///////////////////////////////////////////////////////////////////////////////
// General Information:
// 
// Author:  Dean Lee
//          mailto:deanlee2@hotmail.com
//          http://www.deanlee.cn
//
// Purpose: 
// 
// Platforms: Windows
// ============================================================================
// Revision History:
// 
// 10/12/2006 12:51:22 PM   Dean Lee   Initial Version
// 
// ============================================================================
// Acknowledgements:
//   <> Many thanks to all of you, who have encouraged me to update my articles
//     and code, and who sent in bug reports and fixes.
// 
///////////////////////////////////////////////////////////////////////////////

#pragma once
#define IP_RECORD_LENGTH  7

#define READINT3(X) (( X[0] & 0xFF )|(( X[1] & 0xFF)<< 8 )|(( X[2] & 0xFF )<< 16 ))
#define READINT4(X) (( X[0] & 0xFF )|(( X[1] & 0xFF)<< 8 )|(( X[2] & 0xFF )<< 16 )|(( X[3] & 0xFF ) << 24 ))

class CIPSeeker
{
public:
	CIPSeeker();
	~CIPSeeker();

	bool Create(HINSTANCE hInstance);
	inline bool getIPLocation(char* pszIP, char szDest[], size_t nSize)
	{
		ATLASSERT(NULL != m_pBuffer);
		return getIPRecord(searchIP(getIntIP(pszIP)), szDest, nSize);
	}
	inline bool getIPLocation(ULONG dwIP, char szDest[], size_t nSize)
	{
		ATLASSERT(NULL != m_pBuffer);
		return getIPRecord(searchIP(dwIP), szDest, nSize);
	}
private:
	bool GetIndexOffset();
	unsigned int readIP(unsigned int offset)
	{
		unsigned int tmpIP;
		memcpy(byte4, m_pBuffer + offset, 4 * sizeof(BYTE));
		tmpIP = READINT4(byte4);
		return tmpIP;
	}
	int compareIP(const unsigned int ip1, const unsigned int ip2)
	{
		if( ip1 > ip2 ) return 1;
		else if ( ip1 < ip2 ) return -1;
		else  return 0;
	}

	unsigned int getMiddleOffset(const unsigned int begin, const unsigned int end)
	{
		int records = (end - begin) / IP_RECORD_LENGTH;
		records >>= 1;
		if(records == 0) records = 1;
		return begin + records * IP_RECORD_LENGTH;
	}
	unsigned int searchIP(const unsigned int ip);
	//read a string start from the offset until meet a char '\0'
	//param: unsigned int offset
	//return: string str
	void readString(const unsigned int offset, char szString[], size_t nSize)
	{
		strncpy_s(szString, nSize, (char*)(m_pBuffer+offset), _TRUNCATE);
		if (szString[nSize - 1] != '\0')
			szString[nSize - 1] = 0;
		m_pCurPos = m_pBuffer + offset + strlen(szString) + 1;
	}

	//read the Area data start from the offset.
	//param: unsigned int offset
	//return: string areaData
	void readArea(const unsigned int offset, char szArea[], size_t nSize);
	//get one IP record (country and area) of the offset
	//param: unsigned int offset
	//return: string location
	bool getIPRecord(const unsigned int offset, char szIPRecord[], size_t nSize);
	UINT getIntIP(const char *strIP);
	
	BYTE *m_pBuffer;
	BYTE *m_pCurPos;
	BYTE byte4[4];           //tmp char array
	BYTE byte3[3];           //tmp char array
	int firstIndexOffset;    //the first index offset of the index area
	int lastIndexOffset;     //the last index offset of the index area

};