#ifndef LLARP_LINK_SESSION_HPP
#define LLARP_LINK_SESSION_HPP

#include <crypto/types.hpp>
#include <net/net.hpp>
#include <ev/ev.hpp>
#include <router_contact.hpp>
#include <util/types.hpp>

#include <functional>

namespace llarp
{
  struct LinkIntroMessage;
  struct ILinkMessage;
  struct ILinkLayer;

  struct SessionStats
  {
    // rate
    uint64_t currentRateRX = 0;
    uint64_t currentRateTX = 0;

    uint64_t totalPacketsRX = 0;

    uint64_t totalAckedTX = 0;
    uint64_t totalDroppedTX = 0;
    uint64_t totalInFlightTX = 0;
  };

  struct ILinkSession
  {
    virtual ~ILinkSession() = default;

    /// delivery status of a message
    enum class DeliveryStatus
    {
      eDeliverySuccess = 0,
      eDeliveryDropped = 1
    };

    /// hook for utp for when we have established a connection
    virtual void
    OnLinkEstablished(ILinkLayer*){};

    /// called every event loop tick
    virtual void
    Pump() = 0;

    /// called every timer tick
    virtual void Tick(llarp_time_t) = 0;

    /// message delivery result hook function
    using CompletionHandler = std::function<void(DeliveryStatus)>;

    using Packet_t = std::vector<byte_t>;
    using Message_t = std::vector<byte_t>;

    /// send a message buffer to the remote endpoint
    virtual bool
    SendMessageBuffer(Message_t, CompletionHandler handler) = 0;

    /// start the connection
    virtual void
    Start() = 0;

    virtual void
    Close() = 0;

    /// recv packet on low layer
    /// not used by utp
    virtual bool Recv_LL(Packet_t)
    {
      return true;
    }

    /// send a keepalive to the remote endpoint
    virtual bool
    SendKeepAlive() = 0;

    /// return true if we are established
    virtual bool
    IsEstablished() const = 0;

    /// return true if this session has timed out
    virtual bool
    TimedOut(llarp_time_t now) const = 0;

    /// get remote public identity key
    virtual PubKey
    GetPubKey() const = 0;

    /// is an inbound session or not
    virtual bool
    IsInbound() const = 0;

    /// get remote address
    virtual IpAddress
    GetRemoteEndpoint() const = 0;

    // get remote rc
    virtual RouterContact
    GetRemoteRC() const = 0;

    /// is this session a session to a relay?
    bool
    IsRelay() const;

    /// handle a valid LIM
    std::function<bool(const LinkIntroMessage* msg)> GotLIM;

    /// send queue current blacklog
    virtual size_t
    SendQueueBacklog() const = 0;

    /// get parent link layer
    virtual ILinkLayer*
    GetLinkLayer() const = 0;

    /// renegotiate session when we have a new RC locally
    virtual bool
    RenegotiateSession() = 0;

    /// return true if we should send an explicit keepalive message
    virtual bool
    ShouldPing() const = 0;

    /// return the current stats for this session
    virtual SessionStats
    GetSessionStats() const = 0;

    virtual util::StatusObject
    ExtractStatus() const = 0;
  };
}  // namespace llarp

#endif