function Room(domElem, lib) {
  var players = {};
  var sortedKeys = [];
  var session = {
    key: null,
    loggedIn: false,
    selected: null
  };
  var playersList = domElem.getElementsByClassName('players')[0];
  domElem.addEventListener('submit', function(e) {
    e.preventDefault();
    lib.send({tag: "Invitation", to: session.selected})
  });
  var compareKeysByLogin = lib.funMap(function(key) {return players[key].name;}, lib.defaultCompare);

  return {
    populate: populate,
    enter: enter,
    leave: leave,
    name: name
  };

  function Player(key, name) {
    var player = {
      name: name,
      dom: document.createElement('li'),
      position: null
    };
    player.dom.textContent = name;
    if(key != session.key) {
      player.dom.addEventListener('click', function(e) {
        e.preventDefault();
        if(session.loggedIn) {
          select(key);
        }
      });
    } else {
      on();
      player.dom.title = "Hey ! That's you !";
    }
    return player;
  }

  function populate(playersHash, sessionKey) {
    session.key = sessionKey;
    lib.clearElement(playersList);
    for(var key in playersHash) {
      enter(parseInt(key), playersHash[key] || "anon");
    }
  }

  function enter(key, name) {
    var player = Player(key, name);
    players[key] = player;
    player.position = lib.insert(key, sortedKeys, compareKeysByLogin);
    beforePlayer = players[sortedKeys[player.position]];
    playersList.insertBefore(player.dom, beforePlayer && beforePlayer.dom);
    sortedKeys.splice(player.position, 0, key);
  }

  function leave(key) {
    var player = players[key];
    if(key === session.key) {
      off();
    } else if(key === session.selected) {
      reset();
    }
    if(player != undefined) {
      playersList.removeChild(player.dom);
      sortedKeys.splice(player.position, 1);
      delete players[key];
    }
  }

  function name(key) {
    player = players[key];
    return player && player.name;
  }

  function on() {
    domElem.className = "";
    session.loggedIn = true;
  }

  function off() {
    domElem.className = "off";
    session.loggedIn = false;
    reset();
  }

  function select(key) {
    if(key === session.selected) {
      unselect(key);
    } else {
      reset();
      players[key].dom.className = "selected";
      session.selected = key;
      domElem.invite.disabled = false;
    }
  }

  function reset() {
    if(session.selected) {
      unselect(session.selected);
    }
  }

  function unselect(key) {
    players[key].dom.className = "";
    session.selected = null;
    domElem.invite.disabled = true;
  }
}