class CVMTHookManager
{
public:
	CVMTHookManager( void )
	{
		memset( this, 0, sizeof( CVMTHookManager ) );
	}

	CVMTHookManager( PDWORD* ppdwClassBase )
	{
		bInitialize( ppdwClassBase );
	}

	bool UnhookVMT( PDWORD* ppdwClassBase )
	{
		*ppdwClassBase = m_pdwOldVMT;
		return true;
	}

	bool bInitialize( PDWORD* ppdwClassBase )
	{
		m_pdwOldVMT = *ppdwClassBase;
		m_dwVMTSize = dwGetVMTCount( *ppdwClassBase );
		m_pdwNewVMT = new DWORD[ m_dwVMTSize + 2 ];
		memcpy( m_pdwNewVMT, m_pdwOldVMT, sizeof( DWORD ) * m_dwVMTSize );
		*ppdwClassBase = m_pdwNewVMT;
		return true;
	}

	bool bInitialize( PDWORD** pppdwClassBase )
	{
		return bInitialize( *pppdwClassBase );
	}

	DWORD dwHookMethod( DWORD dwNewFunc, int iIndex )
	{
		if ( m_pdwNewVMT && m_pdwOldVMT && iIndex >= 0 && iIndex <= m_dwVMTSize )
		{
			m_pdwNewVMT[ iIndex ] = dwNewFunc;
			return m_pdwOldVMT[ iIndex ];
		}

		return NULL;
	}

	VOID dwUnHookMethod( int iIndex )
	{
		m_pdwNewVMT[ iIndex ] = m_pdwOldVMT[ iIndex ];
	}

private:
	DWORD dwGetVMTCount( PDWORD pdwVMT )
	{
		DWORD dwIndex;
		for ( dwIndex = 0; pdwVMT[ dwIndex ]; dwIndex++ )
		{
			if ( IsBadCodePtr( ( FARPROC ) pdwVMT[ dwIndex ] ) )
			{
				break;
			}
		}
		return dwIndex;
	}
	PDWORD	m_pdwNewVMT, m_pdwOldVMT;
	DWORD	m_dwVMTSize;
};