/*
* AjaxHelper
* -----------------------
* @author        : Filatov Dmitry <alpha@design.ru>
* @last_modified : 13.04.2007
*/

function AjaxHelper(
	sUrl,
	fSuccessCallback,
	fErrorCallback,
	aParams,
	oOptions
	) {

	this.sUrl = sUrl;
	this.fSuccessCallback = fSuccessCallback;
	this.fErrorCallback = fErrorCallback;
	this.aParams = aParams || [];
	this.oRequest = null;

	this.oOptions = Common.Object.extend(
		{
			bIgnoreCache : true,
			sMethod      : 'POST'
		},
		oOptions,
		true
		);

}

AjaxHelper.READY_STATE_UNITIALIZED = 0;
AjaxHelper.READY_STATE_LOADING     = 1;
AjaxHelper.READY_STATE_LOADED      = 2;
AjaxHelper.READY_STATE_INTERACTIVE = 3;
AjaxHelper.READY_STATE_COMPLETE    = 4;

AjaxHelper.getTransport = function() {

	if(window.XMLHttpRequest) {
		return new XMLHttpRequest();
	}

	if(window.ActiveXObject) {

		try {
			return new ActiveXObject('Msxml2.XMLHTTP');
		}
		catch(oError) {
			return new ActiveXObject('Microsoft.XMLHTTP');
		}

	}

	return null;

};

AjaxHelper.generateId = function() {

	var sId = '';

	for(var i = 0; i < 4; i++) {
		sId += (i > 0? '-' : '') + Math.floor(Math.random() * 9999);
	}

	return sId;

};

AjaxHelper.encodeForRequest = function(sText) {

	return escape(AjaxHelper.encodeUTF8(sText));

};

AjaxHelper.encodeUTF8 = function(sText) {

	sText = sText.replace(/\r\n/g, '\n');

	var sResult = "";

	for(var i = 0, sCharCode; i < sText.length; i++) {

		sCharCode = sText.charCodeAt(i);

		if(sCharCode < 128) {
			sResult += String.fromCharCode(sCharCode);
		}
		else if((sCharCode > 127) && (sCharCode < 2048)) {

			sResult += String.fromCharCode((sCharCode >> 6) | 192);
			sResult += String.fromCharCode((sCharCode & 63) | 128);

		}
		else {

			sResult += String.fromCharCode((sCharCode >> 12) | 224);
			sResult += String.fromCharCode(((sCharCode >> 6) & 63) | 128);
			sResult += String.fromCharCode((sCharCode & 63) | 128);

		}

	}

    return sResult;

};

AjaxHelper.prototype = {

	send : function() {

		var
			sQueryParams = '',
			iParamsCount = 0,
			sId = AjaxHelper.generateId()
			;

		this.aParams.foreach(function(mKey, mParam) {
			sQueryParams += (++iParamsCount == 1? '' : '&') + mKey + '=' + AjaxHelper.encodeForRequest(mParam);
		});

		this.oRequest = AjaxHelper.getTransport();

		if(this.oRequest) {

			this.oRequest.open(
				this.oOptions.sMethod,
				this.sUrl + (this.sUrl.indexOf('?')>=0? '' : '?') + (this.oOptions.bIgnoreCache? 'uid=' + sId : ''),
				true
				);

			this.oRequest.setRequestHeader(
				'Content-type',
				'application/x-www-form-urlencoded'
				);

			var oThis = this;

			this.oRequest.onreadystatechange = function() {

				oThis.handleResponse();

			}

			this.oRequest.send(sQueryParams);

			return sId;

		}

	},

	handleResponse : function() {

		var fCallback = null;

		try {

			if(this.oRequest.readyState != AjaxHelper.READY_STATE_COMPLETE) {
				return;
			}

			if(this.success()) {
				if(this.fSuccessCallback) {
					fCallback = this.fSuccessCallback;
				}
			}
			else if(this.fErrorCallback) {
				fCallback = this.fErrorCallback;
			}

		}
		catch(oException) {};

		fCallback(this.oRequest);

		this.oRequest.onreadystatechange = function() {};

	},

	success : function() {

		return this.oRequest &&
			(
				this.oRequest.status == 0 ||
				(this.oRequest.status >= 200 && this.oRequest.status < 300)
			)
			;

	}

}