var Class = require('../utils/Class'); 
var EventEmitter = require('eventemitter3'); 
var Events = require('./events'); 
var ProcessQueue = new Class({ 
Extends: EventEmitter,
initialize: function ProcessQueue(){ 
EventEmitter.call(this); 
this._pending = [] ; 
this._active = [] ; 
this._destroy = [] ; 
this._toProcess = 0; 
this.checkQueue = false ; 
} 
,
add: function (item){ 
this._pending.push(item); 
this._toProcess++ ; 
return item; 
} 
,
remove: function (item){ 
this._destroy.push(item); 
this._toProcess++ ; 
return item; 
} 
,
removeAll: function (){ 
var list = this._active; 
var destroy = this._destroy; 
var i = _AN_Read_length('length', list); 
while (i-- ){ 
destroy.push(list[i]); 
this._toProcess++ ; 
} 
return this; 
} 
,
update: function (){ 
if (this._toProcess === 0) { 
return this._active; 
} 
var list = this._destroy; 
var active = this._active; 
var i; 
var item; 
for (i = 0; i < (_AN_Read_length('length', list)); i++ ){ 
item = list[i]; 
var idx = active.indexOf(item); 
if (idx !== -1) { 
active.splice(idx, 1); 
this.emit(Events.PROCESS_QUEUE_REMOVE, item); 
} 
} 
list.length = 0; 
list = this._pending; 
for (i = 0; i < (_AN_Read_length('length', list)); i++ ){ 
item = list[i]; 
if (!this.checkQueue || (this.checkQueue && active.indexOf(item) === -1)) { 
active.push(item); 
this.emit(Events.PROCESS_QUEUE_ADD, item); 
} 
} 
list.length = 0; 
this._toProcess = 0; 
return active; 
} 
,
getActive: function (){ 
return this._active; 
} 
,
length: { 
get: function (){ 
return (_AN_Read_length('length', this._active)); 
} 
}
,
destroy: function (){ 
this._toProcess = 0; 
this._pending = [] ; 
this._active = [] ; 
this._destroy = [] ; 
} 
}
); 
module.exports = ProcessQueue;