function NutzerApp() {
  var self = this;
  var userid;
  this.cache = {}; // mustache template cache

  this.init = function () {
    //self.vorlagen = new Vorlagen();
    var dlg = document.querySelector(".dialog");
    dlg.style.flexBasis = '0em';
    document.querySelector('#top-neu-btn').addEventListener('click', self.nutzer_neu_dialog_zeigen);
    document.querySelector('.west').style.flexBasis = '0em';
    document.querySelector('.ost').style.flexBasis = '0em';
    self.get_login();
    self.get_user_list();
  };

  /* Nutzerverwaltung */
  
  this.nutzer_neu_dialog_zeigen = function () {
    self.dialog_zeigen('data/tpl/dlg-nutzer-neu.tpl', '', function(){
      var btn = document.getElementById('nutzer-speichern-btn');
      if(btn !== null) {
        btn.addEventListener('click', self.nutzer_speichern);                         
      }                      
    });
  };

  this.nutzerliste_klick = function(event) {
    var target = event.target;
    var gewaehlterNutzer = document.querySelector(".nutzer-gewaehlt");
    if(gewaehlterNutzer !== null) {
      gewaehlterNutzer.classList.remove("nutzer-gewaehlt");
    }
    target.classList.add("nutzer-gewaehlt");
    var nutzerId = target.innerHTML;
    self.rollen_zeigen(nutzerId);
  };
  
  this.nutzer_speichern = function() {
    var user = self.nutzer_dialog_lesen();
    var kww = document.getElementById('nutzer-wkw').value;
    if(user.pw !== kww) {
      self.meldung_mit_timeout("Kennworte stimmen nicht ueberein.", 1500);
    } else {
      self.neuen_nutzer_speichern('p=' + self.serialisieren(user));
    }
  };
  
  this.nutzer_dialog_lesen = function() {
    var id = document.getElementById('nutzer-id').value;
    var vname = document.getElementById('nutzer-vorname').value;
    var nname = document.getElementById('nutzer-name').value;
    var email = document.getElementById('nutzer-email').value;
    var kw = document.getElementById('nutzer-kw').value;
    var user = new User(id, kw, vname, nname, email);
    return user;
  };

  /* Rollen erteilen und entziehen */
  
  this.rollen_zeigen = function(nutzerId) {
    var topBtn = document.querySelector('#top-neu-btn');
    topBtn.removeEventListener('click', self.nutzer_neu_dialog_zeigen);
    topBtn.addEventListener('click', self.rolle_neu_dialog_zeigen);
    topBtn.title = "Neue Rolle";
    
    var m = 'getUserRoleNames';
    var u = '../svc/' + m + '?p=' + nutzerId;
    self.http_get(u, function (antwort) {
      var jsonAntwort = JSON.parse(antwort);
      var rollen = jsonAntwort.List[0];
      if(typeof rollen === 'object') {
        rollen = jsonAntwort;
      } else {
        rollen = 'keine';
      }
      self.html_erzeugen(
        'data/tpl/nutzer-rollen-dlg.tpl',
        rollen,
        function (html) {
          document.querySelector("#nutzer").innerHTML = html;
          document.querySelector("#nutzer-id").textContent = nutzerId;          
          self.addEvtListener('.granted-role-btn', 'click', self.revoke_role_klick);
          document.querySelector("#del-user-btn").addEventListener(
                  'click', self.nutzer_loeschen_bestaetigen);
          self.alle_rollen_zeigen();
        });
    });
    document.querySelector('.zurueck-btn').style.color = 'black';
  };
  
  this.nutzer_loeschen_bestaetigen = function() {
    var nutzerId = document.querySelector("#nutzer-id").textContent;
    self.dialog_zeigen(
      'data/tpl/dlg-del-conf.tpl',
      JSON.parse('{"nutzername": "' + nutzerId + '"}'), 
      function(){
        var btn = document.getElementById('nutzer-loeschen-btn');
        if(btn !== null) {
          btn.addEventListener('click', function() {
            var user = new User(nutzerId, '', '', '');
            self.nutzer_loeschen(user);
          });                         
        }                      
      });
  };
  
  this.alle_rollen_zeigen = function() {
    var m = 'getRoleNamesGranted';
    var u = '../svc/' + m;
    self.http_get(u, function (antwort2) {
      self.html_erzeugen(
        'data/tpl/alle-rollen.tpl',
        JSON.parse(antwort2),
        function (html) {
          document.querySelector(".alle-rollen-behaelter").innerHTML = html;
          document.querySelector('.zurueck-btn').addEventListener('click', function (e) {
            self.get_user_list();
          });
          self.addEvtListener('.avl-role-btn', 'click', self.grant_role_klick);
        });
    });
  };
  
