var com={};
com.cctv={};
com.cctv.util={};
com.cctv.util.Connect = {
	_msxml_progid: ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'],
	_http_header: {},
	_has_http_headers: false,
	_isFormSubmit: false,
	_sFormData: null,
	_poll: [],
	_polling_interval: 50,
	_transaction_id: 0,
	setProgId: function(id){
		this.msxml_progid.unshift(id);
	},
	setPollingInterval: function(i){
		if(typeof i == 'number' && isFinite(i)){
			this._polling_interval = i;
		}
	},
	createXhrObject: function(transactionId){
		//可以改善，不用每次都试一遍
		var obj, http;
		try{
			http = new XMLHttpRequest();
			obj = {
				conn: http,
				tId: transactionId
			};
		}
		catch(e){
			for(var i = 0; i < this._msxml_progid.length; ++i){
				try{
					http = new ActiveXObject(this._msxml_progid[i]);
					if(http){
						obj = {
							conn: http, tId: transactionId
						};
						break;
					}
				}
				catch(e){}
			}
		}
		finally{
			return obj;
		}
	},
	getConnectionObject: function(){
		var o;
		var tId = this._transaction_id;
		try{
			o = this.createXhrObject(tId);
			if(o){
				this._transaction_id++;
			}
		}
		catch(e){}
		finally{
			return o;
		}
	},
	asyncRequest: function(method, uri, callback, postData){
		var o = this.getConnectionObject();
		if(!o){
			return null;
		}
		else{
			if(this._isFormSubmit){
				if(method == 'GET'){
					uri += "?" + this._sFormData;
				}
				else if(method == 'POST'){
					postData = this._sFormData;
				}
				this._sFormData = '';
				this._isFormSubmit = false;
			}
			o.conn.open(method, uri, true);
			if(postData){
				this.initHeader('Content-Type', 'application/x-www-form-urlencoded ');
			}
			if(this._has_http_headers){
				this.setHeader(o);
			}
			this.handleReadyState(o, callback);
			postData ? o.conn.send(postData): o.conn.send(null);
			return o;
		}
	},
	handleReadyState: function(o, callback){
		var oConn = this;
		try{
			this._poll[o.tId] = window.setInterval(function(){
				if(o.conn && o.conn.readyState == 4){
					window.clearInterval(oConn._poll[o.tId]);
					oConn._poll.splice(o.tId);
					oConn.handleTransactionResponse(o, callback);
				}
			},this._polling_interval);
		}
		catch(e){
			window.clearInterval(oConn._poll[o.tId]);
			oConn._poll.splice(o.tId);
			oConn.handleTransactionResponse(o, callback);
		}
	},
	handleTransactionResponse: function(o, callback){
		if(!callback){
			this.releaseObject(o);
			return ;
		}
		var httpStatus;
		var responseObject;
		try{
			httpStatus = o.conn.status;
		}
		catch(e){
			httpStatus = 13030;
		}
		if(httpStatus >= 200 && httpStatus < 300){
			responseObject = this.createResponseObject(o, callback.argument);
			if(callback.success){
				if(!callback.scope){
					callback.success(responseObject);
				}
				else{
					callback.success.apply(callback.scope, [responseObject]);
				}
			}
		}
		else{
			switch(httpStatus){
				case 12002:
				case 12029:
				case 12030:
				case 12031:
				case 12152:
				case 13030:
					responseObject = this.createExceptionObject(o, callback.argument);
					if(callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}
					break;
				default:
					responseObject = this.createResponseObject(o, callback.argument);
					if(callback.failure){
						if(!callback.scope){
							callback.failure(responseObject);
						}
						else{
							callback.failure.apply(callback.scope, [responseObject]);
						}
					}
			}
		}
		this.releaseObject(o);
	},
	createResponseObject: function(o, callbackArg){
		var obj = {};
		var headerObj = {};
		try{
			var headerStr = o.conn.getAllResponseHeaders();
			var header = headerStr.split("\n");
			for(var i = 0; i < header.length; i++){
				var delimitPos = header[i].indexOf(':');
				if(delimitPos !=  - 1){
					headerObj[header[i].substring(0, delimitPos)] = header[i].substring(delimitPos + 1);
				}
			}
			obj.tId = o.tId;
			obj.status = o.conn.status;
			obj.statusText = o.conn.statusText;
			obj.getResponseHeader = headerObj;
			obj.getAllResponseHeaders = headerStr;
			obj.responseText = o.conn.responseText;
			obj.responseXML = o.conn.responseXML;
			if(typeof callbackArg !== undefined){
				obj.argument = callbackArg;
			}
		}
		catch(e){}
		finally{
			return obj;
		}
	},
	createExceptionObject: function(tId, callbackArg){
		var COMM_CODE = 0;
		var COMM_ERROR = 'communication failure';
		var obj = {};
		obj.tId = tId;
		obj.status = COMM_CODE;
		obj.statusText = COMM_ERROR;
		if(callbackArg){
			obj.argument = callbackArg;
		}
		return obj;
	},
	initHeader: function(label, value){
		if(this._http_header[label] === undefined){
			this._http_header[label] = value;
		}
		else{
			this._http_header[label] = value + "," + this._http_header[label];
		}
		this._has_http_headers = true;
	},
	setHeader: function(o){
		for(var prop in this._http_header){
			o.conn.setRequestHeader(prop, this._http_header[prop]);
		}
		delete this._http_header;
		this._http_header = {};
		this._has_http_headers = false;
	},
	setForm: function(formId){
		this._sFormData = '';
		if(typeof formId == 'string'){
			var oForm = (document.getElementById(formId) || document.forms[formId]);
		}else if(typeof formId == 'object'){
			var oForm = formId;
		}else{
			return ;
		}
		var oElement, oName, oValue, oDisabled;
		var hasSubmit = false;
		for(var i = 0; i < oForm.elements.length; i++){
			oDisabled = oForm.elements[i].disabled;
			oElement = oForm.elements[i];
			oName = oForm.elements[i].name;
			oValue = oForm.elements[i].value;
			if(!oDisabled){
				switch(oElement.type){
					case 'select-one':
					case 'select-multiple':
						for(var j = 0; j < oElement.options.length; j++){
							if(oElement.options[j].selected){
								this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oElement.options[j].value || oElement.options[j].text) + '&';
							}
						}
						break;
					case 'radio':
					case 'checkbox':
						if(oElement.checked){
							this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
						}
						break;
					case 'file':
					case undefined:
					case 'reset':
					case 'button':
						break;
					case 'submit':
						if(hasSubmit == false){
							this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
							hasSubmit = true;
						}
						break;
					default:
						this._sFormData += encodeURIComponent(oName) + '=' + encodeURIComponent(oValue) + '&';
						break;
				}
			}
		}
		this._isFormSubmit = true;
		this._sFormData = this._sFormData.substr(0, this._sFormData.length - 1);
	},
	abort: function(o){
		if(this.isCallInProgress(o)){
			window.clearInterval(this._poll[o.tId]);
			this._poll.splice(o.tId);
			o.conn.abort();
			this.releaseObject(o);
			return true;
		}
		else{
			return false;
		}
	},
	isCallInProgress: function(o){
		if(o.conn){
			return o.conn.readyState != 4 && o.conn.readyState != 0;
		}
		else{
			return false;
		}
	},
	releaseObject: function(o){
		o.conn = null;
		o = null;
	}
};