// xhr request object

var XHR = {

	indicator: 'load_indicator', // the element id of the load indicator
	active: false, // the state of the request system
	pending: 0,	// the current number of uncomplete requests
	current: {}, // a place to keep track open requests


	create: function() {

		if (XHR.active == false) if ($(XHR.indicator)) $(XHR.indicator).className = 'loading_active';
		XHR.pending++; // increment the pending requests counter
		XHR.active = true; // set the request handler state to active
	},


	complete: function(key) {

		XHR.pending--; // reduce the number of pending requests by 1

		// if there are no more pending requests
		if (XHR.pending == 0)
		{
			XHR.active = false; // set the request handler state to inactive
			if ($(XHR.indicator)) $(XHR.indicator).className = 'loading_inactive'; // hide the load indicator
		}

		this.current[ key ]['stop'] = parseInt(new Date().getTime().toString().substring(0, 10));
		setTimeout('XHR.cleanUp()', 30000);
	},


	init: function(url) {

		var parts = url.split("?"); // split the url into address / parameter data
		var url = parts[0]; // the url is in part 0
		var params = {}; // set params to nothing

		if (parts[1]) // if there appears to be a parameter string, handle it
		{
			params = parts[1].toQueryParams(); // convert the parameter string to an object

			if (params['f'] != undefined) // if there appears to be a form id
			{
				if ($(params['f'])) // if the form actually exists
				{
					var form_params = $(params['f']).serialize(true); // serialize the form
					for (i in form_params) params[i] = form_params[i]; // add the form params to the other params
				}
			}
		}

		params['requested_via_ajax'] = true; // add a value to signify that the request if being handled using ajax

		var start = parseInt(new Date().getTime().toString().substring(0, 10));
		var key = md5(start+url); // handle for this request

		// add the request to the current object
		this.current[ key ] = { start:start, stop:0, url:url, params:params, ajax:null, response:null };

		return key;
	},

	// perform an ajax request
	load: function(url, flag, function) {

		var key = this.init(url); // parse the url and create a new record
		var flag = flag || 'update'; // default action is update

		XHR.current[ key ]['ajax'] = new Ajax.Request(XHR.current[ key ]['url'], {
			parameters: XHR.current[ key ]['params'],
			onCreate: function() { XHR.create(); },
			onSuccess: function(transport) {

				XHR.current[ key ]['response'] = transport.responseText;

				if (flag == 'json')
					return transport.responseText;
				else
					XHR.update(key); // otherwise use the response to update the document
			},
			onFailure: function() { alert('failed!') },
			onComplete: function() {
				XHR.complete(key);
				return XHR.current[ key ]['response'];
			}
		});
	},


	update: function(key) {

		var element = 'viewport'; // set the default element to update to the viewport div
		var content = false; // set the content to false
		var data = false; // set the data to false
		var js = false; // set the js to false

		// check to see if the element to update was provided in the parameter string
		if (XHR.current[ key ] != undefined)
			if (XHR.current[ key ]['params']['e'] != undefined) element = XHR.current[ key ]['params']['e'];

		// if the request returns JSON data
		if (XHR.current[ key ]['response'].isJSON())
		{
			// evaluate the json response
			var json = XHR.current[ key ]['response'].evalJSON();

			// if an element is supplied in the response it supercedes the element from the parameter string
			if (json['e'] != undefined) element = json['e'];

			// if there is content in the response update the appropriate element with the content
			if (json['content'] != undefined) if ($(element)) $(element).update(json['content']).show();

			// if there is data in
			if (json['data'] != undefined) data = jason['data'];

			// if there is any javascript, supply it with any response data and evaluate it
			if (json['js'] != undefined) eval("var data = "+data+";"+json['js']);
		}

		// the response is not JSON
		else
		{
			// update the contents of the element, then show it
			if ($(element)) $(element).update(XHR.current[ key ]['response']).show();
		}

		return true;
	},

	// clear completed requests from XHR.current
	cleanUp: function() {

		var now = parseInt(new Date().getTime().toString().substring(0, 10));

		for (key in XHR.current)
		{
			if (now - XHR.current[ key ]['stop'] > 10) delete XHR.current[ key ];
		}

	}
}