/**
* Digital Voice Modem - Host Software
* GPLv2 Open Source. Use is subject to license terms.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* @package DVM / Host Software
*
*/
//
// Based on code from the CRUD project. (https://github.com/venediktov/CRUD)
// Licensed under the BPL-1.0 License (https://opensource.org/license/bsl1-0-html)
//
/*
*   Copyright (c) 2003-2013 Christopher M. Kohlhoff
*   Copyright (C) 2023 by Bryan Biedenkapp N2PLL
*
*   Permission is hereby granted, free of charge, to any person or organization 
*   obtaining a copy of the software and accompanying documentation covered by 
*   this license (the “Software”) to use, reproduce, display, distribute, execute, 
*   and transmit the Software, and to prepare derivative works of the Software, and
*   to permit third-parties to whom the Software is furnished to do so, all subject
*   to the following:
*
*   The copyright notices in the Software and this entire statement, including the
*   above license grant, this restriction and the following disclaimer, must be included
*   in all copies of the Software, in whole or in part, and all derivative works of the
*   Software, unless such copies or derivative works are solely in the form of
*   machine-executable object code generated by a source language processor.
*
*   THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
*   INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
*   PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR ANYONE
*   DISTRIBUTING THE SOFTWARE BE LIABLE FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN
*   CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE
*   OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
 #if !defined(__REST_HTTP__HTTP_SERVER_H__)
#define __REST_HTTP__HTTP_SERVER_H__

#include "Defines.h"
#include "network/rest/Connection.h"
#include "network/rest/ConnectionManager.h"
#include "network/rest/HTTPRequestHandler.h"

#include <asio.hpp>

#include <thread>
#include <string>
#include <signal.h>
#include <utility>
#include <memory>
 
namespace rest {
    namespace server {

        // ---------------------------------------------------------------------------
        //  Class Declaration
        //      This class implements top-level routines of the HTTP server.
        // ---------------------------------------------------------------------------

        template<typename RequestHandlerType, template<class> class ConnectionImpl = Connection>
        class HTTPServer {
        public:
            /// <summary>Initializes a new instance of the HTTPServer class.</summary>
            template<typename Handler>
            explicit HTTPServer(const std::string& address, const std::string& port, Handler&& handler) :
                m_ioService(), 
                m_signals(m_ioService), 
                m_acceptor(m_ioService), 
                m_connectionManager(),
                m_socket(m_ioService), 
                m_requestHandler(std::forward<Handler>(handler))
            {
                // register to handle the signals that indicate when the server should exit
                // it is safe to register for the same signal multiple times in a program,
                // provided all registration for the specified signal is made through ASIO
                m_signals.add(SIGINT);
                m_signals.add(SIGTERM);
#if defined(SIGQUIT)
                m_signals.add(SIGQUIT);
#endif
            
                awaitStop();
            
                // open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR)
                asio::ip::tcp::resolver resolver(m_ioService);
                asio::ip::tcp::endpoint endpoint = *resolver.resolve({address, port});

                m_acceptor.open(endpoint.protocol());
                m_acceptor.set_option(asio::ip::tcp::acceptor::reuse_address(true));
                m_acceptor.set_option(asio::socket_base::keep_alive(true));
                m_acceptor.bind(endpoint);
                m_acceptor.listen();
            
                accept();
            }
            /// <summary>Initializes a copy instance of the HTTPServer class.</summary>
            HTTPServer(const HTTPServer&) = delete;
 
            /// <summary></summary>
            HTTPServer& operator=(const HTTPServer&) = delete;

            /// <summary>Run the servers ASIO IO service loop.</summary>
            void run()
            {
                // the run() call will block until all asynchronous operations
                // have finished; while the server is running, there is always at least one
                // asynchronous operation outstanding: the asynchronous accept call waiting
                // for new incoming connections
                m_ioService.run();
            }
            
        private:
            /// <summary>Perform an asynchronous accept operation.</summary>
            void accept()
            {
                m_acceptor.async_accept(m_socket, [this](asio::error_code ec) {
                    // check whether the server was stopped by a signal before this
                    // completion handler had a chance to run
                    if (!m_acceptor.is_open()) {
                        return;
                    }
                
                    if (!ec) {
                        m_connectionManager.start(std::make_shared<connection_type>(std::move(m_socket), m_connectionManager, m_requestHandler));
                    }
                
                    accept();
                });
            }
            
            /// <summary>Wait for a request to stop the server.</summary>
            void awaitStop()
            {
                m_signals.async_wait([this](asio::error_code /*ec*/, int /*signo*/) {
                    // the server is stopped by cancelling all outstanding asynchronous
                    // operations; once all operations have finished the m_ioService::run()
                    // call will exit
                    m_acceptor.close();
                    m_connectionManager.stopAll();
                });
            }
            
            typedef ConnectionImpl<RequestHandlerType> ConnectionType;
            typedef std::shared_ptr<ConnectionType> ConnectionTypePtr;
            
            asio::io_service m_ioService;
            asio::signal_set m_signals;
            asio::ip::tcp::acceptor m_acceptor;
            
            ConnectionManager<ConnectionTypePtr> m_connectionManager;
            
            asio::ip::tcp::socket m_socket;
            
            RequestHandlerType m_requestHandler;
        };
     } // namespace server
} // namespace rest
 
#endif // __REST_HTTP__HTTP_SERVER_H__