// $Id$
//
// Copyright (C) 2007
// Fraunhofer Institute for Open Communication Systems (FOKUS)
// Competence Center NETwork research (NET), St. Augustin, GERMANY
//     Stefan Bund <g0dil@berlios.de>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the
// Free Software Foundation, Inc.,
// 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

/** \file
    \brief Route internal header */

#ifndef IH_SENF_PPI_Route_
#define IH_SENF_PPI_Route_ 1

// Custom includes
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_base_of.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/static_assert.hpp>

///////////////////////////////ih.p////////////////////////////////////////

#ifndef DOXYGEN

namespace senf {
namespace ppi {
namespace detail {

    // This is the RoutingTraits implementation for Connectors. Events are handled in the
    // specialization below
    template <class Connector, bool isEvent>
    struct RoutingTraitsImplementation
    {
        BOOST_STATIC_ASSERT((boost::is_base_of<connector::Connector, Connector>::value));
        
        static bool const event = false;

        static bool const notifySource = boost::is_base_of<
            connector::ActiveConnector, Connector>::value;
        static bool const notifyTarget = boost::is_base_of<
            connector::PassiveConnector, Connector>::value;

        static bool const dataSource = boost::is_base_of<
            connector::InputConnector, Connector>::value;
        static bool const dataTarget = boost::is_base_of<
            connector::OutputConnector, Connector>::value;
        
        typedef Connector type;
    };

    // RoutingTraits specialization for Event types. Events may be both dataSource or dataTarget but
    // cannot be notifySource.
    template <class Event>
    struct RoutingTraitsImplementation<Event,true>
    {
        static bool const event = true;

        static bool const notifySource = false;
        static bool const notifyTarget = true;

        static bool const dataSource = true;
        static bool const dataTarget = true;

        typedef EventDescriptor type;
    };

    // The RoutingTraits give routing related information about the argument type:
    //  - Wether the type is a notifySource or notifyTarget
    //  - Wether the type is dataSource or dataTarget
    //  - Provide the generalized target type
    //
    // The real implementation is in RoutingTraitsImplementation which is appropriately specialized
    // for Events
    template <class Object>
    struct RoutingTraits
        : public RoutingTraitsImplementation<Object, 
                                             boost::is_convertible<Object*,
                                                                   EventDescriptor*>::value>
    {};

    // This is the generic route implementation for all routes. It just provides access to the 
    // source and target.
    template <class Source, class Target, class Base>
    class BaseRouteImplementation
        : public Base
    {
    public:
        typedef Source source_type;
        typedef Target target_type;

        Source & source() const;
        Target & target() const;

    protected:
        BaseRouteImplementation(module::Module & module, Source & source, Target & target);

    private:
        Source * source_;
        Target * target_;
    };

    // The ForwardingRouteImplementation is based on the same BaseRouteImplementation
    // as non-forwarding routes are but injects a different base-class (the third template
    // argument to BaseRouteImplementation). ForwardingRouteImplementation has two additional
    // functions:
    //  1) Register the ForwardingRoute with the notifySource
    //  2) Implement the abstract ForwardingRoute interface
    //
    // Since we don't know explicitly, which of Source or Target is the notifySource or
    // notifyTarget, the implementation calls registerRoute and notifyThrottle/notifyUnthrottle on
    // *both*, the source and target, however qualified with an additional argument of type
    // boost::mpl::bool_ which is used to select the correct overloads, of which the 'false'
    // overload always is a no-op. This way, only the correct call will generate any code, the
    // disabled call will be optimized away.
    template <class Source, class Target>
    class ForwardingRouteImplementation
        : public BaseRouteImplementation<Source, Target, ForwardingRoute>
    {
        typedef BaseRouteImplementation<Source, Target, ForwardingRoute> Base;
        
    protected:
        ForwardingRouteImplementation(module::Module & module, Source & source, Target & target);

    private:
        // send a throttle/unthrottle notification  only if the second argument is a 'true' type
        template <class T> void notifyThrottle(T & ob, boost::mpl::bool_<true> const &);
        template <class T> void notifyThrottle(T & ob, boost::mpl::bool_<false> const &);
        template <class T> void notifyUnthrottle(T & ob, boost::mpl::bool_<true> const &);
        template <class T> void notifyUnthrottle(T & ob, boost::mpl::bool_<false> const &);

        template <class T> bool throttled(T & ob, boost::mpl::bool_<true> const &) const;
        template <class T> bool throttled(T & ob, boost::mpl::bool_<false> const &) const;

        virtual void v_notifyThrottle();
        virtual void v_notifyUnthrottle();
        virtual bool v_throttled() const;
    };

    // This helper class finds the base-class suitable for a specific route. Routes are classified
    // into two groups: 
    //  1) A forwarding routes is a routed which forwards notifications from a notifySource to a
    //     notifyTarget. Forwarding routes are implemneted using ForwardingRouteImplementation
    //  2) Non-forwarding routes don't forward notifications. They are implemented directly
    //     using BaseRouteImplementation
    template <class Source, class Target>
    struct RouteImplementationBase
    {
        typedef RoutingTraits<Source> srcTrait;
        typedef RoutingTraits<Target> trgTrait;

        static bool const isForwarding = (srcTrait::notifySource && trgTrait::notifyTarget)
            || (srcTrait::notifyTarget && trgTrait::notifySource);
        
        typedef typename boost::mpl::if_c<
            isForwarding, 
            ForwardingRouteImplementation<Source,Target>, 
            BaseRouteImplementation<Source,Target,RouteBase> >::type base;
    };

    // RouteImplementation2 has two purposes: 
    //  1) Ensure, that routing is always from a data source to a data target
    //  2) To find the correct base-class. This is delegated to RouteImplementationBase
    template <class Source, class Target>
    class RouteImplementation2
        : public RouteImplementationBase<Source,Target>::base
    {
        typedef typename RouteImplementationBase<Source,Target>::base Base;

        BOOST_STATIC_ASSERT( RoutingTraits<Source>::dataSource && 
                             RoutingTraits<Target>::dataTarget );

    protected:
        RouteImplementation2(module::Module & module, Source & source, Target & target);
    };

    // RouteImplementation just forwards to RouteImplementation2 replacing the template arguments
    // with the appropriately generalized type: If either Source or Target is an Event type, it is
    // replaced with the general Event base-class EventDescriptor. Connector types are left as is.
    template <class Source, class Target>
    class RouteImplementation
        : public RouteImplementation2<typename RoutingTraits<Source>::type,
                                      typename RoutingTraits<Target>::type>
    {
        typedef RouteImplementation2<typename RoutingTraits<Source>::type,
                                     typename RoutingTraits<Target>::type> Base;

    protected:
        RouteImplementation(module::Module & module, Source & source, Target & target);
    };

}}}

#endif

///////////////////////////////ih.e////////////////////////////////////////
#endif


// Local Variables:
// mode: c++
// fill-column: 100
// comment-column: 40
// c-file-style: "senf"
// indent-tabs-mode: nil
// ispell-local-dictionary: "american"
// compile-command: "scons -u test"
// End: