AjaxRequest.METHOD_POST = 'POST';


AjaxRequest.METHOD_GET = 'GET';


AjaxRequest.METHOD_PUT = 'PUT';


AjaxRequest.READY_STATE_UNINITIALIZED = 0;


AjaxRequest.READY_STATE_LOADING = 1;


AjaxRequest.READY_STATE_LOADED = 2;


AjaxRequest.READY_STATE_INTERACTIVE = 3;


AjaxRequest.READY_STATE_COMPLETE = 4;


AjaxRequest.STATUS_OK = 200;


AjaxRequest.STATUS_NOT_FOUND = 404;


AjaxRequest.CONTENT_TYPE = 'Content-Type';


AjaxRequest.CONTENT_TYPE_URL_ENCODED = 'application/x-www-form-urlencoded';


AjaxRequest.ACTIVEX_MSXML2_XMLHTTP = "Msxml2.XMLHTTP";


AjaxRequest.ACTIVEX_LEGACY_XMLHTTP = "Microsoft.XMLHTTP";


AjaxRequest.FORM_FIELD_BUTTON = 'button';


AjaxRequest.FORM_FIELD_SUBMIT = 'submit';


AjaxRequest.FORM_FIELD_TEXT = 'text';


AjaxRequest.FORM_FIELD_HIDDEN = 'hidden';


AjaxRequest.FORM_FIELD_TEXTAREA = 'textarea';


AjaxRequest.FORM_FIELD_RADIO = 'radio';


AjaxRequest.FORM_FIELD_CHECKBOX = 'checkbox';


AjaxRequest.FORM_FIELD_SELECT_ONE = 'select-one';


AjaxRequest.FORM_FIELD_SELECT_MULTIPLE = 'select-multiple';


AjaxRequest.DELIM_QS = '?';


AjaxRequest.DELIM_PARAM = '&';


AjaxRequest.DELIM_KEY_VALUE = '=';


AjaxRequest.ERROR_CREATE_REQUEST = 'Unable to create ActiveX XMLHttpRequest.'


//AjaxRequest.ERROR_REQUEST_STATE = 'Error in XMLHttpRequest [$code/$text]';
AjaxRequest.ERROR_REQUEST_STATE = "Oops! \n Something has gone wrong.\n\n If this issue persists please contact support on:\n\n1800 338 483 \n \n Error : [$code/$text]";

var AjaxAlertIsShowing = false;

function AjaxRequest(url, handlerFunction){
    // Object properties
    
    this.mUrl = url;
    this.mHandler = handlerFunction;
    this.mMethod = AjaxRequest.METHOD_POST;
    
    this.mContentType = null;
    this.mRequestBody = null;
    this.mDebug = false;
    
    this.mAsynchronous = true;
    
    this.clearParameters();
}



AjaxRequest.prototype.setDebug = function(isDebugMode){
    this.mDebug = isDebugMode;
    return this;
}



AjaxRequest.prototype.setUrl = function(url){
    this.mUrl = url;
    return this;
}



AjaxRequest.prototype.setHandler = function(handlerFunction){
    this.mHandler = handlerFunction;
    return this;
}



AjaxRequest.prototype.setMethod = function(method){
    this.mMethod = method;
    return this;
}



AjaxRequest.prototype.setContentType = function(contentType){
    this.mContentType = contentType;
    return this;
}



AjaxRequest.prototype.setRequestBody = function(data){
    this.mRequestBody = data;
    return this;
}


AjaxRequest.prototype.setAsynchronous = function(isAsynchronous){
    this.mAsynchronous = isAsynchronous;
    return this;
}



AjaxRequest.prototype.clearParameters = function(){
    this.mParams = new Array();
    return this;
}



AjaxRequest.prototype.setParameter = function(key, value){
    this.mParams[this.mParams.length] = encodeURIComponent(key) +
    AjaxRequest.DELIM_KEY_VALUE +
    encodeURIComponent(value);
    return this;
}



