var _xmlObjs = new Array();			// Array of XmlHttpRequests
var _xmlArgs = new Array();			// Array for keeping all parameters of the custom call back
var _index = -1;							// Current XmlHttpRequest index

/**
 * Calls AJAX for a given URL, and provides the corresponding callback for reacting.
 */
function tbAJAX(url,callback) {
	_index++;
	if(window.XMLHttpRequest) {
		_xmlObjs[_index]=new XMLHttpRequest()
	} else if (window.ActiveXObject) {
		_xmlObjs[_index]=new ActiveXObject("Microsoft.XMLHTTP")
	}

	// Getting arguments for the custom call back (localArgs[0] contains the  callback function)
	var localArgs = new Array();
	for(var i=1; i<arguments.length; i++)
		localArgs[i-1] = arguments[i];

	_xmlArgs[_index] = localArgs;	// Store the callback arguments

	// The real callback is a simple transient function, that allows for passing parameters, something we were missing
	_xmlObjs[_index].onreadystatechange = new Function("transientChangeState","_changeState(_xmlObjs["+_index+"],_xmlArgs["+_index+"]);");
	_xmlObjs[_index].open("GET",url,true);
	_xmlObjs[_index].send(null);
}


function tbAJAX_post(url,parameters,callback) {
	_index++;
	if(window.XMLHttpRequest) {
		_xmlObjs[_index]=new XMLHttpRequest()
	} else if (window.ActiveXObject) {
		_xmlObjs[_index]=new ActiveXObject("Microsoft.XMLHTTP")
	}

	// Getting arguments for the custom call back (localArgs[0] contains the  callback function)
	var localArgs = new Array();
	for(var i=1; i<arguments.length; i++)
		localArgs[i-2] = arguments[i];

	_xmlArgs[_index] = localArgs;	// Store the callback arguments
	
	// Computing POST parameters
	var paramstr = "";
	if(parameters != null)
		for(i in parameters)
			paramstr += "&"+i+"="+encodeURI(parameters[i]);
			
	paramstr = paramstr.substr(1); // Removes the leading ampersand
	
	// The real callback is a simple transient function, that allows for passing parameters, something we were missing
	_xmlObjs[_index].onreadystatechange = new Function("transientChangeState","_changeState(_xmlObjs["+_index+"],_xmlArgs["+_index+"]);");
	_xmlObjs[_index].open("POST",url,true);
	_xmlObjs[_index].setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	_xmlObjs[_index].setRequestHeader("Content-length", paramstr.length);
	_xmlObjs[_index].setRequestHeader("Connection", "close");
	_xmlObjs[_index].send(paramstr);
}


/**
 * The generic callback. Calls the custom callback with its corresponding parameters.
 * The first parameter passed to the callback is the XmlHttpRequest object itself, used for getting the data back.
 */
function _changeState(xmlObj,args) { 
	if(xmlObj.readyState==4 || xmlObj.readyState=="complete") { 
	
		// Constructs the list of arguments
		var argslist = "";
		for(var i=1; i<args.length; i++)
			argslist += "args["+i+"],";
		if(args.length > 1)
			argslist = ","+argslist+"args["+(args.length-1)+"]";

		// Calls the callback function, with all its arguments.
		eval("args[0](xmlObj"+argslist+")");
	}
}


/**
 * Callback function for tbAJAX. Loads an HTML snippet in the given layer (id of a container tag).
 * This function takes care of loading JavaScripts! (However functions with declarations not on a single line may be omitted).
 */
function tbAJAXLoad(xmlObj,layer) {
	document.getElementById(layer).innerHTML = xmlObj.responseText;

	// Scripts are not evaluated... make sure it's executed
	var scripts = document.getElementById(layer).getElementsByTagName("script");

	// Whenever scripts are executed, functions get "forgotten". Assigning functions as members of
	// the window object make them survive...
	for(i = 0; i<scripts.length; i++) {
		var s = scripts[i].innerHTML;
		var res = s.match(/function [^(]+\(/g);

		for(j = 0; j<res.length; j++) {
			var funcName = res[j].replace(/(function\W+)|(\W*\()/g,"");	// Isolates the function name
			s += "\nwindow."+funcName+" = "+funcName;
		}
        
		eval(s);
	}
}


/**
 * Shows a window containing the HTML code of the current document, with AJAX loaded HTML code in place.
 */
function tbAJAXShowDebugWindow() {
	var dbg = window.open('about:blank','_DEBUG_','dependent=yes,width=1024,height=768,location=no,menubar=no,status=no,toolbar=no,scrollbars=yes');
	var html = document.getElementsByTagName('html')[0].outerHTML;
	if(html == null)	// Firefox does not bring anything for <html>.outerHTML...
		html = '<html>\n'+document.getElementsByTagName('html')[0].innerHTML+'\n</html>';
	html = html.replace(/&/g,'&amp;');
	html = html.replace(/</g,'&lt;');
	html = html.replace(/>/g,'&gt;');
	
	// Line counter
	var index = 0;
	html = html.replace(/^|\n/g,function (str) { return '\n'+(++index)+':\t'; } );

	// Writing contents in the window	
	dbg.document.open();
	dbg.document.writeln('</html>');
	dbg.document.writeln('<head><title>tbAJAX Debug Window</title></head>');
	dbg.document.writeln('<body><h2>tbAJAX Debug Window</h2><pre>'+html+'</pre></body></html>');
	dbg.document.close();
}

/**
 * Function used to replace the URL of the active page when called through frmRelocator
 * Needs String management JS Library to be included to work
 */
function GotoURL( stLink, stDb ) {
	stHref = document.location.href;
	stHref = replaceSubstring(stHref, Sleft( Sright( stHref , '&Element='), '&' ), stLink);
	if(stDb != null){
		stHref = replaceSubstring(stHref, Sleft( Sright( stHref , '&Database='), '&' ), stDb);
	}
	document.location.href = stHref;
}