// ReDucTor is an awesome guy who helped me a lot

#include "Globals.h"  // NOTE: MSVC stupidness requires this to be the same across all modules

#include "Server.h"
#include "ClientHandle.h"
#include "OSSupport/Timer.h"
#include "Mobs/Monster.h"
#include "OSSupport/Socket.h"
#include "Root.h"
#include "World.h"
#include "ChunkDef.h"
#include "PluginManager.h"
#include "GroupManager.h"
#include "ChatColor.h"
#include "Entities/Player.h"
#include "Inventory.h"
#include "Item.h"
#include "FurnaceRecipe.h"
#include "WebAdmin.h"
#include "Protocol/ProtocolRecognizer.h"
#include "CommandOutput.h"

#include "MersenneTwister.h"

#include "../iniFile/iniFile.h"
#include "Vector3f.h"

#include <fstream>
#include <sstream>
#include <iostream>

extern "C" {
	#include "zlib.h"
}




// For the "dumpmem" server command:
/// Synchronize this with main.cpp - the leak finder needs initialization before it can be used to dump memory
#define ENABLE_LEAK_FINDER

#if defined(_MSC_VER) && defined(_DEBUG) && defined(ENABLE_LEAK_FINDER)
	#pragma warning(push)
	#pragma warning(disable:4100)
	#include "LeakFinder.h"
	#pragma warning(pop)
#endif





typedef std::list< cClientHandle* > ClientList;





///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// cServer::cTickThread:

cServer::cTickThread::cTickThread(cServer & a_Server) :
	super("ServerTickThread"),
	m_Server(a_Server)
{
}





void cServer::cTickThread::Execute(void)
{
	cTimer Timer;

	long long msPerTick = 50;
	long long LastTime = Timer.GetNowTime();

	while (!m_ShouldTerminate)
	{
		long long NowTime = Timer.GetNowTime();
		float DeltaTime = (float)(NowTime-LastTime);
		m_ShouldTerminate = !m_Server.Tick(DeltaTime);
		long long TickTime = Timer.GetNowTime() - NowTime;
		
		if (TickTime < msPerTick)
		{
			// Stretch tick time until it's at least msPerTick
			cSleep::MilliSleep((unsigned int)(msPerTick - TickTime));
		}

		LastTime = NowTime;
	}
}





///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// cServer:

cServer::cServer(void) :
	m_ListenThreadIPv4(*this, cSocket::IPv4, "Client IPv4"),
	m_ListenThreadIPv6(*this, cSocket::IPv6, "Client IPv6"),
	m_bIsConnected(false),
	m_bRestarting(false),
	m_RCONServer(*this),
	m_TickThread(*this)
{
}





void cServer::ClientDestroying(const cClientHandle * a_Client)
{
	m_SocketThreads.StopReading(a_Client);
}





void cServer::NotifyClientWrite(const cClientHandle * a_Client)
{
	m_NotifyWriteThread.NotifyClientWrite(a_Client);
}





void cServer::WriteToClient(const cClientHandle * a_Client, const AString & a_Data)
{
	m_SocketThreads.Write(a_Client, a_Data);
}





void cServer::QueueClientClose(const cClientHandle * a_Client)
{
	m_SocketThreads.QueueClose(a_Client);
}





void cServer::RemoveClient(const cClientHandle * a_Client)
{
	m_SocketThreads.RemoveClient(a_Client);
}





void cServer::ClientMovedToWorld(const cClientHandle * a_Client)
{
	cCSLock Lock(m_CSClients);
	m_ClientsToRemove.push_back(const_cast<cClientHandle *>(a_Client));
}





void cServer::PlayerCreated(const cPlayer * a_Player)
{
	// To avoid deadlocks, the player count is not handled directly, but rather posted onto the tick thread
	cCSLock Lock(m_CSPlayerCountDiff);
	m_PlayerCountDiff += 1;
}





void cServer::PlayerDestroying(const cPlayer * a_Player)
{
	// To avoid deadlocks, the player count is not handled directly, but rather posted onto the tick thread
	cCSLock Lock(m_CSPlayerCountDiff);
	m_PlayerCountDiff -= 1;
}





bool cServer::InitServer(cIniFile & a_SettingsIni)
{
	m_Description = a_SettingsIni.GetValue ("Server", "Description", "MCServer! - In C++!").c_str();
	m_MaxPlayers  = a_SettingsIni.GetValueI("Server", "MaxPlayers", 100);
	m_PlayerCount = 0;
	m_PlayerCountDiff = 0;

	if (m_bIsConnected)
	{
		LOGERROR("ERROR: Trying to initialize server while server is already running!");
		return false;
	}

