var chatTimer, lagTimer, scrollTimer = null, getAllowed = true, putAllowed = true; microtime = 0, channelId =  "489";//window.location.search.replace( /.*channel_id=(\d+).*/g, "$1")

// create requests
var getRequest = putRequest = null;

function createGetRequest() {
	try {
		getRequest = new XMLHttpRequest();
	} catch (trymicrosoft) {
		try {
			getRequest = new ActiveXObject( "Msxml2.XMLHTTP" );
		} catch (othermicrosoft) {
			try{
				getRequest = new ActiveXObject( "Microsoft.XMLHTTP" );
			} catch (failed) {
				getRequest = false;
			}
		}
	}
}

function createPutRequest() {
	try {
		putRequest = new XMLHttpRequest();
	} catch (trymicrosoft) {
		try {
			putRequest = new ActiveXObject( "Msxml2.XMLHTTP" );
		} catch (othermicrosoft) {
			try{
				putRequest = new ActiveXObject( "Microsoft.XMLHTTP" );
			} catch (failed) {
				putRequest = false;
			}
		}
	}
}

function getMessages() {
	if (!getAllowed) {
		return;
	}
	getAllowed = false;
	// start lag timer / chat-reconnecter
	lagTimer = setTimeout( "getAllowed = true; getRequest = null; getMessages();", 10000 );
	createGetRequest();
	getRequest.open( "GET", "/index.php?task=chat&action=get_messages&channel_id=" + "489" + "&microtime=" + microtime, true );
	getRequest.onreadystatechange = showMessages;
	getRequest.send( null );
}

function showMessages() {
	if (getRequest.readyState == 4) {
		if(getRequest.status == 200) {
			if (getRequest.responseText != "-1") {
				responseDataArray = eval( getRequest.responseText );
				// check response consistency
				if (typeof responseDataArray == "undefined") {
					getAllowed = true;
					// reset lag timer
					clearTimeout( lagTimer );
					getRequest = null;
					return;
				}
				// update microtime
				microtime = responseDataArray[0];
				// draw user list
				$( "userList" ).innerHTML = responseDataArray[1].join( "" );
				// update counter
				$( "userCounter" ).innerHTML = responseDataArray[1].length;
				if (responseDataArray[2].length) {
					// update chat window
					$( "chatWindow" ).innerHTML += responseDataArray[2];
					// scroll it down on new messages
					chatScrollDown();
				}
				getAllowed = true;
				// reset lag timer
				clearTimeout( lagTimer );
				getRequest = null;
			} else {
				alert( "Channel does not anymore exist!" );
				window.location = "/index.php";
			}
		}
	}
}

function putMessage() {
	if (!putAllowed) {
		return;
	}
	putAllowed = false;
	createPutRequest();
	parameters = "message=" + escape( encodeURIComponent( $( "chatMessage" ).value ) );
	// disable input
	$( "chatMessage" ).blur();
	$( "chatMessage" ).disabled = true;
	$( "chatButton" ).disabled = true;
	putRequest.open( "POST", "/index.php?task=chat&action=put_message&channel_id=" + "489", true );
	putRequest.onreadystatechange = checkStatus;
	putRequest.setRequestHeader( "Content-type", "application/x-www-form-urlencoded" );
	putRequest.setRequestHeader( "Content-length", parameters.length );
	putRequest.setRequestHeader( "Connection", "close" );
	putRequest.send( parameters );
}

function checkStatus() {
	if (putRequest.readyState == 4) {
		if(putRequest.status == 200) {
			// empty and enable input
			$( "chatMessage" ).value = "";
			$( "chatMessage" ).disabled = false;
			$( "chatMessage" ).focus();
			// force get messages
			getMessages();
			putAllowed = true;
			putRequest = null;
		}
	}
}

function chatScrollDown() {
	if (!scrollTimer) {
		scrollTimer = setInterval( "scrollDown()", 10 );
	}
}

function scrollDown() {
	var chatWindow = $( "chatWindow" );

	if (chatWindow.scrollTop < chatWindow.scrollHeight - chatWindow.offsetHeight + (isOpera) ? 10 : 0) {
		chatWindow.scrollTop += 10;
	} else {
		clearInterval( scrollTimer );
		scrollTimer = null;
	}
}