
/*
 * Copyright 2011-2022 Cuberite Contributors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// cServer.h

// Interfaces to the cServer object representing the network server





#pragma once

#include "RCONServer.h"
#include "OSSupport/IsThread.h"
#include "OSSupport/Network.h"

#ifdef _MSC_VER
	#pragma warning(push)
	#pragma warning(disable:4127)
	#pragma warning(disable:4244)
	#pragma warning(disable:4231)
	#pragma warning(disable:4189)
	#pragma warning(disable:4702)
#endif

#include "mbedTLS++/RsaPrivateKey.h"

#ifdef _MSC_VER
	#pragma warning(pop)
#endif





// fwd:
class cClientHandle;
typedef std::shared_ptr<cClientHandle> cClientHandlePtr;
typedef std::list<cClientHandlePtr> cClientHandlePtrs;
typedef std::list<cClientHandle *> cClientHandles;
class cCommandOutputCallback;
class cSettingsRepositoryInterface;
class cUUID;


namespace Json
{
	class Value;
}





// tolua_begin
class cServer
{
public:
	// tolua_end

	virtual ~cServer() {}
	bool InitServer(cSettingsRepositoryInterface & a_Settings, bool a_ShouldAuth);

	// tolua_begin

	const AString & GetDescription(void) const {return m_Description; }

	const AString & GetShutdownMessage(void) const { return m_ShutdownMessage; }

	// Player counts:
	size_t GetMaxPlayers(void) const { return m_MaxPlayers; }
	size_t GetNumPlayers(void) const { return m_PlayerCount; }
	void SetMaxPlayers(size_t a_MaxPlayers) { m_MaxPlayers = a_MaxPlayers; }

	// tolua_end

	/** Add a Forge mod to the server ping list. */
	bool RegisterForgeMod(const AString & a_ModName, const AString & a_ModVersion, UInt32 a_ProtocolVersionNumber);

	// tolua_begin

	/** Remove a Forge mod to the server ping list. */
	void UnregisterForgeMod(const AString & a_ModName, UInt32 a_ProtocolVersionNumber);

	/** Check if the player is queued to be transferred to a World.
	Returns true is Player is found in queue. */
	bool IsPlayerInQueue(const AString & a_Username);

	/** Can login more than once with same username.
	Returns false if it is not allowed, true otherwise. */
	bool DoesAllowMultiLogin(void) { return m_bAllowMultiLogin; }

	// Hardcore mode or not:
	bool IsHardcore(void) const { return m_bIsHardcore; }

	// tolua_end

	/** Returns true if clients must accept resource pack. This is read from the settings. */
	bool ShouldRequireResourcePack(void) { return m_RequireResourcePack; }

	const AString & GetResourcePackUrl(void) { return m_ResourcePackUrl; }

	std::string_view GetCustomRedirectUrl(void) { return m_CustomRedirectUrl; }

	bool Start(void);

	bool Command(cClientHandle & a_Client, AString & a_Cmd);

	/** Queues a console command for execution through the cServer class.
	The command will be executed in the server tick thread.
	The command's output will be written to the a_Output callback. */
	void QueueExecuteConsoleCommand(const AString & a_Cmd, cCommandOutputCallback & a_Output);

	/** Queues a lambda task onto the server tick thread, with the specified delay in ticks. */
	void ScheduleTask(cTickTime a_DelayTicks, std::function<void(class cServer &)> a_Task);

	/** Lists all available console commands and their helpstrings */
	void PrintHelp(const AStringVector & a_Split, cCommandOutputCallback & a_Output);

	/** Binds the built-in console commands with the plugin manager */
	static void BindBuiltInConsoleCommands(void);

	void Shutdown(void);

	void KickUser(int a_ClientID, const AString & a_Reason);

	/** Authenticates the specified user, called by cAuthenticator supplying player details from Mojang. */
	void AuthenticateUser(int a_ClientID, AString && a_Username, const cUUID & a_UUID, Json::Value && a_Properties);

	const AString & GetServerID(void) const { return m_ServerID; }  // tolua_export

	/** Don't tick a_Client anymore, it will be ticked from its cPlayer instead */
	void ClientMovedToWorld(const cClientHandle * a_Client);

	/** Notifies the server that a player was created; the server uses this to adjust the number of players */
	void PlayerCreated();

	/** Notifies the server that a player is being destroyed; the server uses this to adjust the number of players */
	void PlayerDestroyed();

	/** Returns base64 encoded favicon data (obtained from favicon.png) */
	const AString & GetFaviconData(void) const { return m_FaviconData; }

	cRsaPrivateKey & GetPrivateKey(void) { return m_PrivateKey; }
	ContiguousByteBufferView GetPublicKeyDER(void) const { return m_PublicKeyDER; }

	/** Returns true if authentication has been turned on in server settings. */
	bool ShouldAuthenticate(void) const { return m_ShouldAuthenticate; }  // tolua_export

	/** Returns true if limit for number of block changes per tick by a player has been turned on in server settings. */
	bool ShouldLimitPlayerBlockChanges(void) const { return m_ShouldLimitPlayerBlockChanges; }

