// How to use this script:
// (1) Create a new AR Studio project
// (2) Add a new PlaneTracker "planeTracker0"
// (3) Add 10 objects as a child of the planeTacker, call them "object0", "object1", etc..
// (4) Assign a different material to each object
// (5) Import this script
// (6) Run

var S = require('Scene');
var D = require('Diagnostics');
var Time = require('Time');

// Return a list of objects from a Scene node
function getAllObjects(parent, objectName, count) {
  var objects = [];
  for (var i = 0; i < count; i++) {
    objects.push(parent.child(objectName + i));
  }
  return objects;
}

// The ObjectManager entity takes a list of objects created in the Scene before hand
// and presents 2 methods add() and remove() that enable you to virtually add and
// remove object from the Scene
function ObjectManager(objects, name) {
  this.name = name || 'ObjectManager' + (ObjectManager.id++);
  this.objects = objects;
  this.unusedObjects = objects.splice(0);
  this.usedObjects = [];
}

ObjectManager.id = 0;

// Set the props of a created object
ObjectManager.setProps = function (object, props) {
  if (props.x) object.transform.x = props.x;
  if (props.y) object.transform.y = props.y;
  if (props.z) object.transform.z = props.z;
  object.material.opacity = props.opacity ? props.opacity : 1.0;
};

// Reset the props of a removed object
ObjectManager.resetProps = function (object) {
  object.transform.x = 0.0;
  object.transform.y = 0.0;
  object.transform.z = 0.0;
  object.material.opacity = 0.0;
};

ObjectManager.prototype = {
  // Add an object with the given props in the Scene
  // and returns a reference to this object
  add: function (props) {
    if (this.isFull()) {
      D.log(this.name + ': Could not add object because all occurences are used');
      return;
    }
    var object = this.unusedObjects.shift();
    this.usedObjects.push(object);
    ObjectManager.setProps(object, props);
    return object;
  },
  // Remove an object from the scene
  remove: function (object) {
    var index = this.usedObjects.indexOf(object);
    if (index > -1) {
      var object = this.usedObjects[index];
      ObjectManager.resetProps(object);
      this.usedObjects.splice(index, 1);
      this.unusedObjects.push(object);
    } else {
      if (this.unusedObjects.indexOf(object) > -1) {
        D.log(this.name + ': Attempt to remove object "' + object.name + '" which is not used');
      } else {
        D.log(this.name + ': Unknown object "' + object.name + '"');
      }
    }
  },
  isFull: function () {
    return this.unusedObjects.length === 0;
  },
  isEmpty: function () {
    return this.usedObjects.length === 0;
  }
};

// Get the list of template objects and create the ObjectManager instance
var templates = getAllObjects(S.root.child('planeTracker0'), 'object', 10);
var objMgr = new ObjectManager(templates, 'objMgr');

// Add or remove objects from the Scene
Time.ms.interval(100).subscribe(function (elapsedTime) {
  var action = '';
  if (objMgr.isFull()) action = 'remove';
  else if (objMgr.isEmpty()) action = 'add';
  else action = Math.random() > 0.5 ? 'add' : 'remove';

  if (action === 'add') {
    // add object at random position
    objMgr.add({
      x: (Math.random() - 0.5) * 50.0,
      y: (Math.random() - 0.5) * 50.0,
      z: (Math.random() - 0.5) * 50.0
    });
  } else if (action === 'remove') {
    // remove random object
    var index = Math.floor(Math.random() * objMgr.usedObjects.length);
    var object = objMgr.usedObjects[index];
    objMgr.remove(object);
  }
});