FS/include/fs/zip/ZipBase.h

#pragma once
#include "tl/flag_set.h"
#include "fs/Api.h"

namespace fs
{

class FS_API ZipBase
{
public:
	enum class GeneralBitFlag : uint16_t
	{
		Encrypted = 1 << 0,
		CompressionMethodSpecific1 = 1 << 1,
		CompressionMethodSpecific2 = 1 << 2,
		DataDescriptorNeeded = 1 << 3,
		StrongEncryption = 1 << 6,
		LanguageEncodingFlag = 1 << 11,
		LocalHeaderFieldsMasked = 1 << 13,
	};
	typedef tl::flag_set<GeneralBitFlag> GeneralBitFlags;

	enum class CompressionMethod : uint16_t
	{
		Store = 0,
		Shrunk = 1,
		Reduced1 = 2,
		Reduced2 = 3,
		Reduced3 = 4,
		Reduced4 = 5,
		Implode = 6,
		//Reserved = 7,
		Deflate = 8,
		Deflate64 = 9, 
		PKWareImplode = 10,
		//Reserved = 11,
		BZip2 = 12,
		//Reserved = 13,
		LZMA = 14,
		//Reserved = 15,
		//Reserved = 16,
		//Reserved = 17,
		Terse = 18,
		LZ77 = 19,

		LZ4 = 20, // non-standard
		ZStd = 21, // non-standard

		WavPack = 97,
		PPMd = 98,
	};

protected:
	//////////////////////////////////////////////////////////////////////////
	//These structs follow pretty closely the https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT standard

#pragma pack(push, 1)

	struct LocalFileHeader
	{
		static constexpr uint32_t k_signature = 0x04034b50u;
		uint32_t signature = k_signature;
		uint16_t versionNeededToExtract = 0;
		uint16_t generalBitFlag = 0;
		uint16_t compressionMethod = 0;
		uint16_t lastModFileTime = 0;
		uint16_t lastModFileDate = 0;
		uint32_t crc32 = 0;
		uint32_t compressedSize = 0;
		uint32_t uncompressedSize = 0;
		uint16_t filenameLength = 0;
		uint16_t extraFieldLength = 0;
	};

	struct DataDescriptor
	{
		uint32_t crc32 = 0;
		uint32_t compressedSize = 0;
		uint32_t uncompressedSize = 0;
	};

	struct CentralDirectoryFileHeader
	{
		static constexpr uint32_t k_signature = 0x02014b50u;
		uint32_t signature = k_signature;
		uint16_t versionMadeBy = 0;
		uint16_t versionNeededToExtract = 0;
		uint16_t generalBitFlag = 0;
		uint16_t compressionMethod = 0;
		uint16_t lastModFileTime = 0;
		uint16_t lastModFileDate = 0;
		uint32_t crc32 = 0;
		uint32_t compressedSize = 0;
		uint32_t uncompressedSize = 0;
		uint16_t filenameLength = 0;
		uint16_t extraFieldLength = 0;
		uint16_t fileCommentLength = 0;
		uint16_t diskNumberStart = 0;
		uint16_t internalFileAttributes = 0;
		uint32_t externalFileAttributes = 0;
		uint32_t localHeaderOffset = 0;
	};

	struct EndOfCentralDirectoryRecord
	{
		static constexpr uint32_t k_signature = 0x06054b50u;
		uint32_t signature = k_signature;
		uint16_t diskNumber = 0;
		uint16_t centralDirectoryStartDiskNumber = 0;
		uint16_t centralDirectoryRecordCountOnThisDisk = 0;
		uint16_t centralDirectoryRecordCount = 0;
		uint32_t centralDirectorySize = 0;
		uint32_t centralDirectoryOffset = 0;
		uint16_t zipFileCommentLength = 0;
	};

	struct ExtendedInformationExtraField64
	{
		static constexpr uint32_t k_tag = 0x0001;
		uint16_t tag = k_tag;
		uint16_t size = 0;
		uint64_t originalSize = 0;
		uint64_t compressedSize = 0;
		uint64_t localHeaderOffset = 0;
		uint32_t diskNumber = 0;
	};

	struct EndOfCentralDirectoryRecord64
	{
		static constexpr uint32_t k_signature = 0x06064b50u;
		uint32_t signature = k_signature;
		uint64_t endOfCentralDirectorySize = 0;
		uint16_t versionMadeBy = 0;
		uint16_t versionNeededToExtract = 0;
		uint32_t diskNumber = 0;
		uint32_t centralDirectoryStartDiskNumber = 0;
		uint64_t centralDirectoryRecordCountOnThisDisk = 0;
		uint64_t centralDirectoryRecordCount = 0;
		uint64_t centralDirectorySize = 0;
		uint64_t centralDirectoryOffset = 0;
	};

	struct EndOfCentralDirectoryLocator64
	{
		static constexpr uint32_t k_signature = 0x07064b50u;
		uint32_t signature = k_signature;
		uint32_t centralDirectoryStartDiskNumber = 0;
		uint64_t endOfCentralDirectoryRecordOffset = 0;
		uint32_t diskCount = 0;
	};

#pragma pack(pop)

	static void computeMsDosTime(time_t time, uint16_t& o_date, uint16_t& o_time);
	static CentralDirectoryFileHeader computeCentralDirectoryFileHeader(const LocalFileHeader& header, bool zip64);
};

}