/**
 * XMLHttpRequest Wrapper
 * @category    HTML
 * @package 	AJAX
 * @author      Joshua Eichorn <josh@bluga.net>
 * @copyright   2005 Joshua Eichorn
 * @license     http://www.opensource.org/licenses/lgpl-license.php  LGPL
 */
function HTML_AJAX_HttpClient() { }
HTML_AJAX_HttpClient.prototype = {
	// request object
	request: null,

	// timeout id
	_timeoutId: null,

	callbackComplete: true,

	// has this request been aborted
	aborted: false,
	
	// method to initialize an xmlhttpclient
	init:function() 
	{
		try {
			// Mozilla / Safari
			//this.xmlhttp = new HTML_AJAX_IframeXHR(); //uncomment these two lines to test iframe
			//return;
			this.xmlhttp = new XMLHttpRequest();
		} catch (e) {
			// IE
			var XMLHTTP_IDS = new Array(
			'MSXML2.XMLHTTP.5.0',
			'MSXML2.XMLHTTP.4.0',
			'MSXML2.XMLHTTP.3.0',
			'MSXML2.XMLHTTP',
			'Microsoft.XMLHTTP' );
			var success = false;
			for (var i=0;i < XMLHTTP_IDS.length && !success; i++) {
				try {
					this.xmlhttp = new ActiveXObject(XMLHTTP_IDS[i]);
					success = true;
				} catch (e) {}
			}
			if (!success) {
				try{
					this.xmlhttp = new HTML_AJAX_IframeXHR();
					this.request.iframe = true;
				} catch(e) {
					throw new Error('Unable to create XMLHttpRequest.');
				}
			}
		}
	},

	// check if there is a call in progress
	callInProgress: function() 
	{
		switch ( this.xmlhttp.readyState ) {
			case 1:
			case 2:
			case 3:
				return true;
			break;
			default:
				return false;
			break;
		}
	},

	// make the request defined in the request object
	makeRequest: function() 
	{
		if (!this.xmlhttp) {
			this.init();
		}

		try {
			if (this.request.Open) {
				this.request.Open();
			}
			else if (HTML_AJAX.Open) {
				HTML_AJAX.Open(this.request);
			}

			if (this.request.multipart) {
				if (document.all) {
					this.iframe = true;
				} else {
					this.xmlhttp.multipart = true;
				}
			}
	
			// set onreadystatechange here since it will be reset after a completed call in Mozilla
			var self = this;
			this.xmlhttp.open(this.request.requestType,this.request.completeUrl(),this.request.isAsync);
			if (this.request.customHeaders) {
				for (i in this.request.customHeaders) {
					this.xmlhttp.setRequestHeader(i, this.request.customHeaders[i]);
				}
			}
			if (this.request.customHeaders && !this.request.customHeaders['Content-Type']) {
				var content = this.request.getContentType();
				//opera is stupid for anything but plain text or xml!!
				if(window.opera && content != 'application/xml')
				{
					this.xmlhttp.setRequestHeader('Content-Type','text/plain; charset=utf-8');
					this.xmlhttp.setRequestHeader('x-Content-Type', content + '; charset=utf-8');
				}
				else
				{
					this.xmlhttp.setRequestHeader('Content-Type', content +  '; charset=utf-8');
				}
			}

			if (this.request.isAsync) {
				if (this.request.callback) {
					this.callbackComplete = false;
				}
				this.xmlhttp.onreadystatechange = function() { self._readyStateChangeCallback(); }
			} else {
				this.xmlhttp.onreadystatechange = function() {}
			}
			var payload = this.request.getSerializedPayload();
			if (payload) {
				this.xmlhttp.setRequestHeader('Content-Length', payload.length);
			}
			this.xmlhttp.send(payload);

			if (!this.request.isAsync) {
				if ( this.xmlhttp.status == 200 ) {
					HTML_AJAX.requestComplete(this.request);
					if (this.request.Load) {
						this.request.Load();
					} else if (HTML_AJAX.Load) {
						HTML_AJAX.Load(this.request);
					}
						
					return this._decodeResponse();
				} else {
					var e = new Error('['+this.xmlhttp.status +'] '+this.xmlhttp.statusText);
					e.headers = this.xmlhttp.getAllResponseHeaders();
					this._handleError(e);
				}
			}
			else {
				// setup timeout
				var self = this;
				this._timeoutId = window.setTimeout(function() { self.abort(true); },this.request.timeout);
			}
		} catch (e) {
			this._handleError(e);
		}
	},
	
	// abort an inprogress request
	abort: function (automatic) 
	{
		if (this.callInProgress()) {
			this.aborted = true;
			this.xmlhttp.abort();

			if (automatic) {
				HTML_AJAX.requestComplete(this.request);
				this._handleError(new Error('Request Timed Out: time out was '+this.request.timeout+'ms'));
			}
		}
	},

	// internal method used to handle ready state changes
	_readyStateChangeCallback:function() 
	{
		try {
			switch(this.xmlhttp.readyState) {
				// XMLHTTPRequest.open() has just been called
				case 1:
					break;
				// XMLHTTPRequest.send() has just been called
				case 2:
					if (this.request.Send) {
						this.request.Send();
					} else if (HTML_AJAX.Send) {
						HTML_AJAX.Send(this.request);
					}
					break;
				// Fetching response from server in progress
				case 3:
					if (this.request.Progress) {
						this.request.Progress();
					} else if (HTML_AJAX.Progress ) {
						HTML_AJAX.Progress(this.request);
					}
				break;
				// Download complete
				case 4:
					window.clearTimeout(this._timeoutId);
					if (this.aborted) {
						if (this.request.Load) {
							this.request.Load();
						} else if (HTML_AJAX.Load) {
							HTML_AJAX.Load(this.request);
						}
					}
					else if (this.xmlhttp.status == 200) {
						if (this.request.Load) {
							this.request.Load();
						} else if (HTML_AJAX.Load ) {
							HTML_AJAX.Load(this.request);
						}

						var response = this._decodeResponse();

						if (this.request.callback) {
							this.request.callback(response);
							this.callbackComplete = true;
						}
					}
					else {
						var e = new Error('HTTP Error Making Request: ['+this.xmlhttp.status+'] '+this.xmlhttp.statusText);
						this._handleError(e);
					}
					HTML_AJAX.requestComplete(this.request);
				break;
			}
		} catch (e) {
				this._handleError(e);
		}
	},

	// decode response as needed
	_decodeResponse: function() {
		//try for x-Content-Type first
		var content = null;
		try {
			content = this.xmlhttp.getResponseHeader('X-Content-Type');
		} catch(e) {}
		if(!content || content == null)
		{
			content = this.xmlhttp.getResponseHeader('Content-Type');
		}
		//strip anything after ;
		if(content.indexOf(';') != -1)
		{
			content = content.substring(0, content.indexOf(';'));
		}
		// hook for xml, it doesn't need to be unserialized
		if(content == 'application/xml')
		{
			return this.xmlhttp.responseXML;
		}
		var unserializer = HTML_AJAX.serializerForEncoding(content);
		//alert(this.xmlhttp.getAllResponseHeaders()); // some sort of debug hook is needed here
		return unserializer.unserialize(this.xmlhttp.responseText);
	},

	// handle sending an error where it needs to go
	_handleError: function(e) 
	{
		HTML_AJAX.requestComplete(this.request,e);
		if (this.request.onError) {
			this.request.onError(e);
		} else if (HTML_AJAX.onError) {
			HTML_AJAX.onError(e,this.request);
		}
		else {
			throw e;
		}
	}
}