#ifndef MS_RTC_DTLS_TRANSPORT_HPP
#define MS_RTC_DTLS_TRANSPORT_HPP

#include "SrtpSession.hpp"
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/x509.h>
#include <map>
#include <string>
#include <vector>
#include "Poller/Timer.h"
#include "Poller/EventPoller.h"
using namespace toolkit;

namespace RTC
{
    class DtlsTransport : public std::enable_shared_from_this<DtlsTransport>
	{
	public:
		enum class DtlsState
		{
			NEW = 1,
			CONNECTING,
			CONNECTED,
			FAILED,
			CLOSED
		};

	public:
		enum class Role
		{
			NONE = 0,
			AUTO = 1,
			CLIENT,
			SERVER
		};

	public:
		enum class FingerprintAlgorithm
		{
			NONE = 0,
			SHA1 = 1,
			SHA224,
			SHA256,
			SHA384,
			SHA512
		};

	public:
		struct Fingerprint
		{
			FingerprintAlgorithm algorithm{ FingerprintAlgorithm::NONE };
			std::string value;
		};

	private:
		struct SrtpCryptoSuiteMapEntry
		{
			RTC::SrtpSession::CryptoSuite cryptoSuite;
			const char* name;
		};

        class DtlsEnvironment : public std::enable_shared_from_this<DtlsEnvironment>
        {
        public:
            using Ptr = std::shared_ptr<DtlsEnvironment>;
            ~DtlsEnvironment();
            static DtlsEnvironment& Instance();

        private:
            DtlsEnvironment();
            void GenerateCertificateAndPrivateKey();
            void ReadCertificateAndPrivateKeyFromFiles();
            void CreateSslCtx();
            void GenerateFingerprints();

        public:
            X509* certificate{ nullptr };
            EVP_PKEY* privateKey{ nullptr };
            SSL_CTX* sslCtx{ nullptr };
            std::vector<Fingerprint> localFingerprints;
        };

	public:
		class Listener
		{
		public:
			// DTLS is in the process of negotiating a secure connection. Incoming
			// media can flow through.
			// NOTE: The caller MUST NOT call any method during this callback.
			virtual void OnDtlsTransportConnecting(const RTC::DtlsTransport* dtlsTransport) = 0;
			// DTLS has completed negotiation of a secure connection (including DTLS-SRTP
			// and remote fingerprint verification). Outgoing media can now flow through.
			// NOTE: The caller MUST NOT call any method during this callback.
			virtual void OnDtlsTransportConnected(
			  const RTC::DtlsTransport* dtlsTransport,
			  RTC::SrtpSession::CryptoSuite srtpCryptoSuite,
			  uint8_t* srtpLocalKey,
			  size_t srtpLocalKeyLen,
			  uint8_t* srtpRemoteKey,
			  size_t srtpRemoteKeyLen,
			  std::string& remoteCert) = 0;
			// The DTLS connection has been closed as the result of an error (such as a
			// DTLS alert or a failure to validate the remote fingerprint).
			virtual void OnDtlsTransportFailed(const RTC::DtlsTransport* dtlsTransport) = 0;
			// The DTLS connection has been closed due to receipt of a close_notify alert.
			virtual void OnDtlsTransportClosed(const RTC::DtlsTransport* dtlsTransport) = 0;
			// Need to send DTLS data to the peer.
			virtual void OnDtlsTransportSendData(
			  const RTC::DtlsTransport* dtlsTransport, const uint8_t* data, size_t len) = 0;
			// DTLS application data received.
			virtual void OnDtlsTransportApplicationDataReceived(
			  const RTC::DtlsTransport* dtlsTransport, const uint8_t* data, size_t len) = 0;
		};

	public:
		static Role StringToRole(const std::string& role)
		{
			auto it = DtlsTransport::string2Role.find(role);

			if (it != DtlsTransport::string2Role.end())
				return it->second;
			else
				return DtlsTransport::Role::NONE;
		}
		static FingerprintAlgorithm GetFingerprintAlgorithm(const std::string& fingerprint)
		{
			auto it = DtlsTransport::string2FingerprintAlgorithm.find(fingerprint);

			if (it != DtlsTransport::string2FingerprintAlgorithm.end())
				return it->second;
			else
				return DtlsTransport::FingerprintAlgorithm::NONE;
		}
		static std::string& GetFingerprintAlgorithmString(FingerprintAlgorithm fingerprint)
		{
			auto it = DtlsTransport::fingerprintAlgorithm2String.find(fingerprint);

			return it->second;
		}
		static bool IsDtls(const uint8_t* data, size_t len)
		{
			// clang-format off
			return (
				// Minimum DTLS record length is 13 bytes.
				(len >= 13) &&
				// DOC: https://tools.ietf.org/html/draft-ietf-avtcore-rfc5764-mux-fixes
				(data[0] > 19 && data[0] < 64)
			);
			// clang-format on
		}

	private:
		static std::map<std::string, Role> string2Role;
		static std::map<std::string, FingerprintAlgorithm> string2FingerprintAlgorithm;
		static std::map<FingerprintAlgorithm, std::string> fingerprintAlgorithm2String;
		static std::vector<SrtpCryptoSuiteMapEntry> srtpCryptoSuites;

	public:
		DtlsTransport(EventPoller::Ptr poller, Listener* listener);
		~DtlsTransport();

	public:
		void Dump() const;
		void Run(Role localRole);
		std::vector<Fingerprint>& GetLocalFingerprints() const
		{
			return env->localFingerprints;
		}
		bool SetRemoteFingerprint(Fingerprint fingerprint);
		void ProcessDtlsData(const uint8_t* data, size_t len);
		DtlsState GetState() const
		{
			return this->state;
		}
		Role GetLocalRole() const
		{
			return this->localRole;
		}
		void SendApplicationData(const uint8_t* data, size_t len);

	private:
		bool IsRunning() const
		{
			switch (this->state)
			{
				case DtlsState::NEW:
					return false;
				case DtlsState::CONNECTING:
				case DtlsState::CONNECTED:
					return true;
				case DtlsState::FAILED:
				case DtlsState::CLOSED:
					return false;
			}

			// Make GCC 4.9 happy.
			return false;
		}
		void Reset();
		bool CheckStatus(int returnCode);
		void SendPendingOutgoingDtlsData();
		bool SetTimeout();
		bool ProcessHandshake();
		bool CheckRemoteFingerprint();
		void ExtractSrtpKeys(RTC::SrtpSession::CryptoSuite srtpCryptoSuite);
		RTC::SrtpSession::CryptoSuite GetNegotiatedSrtpCryptoSuite();

    private:
	    void OnSslInfo(int where, int ret);
		void OnTimer();

	private:
        DtlsEnvironment::Ptr env;
        EventPoller::Ptr poller;
        // Passed by argument.
		Listener* listener{ nullptr };
		// Allocated by this.
		SSL* ssl{ nullptr };
		BIO* sslBioFromNetwork{ nullptr }; // The BIO from which ssl reads.
		BIO* sslBioToNetwork{ nullptr };   // The BIO in which ssl writes.
		Timer::Ptr timer;
		// Others.
		DtlsState state{ DtlsState::NEW };
		Role localRole{ Role::NONE };
		Fingerprint remoteFingerprint;
		bool handshakeDone{ false };
		bool handshakeDoneNow{ false };
		std::string remoteCert;
		//最大不超过mtu
		static constexpr int SslReadBufferSize{ 1600 };
        uint8_t sslReadBuffer[SslReadBufferSize];
};
} // namespace RTC

#endif