/*
 * 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.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) {
		this.url = url;
		this.handleResp = hand;
		this.responseFormat = format || 'text';
		this.doReq();
	};
  
	this.doPost = function(url, dataPayload, hand, format) {
		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;
		try {
			// Create new window and display error
			errorWin = window.open('', 'errorWin');
			errorWin.document.body.innerHTML = this.responseText;
		} catch(e) {
		// If pop-up gets blocked, inform user
			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);
	};

}