//////////////////////////////////////////////////////////////////////////////
// This file is part of the Journey MMORPG client                           //
// Copyright © 2015-2016 Daniel Allendorf                                   //
//                                                                          //
// This program is free software: you can redistribute it and/or modify     //
// it under the terms of the GNU Affero General Public License as           //
// published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.                      //
//                                                                          //
// You should have received a copy of the GNU Affero General Public License //
// along with this program.  If not, see <http://www.gnu.org/licenses/>.    //
//////////////////////////////////////////////////////////////////////////////
#pragma once
#include "PacketHandler.h"

#include <type_traits>
#include <memory>

namespace jrc
{
    /// Class which contains the array of handler classes to use.
    class PacketSwitch
    {
    public:
        /// Register all handlers.
        PacketSwitch();

        /// Forward a packet to the correct handler.
        void forward(const int8_t* bytes, size_t length) const;

    private:
        /// Print a warning to the console about something strange or amiss in
        /// the packet switcher.
        void warn(const std::string& message, size_t opcode) const;

        /// Opcodes for which handlers can be registered.
        enum Opcode : uint16_t;

        /// Message when an unhandled packet is received.
        static constexpr const char* MSG_UNHANDLED = "Unhandled packet detected";
        /// Message when a packet with a larger opcode than the array size is received.
        static constexpr const char* MSG_OUTOFBOUNDS = "Large opcode detected";
        /// Message when a handler is registered more than once.
        static constexpr const char* MSG_REREGISTER = "Handler was registered twice";
        /// Maximum number of handlers needed.
        static constexpr const size_t NUM_HANDLERS = 500;

        std::unique_ptr<PacketHandler> handlers[NUM_HANDLERS];

        /// Register a handler for the specified opcode.
        template <size_t O, typename T, typename... Args>
        void emplace(Args&&... args)
        {
            static_assert(
                O < NUM_HANDLERS,
                "PacketSwitch::emplace - Opcode out of array bounds."
            );
            static_assert(
                std::is_base_of<PacketHandler, T>::value,
                "Error: Packet handlers must derive from PacketHandler."
            );

            if (handlers[O])
            {
                warn(MSG_REREGISTER, O);
            }

            handlers[O] = std::make_unique<T>(
                std::forward<Args>(args)...
            );
        }
    };
}