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/**
 * DUI.Stream: A JavaScript MXHR client
 *
 * Copyright (c) 2009, Digg, Inc.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, 
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice, 
 *   this list of conditions and the following disclaimer in the documentation 
 *   and/or other materials provided with the distribution.
 * - Neither the name of the Digg, Inc. nor the names of its contributors 
 *   may be used to endorse or promote products derived from this software 
 *   without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * @module DUI.Stream
 * @author Micah Snyder <micah@digg.com>
 * @author Jordan Alperin <alpjor@digg.com>
 * @description A JavaScript MXHR client
 * @version 0.0.3
 * @link http://github.com/digg/dui
 *
 */
(function($) {
DUI.create('Stream', {
    pong: null,
    lastLength: 0,
    streams: [],
    listeners: {},
    
    init: function() {
        
    },
    
    load: function(url) {
        //These versions of XHR are known to work with MXHR
        try { this.req = new ActiveXObject('MSXML2.XMLHTTP.6.0'); } catch(nope) {
            try { this.req = new ActiveXObject('MSXML3.XMLHTTP'); } catch(nuhuh) {
                try { this.req = new XMLHttpRequest(); } catch(noway) {
                    throw new Error('Could not find supported version of XMLHttpRequest.');
                }
            }
        }
        
        //These versions don't support readyState == 3 header requests
        //try { this.req = new ActiveXObject('Microsoft.XMLHTTP'); } catch(err) {}
        //try { this.req = new ActiveXObject('MSXML2.XMLHTTP.3.0'); } catch(err) {}
        
        this.req.open('GET', url, true);
        
        var _this = this;
        this.req.onreadystatechange = function() {
            _this.readyStateNanny.apply(_this);
        }
        
        this.req.send(null);
    },
    
    readyStateNanny: function() {
        if(this.req.readyState == 3 && this.pong == null) {
            var contentTypeHeader = this.req.getResponseHeader("Content-Type");
            
            if(contentTypeHeader.indexOf("multipart/mixed") == -1) {
                this.req.onreadystatechange = function() {
                    throw new Error('Send it as multipart/mixed, genius.');
                    this.req.onreadystatechange = function() {};
                }.bind(this);
                
            } else {
                this.boundary = '--' + contentTypeHeader.split('"')[1];
                
                //Start pinging
                this.pong = window.setInterval(this.ping.bind(this), 15);
            }
        }
        
        if(this.req.readyState == 4) {
            //var contentTypeHeader = this.req.getResponseHeader("Content-Type");
            
            //Stop the insanity!
            clearInterval(this.pong);
            
            //One last ping to clean up
            this.ping();
            
            if(typeof this.listeners.complete != 'undefined') {
                var _this = this;
                $.each(this.listeners.complete, function() {
                    this.apply(_this);
                });
            }
        }
    },
    
    ping: function() {
        var length = this.req.responseText.length;
        
        var packet = this.req.responseText.substring(this.lastLength, length);
        
        this.processPacket(packet);
        
        this.lastLength = length;
    },
    
    processPacket: function(packet) {
        if(packet.length < 1) return;
        
        //I don't know if we can count on this, but it's fast as hell
        var startFlag = packet.indexOf(this.boundary);
        
        var endFlag = -1;
        
        //Is there a startFlag?
        if(startFlag > -1) {
            if(typeof this.currentStream != 'undefined') {
            //If there's an open stream, that's an endFlag, not a startFlag
                endFlag = startFlag;
                startFlag = -1;
            } else {
            //No open stream? Ok, valid startFlag. Let's try find an endFlag then.
                endFlag = packet.indexOf(this.boundary, startFlag + this.boundary.length);
            }
        }
        
        //No stream is open