//
// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef BEAST_BIND_DETAIL_HANDLER_HPP
#define BEAST_BIND_DETAIL_HANDLER_HPP

#include <beast/detail/integer_sequence.hpp>
#include <boost/asio/detail/handler_alloc_helpers.hpp>
#include <boost/asio/detail/handler_cont_helpers.hpp>
#include <boost/asio/detail/handler_invoke_helpers.hpp>
#include <utility>

namespace beast {
namespace detail {

/*  Nullary handler that calls Handler with bound arguments.

    The bound handler provides the same io_service execution
    guarantees as the original handler.
*/
template<class Handler, class... Args>
class bound_handler
{
private:
    using args_type = std::tuple<
        typename std::decay<Args>::type...>;

    Handler h_;
    args_type args_;

    template<class Tuple, std::size_t... S>
    static void invoke(Handler& h, Tuple& args,
        index_sequence<S...>)
    {
        h(std::get<S>(args)...);
    }

public:
    using result_type = void;

    template<class DeducedHandler>
    explicit
    bound_handler(DeducedHandler&& handler, Args&&... args)
        : h_(std::forward<DeducedHandler>(handler))
        , args_(std::forward<Args>(args)...)
    {
    }

    void
    operator()()
    {
        invoke(h_, args_,
            index_sequence_for<Args...> ());
    }

    void
    operator()() const
    {
        invoke(h_, args_,
            index_sequence_for<Args...> ());
    }

    friend
    void*
    asio_handler_allocate(
        std::size_t size, bound_handler* h)
    {
        return boost_asio_handler_alloc_helpers::
            allocate(size, h->h_);
    }

    friend
    void
    asio_handler_deallocate(
        void* p, std::size_t size, bound_handler* h)
    {
        boost_asio_handler_alloc_helpers::
            deallocate(p, size, h->h_);
    }

    friend
    bool
    asio_handler_is_continuation(bound_handler* h)
    {
        return boost_asio_handler_cont_helpers::
            is_continuation (h->h_);
    }

    template<class F>
    friend
    void
    asio_handler_invoke(F&& f, bound_handler* h)
    {
        boost_asio_handler_invoke_helpers::
            invoke(f, h->h_);
    }
};

} // detail
} // beast

#include <functional>
namespace std {
template<class Handler, class... Args>
void bind(beast::detail::bound_handler<
    Handler, Args...>, ...) = delete;
} // std

#endif