#include "I2PEndian.h"
#include <thread>
#include <cryptopp/sha.h>
#include "RouterContext.h"
#include "Log.h"
#include "Timestamp.h"
#include "I2NPProtocol.h"
#include "Transports.h"
#include "NetDb.h"
#include "Tunnel.h"

namespace i2p
{	
namespace tunnel
{		
	
	Tunnel::Tunnel (TunnelConfig * config): m_Config (config), m_Pool (nullptr), m_IsEstablished (false)
	{
	}	

	Tunnel::~Tunnel ()
	{
		delete m_Config;
	}	

	void Tunnel::Build (uint32_t replyMsgID, OutboundTunnel * outboundTunnel)
	{
		CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
		size_t numRecords = m_Config->GetNumHops ();
		I2NPMessage * msg = NewI2NPMessage ();
		*msg->GetPayload () = numRecords;
		msg->len += numRecords*sizeof (I2NPBuildRequestRecordElGamalEncrypted) + 1;
		
		I2NPBuildRequestRecordElGamalEncrypted * records = (I2NPBuildRequestRecordElGamalEncrypted *)(msg->GetPayload () + 1); 

		TunnelHopConfig * hop = m_Config->GetFirstHop ();
		int i = 0;
		while (hop)
		{
			EncryptBuildRequestRecord (*hop->router,
				CreateBuildRequestRecord (hop->router->GetIdentHash (), 
				    hop->tunnelID,
					hop->nextRouter->GetIdentHash (), 
					hop->nextTunnelID,
					hop->layerKey, hop->ivKey,                  
					hop->replyKey, hop->replyIV,
					hop->next ? rnd.GenerateWord32 () : replyMsgID, // we set replyMsgID for last hop only
				    hop->isGateway, hop->isEndpoint), 
		    	records[i]);
			i++;
			hop = hop->next;
		}	
		
		hop = m_Config->GetLastHop ()->prev;
		size_t ind = numRecords - 1;
		while (hop)
		{
			for (size_t i = ind; i < numRecords; i++)
			{	
				m_CBCDecryption.SetKeyWithIV (hop->replyKey, 32, hop->replyIV);
				m_CBCDecryption.ProcessData((uint8_t *)&records[i], (uint8_t *)&records[i], sizeof (I2NPBuildRequestRecordElGamalEncrypted));
			}	
			hop = hop->prev;
			ind--;
		}	
		FillI2NPMessageHeader (msg, eI2NPVariableTunnelBuild);
		
		if (outboundTunnel)
			outboundTunnel->SendTunnelDataMsg (GetNextIdentHash (), 0, msg);	
		else
			i2p::transports.SendMessage (GetNextIdentHash (), msg);
	}	
		
	bool Tunnel::HandleTunnelBuildResponse (uint8_t * msg, size_t len)
	{
		LogPrint ("TunnelBuildResponse ", (int)msg[0], " records.");

		TunnelHopConfig * hop = m_Config->GetLastHop (); 
		int num = msg[0];
		while (hop)
		{	
			for (int i = 0; i < num; i++)
			{			
				uint8_t * record = msg + 1 + i*sizeof (I2NPBuildResponseRecord);
				m_CBCDecryption.SetKeyWithIV(hop->replyKey, 32, hop->replyIV);
				m_CBCDecryption.ProcessData(record, record, sizeof (I2NPBuildResponseRecord));
			}
			hop = hop->prev;
			num--;
		}

		m_IsEstablished = true;
		for (int i = 0; i < msg[0]; i++)
		{			
			I2NPBuildResponseRecord * record = (I2NPBuildResponseRecord *)(msg + 1 + i*sizeof (I2NPBuildResponseRecord));
			LogPrint ("Ret code=", (int)record->ret);
			if (record->ret) 
				// if any of participants declined the tunnel is not established
				m_IsEstablished = false; 
		}
		return m_IsEstablished;
	}	
	
	void Tunnel::LayerDecrypt (const uint8_t * in, size_t len, const uint8_t * layerKey, 
		const uint8_t * iv, uint8_t * out)
	{
		m_CBCDecryption.SetKeyWithIV (layerKey, 32, iv); 
		m_CBCDecryption.ProcessData(out, in, len); 
	}	

	void Tunnel::IVDecrypt (const uint8_t * in, const uint8_t * ivKey, uint8_t * out)
	{
		m_ECBDecryption.SetKey (ivKey, 32); 
		m_ECBDecryption.ProcessData(out, in, 16); 
	}		

	void Tunnel::EncryptTunnelMsg (I2NPMessage * tunnelMsg)
	{
		uint8_t * payload = tunnelMsg->GetPayload () + 4;
		TunnelHopConfig * hop = m_Config->GetLastHop (); 
		while (hop)
		{	
			// iv + data
			IVDecrypt (payload, hop->ivKey, payload);
			LayerDecrypt (payload + 16, TUNNEL_DATA_ENCRYPTED_SIZE, hop->layerKey, payload, payload+16);
			IVDecrypt (payload, hop->ivKey, payload);
			hop = hop->prev;
		}
	}	
	
	void InboundTunnel::HandleTunnelDataMsg (I2NPMessage * msg)
	{
		msg->from = this;
		EncryptTunnelMsg (msg);
		m_Endpoint.HandleDecryptedTunnelDataMsg (msg);	
	}	

	void OutboundTunnel::SendTunnelDataMsg (const uint8_t * gwHash, uint32_t gwTunnel, i2p::I2NPMessage * msg)
	{
		TunnelMessageBlock block;
		if (gwHash)
		{
			block.hash = gwHash;
			if (gwTunnel)
			{	
				block.deliveryType = eDeliveryTypeTunnel;
				block.tunnelID = gwTunnel;
			}	
			else
				block.deliveryType = eDeliveryTypeRouter;
		}	
		else	
			block.deliveryType = eDeliveryTypeLocal;
		block.data = msg;
		m_Gateway.SendTunnelDataMsg (block);
	}
		
	void OutboundTunnel::SendTunnelDataMsg (std::vector<TunnelMessageBlock> msgs)
	{
		for (auto& it : msgs)
			m_Gateway.PutTunnelDataMsg (it);
		m_Gateway.SendBuffer ();
	}	
	
	Tunnels tunnels;
	
	Tunnels::Tunnels (): m_IsRunning (false), m_IsTunnelCreated (false), 
		m_NextReplyMsgID (555),m_Thread (0)
	{
	}
	
	Tunnels::~Tunnels ()	
	{
		for (auto& it : m_OutboundTunnels)
			delete it;
		m_OutboundTunnels.clear ();

		for (auto& it : m_InboundTunnels)
			delete it.second;
		m_InboundTunnels.clear ();
		
		for (auto& it : m_TransitTunnels)
			delete it.second;
		m_TransitTunnels.clear ();

		for (auto& it : m_PendingTunnels)
			delete it.second;
		m_PendingTunnels.clear ();
	}	
	
	InboundTunnel * Tunnels::GetInboundTunnel (uint32_t tunnelID)
	{
		auto it = m_InboundTunnels.find(tunnelID);
		if (it != m_InboundTunnels.end ())
			return it->second;
		return nullptr;
	}	
	
	TransitTunnel * Tunnels::GetTransitTunnel (uint32_t tunnelID)
	{
		auto it = m_TransitTunnels.find(tunnelID);
		if (it != m_TransitTunnels.end ())
			return it->second;
		return nullptr;
	}	
		
	Tunnel * Tunnels::GetPendingTunnel (uint32_t replyMsgID)
	{
		auto it = m_PendingTunnels.find(replyMsgID);
		if (it != m_PendingTunnels.end ())
		{
			Tunnel * t = it->second;
			m_PendingTunnels.erase (it);
			return t;
		}	
		return nullptr;
	}	

	InboundTunnel * Tunnels::GetNextInboundTunnel ()
	{
		InboundTunnel * tunnel  = nullptr; 
		size_t minReceived = 0;
		for (auto it : m_InboundTunnels)
			if (!tunnel || it.second->GetNumReceivedBytes () < minReceived)
			{
				tunnel = it.second;
				minReceived = it.second->GetNumReceivedBytes ();
			}		
		return tunnel;
	}

	std::vector<InboundTunnel *> Tunnels::GetInboundTunnels (int num) const
	{
		std::vector<InboundTunnel *> v;
		int i = 0;
		for (auto it : m_InboundTunnels)
		{
			if (i >= num) break;
			if (it.second->GetNextIdentHash () != i2p::context.GetRouterInfo ().GetIdentHash ())
			{
				// exclude one hop tunnels
				v.push_back (it.second);
				i++;
			}	
		}	
		return v;
	}	
	
	OutboundTunnel * Tunnels::GetNextOutboundTunnel ()
	{
		CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
		uint32_t ind = rnd.GenerateWord32 (0, m_OutboundTunnels.size () - 1), i = 0;
		for (auto it: m_OutboundTunnels)
		{	
			if (i >= ind) return it;
			else i++;
		}	
		return nullptr;
		
		// TODO: implement it base on profiling
		/*OutboundTunnel * tunnel  = nullptr; 
		size_t minSent = 0;
		for (auto it : m_OutboundTunnels)
			if (!tunnel || it->GetNumSentBytes () < minSent)
			{
				tunnel = it;
				minSent = it->GetNumSentBytes ();
			}		
		return tunnel;*/
	}	
	
	void Tunnels::AddTransitTunnel (TransitTunnel * tunnel)
	{
		m_TransitTunnels[tunnel->GetTunnelID ()] = tunnel;
	}	

	void Tunnels::Start ()
	{
		m_IsRunning = true;
		m_Thread = new std::thread (std::bind (&Tunnels::Run, this));
	}
	
	void Tunnels::Stop ()
	{
		m_IsRunning = false;
		m_Queue.WakeUp ();
		if (m_Thread)
		{	
			m_Thread->join (); 
			delete m_Thread;
			m_Thread = 0;
		}	
	}	

	void Tunnels::Run ()
	{
		std::this_thread::sleep_for (std::chrono::seconds(1)); // wait for other parts are ready
		
		uint64_t lastTs = 0;
		while (m_IsRunning)
		{
			try
			{	
				I2NPMessage * msg = m_Queue.GetNextWithTimeout (1000); // 1 sec
				while (msg)
				{
					uint32_t  tunnelID = be32toh (*(uint32_t *)msg->GetPayload ()); 
					InboundTunnel * tunnel = GetInboundTunnel (tunnelID);
					if (tunnel)
						tunnel->HandleTunnelDataMsg (msg);
					else
					{	
						TransitTunnel * transitTunnel = GetTransitTunnel (tunnelID);
						if (transitTunnel)
							transitTunnel->HandleTunnelDataMsg (msg);
						else	
						{	
							LogPrint ("Tunnel ", tunnelID, " not found");
							i2p::DeleteI2NPMessage (msg);
						}	
					}	
					msg = m_Queue.Get ();
				}	
			
				uint64_t ts = i2p::util::GetSecondsSinceEpoch ();
				if (ts - lastTs >= 15) // manage tunnels every 15 seconds
				{
					ManageTunnels ();
					lastTs = ts;
				}
			}
			catch (std::exception& ex)
			{
				LogPrint ("Tunnels: ", ex.what ());
			}	
		}	
	}	

	void Tunnels::ManageTunnels ()
	{
		// check pending tunnel. if something is still there, wipe it out
		// because it wouldn't be reponded anyway
		for (auto& it : m_PendingTunnels)
		{	
			LogPrint ("Pending tunnel build request ", it.first, " has not been responded. Deleted");
			auto pool = it.second->GetTunnelPool ();
			if (pool)
				pool->TunnelCreationFailed (it.second);
			delete it.second;
		}	
		m_PendingTunnels.clear ();
		
		ManageInboundTunnels ();
		ManageOutboundTunnels ();
		ManageTransitTunnels ();
		
