP252DMRPort() > 0U)
		reflectors.setP252DMR(m_conf.getNetworkP252DMRAddress(), m_conf.getNetworkP252DMRPort());
	reflectors.load();

	CDMRLookup* lookup = new CDMRLookup(m_conf.getLookupName(), m_conf.getLookupTime());
	lookup->read();

	unsigned int rfHangTime  = m_conf.getNetworkRFHangTime();
	unsigned int netHangTime = m_conf.getNetworkNetHangTime();

	CTimer hangTimer(1000U);

	CTimer pollTimer(1000U, 5U);
	pollTimer.start();

	CStopWatch stopWatch;
	stopWatch.start();

	CVoice* voice = NULL;
	if (m_conf.getVoiceEnabled()) {
		voice = new CVoice(m_conf.getVoiceDirectory(), m_conf.getVoiceLanguage(), P25_VOICE_ID);
		bool ok = voice->open();
		if (!ok) {
			delete voice;
			voice = NULL;
		}
	}

	LogMessage("Starting P25Gateway-%s", VERSION);

	unsigned int srcId = 0U;
	unsigned int dstTG = 0U;

	bool currentIsStatic        = false;
	unsigned int currentTG      = 0U;
	unsigned int currentAddrLen = 0U;
	sockaddr_storage currentAddr;

	std::vector<unsigned int> staticIds = m_conf.getNetworkStatic();

	std::vector<CStaticTG> staticTGs;
	for (std::vector<unsigned int>::const_iterator it = staticIds.cbegin(); it != staticIds.cend(); ++it) {
		CP25Reflector* reflector = reflectors.find(*it);
		if (reflector != NULL) {
			CStaticTG staticTG;
			staticTG.m_tg      = *it;
			staticTG.m_addr    = reflector->m_addr;
			staticTG.m_addrLen = reflector->m_addrLen;
			staticTGs.push_back(staticTG);

			remoteNetwork.writePoll(staticTG.m_addr, staticTG.m_addrLen);
			remoteNetwork.writePoll(staticTG.m_addr, staticTG.m_addrLen);
			remoteNetwork.writePoll(staticTG.m_addr, staticTG.m_addrLen);

			LogMessage("Statically linked to reflector %u", *it);
		}
	}

	for (;;) {
		unsigned char buffer[200U];
		sockaddr_storage addr;
		unsigned int addrLen;

		// From the reflector to the MMDVM
		unsigned int len = remoteNetwork.readData(buffer, 200U, addr, addrLen);
		if (len > 0U) {
			// If we're linked and it's from the right place, send it on
			if (currentAddrLen > 0U && CUDPSocket::match(currentAddr, addr)) {
				// Don't pass reflector control data through to the MMDVM
				if (buffer[0U] != 0xF0U && buffer[0U] != 0xF1U) {
					// Rewrite the LCF and the destination TG
					if (buffer[0U] == 0x64U) {
						buffer[1U] = 0x00U;			// LCF is for TGs
					} else if (buffer[0U] == 0x65U) {
						buffer[1U] = (currentTG >> 16) & 0xFFU;
						buffer[2U] = (currentTG >> 8)  & 0xFFU;
						buffer[3U] = (currentTG >> 0)  & 0xFFU;
					}

					localNetwork.writeData(buffer, len, rptAddr, rptAddrLen);

					hangTimer.start();
				}
			} else if (currentTG == 0U) {
				// Don't pass reflector control data through to the MMDVM
				if (buffer[0U] != 0xF0U && buffer[0U] != 0xF1U) {
					// Find the static TG that this audio data belongs to
					for (std::vector<CStaticTG>::const_iterator it = staticTGs.cbegin(); it != staticTGs.cend(); ++it) {
						if (CUDPSocket::match(addr, (*it).m_addr)) {
							currentTG = (*it).m_tg;
							break;
						}
					}

					if (currentTG > 0U) {
						currentAddr     = addr;
						currentAddrLen  = addrLen;
						currentIsStatic = true;

