/**
 * @file llfunctorregistry.h
 * @author Kent Quirk
 * @brief Maintains a registry of named callback functors taking a single LLSD parameter
 *
 * $LicenseInfo:firstyear=2008&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_LLFUNCTORREGISTRY_H
#define LL_LLFUNCTORREGISTRY_H

#include <string>
#include <map>

#include <boost/function.hpp>

#include "llsd.h"
#include "llsingleton.h"

/**
 * @class LLFunctorRegistry
 * @brief Maintains a collection of named functors for remote binding
 * (mainly for use in callbacks from notifications and other signals)
 * @see LLNotifications
 *
 * This class maintains a collection of named functors in a singleton.
 * We wanted to be able to persist notifications with their callbacks
 * across restarts of the viewer; we couldn't store functors that way.
 * Using this registry, systems that require a functor to be maintained
 * long term can register it at system startup, and then pass in the
 * functor by name.
 */

template <typename FUNCTOR_TYPE>
class LLFunctorRegistry : public LLSingleton<LLFunctorRegistry<FUNCTOR_TYPE> >
{
    LLSINGLETON(LLFunctorRegistry);
    LOG_CLASS(LLFunctorRegistry);

public:
    typedef FUNCTOR_TYPE ResponseFunctor;
    typedef typename std::map<std::string, FUNCTOR_TYPE> FunctorMap;

    bool registerFunctor(const std::string& name, ResponseFunctor f)
    {
        bool retval = true;
        if (mMap.count(name) == 0)
        {
            mMap[name] = f;
        }
        else
        {
            LL_ERRS() << "attempt to store duplicate name '" << name << "' in LLFunctorRegistry. NOT ADDED." << LL_ENDL;
            retval = false;
        }

        return retval;
    }

    bool unregisterFunctor(const std::string& name)
    {
        if (mMap.count(name) == 0)
        {
            LL_WARNS() << "trying to remove '" << name << "' from LLFunctorRegistry but it's not there." << LL_ENDL;
            return false;
        }
        mMap.erase(name);
        return true;
    }

    FUNCTOR_TYPE getFunctor(const std::string& name)
    {
        if (mMap.count(name) != 0)
        {
            return mMap[name];
        }
        else
        {
            LL_DEBUGS() << "tried to find '" << name << "' in LLFunctorRegistry, but it wasn't there." << LL_ENDL;
            return mMap[LOGFUNCTOR];
        }
    }

    const std::string LOGFUNCTOR;
    const std::string DONOTHING;

private:

    static void log_functor(const LLSD& notification, const LLSD& payload)
    {
        LL_DEBUGS() << "log_functor called with payload: " << payload << LL_ENDL;
    }

    static void do_nothing(const LLSD& notification, const LLSD& payload)
    {
        // what the sign sez
    }

    FunctorMap mMap;
};

template <typename FUNCTOR_TYPE>
LLFunctorRegistry<FUNCTOR_TYPE>::LLFunctorRegistry() :
    LOGFUNCTOR("LogFunctor"), DONOTHING("DoNothing")
{
    mMap[LOGFUNCTOR] = log_functor;
    mMap[DONOTHING] = do_nothing;
}

template <typename FUNCTOR_TYPE>
class LLFunctorRegistration
{
public:
    LLFunctorRegistration(const std::string& name, FUNCTOR_TYPE functor)
    {
        LLFunctorRegistry<FUNCTOR_TYPE>::instance().registerFunctor(name, functor);
    }
};

#endif//LL_LLFUNCTORREGISTRY_H