	LOG("Starting up server.");
	LOGINFO("Compatible clients: %s", MCS_CLIENT_VERSIONS);
	LOGINFO("Compatible protocol versions %s", MCS_PROTOCOL_VERSIONS);

	if (cSocket::WSAStartup() != 0) // Only does anything on Windows, but whatever
	{
		LOGERROR("WSAStartup() != 0");
		return false;
	}

	bool HasAnyPorts = false;
	AString Ports = a_SettingsIni.GetValueSet("Server", "Port", "25565");
	m_ListenThreadIPv4.SetReuseAddr(true);
	if (m_ListenThreadIPv4.Initialize(Ports))
	{
		HasAnyPorts = true;
	}

	Ports = a_SettingsIni.GetValueSet("Server", "PortsIPv6", "25565");
	m_ListenThreadIPv6.SetReuseAddr(true);
	if (m_ListenThreadIPv6.Initialize(Ports))
	{
		HasAnyPorts = true;
	}
	
	if (!HasAnyPorts)
	{
		LOGERROR("Couldn't open any ports. Aborting the server");
		return false;
	}

	m_RCONServer.Initialize(a_SettingsIni);

	m_bIsConnected = true;

	m_ServerID = "-";
	if (a_SettingsIni.GetValueSetB("Authentication", "Authenticate", true))
	{
		MTRand mtrand1;
		unsigned int r1 = (mtrand1.randInt() % 1147483647) + 1000000000;
		unsigned int r2 = (mtrand1.randInt() % 1147483647) + 1000000000;
		std::ostringstream sid;
		sid << std::hex << r1;
		sid << std::hex << r2;
		m_ServerID = sid.str();
		m_ServerID.resize(16, '0');
	}
	
	m_ClientViewDistance = a_SettingsIni.GetValueSetI("Server", "DefaultViewDistance", cClientHandle::DEFAULT_VIEW_DISTANCE);
	if (m_ClientViewDistance < cClientHandle::MIN_VIEW_DISTANCE)
	{
		m_ClientViewDistance = cClientHandle::MIN_VIEW_DISTANCE;
		LOGINFO("Setting default viewdistance to the minimum of %d", m_ClientViewDistance);
	}
	if (m_ClientViewDistance > cClientHandle::MAX_VIEW_DISTANCE)
	{
		m_ClientViewDistance = cClientHandle::MAX_VIEW_DISTANCE;
		LOGINFO("Setting default viewdistance to the maximum of %d", m_ClientViewDistance);
	}
	
	m_NotifyWriteThread.Start(this);
	
	PrepareKeys();
	
	return true;
}





int cServer::GetNumPlayers(void)
{
	cCSLock Lock(m_CSPlayerCount);
	return m_PlayerCount;
}





void cServer::PrepareKeys(void)
{
	// TODO: Save and load key for persistence across sessions
	// But generating the key takes only a moment, do we even need that?
	
	LOG("Generating protocol encryption keypair...");
	
	time_t CurTime = time(NULL);
	CryptoPP::RandomPool rng;
	rng.Put((const byte *)&CurTime, sizeof(CurTime));
	m_PrivateKey.GenerateRandomWithKeySize(rng, 1024);
	CryptoPP::RSA::PublicKey pk(m_PrivateKey);
	m_PublicKey = pk;
}





void cServer::OnConnectionAccepted(cSocket & a_Socket)
{
	if (!a_Socket.IsValid())
	{
		return;
	}
	
	const AString & ClientIP = a_Socket.GetIPString();
	if (ClientIP.empty())
	{
		LOGWARN("cServer: A client connected, but didn't present its IP, disconnecting.");
		a_Socket.CloseSocket();
		return;
	}