						// Rewrite the LCF and the destination TG
						if (buffer[0U] == 0x64U) {
							buffer[1U] = 0x00U;			// LCF is for TGs
						} else if (buffer[0U] == 0x65U) {
							buffer[1U] = (currentTG >> 16) & 0xFFU;
							buffer[2U] = (currentTG >> 8)  & 0xFFU;
							buffer[3U] = (currentTG >> 0)  & 0xFFU;
						}

						localNetwork.writeData(buffer, len, rptAddr, rptAddrLen);

						LogMessage("Switched to reflector %u due to network activity", currentTG);

						hangTimer.setTimeout(netHangTime);
						hangTimer.start();
					}
				}
			}
		}

		// From the MMDVM to the reflector or control data
		len = localNetwork.readData(buffer, 200U, addr, addrLen);
		if (len > 0U) {
			if (buffer[0U] == 0x65U) {
				dstTG  = (buffer[1U] << 16) & 0xFF0000U;
				dstTG |= (buffer[2U] << 8)  & 0x00FF00U;
				dstTG |= (buffer[3U] << 0)  & 0x0000FFU;
			} else if (buffer[0U] == 0x66U) {
				srcId  = (buffer[1U] << 16) & 0xFF0000U;
				srcId |= (buffer[2U] << 8)  & 0x00FF00U;
				srcId |= (buffer[3U] << 0)  & 0x0000FFU;
				
				if (dstTG != currentTG) {
					if (currentAddrLen > 0U) {
						std::string callsign = lookup->find(srcId);
						LogMessage("Unlinking from reflector %u by %s", currentTG, callsign.c_str());

						if (!currentIsStatic) {
							remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
							remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
							remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
						}

						hangTimer.stop();
					}

					const CStaticTG* found = NULL;
					for (std::vector<CStaticTG>::const_iterator it = staticTGs.cbegin(); it != staticTGs.cend(); ++it) {
						if (dstTG == (*it).m_tg) {
							found = &(*it);
							break;
						}
					}

					if (found == NULL) {
						CP25Reflector* refl = reflectors.find(dstTG);
						if (refl != NULL) {
							currentTG       = dstTG;
							currentAddr     = refl->m_addr;
							currentAddrLen  = refl->m_addrLen;
							currentIsStatic = false;
						} else {
							currentTG       = dstTG;
							currentAddrLen  = 0U;
							currentIsStatic = false;
						}
					} else {
						currentTG       = found->m_tg;
						currentAddr     = found->m_addr;
						currentAddrLen  = found->m_addrLen;
						currentIsStatic = true;
					}

					// Link to the new reflector
					if (currentAddrLen > 0U) {
						std::string callsign = lookup->find(srcId);
						LogMessage("Switched to reflector %u due to RF activity from %s", currentTG, callsign.c_str());

						if (!currentIsStatic) {
							remoteNetwork.writePoll(currentAddr, currentAddrLen);
							remoteNetwork.writePoll(currentAddr, currentAddrLen);
							remoteNetwork.writePoll(currentAddr, currentAddrLen);
						}

						hangTimer.setTimeout(rfHangTime);
						hangTimer.start();
					} else {
						hangTimer.stop();
					}

					if (voice != NULL) {
						if (currentAddrLen == 0U)
							voice->unlinked();
						else
							voice->linkedTo(dstTG);
					}
				}
			}

			if (buffer[0U] == 0x80U) {
				if (voice != NULL)
					voice->eof();
			}

			// If we're linked and we have a network, send it on
			if (currentAddrLen > 0U) {
				// Rewrite the LCF and the destination TG
				if (buffer[0U] == 0x64U) {
					buffer[1U] = 0x00U;			// LCF is for TGs
				} else if (buffer[0U] == 0x65U) {
					buffer[1U] = (currentTG >> 16) & 0xFFU;
					buffer[2U] = (currentTG >> 8)  & 0xFFU;
					buffer[3U] = (currentTG >> 0)  & 0xFFU;
				}

				remoteNetwork.writeData(buffer, len, currentAddr, currentAddrLen);
				hangTimer.start();
			}
		}

