var mouse_move = function (e) {
	if (this.rrdgraph.mousedown) {
		var factor = (this.rrdgraph.end - this.rrdgraph.start) / this.rrdgraph.xsize;
		var x = e.pageX - this.offsetLeft;
		var diff = x - this.rrdgraph.mousex;
		var difffactor = Math.abs(Math.round(diff*factor));
		if (diff > 0) {
			this.rrdgraph.end -= difffactor;
			this.rrdgraph.start -= difffactor;
		} else {
			this.rrdgraph.end += difffactor;
			this.rrdgraph.start += difffactor;
		}
		this.rrdgraph.mousex = x;
		try {
			this.rrdgraph.graph_paint();
		} catch (e) {
			alert(e+"\n"+e.stack);
		}
	}
};
var mouse_up = function (e) {
	this.rrdgraph.mousedown = false;
	this.style.cursor="default";
};
var mouse_down = function (e) {
	var x = e.pageX - this.offsetLeft;
	this.rrdgraph.mousedown = true;
	this.rrdgraph.mousex = x;
	this.style.cursor="move";
};
var mouse_scroll = function (e) {
	e = e ? e : window.event;
	var wheel = e.detail ? e.detail * -1 : e.wheelDelta / 40;
	var cstime = this.stime[this.stidx];
	if (wheel < 0) {
		this.stidx++;
		if (this.stidx >= this.stlen) this.stidx = this.stlen-1;
	} else {
		this.stidx--;
		if (this.stidx < 0) this.stidx = 0;
	}
	if (cstime !== this.stime[this.stidx])  {
		var middle = this.rrdgraph.start + Math.abs(Math.round((this.rrdgraph.end - this.rrdgraph.start)/2));
		this.rrdgraph.start = Math.round(middle - this.stime[this.stidx]/2);
		this.rrdgraph.end = this.rrdgraph.start + this.stime[this.stidx];

		try {
			this.rrdgraph.graph_paint();
		} catch (e) {
			alert(e+"\n"+e.stack);
		}
	}

	if(e.stopPropagation)
		e.stopPropagation();
	if(e.preventDefault)
		e.preventDefault();
	e.cancelBubble = true;
	e.cancel = true;
	e.returnValue = false;
	return false;
};

function prepare_draw(id) {
	RrdGraph.prototype.mousex = 0;
	RrdGraph.prototype.mousedown = false;

	var cmdline = document.getElementById(id).innerHTML;
	var gfx = new RrdGfxCanvas(id);
	var fetch = new RrdDataFile();
	var rrdcmdline = null;

	try {
		rrdcmdline = new RrdCmdLine(gfx, fetch, cmdline);
	} catch (e) {
		alert(e+"\n"+e.stack);
	}

	var rrdgraph = rrdcmdline.graph;

	gfx.canvas.stime = [ 300, 600, 900, 1200, 1800, 3600, 7200, 21600, 43200, 86400, 172800, 604800, 2592000, 5184000, 15768000, 31536000 ];
	gfx.canvas.stlen = gfx.canvas.stime.length;
	gfx.canvas.stidx = 0;

	gfx.canvas.rrdgraph = rrdgraph;
	gfx.canvas.removeEventListener('mousemove', mouse_move, false);
	gfx.canvas.addEventListener('mousemove', mouse_move, false);
	gfx.canvas.removeEventListener('mouseup', mouse_up, false);
	gfx.canvas.addEventListener('mouseup', mouse_up, false);
	gfx.canvas.removeEventListener('mousedown', mouse_down, false);
	gfx.canvas.addEventListener('mousedown', mouse_down, false);
	gfx.canvas.removeEventListener('mouseout', mouse_up, false);
	gfx.canvas.addEventListener('mouseout', mouse_up, false);
	gfx.canvas.removeEventListener('DOMMouseScroll', mouse_scroll, false);
	gfx.canvas.addEventListener('DOMMouseScroll', mouse_scroll, false);
	gfx.canvas.removeEventListener('mousewheel', mouse_scroll, false);
	gfx.canvas.addEventListener('mousewheel', mouse_scroll, false);

	var diff = rrdgraph.end - rrdgraph.start;
	for (var i=0; i < gfx.canvas.stlen; i++) {
		if (gfx.canvas.stime[i] >= diff)  break;
	}
	if (i === gfx.canvas.stlen) gfx.canvas.stidx = gfx.canvas.stlen-1;
	else gfx.canvas.stidx = i;

	return rrdgraph;
}