  this.grant_role_klick = function(event) {
    self.alter_role(event, 'grantRole', function(roleId) {
      self.add_role_to_user_roles(roleId);
    });
  };
  
  this.add_role_to_user_roles = function(roleId) {
    var btn = document.createElement("button");
    btn.type = "button";
    btn.classList.add("granted-role-btn");
    btn.id = roleId;
    btn.textContent = roleId;
    document.querySelector('.rollen-behaelter').appendChild(btn);
  };
  
  this.revoke_role_klick = function(event) {
    self.alter_role(event, 'revokeRole', function(roleId) {
      var btn = document.querySelector("#" + roleId);
      btn.parentNode.removeChild(btn);
    });
  };
  
  this.alter_role = function(event, method, updateCallback) {
    var target = event.target;
    var nutzerId = document.querySelector("#nutzer-id").textContent;
    var roleId = target.textContent;
    self.alter_role_call(method, nutzerId, roleId, updateCallback);
  };
  
  this.rolle_neu_dialog_zeigen = function () {
    self.dialog_zeigen('data/tpl/dlg-rolle-neu.tpl', '', function(){
      var btn = document.getElementById('rolle-speichern-btn');
      if(btn !== null) {
        btn.addEventListener('click', function() {
          var nutzerId = document.querySelector("#nutzer-id").textContent;
          var rolle = document.getElementById('rollen-id').value;
          self.alter_role_call('grantRole', nutzerId, rolle, function(roleId) {
            self.add_role_to_user_roles(roleId);
            self.dialog_schliessen();
          });
        });                         
      }                      
    });
  };

  /* Funktionen aus App-Vorlage */

  this.login_zeigen = function() {
    self.meldung_mit_timeout("Benutzer: " + self.userid, 1500);
  };
  
  
  this.info_dialog_zeigen = function () {
    self.dialog_zeigen('data/tpl/dlg-info.tpl', '');
  };

  this.seitenleiste_umschalten = function () {
    var ostDiv = document.querySelector('.ost');
    if (ostDiv.classList.contains('ost-open')) {
      ostDiv.classList.remove('ost-open');
      ostDiv.style.flexBasis = '0em';
    } else {
      ostDiv.classList.add('ost-open');
      ostDiv.style.flexBasis = '6em';
    }
  };

  this.fusszeile_umschalten = function () {
    var suedDiv = document.querySelector('.sued');
    if (suedDiv.classList.contains('sued-open')) {
      suedDiv.classList.remove('sued-open');
      suedDiv.style.height = '0';
    } else {
      suedDiv.classList.add('sued-open');
      suedDiv.style.height = '1.5em';
    }
  };

  this.meldung_mit_timeout = function (meldung, timeout) {
    var s = document.querySelector('.sued');
    s.textContent = meldung;
    if (!s.classList.contains('sued-open')) {
      s.classList.add('sued-open');
      s.style.height = '1.5em';
    }
    setTimeout(function () {
      s.textContent = 'Bereit.';
      setTimeout(function () {
        var suedDiv = document.querySelector('.sued');
        if (suedDiv.classList.contains('sued-open')) {
          suedDiv.classList.remove('sued-open');
          suedDiv.style.height = '0';
        }
      }, 500);
    }, timeout);
  };

  /* Dialog-Funktionen */

  /*
   * Einen Dialog erzeugen
   * 
   * Die Vorlage, auf die im Parameter vurl verwiesen wird, wird geladen, 
   * wenn sie noch nicht benutzt wurde
   * 
   * @param {String} vurl - der URL mit der Dialogvorlage
   * @param {JSON-Objekt} inhalt - was im Dialog an dynamischem Inhalt angezeigt werden soll
   * @param {function} renderCallback - 
   *     Funktion, die aufgerufen wird nachdem der Dialog gerendert wurde 
   * @returns {undefined}
   */
  this.dialog_zeigen = function (vurl, inhalt, renderCallback) {
    var dlg = document.querySelector(".dialog");
    self.html_erzeugen(
            vurl,
            inhalt,
            function (html) {
              dlg.style.flexBasis = '14em';
              setTimeout(function () {
                dlg.innerHTML = html;
                document.querySelector('.close-btn').addEventListener(
                        'click', self.dialog_schliessen);
                if(renderCallback !== undefined) {
                  renderCallback();
                }
              }, 300);
            });
  };

  this.dialog_schliessen = function () {
    document.querySelector('.close-btn').removeEventListener(
            'click', self.dialog_schliessen);
    var dlg = document.querySelector('.dialog');
    dlg.innerHTML = '';
    dlg.style.flexBasis = '0em';
  };