	/*	if (!m_IsTunnelCreated)
		{	
			InboundTunnel * inboundTunnel = CreateOneHopInboundTestTunnel ();
			if (inboundTunnel)
			    CreateOneHopOutboundTestTunnel (inboundTunnel);
			inboundTunnel = CreateTwoHopsInboundTestTunnel ();
			if (inboundTunnel)
				CreateTwoHopsOutboundTestTunnel (inboundTunnel);
				
			m_IsTunnelCreated = true;
		}*/
	}	

	void Tunnels::ManageOutboundTunnels ()
	{
		uint64_t ts = i2p::util::GetSecondsSinceEpoch ();
		for (auto it = m_OutboundTunnels.begin (); it != m_OutboundTunnels.end ();)
		{
			if (ts > (*it)->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
			{
				LogPrint ("Tunnel ", (*it)->GetTunnelID (), " expired");
				it = m_OutboundTunnels.erase (it);
			}	
			else 
				it++;
		}
	
		if (m_OutboundTunnels.size () < 10)
		{
			// trying to create one more oubound tunnel
			if (m_InboundTunnels.empty ())	return;
			
			InboundTunnel * inboundTunnel = GetNextInboundTunnel ();
			if (m_OutboundTunnels.empty () || m_OutboundTunnels.size () < 3)
			{	
				LogPrint ("Creating one hop outbound tunnel...");
				CreateTunnel<OutboundTunnel> (
				  	new TunnelConfig (std::vector<const i2p::data::RouterInfo *> 
					    { 
							i2p::data::netdb.GetRandomRouter ()
						},		
			     		inboundTunnel->GetTunnelConfig ()));
			}	
			else
			{

				LogPrint ("Creating two hops outbound tunnel...");
				auto firstHop = i2p::data::netdb.GetRandomRouter (); 
				CreateTunnel<OutboundTunnel> (
				  	new TunnelConfig (std::vector<const i2p::data::RouterInfo *>
				    	{
							firstHop,
							i2p::data::netdb.GetRandomRouter (firstHop)
						},		
			     		inboundTunnel->GetTunnelConfig ()));
			}	
		}
	}
	
	void Tunnels::ManageInboundTunnels ()
	{
		uint64_t ts = i2p::util::GetSecondsSinceEpoch ();
		for (auto it = m_InboundTunnels.begin (); it != m_InboundTunnels.end ();)
		{
			if (ts > it->second->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
			{
				LogPrint ("Tunnel ", it->second->GetTunnelID (), " expired");
				auto pool = it->second->GetTunnelPool ();
				if (pool)
					pool->TunnelExpired (it->second);
				it = m_InboundTunnels.erase (it);
			}	
			else 
				it++;
		}

		if (m_InboundTunnels.empty ())
		{
			LogPrint ("Creating zero hops inbound tunnel...");
			CreateZeroHopsInboundTunnel ();
			return;
		}
		
		if (m_InboundTunnels.size () < 10)
		{
			// trying to create one more inbound tunnel
			if (m_OutboundTunnels.empty () || m_InboundTunnels.size () < 3)
			{	
				LogPrint ("Creating one hop inbound tunnel...");
				CreateTunnel<InboundTunnel> (
					new TunnelConfig (std::vector<const i2p::data::RouterInfo *>
					    {              
							i2p::data::netdb.GetRandomRouter ()
						}));
			}
			else
			{
				OutboundTunnel * outboundTunnel = GetNextOutboundTunnel ();
				LogPrint ("Creating two hops inbound tunnel...");
				auto router = outboundTunnel->GetTunnelConfig ()->GetFirstHop ()->router;
				auto firstHop = i2p::data::netdb.GetRandomRouter (outboundTunnel->GetEndpointRouter ()); 
				CreateTunnel<InboundTunnel> (
					new TunnelConfig (std::vector<const i2p::data::RouterInfo *>
						{                
				            firstHop, 
							router != &i2p::context.GetRouterInfo () ? router : i2p::data::netdb.GetRandomRouter (firstHop) 
		                }),                 
				    outboundTunnel);
			}	
		}
	}	

