lay/toREST/include/http.hpp

#ifndef _TOREST_HTTP_HPP_
#define _TOREST_HTTP_HPP_

#include <json.hpp>
#include <unordered_map>

class http {
public:
  /// http codes 
  enum status {
    /*! Standard response for successful HTTP requests. */ ok=200,
    /*! The request has been fulfilled, resulting in the creation of a new resource. */ created=201,
    /*! The request has been accepted for processing, but the processing has not been completed. */ accepted=202,
    /*! The server successfully processed the request and is not returning any content. */ no_content=204,
    /*! The server cannot or will not process the request due to an apparent client error */ bad_request=400,
    /*! Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. */ unauthorized=401,
    /*! Reserved for future use. The */ payment_required=402,
    /*! the request was a valid request, but the server is refusing to respond to it. */ forbidden=403,
    /*! The requested resource could not be found but may be available in the future. */ not_found=404,
    /*! Allowed A request method is not supported for the requested resource */ method_not_allowed=405,
    /*! The resource identified by the request is only capable of generating response entities which have content characteristics not acceptable according to the accept headers sent in the request. */ not_acceptable=406,
    /*! A generic error message, given when an unexpected condition was encountered and no more specific message is suitable. */ internal_server_error=500,
    /*! The server either does not recognize the request method, or it lacks the ability to fulfill the request. */ not_implemented=501,
    /*! The server was acting as a gateway or proxy and received an invalid response from the upstream server. */ bad_gateway=502,
    /*! The server is currently unavailable (because it is overloaded or down for maintenance). Generally, this is a temporary state. */ service_unavailable=503,
    /*! Gateway timed out */ gateway_timeout=504,
    /*! http-version not supported */ http_version_not_supported=505
  };
  typedef std::pair<status,std::string> code;
  typedef std::pair<std::string,std::string> header;
  typedef std::unordered_map<std::string,std::string> headers;
  
  /// creates a http::code object out of a http::status code
  static code http_code(status status){switch(status){case accepted:return{status,"Accepted"};case bad_gateway:return{status,"Bad gateway"};case bad_request:return{status,"Bad Request"};case created:return{status,"Created"};case forbidden:return{status,"Forbidden"};case gateway_timeout:return{status,"Gateway Timeout"};case http_version_not_supported:return{status,"HTTP Version Not Supported"};case internal_server_error:return{status,"Internal Server Error"};case method_not_allowed:return{status,"Method Not Allowed"};case not_acceptable:return{status,"Not Acceptable"};case no_content:return{status,"No Content"};case not_found:return{status,"Not Found"};case not_implemented:return{status,"Not Implemented"};case ok:return{status,"OK"};case payment_required:return{status,"Payment Required"};case service_unavailable:return{status,"Service Unavailable"};case unauthorized:return{status,"Unauthorized"};default: return {status,"UNKNOWN"};}}

  class basic_response {
  protected:
    virtual std::ostream& do_response(std::ostream& os)const=0;
  public:
    virtual ~basic_response(){}
    virtual void add_header(const http::header &header)=0;
    virtual void set_status(http::status code)=0;
    virtual void set_body(const std::string &content)=0;
    friend std::ostream& operator<<(std::ostream& os,const http::basic_response &rh){ return rh.do_response(os); }
  };
  
  class response : public basic_response {
  public:
    response():status_code(http::http_code(http::ok)){}
    void set_body(const std::string &content) override { body=content; }
    void add_header(const http::header &header) override { response_headers.emplace(header); }
    void set_status(http::status code) override { status_code=http_code(code); }
  protected:
    std::ostream& do_response(std::ostream &os) const override {
      os << "HTTP/1.1" << " " << status_code.first << " " << status_code.second << "\r\n";
      for(auto &header:response_headers)
        os << header.first << ": " << header.second << "\r\n";
      if(status_code.first!=http::no_content){
        os << "Content-Length: ";
        if(!body.empty()){
          return os << body.size() << "\r\n\r\n" << body;
        } else {
          auto body_replace=std::to_string(status_code.first) + " " + status_code.second;
          return  os << body_replace.size() << "\r\n\r\n" << body_replace;
        }
     }
     return os << "\r\n";
   }
  protected:
    headers response_headers;
    std::string body;
    code status_code;
  };
  
  /// A JSON response. The default constructor sets the Content-Type header to
  /// application/json, the response defaults to 200 OK.
  class json_response : public response {
  public:
    json_response(){
      add_header({"Content-Type","application/json"});
      set_body({{"code",status_code.first},{"status",status_code.second}});
    }
    /// Method updates the http status code. set_statups also updates the body to correspond to the new status.
    /// Notice: if you previously set a body, it will be overwritten by the status code JSON representation.
    void set_status(http::status code) override {
      response::set_status(code);
      set_body({{"code",status_code.first},{"status",status_code.second}});
    }
    void set_body(nlohmann::json json){ response::set_body(json.dump()); }
  };
};

#endif // _TOREST_HTTP_HPP_