#include "libNPK_StdAfx.h"
#include "libNPK_FileStream.h"
#include "libNPK_Errors.h"

#include "libEncrypt_CRC32.h"

namespace NPK
{

CFileStream::CFileStream(CNPKFile* pNPKFile, HANDLE hFile, const FileItemBaseInfo& baseFileInfo)
	: m_pNPKFile(pNPKFile)
	, m_hFileandle(hFile)
	, m_fileName(baseFileInfo.keyName)
	, m_fileOffset(baseFileInfo.fileOffset)
	, m_fileSize(baseFileInfo.fileSize)
	, m_currentOffset(0)
{

}

CFileStream::~CFileStream()
{

}

uint32_t CFileStream::read(void* buffer, uint32_t size)
{
	if(isEOF())
	{
		return 0; // End of file
	}

	DWORD dwOffset = m_fileOffset + m_currentOffset;
	if (dwOffset != ::SetFilePointer(m_hFileandle, dwOffset, NULL, FILE_BEGIN))
	{
		setLastError(NPK_ERR_FILE_READ, "WinErr=%d", ::GetLastError());
		return 0; // Failed to set file pointer
	}

	DWORD dwRemainBytes = m_fileSize - m_currentOffset;
	DWORD dwToRead = (size < dwRemainBytes) ? size : dwRemainBytes;

	DWORD dwBytesRead = 0;
	if(!::ReadFile(m_hFileandle, buffer, dwToRead, &dwBytesRead, NULL))
	{
		setLastError(NPK_ERR_FILE_READ, "WinErr=%d", ::GetLastError());
		return 0; // Failed to read file
	}
	
	m_currentOffset += dwBytesRead;
	return dwBytesRead;
}

bool CFileStream::seek(uint32_t offset)
{
	if(offset > m_fileSize)
	{
		setLastError(NPK_ERR_FILE_READ, "Seek offset %u exceeds file size %u", offset, m_fileSize);
		return false; // Seek offset exceeds file size
	}
	m_currentOffset = offset;
	return true;
}

uint32_t CFileStream::crc32(void)
{
	if (m_crc32Calculated) return m_crc32; // CRC32 already calculated

	const size_t kBufferSize = 1024*4;
	uint8_t pTempBuffer[kBufferSize];

	uint32_t currentOffset = m_currentOffset;
	m_currentOffset = 0;
	m_crc32 = 0;

	// Read the entire file to calculate CRC32
	uint32_t bytesRead = 0;
	while ((bytesRead = read(pTempBuffer, kBufferSize)) > 0)
	{
		m_crc32 = crcMemory32(pTempBuffer, bytesRead, m_crc32);
	}
	m_currentOffset = currentOffset;
	m_crc32Calculated = true;
	return m_crc32;
}

bool CFileStream::writeToDiskFile(const wchar_t* diskPathFile)
{
	HANDLE hFile = ::CreateFileW(diskPathFile,
		FILE_READ_DATA | FILE_WRITE_DATA | FILE_APPEND_DATA,
		FILE_SHARE_READ | FILE_SHARE_WRITE,
		0,
		CREATE_ALWAYS,
		FILE_ATTRIBUTE_ARCHIVE,
		0);

	if (hFile == INVALID_HANDLE_VALUE)
	{
		setLastError(NPK_ERR_FILE_CREATE, "Failed to open output file for writing, LastError=%d.", ::GetLastError());
		return false; // Failed to open output file
	}

	//store current read offset
	uint32_t currentOffset = m_currentOffset;
	m_currentOffset = 0;
	
	//read loop
	char buffer[4096] = { 0 };
	uint32_t bytesRead = 0;

	while ((bytesRead = this->read(buffer, sizeof(buffer))) > 0)
	{
		DWORD dwWriteBytes = 0;
		if (!WriteFile(hFile, buffer, bytesRead, &dwWriteBytes, 0) ||
			dwWriteBytes != bytesRead)
		{
			setLastError(NPK_ERR_FILE_WRITE, "Failed to write to output file, LastError=%d", ::GetLastError());

			CloseHandle(hFile);
			m_currentOffset = currentOffset;
			return false; // Failed to write to output file
		}
	}
	CloseHandle(hFile);
	m_currentOffset = currentOffset;
	return true;
}

}