	LOG("Client \"%s\" connected!", ClientIP.c_str());

	cClientHandle * NewHandle = new cClientHandle(&a_Socket, m_ClientViewDistance);
	if (!m_SocketThreads.AddClient(a_Socket, NewHandle))
	{
		// For some reason SocketThreads have rejected the handle, clean it up
		LOGERROR("Client \"%s\" cannot be handled, server probably unstable", ClientIP.c_str());
		a_Socket.CloseSocket();
		delete NewHandle;
		return;
	}
	
	cCSLock Lock(m_CSClients);
	m_Clients.push_back(NewHandle);
}





bool cServer::Tick(float a_Dt)
{
	// Apply the queued playercount adjustments (postponed to avoid deadlocks)
	int PlayerCountDiff = 0;
	{
		cCSLock Lock(m_CSPlayerCountDiff);
		std::swap(PlayerCountDiff, m_PlayerCountDiff);
	}
	{
		cCSLock Lock(m_CSPlayerCount);
		m_PlayerCount += PlayerCountDiff;
	}
	
	// Send the tick to the plugins, as well as let the plugin manager reload, if asked to (issue #102):
	cPluginManager::Get()->Tick(a_Dt);
	
	// Let the Root process all the queued commands:
	cRoot::Get()->TickCommands();
	
	// Tick all clients not yet assigned to a world:
	TickClients(a_Dt);

	if (!m_bRestarting)
	{
		return true;
	}
	else
	{
		m_bRestarting = false;
		m_RestartEvent.Set();
		return false;
	}
}





void cServer::TickClients(float a_Dt)
{
	cClientHandleList RemoveClients;
	{
		cCSLock Lock(m_CSClients);
		
		// Remove clients that have moved to a world (the world will be ticking them from now on)
		for (cClientHandleList::const_iterator itr = m_ClientsToRemove.begin(), end = m_ClientsToRemove.end(); itr != end; ++itr)
		{
			m_Clients.remove(*itr);
		}  // for itr - m_ClientsToRemove[]
		m_ClientsToRemove.clear();
		
		// Tick the remaining clients, take out those that have been destroyed into RemoveClients
		for (cClientHandleList::iterator itr = m_Clients.begin(); itr != m_Clients.end();)
		{
			if ((*itr)->IsDestroyed())
			{
				// Remove the client later, when CS is not held, to avoid deadlock ( http://forum.mc-server.org/showthread.php?tid=374 )
				RemoveClients.push_back(*itr);
				itr = m_Clients.erase(itr);
				continue;
			}
			(*itr)->Tick(a_Dt);
			++itr;
		}  // for itr - m_Clients[]
	}
	
	// Delete the clients that have been destroyed
	for (cClientHandleList::iterator itr = RemoveClients.begin(); itr != RemoveClients.end(); ++itr)
	{
		delete *itr;
	} // for itr - RemoveClients[]
}





bool cServer::Start(void)
{
	if (!m_ListenThreadIPv4.Start())
	{
		return false;
	}
	if (!m_ListenThreadIPv6.Start())
	{
		return false;
	}
	if (!m_TickThread.Start())
	{
		return false;
	}
	return true;
}





bool cServer::Command(cClientHandle & a_Client, AString & a_Cmd)
{
	return cRoot::Get()->GetPluginManager()->CallHookChat(a_Client.GetPlayer(), a_Cmd);
}





void cServer::ExecuteConsoleCommand(const AString & a_Cmd, cCommandOutputCallback & a_Output)
{
	AStringVector split = StringSplit(a_Cmd, " ");
	if (split.empty())
	{
		return;
	}
	
	// Special handling: "stop" and "restart" are built in
	if ((split[0].compare("stop") == 0) || (split[0].compare("restart") == 0))
	{
		return;
	}
	
