#ifndef _TOREST_SESSION_HPP_
#define _TOREST_SESSION_HPP_

#include <resource.hpp>
#include <util.hpp>
#include <libtorrent/session.hpp>
#include <http.hpp>

namespace session {
  class basic_manager {
  public:
    virtual ~basic_manager()=0;
    virtual nlohmann::json get_json() const = 0;
    virtual bool patch(const nlohmann::json &data) = 0;
    virtual bool is_valid() const = 0;
    virtual int  listen_port() const = 0;
    virtual void set_session(std::shared_ptr<libtorrent::session>) = 0;
    virtual void set_listen_port() = 0;
  };
  
  class manager : public basic_manager {
  public:
    void set_session(std::shared_ptr<libtorrent::session> session) override { handle=session; }
    nlohmann::json get_json() const override ;
    bool is_valid() const override { return handle && handle->is_valid(); }
    bool patch(const nlohmann::json &data) override ;

  private:
    std::shared_ptr<libtorrent::session> handle;
  };
  
  class basic_resource {
  public:
    virtual ~basic_resource() {}
    virtual void set_session(std::shared_ptr<basic_manager>)=0;
  };
  
  class resource : public basic_resource {
  public:
    void set_session(std::shared_ptr<basic_manager> session_manager) override { mgr=session_manager; }
    
    virtual void get(nlohmann::json arg=nullptr) {
      if(mgr && mgr->is_valid()){
        response.set_status(http::ok);
        response.set_body(mgr->get_json());
      }else{
        response.set_status(http::service_unavailable);
      }
    }
    /**
    * PATCH /session
    * --------------
    * \brief Change values on the session.
    * @param[in] data takes an JSON object with at least one `action` set.
    * available `action`s are `is_paused<bool>` `listen_port<bool>`
    */
    void patch(const nlohmann::json&data=nlohmann::json::object());
    
    // @todo should we return service unavailable or just method not allowed?
    void del(nlohmann::json arg=nullptr) { response.set_status(http::method_not_allowed); }
    void put(nlohmann::json arg=nullptr) { response.set_status(http::method_not_allowed); }
    virtual void post(nlohmann::json arg=nullptr) { response.set_status(http::method_not_allowed); }
  protected:
    std::shared_ptr<basic_manager> mgr;
    http::response response;
  };
}
#endif  // _TOREST_RESOURCE_HPP_

/*! Resource: torrents
    Other:
      - If multiple headers with the same key is posted, the server uses only the last.
      - Server can return 503 Service Unavailable if for some reason a service is down  */
/*
class torrents : public Resource<std::shared_ptr<HttpServer::Response>,std::shared_ptr<HttpServer::Request>> {
public:
  torrents(libtorrent::session &session);
};
*/
// std::function<void(StreamType,StreamType)>


  /*! API-End-point: [POST] /v1/session/torrents
    Requirements:
    - Content-Type: application/json
    * This header must be set, otherwise toREST will return 403 Forbidden.
    - Data:
    * A valid JSON-object is required.
    * A valid format:
    ```json
    {
    "torrent": "<torrent_url>",
    "save_path": "<path>"
    }
    ```
    * Fields `torrent` and `save_path` can not be empty. toREST will return 400 Bad Request
    * The `torrent` field can be a `local torrent file`, a `magnet-uri` or a HTTP-resource.
    toREST will Accept every file with a valid url, uri or path, but will not download
    or create torrents if the path is a invalid torrent file.
    * The `save_path` field can be any location on the server machine, in which the invoking
    user has write permissions. If the save_path is a directory, the torrent will download
    into the directory. If the save_path is a file, toREST will return 400 Bad Request.   
                 
    Side-Effects:
    - 202 Accepted, if the request is valid.
    * The `Location` header is set if the torrent info_hash is available
    * If a WebSocket is open a TORRENT_ADDED action is posted when the torrent resource is available.
    *
  POST=[&session](std::shared_ptr<HttpServer::Response> resp,std::shared_ptr<HttpServer::Request> req){
    http::request_handler handler(req,resp);
  
    // If session is invalid there is no point hanging around.
    if(!session.is_valid())
      return handler.respond(i18N::session_unavailable,http::service_unavailable);
  
    // At least one header named with Content-Type, then check if the last one set is application/json
    if(handler.header_equals("Content-Type","application/json"))
      return handler.respond(i18N::content_type_not_set,http::forbidden);
  
    // If the supplied JSON is invalid, bad request
    auto request_json=util::json::parse(req->content);
    if(!request_json.is_object() || request_json.is_null())
      return handler.respond(nlohmann::json(i18N::unable_to_parse_json),http::bad_request);
  
    // handle required fields
    std::vector<std::string> required_fields={
      request_json.value("torrent",""),
      request_json.value("save_path","")
    };
    std::vector<std::string> empty_fields;
    std::copy_if(required_fields.begin(),required_fields.end(),empty_fields.begin(),[](const std::string &field){return field.empty();});
    if(!empty_fields.empty()){
      std::string message;
      for(auto &field:empty_fields)
	message+=" The required field `"+field+"` is empty";
      return handler.respond(nlohmann::json(i18N::wrong_format + message),http::bad_request);
    }
    auto torrent_field=required_fields.front();
    libtorrent::add_torrent_params torrent_options;
    boost::system::error_code ec;
    if(torrent_field.substr(0,6)=="magnet"){
      libtorrent::parse_magnet_uri(torrent_field,torrent_options,ec);
      ECERROR(ec);
    }
    else if(boost::filesystem::exists(torrent_field,ec) && !boost::filesystem::is_directory(torrent_field,ec))
      torrent_options.ti=boost::make_shared<libtorrent::torrent_info>(libtorrent::torrent_info(torrent_field,ec));
    else if(boost::regex_match(torrent_field,util::regex))
      torrent_options.url=torrent_field;
    else {
      ECERROR(ec);
      return handler.respond(nlohmann::json(i18N::unable_to_parse_torrent_uri),http::bad_request);
    }
    boost::filesystem::path save_path(required_fields.back());
    auto status=boost::filesystem::status(save_path,ec);
    if(!ec){
      if(boost::filesystem::exists(status) && !boost::filesystem::is_directory(status))
	return handler.respond(nlohmann::json(i18N::wrong_format + " The save path is invalid"),http::bad_request);
      else {
	// TODO chroot
	try {
	  boost::filesystem::create_directories(save_path);
	} catch(const std::exception &ex){
	  return handler.respond(nlohmann::json(i18N::write_error),http::forbidden);
	}
      } 
    } else {
      // invalid file status
      ECERROR(ec);
    }
    torrent_options.save_path=save_path.generic_string();
    session.async_add_torrent(torrent_options);
    // TODO add websocket event
    std::string info_hash(torrent_options.info_hash.data());
    if(info_hash!="undefined"){
      std::stringstream ss;
      ss << torrent_options.info_hash;
      info_hash=ss.str();
      handler.headers["Location:"]= "/torrents/" + info_hash;
    }
    return handler.respond(nlohmann::json(http::http_code(http::accepted).second), http::accepted);
  };
}*/