	/** Returns true if BungeeCord logins (that specify the player's UUID) are allowed.
	Read from settings, admins should set this to true only when they chain to BungeeCord,
	it makes the server vulnerable to identity theft through direct connections. */
	bool ShouldAllowBungeeCord(void) const { return m_ShouldAllowBungeeCord; }

	bool OnlyAllowBungeeCord(void) const { return m_OnlyAllowBungeeCord; }

	const AString & GetProxySharedSecret(void) const { return m_ProxySharedSecret; }

	/** Returns true if usernames should be completed across worlds. This is read
	from the settings. */
	bool ShouldAllowMultiWorldTabCompletion(void) const { return m_ShouldAllowMultiWorldTabCompletion; }

	/** Get the Forge mods (map of ModName -> ModVersionString) registered for a given protocol. */
	const AStringMap & GetRegisteredForgeMods(const UInt32 a_Protocol);

private:

	friend class cRoot;  // so cRoot can create and destroy cServer
	friend class cServerListenCallbacks;  // Accessing OnConnectionAccepted()



	/** The server tick thread takes care of the players who aren't yet spawned in a world */
	class cTickThread:
		public cIsThread
	{
		using Super = cIsThread;

	public:

		cTickThread(cServer & a_Server);

	protected:
		cServer & m_Server;

		// cIsThread overrides:
		virtual void Execute(void) override;
	} ;



	/** The network sockets listening for client connections. */
	cServerHandlePtrs m_ServerHandles;

	/** Protects m_Clients and m_ClientsToRemove against multithreaded access. */
	cCriticalSection m_CSClients;

	/** Clients that are connected to the server and not yet assigned to a cWorld. */
	cClientHandlePtrs m_Clients;

	/** Clients that have just been moved into a world and are to be removed from m_Clients in the next Tick(). */
	cClientHandles m_ClientsToRemove;

	/** Number of players currently playing in the server. */
	std::atomic_size_t m_PlayerCount;

	cCriticalSection m_CSPendingCommands;
	std::vector<std::pair<AString, cCommandOutputCallback *>> m_PendingCommands;

	int m_ClientViewDistance;  // The default view distance for clients; settable in Settings.ini

	bool m_bIsConnected;  // true - connected false - not connected

	/** The private key used for the assymetric encryption start in the protocols */
	cRsaPrivateKey m_PrivateKey;

	/** Public key for m_PrivateKey, ASN1-DER-encoded */
	ContiguousByteBuffer m_PublicKeyDER;

	cRCONServer m_RCONServer;

	AString m_Description;
	AString m_ShutdownMessage;
	AString m_FaviconData;
	size_t m_MaxPlayers;
	bool m_bIsHardcore;
	bool m_RequireResourcePack;
	AString m_ResourcePackUrl;
	AString m_CustomRedirectUrl;

	/** Map of protocol version to Forge mods (map of ModName -> ModVersionString) */
	std::map<UInt32, AStringMap> m_ForgeModsByVersion;

	/** True - allow same username to login more than once False - only once */
	bool m_bAllowMultiLogin;

	cTickThread m_TickThread;

	/** The server ID used for client authentication */
	AString m_ServerID;

	/** If true, players will be online-authenticated agains Mojang servers.
	This setting is the same as the "online-mode" setting in Vanilla. */
	bool m_ShouldAuthenticate;

	/** True if limit for number of block changes per tick by a player should be enabled. */
	bool m_ShouldLimitPlayerBlockChanges;

	/** True if BungeeCord handshake packets (with player UUID) should be accepted. */
	bool m_ShouldAllowBungeeCord;

	/** True if BungeeCord handshake packets should be the only ones accepted. */
	bool m_OnlyAllowBungeeCord;

	/** Security string that the proxy server should send, compatible with BungeeGuard */
	AString m_ProxySharedSecret;

	/** True if usernames should be completed across worlds. */
	bool m_ShouldAllowMultiWorldTabCompletion;

	/** The list of ports on which the server should listen for connections.
	Initialized in InitServer(), used in Start(). */
	AStringVector m_Ports;


	/** Time, in ticks, since the server started
		Not persistent across server restarts */
	cTickTimeLong m_UpTime;

	/** Guards the m_Tasks */
	cCriticalSection m_CSTasks;

	/** Tasks that have been queued onto the tick thread, possibly to be
	executed at target tick in the future; guarded by m_CSTasks */
	std::vector<std::pair<std::chrono::milliseconds, std::function<void(class cServer &)>>> m_Tasks;


	cServer(void);

	/** Executes the console command, sends output through the specified callback. */
	void ExecuteConsoleCommand(const AString & a_Cmd, cCommandOutputCallback & a_Output);

	/** Get the Forge mods registered for a given protocol, for modification */
	AStringMap & RegisteredForgeMods(const UInt32 a_Protocol);

	/** Loads, or generates, if missing, RSA keys for protocol encryption */
	void PrepareKeys(void);

	/** Creates a new cClientHandle instance and adds it to the list of clients.
	Returns the cClientHandle reinterpreted as cTCPLink callbacks. */
	cTCPLink::cCallbacksPtr OnConnectionAccepted(const AString & a_RemoteIPAddress);

	void Tick(float a_Dt);

	/** Ticks the clients in m_Clients, manages the list in respect to removing clients */
	void TickClients(float a_Dt);

	/** Executes commands queued in the command queue. */
	void TickCommands(void);


	/** Executes all tasks queued onto the tick thread */
	void TickQueuedTasks(void);


};  // tolua_export




