// Public members are defined using this.member
// Private members are defined using "var member" or "function member"

function newDatahubRequest (usexml)
{
	var		req;
        
	// Mozilla/Safari
	if (null)
	{
	}
	else if (window.XMLHttpRequest)
	{
		req = new XMLHttpRequest();

		try
		{
			if (usexml)
				req.overrideMimeType('text/xml');
			else
				req.overrideMimeType('text/plain');
		}
		catch (E)
		{
		}
	}
	// IE
	else if (window.ActiveXObject)
	{
		try {
			req = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				req = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (E) {
				req = null;
			}
		}
	}

	return (req);
}

function DatahubCommand (command)
{
	var xmlHttpReq = newDatahubRequest(false);
	var strSubmit = "command=" + encodeURIComponent(command);
	xmlHttpReq.abort();
	xmlHttpReq.open ('POST', '/ajax', false);
	xmlHttpReq.send(strSubmit);
}

function DatahubConnector (inhost, inport)
{
// public:
	this.requestPoints = "";
	this.onBeginPointUpdate = null;
	this.onEndPointUpdate = null;
	this.timerTick = 1000;
	this.host = inhost;
	this.port = inport;
	this.baseURL = "/points";
	this.extraURLArgs = "";

// private:
	// Mapping DataHub points into functions
	var Fnmap = {};
	var Oldvalmap = {};
	var Oldqualmap = {};
	var count = 0;
	var timerID = 0;
	var _conn = this;
	var usexml = true;
	var in_transaction = false;
	var xmlHttpReq = newDatahubRequest(usexml);
	
// private:
	function do_fn_map (pointname, value, quality, timestamp)
	{
		var oldval = Oldvalmap[pointname];
		var oldqual = Oldqualmap[pointname];
		if (oldval != value || oldqual != quality)
		{
			var	map = Fnmap[pointname];
			if (map)
			{
				for (var i=0; i<map.length; i++)
				{
					eval (map[i]);
				}
			}
			Oldvalmap[pointname] = value;
			Oldqualmap[pointname] = quality;
		}
	}
	
	function process_input_datahub (xmlHttpReq)
	{
		var txt = xmlHttpReq.responseText;
		var output = "";

		start = txt.indexOf("\"") + 1;
		end = txt.indexOf("/[^\\]\"/", start) + 1;
		ptname = txt.substring (start, end);

		output = xmlHttpReq.responseXML;
				
		output += ptname;
		output += start;
		output += " ";
		output += end;
				
		return (output);
	}

	function process_input_xml (req)
	{
		try
		{
			var response = req.responseXML;
	
			// elem is an: Object HTMLCollection in Firefox
			var elem = response.getElementsByTagName("point");

			// for each element: Object Element in Firefox
			for (var i=0; i<elem.length; i++)
			{
				var		name = elem[i].getAttribute("name");
				var		value = elem[i].getAttribute("value");
				var		quality = elem[i].getAttribute("quality");
				var		timestamp = elem[i].getAttribute("timestamp");
				do_fn_map (name, value, quality, timestamp);
			}
		}
		catch (e)
		{
		}
		return (null);
	}

	function processDataChange ()
	{
		if (xmlHttpReq.readyState == 4)
		{
		    try
		    {
			if (_conn.onBeginPointUpdate)
				_conn.onBeginPointUpdate();
			if (usexml)
				process_input_xml (xmlHttpReq);
			else
				process_input_datahub (xmlHttpReq);
			if (_conn.onEndPointUpdate)
				_conn.onEndPointUpdate();
		    }
		    catch (e)
		    {
		    }
		    in_transaction = false;
		}
	}
	
// public:
	this.updatePoints = function ()
	{
		var strSubmit;

		// We use the &req=count++ in the request even though DataHub does
		// not recognize it.  We have to do this because Internet Explorer
		// caches the results indiscriminately.  See
		// http://en.wikipedia.org/wiki/XMLHttpRequest
		// We must open() before setting the callback function or else IE
		// will fail to re-use the request object.

		if (!in_transaction)
		{
		    strSubmit = 'name=' + this.requestPoints + (usexml ? '&style=xml' : '') + '&req=' + count++ + this.extraURLArgs;
			if (strSubmit.length > 16300)
			{
				// maximum length of URL is exceeded
				throw "Maximum URL length exceeded.  Too many DataHub points in AJAX query.";
			}
			else
			{
				xmlHttpReq.abort();
				xmlHttpReq.open ('POST', this.baseURL, true);
				xmlHttpReq.onreadystatechange = processDataChange;
				in_transaction = true;
				xmlHttpReq.send(strSubmit);
			}
		}
	}

	this.addFunctionMap = function (pointname, code)
	{
		if (!Fnmap[pointname])
			Fnmap[pointname] = [];
		Fnmap[pointname][Fnmap[pointname].length] = code;
	}

	this.updateTimer = function ()
	{
		this.updatePoints();
		if (timerID != 0)
			clearTimeout (timerID);
		timerID = setTimeout ("DataHubConnection.updateTimer()", this.timerTick);
	}

	this.stopTimer = function ()
	{
		if (timerID != 0)
			clearTimeout (timerID);
		timerID = 0;
	}

	this.cleanup = function ()
	{
		_conn = null;
		Fnmap = null;
		this.stopTimer();
		xmlHttpReq.onreadystatechange = null;
		xmlHttpReq = null;
		this.requestPoints = null;
		this.onBeginPointUpdate = null;
		this.onEndPointUpdate = null;
	}		
}

var DataHubConnection;

// Functions borrowed from elsewhere.

// Prepend a zero to a single-digit number
function LZ(x) {
    return (x >= 10 || x < 0 ? "" : "0") + x;
}

// Prepend a zero to a single-digit number as string
function lz(x) {
    var t = String(x);
    return t.length == 1 ? "0" + t : t;
}

// Prepend enough zeros to make a number 3 digits long
function LZZ(x) {
    return x < 0 || x >= 100 ? "" + x : "0" + LZ(x);
}

// Convert a floating point number of seconds (the format of
// a DataHub timestamp from ajax) into a string.
function S2T(Secs)
{
    var T1;
    T1 = (new Date(Secs * 1000)).toUTCString().match(/\S{8}/);
	return T1 + "." + LZZ(Math.floor(Secs * 1000) % 1000);
}

Date.prototype.ISOlocaltimeStr =
  new Function("  /* Date.ISOlocaltimeStr hh:mm:ss */\n" +
    "  with (this)\n    return" +
    " LZ(getHours())+':'+LZ(getMinutes())+':'+LZ(getSeconds())")

Date.prototype.ISOlocaldateStr =
  new Function("  /* Date.ISOlocaldateStr YYYY-MM-DD */\n" +
    "  with (this)\n    return " +
    "getFullYear()+'-'+LZ(getMonth()+1)+'-'+LZ(getDate())")

Date.prototype.ISOlocalDTstr =
  new Function("  /* Date.ISOlocalDTstr YYYY-MM-DD hh:mm:ss */\n" +
    "   with (this)\n    return " +
    "ISOlocaldateStr()+' '+ISOlocaltimeStr()")