eqemu-server/common/struct_strategy.h

#pragma once

#include "common/emu_opcodes.h"
#include "common/emu_versions.h"

#include <memory>
#include <string>


class EQApplicationPacket;
class EQStreamInterface;

class StructStrategy {
public:
	//the encoder takes ownership of the supplied packet, and may enqueue multiple resulting packets into the stream
	typedef void(*Encoder)(EQApplicationPacket **p, std::shared_ptr<EQStreamInterface> dest, bool ack_req);
	//the decoder may only edit the supplied packet, producing a single packet for eqemu to consume.
	typedef void (*Decoder)(EQApplicationPacket *p);

	StructStrategy();
	virtual ~StructStrategy() {}

	//this method takes an eqemu struct, and enqueues the produced structs into the stream.
	void Encode(EQApplicationPacket **p, std::shared_ptr<EQStreamInterface> dest, bool ack_req) const;
	//this method takes an EQ wire struct, and converts it into an eqemu struct
	void Decode(EQApplicationPacket *p) const;

	virtual std::string Describe() const = 0;
	virtual const EQ::versions::ClientVersion ClientVersion() const = 0;

protected:
	//some common coders:
	//Print an error saying unknown struct/opcode and drop it
	static void ErrorEncoder(EQApplicationPacket **p, std::shared_ptr<EQStreamInterface> dest, bool ack_req);
	static void ErrorDecoder(EQApplicationPacket *p);
	//pass the packet through without modification (emu == EQ) (default)
	static void PassEncoder(EQApplicationPacket **p, std::shared_ptr<EQStreamInterface> dest, bool ack_req);
	static void PassDecoder(EQApplicationPacket *p);

	Encoder encoders[_maxEmuOpcode];
	Decoder decoders[_maxEmuOpcode];
};

//effectively a singleton, but I decided to do it this way for no apparent reason.
namespace StructStrategyFactory {
	void RegisterPatch(EmuOpcode first_opcode, const StructStrategy *structs);
};