GetUrlSequencer

/*
    CASA Framework for ActionScript 2.0
    Copyright (C) 2006  CASA Framework
    http://casaframework.org
    
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
    
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
    
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

import org.casaframework.time.Interval;

/**
    GetUrlSequencer delays/spaces out <code>getURL</code> requests to prevent browsers from choking from too many requests sent quickly in succession.
    
    @author Aaron Clinger
    @version 09/14/06
    @example
        <code>
            GetUrlSequencer.getURL("javascript:alert('call one');");
            GetUrlSequencer.getURL("javascript:alert('call two');");
            GetUrlSequencer.getURL("javascript:alert('call three');");
        </code>
*/

class org.casaframework.util.GetUrlSequencer {
    private static var $getCue:Array;
    private static var $delay:Number = 250;
    private static var $hasInit:Boolean;
    private static var $interval:Interval;
    
    /**
        Loads a document from a specific URL into a window or passes variables to another application at a defined URL.
        
        @param url: The URL from which to obtain the document.
        @param window: <strong>[optional]</strong> Specifies the window or HTML frame into which the document should load.
        @param method: <strong>[optional]</strong> A <code>GET</code> or <code>POST</code> method for sending variables.
        @usageNote This acts identical to flash's native <code>getURL</code>.
    */
    public static function getURL(url:String, window:String, method:String):Void {
        if (!GetUrlSequencer.$hasInit) GetUrlSequencer.$init();
        
        GetUrlSequencer.$getCue.push({u:url, w:window, m:method});
        
        if (!GetUrlSequencer.$interval.isFiring()) GetUrlSequencer.$interval.start();
    }
    
    /**
        Changes the delay/spacing between <code>getURL</code> calls.
        
        @param delay: The time in milliseconds between calls.
        @usageNote Class defaults to <code>250</code> milliseconds between <code>getURL</code> calls.
    */
    public static function changeDelay(delay:Number):Void {
        if (GetUrlSequencer.$hasInit) GetUrlSequencer.$interval.changeDelay(delay);
        else GetUrlSequencer.$delay = delay;
    }
    
    private static function $init():Void {
        GetUrlSequencer.$getCue   = new Array();
        GetUrlSequencer.$interval = Interval.setInterval(GetUrlSequencer, "$sendRequest", GetUrlSequencer.$delay);
        GetUrlSequencer.$hasInit  = true;
    }
    
    private static function $sendRequest():Void {
        var request:Object = GetUrlSequencer.$getCue.shift();
        _root.getURL(request.u, request.w, request.m);
        
        if (GetUrlSequencer.$getCue.length == 0) GetUrlSequencer.$interval.stop();
    }
    
    
    private function GetUrlSequencer() {} // Prevents instance creation
}