dvmhost/network/rest/RequestDispatcher.h

/**
* 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__DISPATCHER_H__)
#define __REST__DISPATCHER_H__

#include "Defines.h"
#include "network/rest/http/HTTPRequest.h"
#include "network/rest/http/HTTPReply.h"
 
#include <functional>
#include <map>
#include <string>
#include <regex>
#include <memory>
 
namespace network {
    namespace rest {
        // ---------------------------------------------------------------------------
        //  Structure Declaration
        //      
        // ---------------------------------------------------------------------------

        struct RequestMatch : std::smatch 
        {
            /// <summary>Initializes a new instance of the RequestMatch structure.</summary>
            RequestMatch(const std::smatch& m, const std::string& d) : std::smatch(m), data(d) { /* stub */ }
            
            std::string data;
        };

        // ---------------------------------------------------------------------------
        //  Structure Declaration
        //      
        // ---------------------------------------------------------------------------
        
        template<typename Reply>
        struct RequestMatcher {
            typedef std::function<void(Reply&, const RequestMatch&)> RequestHandlerType;

            /// <summary>Initializes a new instance of the RequestMatcher structure.</summary>
            explicit RequestMatcher(const std::string& expression) : m_expression(expression), m_isRegEx(false) { /* stub */ }

            /// <summary></summary>
            RequestMatcher<Reply>& get(RequestHandlerType handler) {
                m_handlers["GET"] = handler;
                return *this;
            }
            /// <summary></summary>
            RequestMatcher<Reply>& post(RequestHandlerType handler) {
                m_handlers["POST"] = handler;
                return *this;
            }
            /// <summary></summary>
            RequestMatcher<Reply>& put(RequestHandlerType handler) {
                m_handlers["PUT"] = handler;
                return *this;
            }
            /// <summary></summary>
            RequestMatcher<Reply>& del(RequestHandlerType handler) {
                m_handlers["DELETE"] = handler;
                return *this;
            }
            /// <summary></summary>
            RequestMatcher<Reply>& options(RequestHandlerType handler) {
                m_handlers["OPTIONS"] = handler;
                return *this;
            }

            bool regex() const { return m_isRegEx; }
            void setRegEx(bool regEx) { m_isRegEx = regEx; }

            /// <summary></summary>
            template<typename Request>
            void handleRequest(const Request& request, Reply& reply, const std::smatch &what) {
                // dispatching to matching based on handler
                RequestMatch match(what, request.data);
                auto& handler = m_handlers[request.method];
                if (handler) {
                    handler(reply, match);
                }
            }
        
        private:
            std::string m_expression;
            bool m_isRegEx;
            std::map<std::string, RequestHandlerType> m_handlers;
        };

        // ---------------------------------------------------------------------------
        //  Class Declaration
        //      This class implements RESTful web request dispatching.
        // ---------------------------------------------------------------------------

        template<typename Request = http::HTTPRequest, typename Reply = http::HTTPReply>
        class RequestDispatcher {
            typedef RequestMatcher<Reply> MatcherType;
        public:
            /// <summary>Initializes a new instance of the RequestDispatcher class.</summary>
            RequestDispatcher() : m_basePath() { /* stub */ }
            /// <summary>Initializes a new instance of the RequestDispatcher class.</summary>
            RequestDispatcher(const std::string& basePath) : m_basePath(basePath) { /* stub */ }

            /// <summary></summary>
            MatcherType& match(const std::string& expression) 
            {
                MatcherTypePtr& p = m_matchers[expression];
                if (!p) {
                    p = std::make_shared<MatcherType>(expression);
                }

                return *p;
            }

            /// <summary></summary>
            void handleRequest(const Request& request, Reply& reply) 
            {
                for (const auto& matcher : m_matchers) {
                    std::smatch what;
                    if (!matcher.second->regex()) {
                        if (request.uri.find(matcher.first) != std::string::npos) {
                            //what = matcher.first;
                            matcher.second->handleRequest(request, reply, what);
                        } else {
                            reply = http::HTTPReply::stockReply(http::HTTPReply::BAD_REQUEST);
                        }
                    } else {
                        if (std::regex_match(request.uri, what, std::regex(matcher.first))) {
                            matcher.second->handleRequest(request, reply, what);
                        } else {
                            reply = http::HTTPReply::stockReply(http::HTTPReply::BAD_REQUEST);
                        }
                    }
                }
            }
        
        private:
            typedef std::shared_ptr<MatcherType> MatcherTypePtr;

            std::string m_basePath;
            std::map<std::string, MatcherTypePtr> m_matchers;
        };

        typedef RequestDispatcher<http::HTTPRequest, http::HTTPReply> DefaultRequestDispatcher;        
    } // namespace rest
} // namespace network
  
#endif // __REST__DISPATCHER_H__