  /* API functions */
  
  this.get_user_list = function() {
    var m = 'getUserNameList';
    var u = '../svc/' + m;
    self.http_get(u, function (antwort) {
      self.html_erzeugen(
        'data/tpl/inhalt.tpl',
        JSON.parse(antwort),
        function (h) {
          var elem = document.getElementById('nutzer');
          elem.innerHTML = h;
          self.addEvtListener('p.nutzer-liste-eintrag', 'click', self.nutzerliste_klick);
          document.querySelector('.zurueck-btn').style.color = '#eee';
          self.removeAllListeners('top-neu-btn'); 
          var topBtn = document.querySelector('#top-neu-btn');
          topBtn.title = "Neuer Benutzer";
          topBtn.addEventListener('click', self.nutzer_neu_dialog_zeigen);
        });
      });
  };
  
  this.neuen_nutzer_speichern = function(u) {
    var url = '../svc/createUser';
    self.http_post(url, u, function (antwort) {
      self.get_user_list();
      document.getElementById('nutzer-speichern-btn').removeEventListener(
        'click', self.nutzer_speichern);
      self.dialog_schliessen();
    });
  };

  this.nutzer_loeschen = function(u) {
    var url = '../svc/deleteUser';
    var data = "p=" + self.serialisieren(u);
    self.http_post(url, data, function (antwort) {
      self.get_user_list();
      document.getElementById('nutzer-loeschen-btn').removeEventListener(
        'click', self.nutzer_loeschen);
      self.dialog_schliessen();
    });
  };
  
  this.alter_role_call = function(method, nutzerId, roleId, updateCallback) {
    var u = '../svc/' + method;
    var data = "p=" + self.serialisieren(new UserRole(nutzerId, roleId));
    self.http_post(u, data, function (antwort) {  
      updateCallback(roleId);
    });            
  };
  
  /* -------- An- und Abmelden ------------- */

  this.get_login = function() {
    var m = '?c=de.uhilger.um.pub.SessionManager&m=getSessionUser';
    var u = '../pub' + m;
    self.http_get(u, function (resp) {
      self.userid = resp;
      self.login_zeigen();
      //document.querySelector("#userMenu").textContent = resp;
    });
  };

  this.um_logout = function() {
    var m = '?c=de.uhilger.um.pub.SessionManager&m=expireSession';
    var u = '../pub' + m;
    self.http_get(u, function (resp) {
      //$('#userMenu').text('nicht angemeldet');
      window.location.href = '../logout.html';
    });
  };

  /* -------- ajax helper functions ----------- */
  
  this.http_get = function(u, cb)  {
    self.http_call('GET', u, null, cb);
  };
  
  this.http_post = function(u, data, cb) {
    self.http_call('POST', u, data, cb);
  };

  this.http_call = function (method, u, data, scallback) {    
    var xhr = new XMLHttpRequest();
    var url = u;
    xhr.onreadystatechange = function() {
      if (this.readyState === 4 && this.status === 200) {
        scallback(this.responseText);
      }
    };
    xhr.open(method, url);
    if(method === 'GET')  {
      xhr.send();
    } else if(method === 'POST' || method === 'PUT') {
      xhr.send(data);
    }
  };
  
/* ----- Hilfsfunktionen ----- */

  this.serialisieren = function(obj) {
    return '{"' + obj.constructor.name + '":' + JSON.stringify(obj) + '}';
  };
  
  this.addEvtListener = function(selector, eventName, func) {
    var elems = document.querySelectorAll(selector);
    var index;
    for (index = 0; index < elems.length; index++) {
      elems[index].addEventListener(eventName, func);
    }
  };
  
  this.removeAllListeners = function(elementId) {
    var el = document.getElementById(elementId);
    elClone = el.cloneNode(true);
    el.parentNode.replaceChild(elClone, el);
  }; // https://stackoverflow.com/questions/19469881/remove-all-event-listeners-of-specific-type

  /* ---- Vorlagen ---- */

  this.html_erzeugen = function(vurl, inhalt, cb) {
    var vorlage = self.cache[vurl];
    if(vorlage === undefined) {
      self.vorlage_laden_und_fuellen(vurl, inhalt, cb);
    } else {
      self.vorlage_fuellen(vurl, inhalt, cb);
    }
  };

  this.vorlage_fuellen = function(vurl, inhalt, cb) {
    cb(Mustache.render(self.cache[vurl], inhalt));
  };

  this.vorlage_laden_und_fuellen = function(vurl, inhalt, cb) {
    app.http_get(vurl, function(antwort) {
      self.cache[vurl] = antwort;
      self.vorlage_fuellen(vurl, inhalt, cb);
    });
  };

}

/* ----- Objekte ----- */

function User(i, p, fn, ln, em) {
  this.id = i;
  this.pw = p;
  this.firstName = fn;
  this.lastName = ln;
  this.email = em;
}

function UserRole(u, r) {
  this.userId = u;
  this.role = r;
}