// THClassFactory.h
/////////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 1999 Simon Fell
// All rights reserved.
//
// 10 March 99 - Initial release, 
//					inspired by Chris Sells & Keith Brown, thanks guys !
//
//
// NO WARRANTIES ARE EXTENDED. USE AT YOUR OWN RISK.
//
// To contact the author with suggestions or comments, use simon@zaks.demon.co.uk
//
/////////////////////////////////////////////////////////////////////////////
//
// THClassFactory provides an overriden implemention of IClassFactory::CreateInstance
// that attatches a TraceHook to the newly created object
//
// You'll need to modify your object's definition to use this class factory
// rather than the ATL provided ones, like
//
// As the template overrides an existing Class Factory, you still get to use all
// the funky ATL provided class factories.
//

/*
class ATL_NO_VTABLE CFoo : 
	public CComObjectRootEx<CComSingleThreadModel>,
	public CComCoClass<CFoo, &CLSID_Foo>,
	public IFoo
{
public:
	CFoo()
	{
	}

DECLARE_REGISTRY_RESOURCEID(IDR_FOO)
DECLARE_GET_CONTROLLING_UNKNOWN()
DECLARE_PROTECT_FINAL_CONSTRUCT()

DECLARE_CLASSFACTORY_EX(CTHClassFactory<CComClassFactory>) 

BEGIN_COM_MAP(CFoo)
	COM_INTERFACE_ENTRY(IFoo)
END_COM_MAP()
*/

#include <delegate.h>
#include <udtracehooksvr.h>

#ifndef HR2
#define HR2(_e) { HRESULT _hr = _e; if( FAILED(_hr) ) return; }
#endif  // HR2

inline void TraceHook(LPCOLESTR pszObjectName, REFIID riid, void** ppItf)
{
	// This parameter is [in, out]
	//assert(ppItf && *ppItf);

	// Create an instance of the UD Trace Hook and hand it the object name
	CComPtr<ITraceHook> spHook;
	HR2(spHook.CoCreateInstance(OLESTR("UDTraceHookSvr.TraceHook")));
	HR2(spHook->SetObjectName(pszObjectName && *pszObjectName ? pszObjectName : OLESTR("<object>")));

	// Get the UD class object
	CComPtr<IDelegatorFactory>  spFactory;
	HR2(CoGetClassObject(__uuidof(CoDelegator21), CLSCTX_INPROC, 0, __uuidof(IDelegatorFactory), (void**)&spFactory));

	// Delegate!
	CComPtr<IUnknown>   spitfDelegator;
	IUnknown*           punk = reinterpret_cast<IUnknown*>(*ppItf);
	HR2(spFactory->CreateDelegator(0, punk, 0, spHook, 0, riid, (void**)&spitfDelegator));

	// Replace the original ppItf with the delegator
	punk->Release();
	*ppItf = spitfDelegator.Detach();
}

template <class baseCF>
class CTHClassFactory :
	public baseCF
{
	STDMETHOD(CreateInstance)(LPUNKNOWN pUnkOuter, REFIID riid, void** ppvObj)
	{
		HRESULT hr = baseCF::CreateInstance(pUnkOuter, riid, ppvObj);
		// you could of course check some registry key here before deciding
		// to attach the hook
		if (SUCCEEDED(hr)) 
			TraceHook(NULL, riid, ppvObj) ;		
		return hr ;
	}
};