function KeyboardInputManager() {
  this.events = {};

  this.listen();
}

KeyboardInputManager.prototype.on = function (event, callback) {
  if (!this.events[event]) {
    this.events[event] = [];
  }
  this.events[event].push(callback);
};

KeyboardInputManager.prototype.emit = function (event, data) {
  var callbacks = this.events[event];
  if (callbacks) {
    callbacks.forEach(function (callback) {
      callback(data);
    });
  }
};

KeyboardInputManager.prototype.listen = function () {
  var self = this;

  function dojump(event) {
    var modifiers = event.altKey || event.ctrlKey || event.metaKey ||
                    event.shiftKey;

    if (!modifiers) {
      if (event.which >= 8 && event.which < 48) event.preventDefault();
      self.emit("jump");
    }
  }

  function dojump2(event) {
    event.preventDefault();
    self.emit("jump");
  }

  document.addEventListener("keydown", dojump);
  var gameContainer = document.querySelector(".game-container");
  gameContainer.addEventListener("click", dojump2);
  gameContainer.addEventListener("touchstart", dojump2);
};

KeyboardInputManager.prototype.restart = function (event) {
  event.preventDefault();
  this.emit("restart");
};

KeyboardInputManager.prototype.keepPlaying = function (event) {
  event.preventDefault();
  this.emit("keepPlaying");
};