function sortiere(sortart : string){
  if(sortart =="vorname"){
      var sortedArray: User[] = userList.sort((n1,n2) => {
          if (n1.vorname > n2.vorname ) {

              return 1;
          }

          if (n1.vorname < n2.vorname) {
              return -1;
          }

          return 0;
      });

  }else if(sortart == "nachname"){
      var sortedArray: User[] = userList.sort((n1,n2) => {
          if (n1.nachname > n2.nachname ) {

              return 1;
          }

          if (n1.nachname < n2.nachname) {
              return -1;
          }

          return 0;
      });

  }else if(sortart == "rolle"){
      var sortedArray: User[] = userList.sort((n1,n2) => {
          if (n1.rolle > n2.rolle ) {

              return 1;
          }

          if (n1.rolle < n2.rolle) {
              return -1;
          }

          return 0;
      });

  }else if(sortart== "id"){
      var sortedArray: User[] = userList.sort((n1,n2) => {
          if (n1.id > n2.id ) {

              return 1;
          }

          if (n1.id < n2.id) {
              return -1;
          }

          return 0;
      });

  }
}

router.get    ("/users/:sortart", function (req: Request, res: Response) {
  let sortart : string = req.params.sortart;

  sortiere(sortart);
  let message    : string;
  let id         : number = userList.length;
  let noElements : number = 0;
  //--- construct message ----------------------------------------------------
  while (id--) { // iterate through list, starting at the end and decrementing
    if ( userList[id] != null) noElements++; // count not deleted elements
  } // remark: loop stops with id = -1
  message = "There are " + noElements + " users in list" + sortart;
  res.status(200); // set http status to "Ok"
  //--- prepare and send response ---------------------------------------------
  res.json( {message: message, userList: userList} );    // return message
});

function nachauswahlsortieren( suchauswahl : string ){
    if(suchauswahl  =="vorname"){
        var sortedArray: User[] = userList.sort((n1,n2) => {
            if (n1.vorname > n2.vorname ) {

                return 1;
            }

            if (n1.vorname < n2.vorname) {
                return -1;
            }

            return 0;
        });

    }else if(suchauswahl  == "nachname"){
        var sortedArray: User[] = userList.sort((n1,n2) => {
            if (n1.nachname > n2.nachname ) {

                return 1;
            }

            if (n1.nachname < n2.nachname) {
                return -1;
            }

            return 0;
        });

    }else if(suchauswahl == "rolle"){
        var sortedArray: User[] = userList.sort((n1,n2) => {
            if (n1.rolle > n2.rolle ) {

                return 1;
            }

            if (n1.rolle < n2.rolle) {
                return -1;
            }

            return 0;
        });

    }else if(suchauswahl == "id"){
        var sortedArray: User[] = userList.sort((n1,n2) => {
            if (n1.id > n2.id ) {

                return 1;
            }

            if (n1.id < n2.id) {
                return -1;
            }

            return 0;
        });

    }
}

router.get    ("/users/:suchauswahl", function (req: Request, res: Response) {

    let suchauswahl : string = req.params.suchauswahl ;
    nachauswahlsortieren( suchauswahl);
    let message    : string;
    let id         : number = userList.length;
    let noElements : number = 0;

    res.json( {userList: userList});
});

router.get    ("/users/:listeaufruf", function (req: Request, res: Response) {



    res.json( {userList: userList});
});