#include "egres_packet_router.hpp"

namespace llarp::vpn
{
  struct EgresUDPPacketHandler : public EgresLayer4Handler
  {
    EgresPacketHandlerFunc m_BaseHandler;
    std::unordered_map<nuint16_t, EgresPacketHandlerFunc> m_LocalPorts;

    explicit EgresUDPPacketHandler(EgresPacketHandlerFunc baseHandler)
        : m_BaseHandler{std::move(baseHandler)}
    {}

    void
    AddSubHandler(nuint16_t localport, EgresPacketHandlerFunc handler) override
    {
      m_LocalPorts.emplace(std::move(localport), std::move(handler));
    }

    void
    RemoveSubHandler(nuint16_t localport) override
    {
      m_LocalPorts.erase(localport);
    }

    void
    HandleIPPacketFrom(AddressVariant_t from, net::IPPacket pkt) override
    {
      if (auto dstPort = pkt.DstPort())
      {
        if (auto itr = m_LocalPorts.find(*dstPort); itr != m_LocalPorts.end())
        {
          itr->second(std::move(from), std::move(pkt));
          return;
        }
      }
      m_BaseHandler(std::move(from), std::move(pkt));
    }
  };

  struct EgresGenericLayer4Handler : public EgresLayer4Handler
  {
    EgresPacketHandlerFunc m_BaseHandler;

    explicit EgresGenericLayer4Handler(EgresPacketHandlerFunc baseHandler)
        : m_BaseHandler{std::move(baseHandler)}
    {}

    void
    HandleIPPacketFrom(AddressVariant_t from, net::IPPacket pkt) override
    {
      m_BaseHandler(std::move(from), std::move(pkt));
    }
  };

  EgresPacketRouter::EgresPacketRouter(EgresPacketHandlerFunc baseHandler)
      : m_BaseHandler{std::move(baseHandler)}
  {}

  void
  EgresPacketRouter::HandleIPPacketFrom(AddressVariant_t from, net::IPPacket pkt)
  {
    const auto proto = pkt.Header()->protocol;
    if (const auto itr = m_IPProtoHandler.find(proto); itr != m_IPProtoHandler.end())
    {
      itr->second->HandleIPPacketFrom(std::move(from), std::move(pkt));
    }
    else
      m_BaseHandler(std::move(from), std::move(pkt));
  }

  namespace
  {
    constexpr byte_t udp_proto = 0x11;
  }

  void
  EgresPacketRouter::AddUDPHandler(huint16_t localport, EgresPacketHandlerFunc func)
  {
    if (m_IPProtoHandler.find(udp_proto) == m_IPProtoHandler.end())
    {
      m_IPProtoHandler.emplace(udp_proto, std::make_unique<EgresUDPPacketHandler>(m_BaseHandler));
    }
    m_IPProtoHandler[udp_proto]->AddSubHandler(ToNet(localport), std::move(func));
  }

  void
  EgresPacketRouter::AddIProtoHandler(uint8_t proto, EgresPacketHandlerFunc func)
  {
    m_IPProtoHandler[proto] = std::make_unique<EgresGenericLayer4Handler>(std::move(func));
  }

  void
  EgresPacketRouter::RemoveUDPHandler(huint16_t localport)
  {
    if (auto itr = m_IPProtoHandler.find(udp_proto); itr != m_IPProtoHandler.end())
    {
      itr->second->RemoveSubHandler(ToNet(localport));
    }
  }

}  // namespace llarp::vpn