// Copyright Epic Games, Inc. All Rights Reserved.

//  _____ __  __ _____   ____  _____ _______       _   _ _______
// |_   _|  \/  |  __ \ / __ \|  __ \__   __|/\   | \ | |__   __|
//   | | | \  / | |__) | |  | | |__) | | |  /  \  |  \| |  | |
//   | | | |\/| |  ___/| |  | |  _  /  | | / /\ \ | . ` |  | |
//  _| |_| |  | | |    | |__| | | \ \  | |/ ____ \| |\  |  | |
// |_____|_|  |_|_|     \____/|_|  \_\ |_/_/    \_\_| \_|  |_|
//
// Most structures in this file are part of binary protocol.
// Modifications of the data types have back-compat implications!

#pragma once

#include "UnsyncBuffer.h"
#include "UnsyncCommon.h"
#include "UnsyncHash.h"

namespace unsync {

enum class EChunkingAlgorithmID : uint64
{
	Invalid		   = 0,
	FixedBlocks	   = 0xE9457636EEF48607ull,	 // "FixedBlocks" as fnv1a64
	VariableBlocks = 0xE62448A75E8B1CC3ull,	 // "VariableBlocks" as fnv1a64
};

const char* ToString(EChunkingAlgorithmID Algorithm);

enum class EWeakHashAlgorithmID : uint64
{
	Invalid = 0,
	Naive	= 0x4BD87A66500A16D6ull,  // "Naive" as fnv1a64
	BuzHash = 0x9A8AB46A97A95962ull,  // "Buzhash" as fnv1a64
};

const char* ToString(EWeakHashAlgorithmID Algorithm);

enum class EStrongHashAlgorithmID : uint64
{
	Invalid	   = 0,
	MD5		   = 0x1E8F2819B58AD6B3ull,	 // "MD5" as fnv1a64
	Meow	   = 0x6D8900AEE47E763Dull,	 // "Meow" as fnv1a64 (deprecated)
	Blake3_128 = 0x7FD87D89C7C1D597ull,	 // "Blake3" as fnv1a64 ("_128" is omitted for backwards compatibility)
	Blake3_160 = 0xB68497EF4370C4F5ull,	 // "Blake3_160" as fnv1a64
	Blake3_256 = 0xBF89BAEF48A68CC5ull,	 // "Blake3_256" as fnv1a64
};

const char* ToString(EStrongHashAlgorithmID Algorithm);

template<typename StrongHashT>
struct TBlock
{
	using StrongHashType = StrongHashT;

	uint64		Offset	   = 0;
	uint32		Size	   = 0;
	uint32		HashWeak   = 0;
	StrongHashT HashStrong = {};
};

using FBlock128 = TBlock<FHash128>;
using FBlock160 = TBlock<FHash160>;
using FBlock256 = TBlock<FHash256>;

using FGenericBlock = TBlock<FGenericHash>;

static constexpr uint64 SERIALIZED_SECTION_ID_TERMINATOR	  = 0;
static constexpr uint64 SERIALIZED_SECTION_ID_METADATA_STRING = 0xC6BD6CDCEEF79533ull;
static constexpr uint64 SERIALIZED_SECTION_ID_MACRO_BLOCK	  = 0x8390AEBB745E08BCull;

struct FSerializedSectionHeader
{
	static constexpr uint64 MAGIC	= 0xEE5037CFF5BC71B2ull;
	uint64					Magic	= MAGIC;
	uint64					Id		= SERIALIZED_SECTION_ID_TERMINATOR;
	uint64					Version = 0;
	uint64					Size	= 0;
};

struct FMetadataStringSection
{
	static constexpr uint64 MAGIC	= SERIALIZED_SECTION_ID_METADATA_STRING;
	static constexpr uint64 VERSION = 1;
	std::string				NameUtf8;
	std::string				ValueUtf8;
};

struct FMacroBlockSection
{
	static constexpr uint64 MAGIC	= SERIALIZED_SECTION_ID_MACRO_BLOCK;
	static constexpr uint64 VERSION = 2;
};

struct FBlockFileHeader
{
	static constexpr uint64 MAGIC	= 0x1DCB86A5BDBA27CFull;
	static constexpr uint64 VERSION = 2;

	uint64 Magic	 = MAGIC;
	uint64 Version	 = VERSION;
	uint64 BlockSize = 0;
	uint64 NumBlocks = 0;
};

struct FBlockRequest
{
	FHash128 FilenameMd5 = {};
	FHash128 BlockHash	 = {};
	uint64	 Offset		 = 0;
	uint64	 Size		 = 0;
};

struct FHandshakePacket
{
	static constexpr uint64 MAGIC	 = 0xAE2C046180D0914Eull;
	uint64					Magic	 = MAGIC;
	uint32					Protocol = 1;
	uint32					Size	 = 0;
};

static constexpr uint64 COMMAND_ID_DISCONNECT = 0;
static constexpr uint64 COMMAND_ID_GET_BLOCKS = 0xBBE2A1CECC8C949Cull;

struct FCommandPacket
{
	static constexpr uint64 MAGIC	  = 0x251B6A201A26EC82ull;
	uint64					Magic	  = MAGIC;
	uint64					CommandId = 0;
};

struct FileListPacket
{
	static constexpr uint64 MAGIC		  = 0x28B96050A327172Aull;
	uint64					Magic		  = MAGIC;
	uint32					DataSizeBytes = 0;
	uint32					NumFiles	  = 0;
};

struct FRequestBlocksPacket
{
	static constexpr uint64 MAGIC				  = 0x6A885827EA6659F7ull;
	uint64					Magic				  = MAGIC;
	uint64					StrongHashAlgorithmId = 0;
	uint32					CompressedSizeBytes	  = 0;
	uint32					DecompressedSizeBytes = 0;
	uint32					NumRequests			  = 0;
};

struct FBlockPacket
{
	FHash128 Hash			  = {};
	uint64	 DecompressedSize = 0;
	FBuffer	 CompressedData;
};

// Protocol V2: support for up to 256bit hashes

struct FBlockRequest256
{
	FHash128 FilenameMd5 = {};
	FHash256 BlockHash	 = {};
	uint64	 Offset		 = 0;
	uint64	 Size		 = 0;
};

struct FBlockPacket256
{
	FHash256 Hash;
	uint64	 DecompressedSize = 0;
	FBuffer	 CompressedData;
};

}  // namespace unsync