/*
 * Copyright 2006 SitePoint Pty. Ltd, www.sitepoint.com
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS;
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
*/

function Ajax() {
	this.req = null;
	this.url = null;
	this.status = null;
	this.statusText = '';
	this.method = 'GET';
	this.async = true;
	this.dataPayload = null;
	this.readyState = null;
	this.responseText = null;
	this.responseXML = null;
	this.handleResp = null;
	this.responseFormat = 'text'; // 'text', 'xml', 'object'
	this.mimeType = null;
	this.headers = [];
	this.ms = 'ms=' + new Date().getTime()

  	this.init = function() {
    	var i = 0;
	    var reqTry = [
    		function() { return new XMLHttpRequest(); },
			function() { return new ActiveXObject('Msxml2.XMLHTTP') },
      		function() { return new ActiveXObject('Microsoft.XMLHTTP' )} ];
		
		while (!this.req && (i < reqTry.length)) {
      		try {
        		this.req = reqTry[i++]();
      		}
			catch(e) {}
    	}
	    return true;
  	};
  	this.doGet = function(url, hand, format) {
  		// added to prevent caching of page.
		var appendValue = (url.indexOf('?')>-1)? '&' + this.ms : '?' + this.ms
		this.url = url + appendValue;
	    this.handleResp = hand;
    	this.responseFormat = format || 'text';
	    this.doReq();
	};
  	this.doPost = function(url, dataPayload, hand, format) {
		// added to prevent caching of page.
		var appendValue = (dataPayload!='')? '&' + this.ms : '?' + this.ms
    	this.url = url;
    	this.dataPayload = dataPayload;
    	this.handleResp = hand;
    	this.responseFormat = format || 'text';
    	this.method = 'POST';
    	this.doReq();
  	};
  	this.doReq = function() {
    	var self = null;
	    var req = null;
    	var headArr = [];

	    if (!this.init()) {
    		alert('Could not create XMLHttpRequest object.');
			return;
    	}
    	req = this.req;
    	req.open(this.method, this.url, this.async);
	
    	if (this.method == "POST") {
			this.req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    	}
    	if (this.method == 'POST') {
      		req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    	}
	
    	self = this;
    	req.onreadystatechange = function() {
      		var resp = null;
      		self.readyState = req.readyState;
	      	if (req.readyState == 4) {
		        self.status = req.status;
	        	self.statusText = req.statusText;
	        	self.responseText = req.responseText;
	        	self.responseXML = req.responseXML;
	        	switch(self.responseFormat) {
	          		case 'text':
	            		resp = self.responseText;
	            		break;
	          		case 'xml':
	            		resp = self.responseXML;
	            		break;
	          		case 'object':
	            		resp = req;
	            		break;
	        	}
	
	        	if (self.status > 199 && self.status < 300) {
	          		if (!self.handleResp) {
	            		alert('No response handler defined ' +
	              		'for this XMLHttpRequest object.');
	            	return;
	          		}else{
	            		self.handleResp(resp);
	          		}
	        	}else{
	        		self.handleErr(resp);
				}
			}
		}
 		req.send(this.dataPayload);
  	};
  this.abort = function() {
    if (this.req) {
      this.req.onreadystatechange = function() { };
      this.req.abort();
      this.req = null;
    }
  };
  this.handleErr = function() {
    var errorWin;
    // Create new window and display error
    try {
      errorWin = window.open('', 'errorWin');
      errorWin.document.body.innerHTML = this.responseText;
    }
    // If pop-up gets blocked, inform user
    catch(e) {
      alert('An error occurred, but the error message cannot be' +
      ' displayed because of your browser\'s pop-up blocker.\n' +
      'Please allow pop-ups from this Web site.');
    }
  };
  this.setMimeType = function(mimeType) {
    this.mimeType = mimeType;
  };
  this.setHandlerResp = function(funcRef) {
    this.handleResp = funcRef;
  };
  this.setHandlerErr = function(funcRef) {
    this.handleErr = funcRef;
  };
  this.setHandlerBoth = function(funcRef) {
    this.handleResp = funcRef;
    this.handleErr = funcRef;
  };
  this.setRequestHeader = function(headerName, headerValue) {
    this.headers.push(headerName + ': ' + headerValue);
  };

}