#include <functional>

//! Generic service for receiving notifications about async operation completion. Used by various other services.
class completion_notify : public service_base {
public:
	//! Called when an async operation has been completed. Note that on_completion is always called from main thread. You can use on_completion_async() helper if you need to signal completion while your context is in another thread.\n
	//! IMPLEMENTATION WARNING: If process being completed creates a window taking caller's window as parent, you must not destroy the parent window inside on_completion(). If you need to do so, use PostMessage() or main_thread_callback to delay the deletion.
	//! @param p_code Context-specific status code. Possible values depend on the operation being performed.
	virtual void on_completion(unsigned p_code) = 0;

	//! Helper. Queues a notification, using main_thread_callback.
	void on_completion_async(unsigned p_code);

	//! Helper. Checks for null ptr and calls on_completion_async when the ptr is not null.
	static void g_signal_completion_async(service_ptr_t<completion_notify> p_notify,unsigned p_code);

	FB2K_MAKE_SERVICE_INTERFACE(completion_notify,service_base);
};

//! Implementation helper.
class completion_notify_dummy : public completion_notify {
public:
	void on_completion(unsigned p_code) {}
};

//! Implementation helper.
class completion_notify_orphanable : public completion_notify {
public:
	virtual void orphan() = 0;
};

//! Helper implementation.
//! IMPLEMENTATION WARNING: If process being completed creates a window taking caller's window as parent, you must not destroy the parent window inside on_task_completion(). If you need to do so, use PostMessage() or main_thread_callback to delay the deletion.
template<typename t_receiver>
class completion_notify_impl : public completion_notify_orphanable {
public:
	void on_completion(unsigned p_code) {
		if (m_receiver != NULL) {
			m_receiver->on_task_completion(m_taskid,p_code);
		}
	}
	void setup(t_receiver * p_receiver, unsigned p_task_id) {m_receiver = p_receiver; m_taskid = p_task_id;}
	void orphan() {m_receiver = NULL; m_taskid = 0;}
private:
	t_receiver * m_receiver;
	unsigned m_taskid;
};

template<typename t_receiver>
service_nnptr_t<completion_notify_orphanable> completion_notify_create(t_receiver * p_receiver,unsigned p_taskid) {
	service_nnptr_t<completion_notify_impl<t_receiver> > instance = new service_impl_t<completion_notify_impl<t_receiver> >();
	instance->setup(p_receiver,p_taskid);
	return instance;
}

typedef service_ptr_t<completion_notify> completion_notify_ptr;
typedef service_ptr_t<completion_notify_orphanable> completion_notify_orphanable_ptr;
typedef service_nnptr_t<completion_notify> completion_notify_nnptr;
typedef service_nnptr_t<completion_notify_orphanable> completion_notify_orphanable_nnptr;

//! Helper base class for classes that manage nonblocking tasks and get notified back thru completion_notify interface.
class completion_notify_receiver {
public:
    completion_notify::ptr create_or_get_task(unsigned p_id);
    completion_notify_ptr create_task(unsigned p_id);
    bool have_task(unsigned p_id) const;
    void orphan_task(unsigned p_id);
    ~completion_notify_receiver();
    void orphan_all_tasks();

	virtual void on_task_completion(unsigned p_id,unsigned p_status) {}
private:
	static void orphanfunc(unsigned,completion_notify_orphanable_nnptr p_item) {p_item->orphan();}
	pfc::map_t<unsigned,completion_notify_orphanable_nnptr> m_tasks;
};

namespace fb2k {
    
    typedef std::function<void (unsigned)> completionNotifyFunc_t;

    //! Modern completion_notify helper
    completion_notify::ptr makeCompletionNotify( completionNotifyFunc_t );
}