AjaxRequest.prototype.setParameters = function(form){
    var fields = form.elements;
    
    for (var i = 0; i < fields.length; i++) {
        if (fields[i].disabled) 
            continue;
        
        var name = fields[i].name;
        
        switch (fields[i].type) {
            case AjaxRequest.FORM_FIELD_TEXT:
            case AjaxRequest.FORM_FIELD_HIDDEN:
            case AjaxRequest.FORM_FIELD_TEXTAREA:
                this.setParameter(name, fields[i].value);
                break;
                
            case AjaxRequest.FORM_FIELD_RADIO:
            case AjaxRequest.FORM_FIELD_CHECKBOX:
                if (fields[i].checked) {
                    this.setParameter(name, fields[i].value);
                }
                break;
                
            case AjaxRequest.FORM_FIELD_SELECT_ONE:
            case AjaxRequest.FORM_FIELD_SELECT_MULTIPLE:
                var options = fields[i].options;
                
                for (var j = 0; j < options.length; j++) {
                    if (options[j].selected) {
                        this.setParameter(name, options[j].value);
                    }
                }
                break;
        }
    }
    return this;
}



AjaxRequest.prototype.submit = function(){
    var request = null;
    
    // INSTANTIATE THE XMLHttpRequest
    
    if (window.XMLHttpRequest) {
        request = new XMLHttpRequest();
    }
    else 
        if (window.ActiveXObject) // MSIE 6 and older
        {
            try {
                request = new ActiveXObject(AjaxRequest.ACTIVEX_MSXML2_XMLHTTP);
            } 
            catch (errorActiveX) {
                try {
                    // older versions of MSIE
                    request = new ActiveXObject(AjaxRequest.ACTIVEX_LEGACY_XMLHTTP);
                } 
                catch (errorLegacyActiveX) {
                    alert(AjaxRequest.ERROR_CREATE_REQUEST);
                }
            }
        }
    
    // SET THE READY STATE CHANGE HANDLER
    
    // cannot reference object member from the anonymous function
    var handlerFunction = this.mHandler;
    var showResponseText = this.mDebug;
    
    var readyStateChangeFunction = function(){
        if (AjaxRequest.READY_STATE_COMPLETE == request.readyState) {
            if (AjaxRequest.STATUS_OK == request.status) {
                if (showResponseText) {
                    window.open().document.write('<xmp>' + request.responseText + '</xmp>');
                }
                
                if (handlerFunction) // only invoke if defined
                {
                    handlerFunction(request.responseXML, request.responseText);
                }
            }
            else {
				if (!AjaxAlertIsShowing) {
					AjaxAlertIsShowing = true;
					alert(AjaxRequest.ERROR_REQUEST_STATE.replace(/\$code/, request.status).replace(/\$text/, request.statusText));
					AjaxAlertIsShowing = false;
				}
            }
        }
    }
    
    // PREPARE THE REQUEST PROPERTIES AND ANY DEFAULTS
    
    var url = this.mUrl;
    var body = this.mRequestBody;
    var type = this.mContentType;
    var params = this.mParams.join(AjaxRequest.DELIM_PARAM);
    
    // if no parameters are set, then there is no need to dispatch them
    
    if (params.length > 0) {
        var paramDelim = (0 > url.indexOf("?")) // if a url already has a query
 ? AjaxRequest.DELIM_QS // string delimiter (?), use an
 : AjaxRequest.DELIM_PARAM // ampersand (&) instead
        if (body != null) // User-set request body, all params go in
        { // the query string for both POST and GET.
            url += paramDelim + params;
        }
        else // no request body
        {
            if (this.mMethod == AjaxRequest.METHOD_GET) {
                url += paramDelim + params;
            }
            else {
                body = params;
                
                if (type == null) // assign default if no type is set
                {
                    type = AjaxRequest.CONTENT_TYPE_URL_ENCODED;
                }
            }
        }
    }
    
    // SUBMIT THE REQUEST
    
    if (this.mAsynchronous) {
        request.onreadystatechange = readyStateChangeFunction;
    }
    
    request.open(this.mMethod, url, this.mAsynchronous);
    
    if (type != null) {
        request.setRequestHeader(AjaxRequest.CONTENT_TYPE, type);
    }
    
    request.send(body);
    
    return request;
}