google drive object

var driveobject = (function ()
{
    function init()
    {
		this.key = "driveobject";
		var t = this;
		t.data = new Array();

		var http = new XMLHttpRequest();
		http.open("GET", "https://www.googleapis.com/drive/v2/files?access_token=" + global.google_access_token);
		http.responseType = "json";
		http.onreadystatechange = function()
		{
			if (this.readyState != this.DONE) 
				return;

			if (this.status != 200) 
				return;

			t.data = this.response.items.slice(0);
		};
		
		http.send();
		this.ANCHOR = localStorage.get_integer(this.key + ".ANCHOR", 0, this.data.length-1, 0);
		this.CURRENT = localStorage.get_integer(this.key + ".CURRENT", 0, this.data.length-1, 0);
    }

    init.prototype =
    {
		anchor : function() {return this.ANCHOR;},
		current : function() {return this.CURRENT;},
		start : function() {return 0;},
		length : function() {return this.data.length;},
		move : function (delta) {this.set_anchor(this.ANCHOR + delta);},

		get : function(index)
		{
			index = typeof(index) == 'undefined' ? this.CURRENT : index;
			index = Math.clamp(0, this.length()-1, index);
			return this.data[index];
		},

		set_anchor : function(index)
		{
			this.ANCHOR = Math.clamp(0, this.data.length-1, index);
			this.CURRENT = Math.clamp(0, this.data.length-1, index);
			localStorage.set_integer(this.key + ".ANCHOR", this.ANCHOR);
			localStorage.set_integer(this.key + ".CURRENT", this.CURRENT);
		},

		set_current : function(index)
		{
			this.CURRENT = Math.clamp(0, this.data.length-1, index);
			localStorage.set_integer(this.key + ".CURRENT", this.CURRENT);
		},
    };

    return init;
})();

var driveobj = new driveobject();