	void Tunnels::ManageTransitTunnels ()
	{
		uint32_t ts = i2p::util::GetSecondsSinceEpoch ();
		for (auto it = m_TransitTunnels.begin (); it != m_TransitTunnels.end ();)
		{
			if (ts > it->second->GetCreationTime () + TUNNEL_EXPIRATION_TIMEOUT)
			{
				LogPrint ("Transit tunnel ", it->second->GetTunnelID (), " expired");
				it = m_TransitTunnels.erase (it);
			}	
			else 
				it++;
		}
	}	
	
	void Tunnels::PostTunnelData (I2NPMessage * msg)
	{
		if (msg) m_Queue.Put (msg);		
	}	

	template<class TTunnel>
	TTunnel * Tunnels::CreateTunnel (TunnelConfig * config, OutboundTunnel * outboundTunnel)
	{
		TTunnel * newTunnel = new TTunnel (config);
		m_PendingTunnels[m_NextReplyMsgID] = newTunnel; 
		newTunnel->Build (m_NextReplyMsgID, outboundTunnel);
		m_NextReplyMsgID++; // TODO: should be atomic
		return newTunnel;
	}	

	void Tunnels::AddOutboundTunnel (OutboundTunnel * newTunnel)
	{
		m_OutboundTunnels.push_back (newTunnel);
	}	

	void Tunnels::AddInboundTunnel (InboundTunnel * newTunnel)
	{
		m_InboundTunnels[newTunnel->GetTunnelID ()] = newTunnel;
		auto pool = newTunnel->GetTunnelPool ();
		if (pool)
			pool->TunnelCreated (newTunnel);
		else
		{
			// build symmetric outbound tunnel
			CreateTunnel<OutboundTunnel> (newTunnel->GetTunnelConfig ()->Invert (), GetNextOutboundTunnel ());		
		}
	}	

	
	void Tunnels::CreateZeroHopsInboundTunnel ()
	{
		CreateTunnel<InboundTunnel> (
			new TunnelConfig (std::vector<const i2p::data::RouterInfo *>
			    { 
					&i2p::context.GetRouterInfo ()
				}));
	}	
	
	OutboundTunnel * Tunnels::CreateOneHopOutboundTestTunnel (InboundTunnel * replyTunnel)
	{	
		return CreateTunnel<OutboundTunnel> (replyTunnel->GetTunnelConfig ()->Invert ());
	}	

	InboundTunnel * Tunnels::CreateOneHopInboundTestTunnel (OutboundTunnel * outboundTunnel)
	{
		i2p::ntcp::NTCPSession * peer = i2p::transports.GetNextNTCPSession ();
		if (peer)
		{
			const i2p::data::RouterInfo& router = peer->GetRemoteRouterInfo ();
			return CreateTunnel<InboundTunnel> (
				new TunnelConfig (std::vector<const i2p::data::RouterInfo *>{&router}), 
			    outboundTunnel);
		}	
		else
			LogPrint ("No established peers");
		return 0;
	}	

	OutboundTunnel * Tunnels::CreateTwoHopsOutboundTestTunnel (InboundTunnel * replyTunnel)
	{		
		return CreateTunnel<OutboundTunnel> (replyTunnel->GetTunnelConfig ()->Invert ());
	}	

	InboundTunnel * Tunnels::CreateTwoHopsInboundTestTunnel (OutboundTunnel * outboundTunnel)
	{
		i2p::ntcp::NTCPSession * peer = i2p::transports.GetNextNTCPSession ();
		if (peer)
		{
			const i2p::data::RouterInfo& router = peer->GetRemoteRouterInfo ();
			return  CreateTunnel<InboundTunnel> (
						new TunnelConfig (std::vector<const i2p::data::RouterInfo *>
						    { 
								&router, 
								&i2p::context.GetRouterInfo ()
							}),
			            	outboundTunnel);		
		}
		else
			LogPrint ("No established peers");
		return 0;
	}	
}
}