vcmi/lib/network/NetworkInterface.h

/*
 * NetworkHandler.h, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#pragma once

#include <boost/asio.hpp>

// Windows headers included by boost/asio.hpp may define these macros which conflict with engine code
#ifdef _WIN32
#ifdef AUTO
#undef AUTO
#endif
#ifdef IGNORE
#undef IGNORE
#endif
#endif

VCMI_LIB_NAMESPACE_BEGIN

#if BOOST_VERSION >= 106600
using NetworkContext = boost::asio::io_context;
#else
using NetworkContext = boost::asio::io_service;
#endif

struct DLL_LINKAGE DiscoveredServer
{
	std::string address;
	uint16_t port;
};

/// Base class for connections with other services, either incoming or outgoing
class DLL_LINKAGE INetworkConnection : boost::noncopyable
{
public:
	virtual ~INetworkConnection() = default;
	virtual void sendPacket(const std::vector<std::byte> & message) = 0;
	virtual void setAsyncWritesEnabled(bool on) = 0;
	virtual void close() = 0;
};

/// Class for internal connections within single process, for use when TCP is not possible or not desired
class IInternalConnection : public INetworkConnection
{
public:
	virtual void receivePacket(const std::vector<std::byte> & message) = 0;
	virtual void disconnect() = 0;
	virtual void connectTo(std::shared_ptr<IInternalConnection> connection) = 0;
};

using NetworkConnectionPtr = std::shared_ptr<INetworkConnection>;
using NetworkConnectionWeakPtr = std::weak_ptr<INetworkConnection>;

/// Base class for outgoing connections support
class DLL_LINKAGE INetworkClient : boost::noncopyable
{
public:
	virtual ~INetworkClient() = default;

	virtual bool isConnected() const = 0;
	virtual void sendPacket(const std::vector<std::byte> & message) = 0;
};

/// Base class for incoming connections support
class DLL_LINKAGE INetworkServer : boost::noncopyable
{
public:
	virtual ~INetworkServer() = default;

	virtual uint16_t start(uint16_t port) = 0;
	virtual void receiveInternalConnection(std::shared_ptr<IInternalConnection> remoteConnection) = 0;
};

/// Base interface that must be implemented by user of networking API to handle any connection callbacks
class DLL_LINKAGE INetworkConnectionListener
{
public:
	virtual void onDisconnected(const std::shared_ptr<INetworkConnection> & connection, const std::string & errorMessage) = 0;
	virtual void onPacketReceived(const std::shared_ptr<INetworkConnection> & connection, const std::vector<std::byte> & message) = 0;

	virtual ~INetworkConnectionListener() = default;
};

/// Interface that must be implemented by user of networking API to handle outgoing connection callbacks
class DLL_LINKAGE INetworkClientListener : public INetworkConnectionListener
{
public:
	virtual void onConnectionFailed(const std::string & errorMessage) = 0;
	virtual void onConnectionEstablished(const std::shared_ptr<INetworkConnection> &) = 0;
};

/// Interface that must be implemented by user of networking API to handle incoming connection callbacks
class DLL_LINKAGE INetworkServerListener : public INetworkConnectionListener
{
public:
	virtual void onNewConnection(const std::shared_ptr<INetworkConnection> &) = 0;
};

/// Interface that must be implemented by user of networking API to handle timers on network thread
class DLL_LINKAGE INetworkTimerListener
{
public:
	virtual ~INetworkTimerListener() = default;

	virtual void onTimer() = 0;
};

/// Base interface that must be implemented by user of networking API to handle server discovery results
class DLL_LINKAGE IServerDiscoveryObserver
{
public:
	virtual ~IServerDiscoveryObserver() = default;
	virtual void onServerDiscovered(const DiscoveredServer & server) = 0;
};

/// Base interface for server discovery component
class DLL_LINKAGE IServerDiscovery : boost::noncopyable
{
public:
	virtual ~IServerDiscovery() = default;
	virtual void start() = 0;
	virtual void abort() = 0;
};

/// Base interface that provides data for responding to discovery requests
class DLL_LINKAGE IServerDiscoveryAnnouncer
{
public:
	virtual ~IServerDiscoveryAnnouncer() = default;
	virtual bool isInLobby() const = 0;
	virtual uint16_t getPort() const = 0;
};

/// Base interface for server discovery listener component
class DLL_LINKAGE IServerDiscoveryListener : boost::noncopyable
{
public:
	virtual ~IServerDiscoveryListener() = default;
	virtual void start() = 0;
	virtual void stop() = 0;
};

/// Main class for handling of all network activity
class DLL_LINKAGE INetworkHandler : boost::noncopyable
{
public:
	virtual ~INetworkHandler() = default;

	/// Constructs default implementation
	static std::unique_ptr<INetworkHandler> createHandler();

	/// Creates an instance of TCP server that allows to receiving connections on a local port
	virtual std::unique_ptr<INetworkServer> createServerTCP(INetworkServerListener & listener) = 0;

	/// Creates an instance of TCP client that allows to establish single outgoing connection to a remote port
	/// On success: INetworkTimerListener::onConnectionEstablished() will be called, established connection provided as parameter
	/// On failure: INetworkTimerListener::onConnectionFailed will be called with human-readable error message
	virtual void connectToRemote(INetworkClientListener & listener, const std::string & host, uint16_t port) = 0;

	/// Creates an instance of internal connection that is connected to a network server, but uses intra-process communication instead of TCP
	/// On success INetworkTimerListener::onConnectionEstablished() will be called asynchronously, established connection provided as parameter
	virtual void createInternalConnection(INetworkClientListener & listener, INetworkServer & server) = 0;

	/// Creates one-way connection that allows sending messages to listener in async form
	virtual std::shared_ptr<INetworkConnection> createAsyncConnection(INetworkConnectionListener & listener) = 0;

	/// Creates a timer that will be called once, after specified interval has passed
	/// On success: INetworkTimerListener::onTimer() will be called
	/// On failure: no-op
	virtual void createTimer(INetworkTimerListener & listener, std::chrono::milliseconds duration) = 0;

	/// Creates a server discovery component that broadcasts discovery messages and reports results
	virtual std::shared_ptr<IServerDiscovery> createServerDiscovery(IServerDiscoveryObserver & listener) = 0;

	/// Creates a server discovery listener that responds to discovery requests
	virtual std::shared_ptr<IServerDiscoveryListener> createServerDiscoveryListener(IServerDiscoveryAnnouncer & announcer, uint16_t port = 3030) = 0;

	/// Starts network processing on this thread. Does not returns until networking processing has been terminated
	virtual void run() = 0;
	virtual void stop() = 0;
};

VCMI_LIB_NAMESPACE_END