	// There is currently no way a plugin can do these (and probably won't ever be):
	if (split[0].compare("chunkstats") == 0)
	{
		cRoot::Get()->LogChunkStats(a_Output);
		a_Output.Finished();
		return;
	}
	#if defined(_MSC_VER) && defined(_DEBUG) && defined(ENABLE_LEAK_FINDER)
	if (split[0].compare("dumpmem") == 0)
	{
		LeakFinderXmlOutput Output("memdump.xml");
		DumpUsedMemory(&Output);
		return;
	}
	
	if (split[0].compare("killmem") == 0)
	{
		while (true)
		{
			new char[100 * 1024 * 1024];  // Allocate and leak 100 MiB in a loop -> fill memory and kill MCS
		}
	}
	#endif
	
	if (cPluginManager::Get()->ExecuteConsoleCommand(split, a_Output))
	{
		a_Output.Finished();
		return;
	}
	
	a_Output.Out("Unknown command, type 'help' for all commands.");
	a_Output.Finished();
}





void cServer::BindBuiltInConsoleCommands(void)
{
	cPluginManager * PlgMgr = cPluginManager::Get();
	PlgMgr->BindConsoleCommand("restart", NULL, " - Restarts the server cleanly");
	PlgMgr->BindConsoleCommand("stop", NULL, " - Stops the server cleanly");
	PlgMgr->BindConsoleCommand("chunkstats", NULL, " - Displays detailed chunk memory statistics");
	#if defined(_MSC_VER) && defined(_DEBUG) && defined(ENABLE_LEAK_FINDER)
	PlgMgr->BindConsoleCommand("dumpmem", NULL, " - Dumps all used memory blocks together with their callstacks into memdump.xml");
	#endif	
}





void cServer::Shutdown(void)
{
	m_ListenThreadIPv4.Stop();
	m_ListenThreadIPv6.Stop();
	
	m_bRestarting = true;
	m_RestartEvent.Wait();

	cRoot::Get()->SaveAllChunks();

	cCSLock Lock(m_CSClients);
	for( ClientList::iterator itr = m_Clients.begin(); itr != m_Clients.end(); ++itr )
	{
		(*itr)->Destroy();
		delete *itr;
	}
	m_Clients.clear();
}





void cServer::KickUser(int a_ClientID, const AString & a_Reason)
{
	cCSLock Lock(m_CSClients);
	for (ClientList::iterator itr = m_Clients.begin(); itr != m_Clients.end(); ++itr)
	{
		if ((*itr)->GetUniqueID() == a_ClientID)
		{
			(*itr)->Kick(a_Reason);
		}
	}  // for itr - m_Clients[]
}





void cServer::AuthenticateUser(int a_ClientID)
{
	cCSLock Lock(m_CSClients);
	for (ClientList::iterator itr = m_Clients.begin(); itr != m_Clients.end(); ++itr)
	{
		if ((*itr)->GetUniqueID() == a_ClientID)
		{
			(*itr)->Authenticate();
			return;
		}
	}  // for itr - m_Clients[]
}





///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// cServer::cNotifyWriteThread:

cServer::cNotifyWriteThread::cNotifyWriteThread(void) :
	super("ClientPacketThread"),
	m_Server(NULL)
{
}





cServer::cNotifyWriteThread::~cNotifyWriteThread()
{
	m_ShouldTerminate = true;
	m_Event.Set();
	Wait();
}





bool cServer::cNotifyWriteThread::Start(cServer * a_Server)
{
	m_Server = a_Server;
	return super::Start();
}





void cServer::cNotifyWriteThread::Execute(void)
{
	cClientHandleList Clients;
	while (!m_ShouldTerminate)
	{
		cCSLock Lock(m_CS);
		while (m_Clients.size() == 0)
		{
			cCSUnlock Unlock(Lock);
			m_Event.Wait();
			if (m_ShouldTerminate)
			{
				return;
			}
		}
		
		// Copy the clients to notify and unlock the CS:
		Clients.splice(Clients.begin(), m_Clients);
		Lock.Unlock();
		
		for (cClientHandleList::iterator itr = Clients.begin(); itr != Clients.end(); ++itr)
		{
			m_Server->m_SocketThreads.NotifyWrite(*itr);
		}  // for itr - Clients[]
		Clients.clear();
	}  // while (!mShouldTerminate)
}





void cServer::cNotifyWriteThread::NotifyClientWrite(const cClientHandle * a_Client)
{
	{
		cCSLock Lock(m_CS);
		m_Clients.remove(const_cast<cClientHandle *>(a_Client));  // Put it there only once
		m_Clients.push_back(const_cast<cClientHandle *>(a_Client));
	}
	m_Event.Set();
}