		if (voice != NULL) {
			unsigned int length = voice->read(buffer);
			if (length > 0U)
				localNetwork.writeData(buffer, length, rptAddr, rptAddrLen);
		}

		if (remoteSocket != NULL) {
			sockaddr_storage addr;
			unsigned int addrLen;
			int res = remoteSocket->read(buffer, 200U, addr, addrLen);
			if (res > 0) {
				buffer[res] = '\0';
				if (::memcmp(buffer + 0U, "TalkGroup", 9U) == 0) {
					unsigned int tg = (unsigned int)::atoi((char*)(buffer + 9U));

					if (tg != currentTG) {
						if (currentAddrLen > 0U) {
							LogMessage("Unlinked from reflector %u by remote command", currentTG);

							if (!currentIsStatic) {
								remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
								remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
								remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
							}

							hangTimer.stop();
						}

						const CStaticTG* found = NULL;
						for (std::vector<CStaticTG>::const_iterator it = staticTGs.cbegin(); it != staticTGs.cend(); ++it) {
							if (tg == (*it).m_tg) {
								found = &(*it);
								break;
							}
						}

						if (found == NULL) {
							CP25Reflector* refl = reflectors.find(tg);
							if (refl != NULL) {
								currentTG       = tg;
								currentAddr     = refl->m_addr;
								currentAddrLen  = refl->m_addrLen;
								currentIsStatic = false;
							} else {
								currentTG       = tg;
								currentAddrLen  = 0U;
								currentIsStatic = false;
							}
						} else {
							currentTG       = found->m_tg;
							currentAddr     = found->m_addr;
							currentAddrLen  = found->m_addrLen;
							currentIsStatic = true;
						}

						// Link to the new reflector
						if (currentAddrLen > 0U) {
							LogMessage("Switched to reflector %u by remote command", currentTG);

							if (!currentIsStatic) {
								remoteNetwork.writePoll(currentAddr, currentAddrLen);
								remoteNetwork.writePoll(currentAddr, currentAddrLen);
								remoteNetwork.writePoll(currentAddr, currentAddrLen);
							}

							hangTimer.setTimeout(rfHangTime);
							hangTimer.start();
						} else {
							hangTimer.stop();
						}

						if (voice != NULL) {
							if (currentAddrLen == 0U)
								voice->unlinked();
							else
								voice->linkedTo(currentTG);
						}
					}
				} else {
					CUtils::dump("Invalid remote command received", buffer, res);
				}
			}
		}

		unsigned int ms = stopWatch.elapsed();
		stopWatch.start();

		reflectors.clock(ms);

		if (voice != NULL)
			voice->clock(ms);

		hangTimer.clock(ms);
		if (hangTimer.isRunning() && hangTimer.hasExpired()) {
			currentTG = 0U;

			if (currentAddrLen > 0U) {
				LogMessage("Unlinking from %u due to inactivity", currentTG);

				if (!currentIsStatic) {
					remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
					remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
					remoteNetwork.writeUnlink(currentAddr, currentAddrLen);
				}

				if (voice != NULL)
					voice->unlinked();

				currentAddrLen = 0U;

				hangTimer.stop();
			}
		}

		pollTimer.clock(ms);
		if (pollTimer.isRunning() && pollTimer.hasExpired()) {
			// Poll the static TGs
			for (std::vector<CStaticTG>::const_iterator it = staticTGs.cbegin(); it != staticTGs.cend(); ++it)
				remoteNetwork.writePoll((*it).m_addr, (*it).m_addrLen);

			// Poll the dynamic TG
			if (!currentIsStatic && currentAddrLen > 0U)
				remoteNetwork.writePoll(currentAddr, currentAddrLen);

			pollTimer.start();
		}

		if (ms < 5U)
			CThread::sleep(5U);
	}

	delete voice;

	localNetwork.close();

	if (remoteSocket != NULL) {
		remoteSocket->close();
		delete remoteSocket;
	}

	remoteNetwork.close();

	lookup->stop();

	::LogFinalise();
}