#ifndef TGCALLS_ENCRYPTED_CONNECTION_H
#define TGCALLS_ENCRYPTED_CONNECTION_H

#include "Instance.h"
#include "Message.h"

namespace rtc {
class ByteBufferReader;
} // namespace rtc

namespace tgcalls {

class EncryptedConnection final {
public:
	enum class Type : uint8_t {
		Signaling,
		Transport,
	};
	EncryptedConnection(
		Type type,
		const EncryptionKey &key,
		std::function<void(int delayMs, int cause)> requestSendService);

	struct EncryptedPacket {
		std::vector<uint8_t> bytes;
		uint32_t counter = 0;
	};
	absl::optional<EncryptedPacket> prepareForSending(const Message &message);
	absl::optional<EncryptedPacket> prepareForSendingService(int cause);

	struct DecryptedPacket {
		DecryptedMessage main;
		std::vector<DecryptedMessage> additional;
	};
	absl::optional<DecryptedPacket> handleIncomingPacket(const char *bytes, size_t size);

private:
	struct DelayIntervals {
		// In milliseconds.
		int minDelayBeforeMessageResend = 0;
		int maxDelayBeforeMessageResend = 0;
		int maxDelayBeforeAckResend = 0;
	};
	struct MessageForResend {
		rtc::CopyOnWriteBuffer data;
		int64_t lastSent = 0;
	};

	bool enoughSpaceInPacket(const rtc::CopyOnWriteBuffer &buffer, size_t amount) const;
	size_t packetLimit() const;
	size_t fullNotAckedLength() const;
	void appendAcksToSend(rtc::CopyOnWriteBuffer &buffer);
	void appendAdditionalMessages(rtc::CopyOnWriteBuffer &buffer);
	EncryptedPacket encryptPrepared(const rtc::CopyOnWriteBuffer &buffer);
	bool registerIncomingCounter(uint32_t incomingCounter);
	absl::optional<DecryptedPacket> processPacket(const rtc::Buffer &fullBuffer, uint32_t packetSeq);
	bool registerSentAck(uint32_t counter, bool firstInPacket);
	void ackMyMessage(uint32_t counter);
	void sendAckPostponed(uint32_t incomingSeq);
	bool haveAdditionalMessages() const;
	absl::optional<uint32_t> computeNextSeq(bool messageRequiresAck, bool singleMessagePacket);
	void appendReceivedMessage(
		absl::optional<DecryptedPacket> &to,
		Message &&message,
		uint32_t incomingSeq);

	const char *logHeader() const;

	static DelayIntervals DelayIntervalsByType(Type type);
	static rtc::CopyOnWriteBuffer SerializeEmptyMessageWithSeq(uint32_t seq);

	Type _type = Type();
	EncryptionKey _key;
	uint32_t _counter = 0;
	DelayIntervals _delayIntervals;
	std::vector<uint32_t> _largestIncomingCounters;
	std::vector<uint32_t> _ackedIncomingCounters;
	std::vector<uint32_t> _acksToSendSeqs;
	std::vector<uint32_t> _acksSentCounters;
	std::vector<MessageForResend> _myNotYetAckedMessages;
	std::function<void(int delayMs, int cause)> _requestSendService;
	bool _resendTimerActive = false;
	bool _sendAcksTimerActive = false;

};

} // namespace tgcalls

#endif