//<![CDATA[

function load() {
  if (GBrowserIsCompatible()) {
	var map = new GMap2(document.getElementById("map"));
	map.addControl(new GLargeMapControl());
	map.addControl(new GMapTypeControl());
	map.addControl(new GScaleControl());
	
	var icon = new GIcon();
	icon.image = "/images/google-marker.png";
	icon.iconSize = new GSize(12, 12);
	icon.iconAnchor = new GPoint(6, 3);
	icon.infoWindowAnchor = new GPoint(5, 1);
	
	var arrowIcon = new GIcon();
	arrowIcon.iconSize = new GSize(24,24);
	arrowIcon.shadowSize = new GSize(1,1);
	arrowIcon.iconAnchor = new GPoint(12,12);
	arrowIcon.infoWindowAnchor = new GPoint(0,0);
	
	var degreesPerRadian = 180.0 / Math.PI;
	
function createMarker(point,date) {
	var marker = new GMarker(point,icon);
	if (date != null) {
	GEvent.addListener(marker, "click", function() {
	  marker.openInfoWindowHtml(date);
	});
	}
	return marker;
  }
  
  function bearing( from, to ) {
	// See T. Vincenty, Survey Review, 23, No 176, p 88-93,1975.
	// Convert to radians.
	var lat1 = from.latRadians();
	var lon1 = from.lngRadians();
	var lat2 = to.latRadians();
	var lon2 = to.lngRadians();

	// Compute the angle.
	var angle = - Math.atan2( Math.sin( lon1 - lon2 ) * Math.cos( lat2 ), Math.cos( lat1 ) * Math.sin( lat2 ) - Math.sin( lat1 ) * Math.cos( lat2 ) * Math.cos( lon1 - lon2 ) );
	if ( angle < 0.0 )
	angle  += Math.PI * 2.0;

	// And convert result to degrees.
	angle = angle * degreesPerRadian;
	angle = angle.toFixed(1);
	return angle;
  }
		 
  // === A function to put arrow heads at intermediate points
  function midArrows(points) {
	for (var i=1; i < points.length-1; i++) {  
	  var p1=points[i];
	  var p2=points[i+1];
	  var dir = bearing(p1,p2);
	  // == round it to a multiple of 3 and cast out 120s
	  var dir = Math.round(dir/3) * 3;
	  while (dir >= 120) {dir -= 120;}
	  // == use the corresponding triangle marker 
	  arrowIcon.image = "http://www.google.com/intl/en_ALL/mapfiles/dir_"+dir+".png";
	  var midx = p1.x+((p2.x-p1.x)/2);
	  var midy = p1.y+((p2.y-p1.y)/2);
	  var middlepoint = new GLatLng(midy, midx);
	  map.addOverlay(new GMarker(middlepoint, arrowIcon));
	}
  }
	
	GDownloadUrl(filename, function(data) {
	  var xml = GXml.parse(data);
	  var markers = xml.documentElement.getElementsByTagName("marker");
	  var numpoints = markers.length - 1;
	  var points = [];
	  var dates = [];
	  var lc = [];
	  for (var i = 0; i < markers.length; i++) {
		var point = new GLatLng(parseFloat(markers[i].getAttribute("lat")),
								parseFloat(markers[i].getAttribute("lng")));
		var adate = markers[i].getAttribute("date");
		var alc = markers[i].getAttribute("lc");
		dates.push(adate);
		points.push(point);
		lc.push(alc);
	  }
	  var points2 = points.slice();
	  points2.sort(function(p1, p2) {
	  return p1.lng() - p2.lng();
	  });
	  var west = points2[0].x;
	  var east = points2[numpoints].x;
	  points2.sort(function(p1, p2) {
	  return p1.lat() - p2.lat();
	  });
	  var north = points2[numpoints].y;
	  var south = points2[0].y;
	  var sw = new GLatLng(south,west);
	  var ne = new GLatLng(north,east);
	  var bounds = new GLatLngBounds(sw, ne);
	  var centerpoint = new GLatLng((north + south)/2, (east + west)/2);
	  var zoomlevel = map.getBoundsZoomLevel(bounds);
	  map.setCenter(centerpoint, zoomlevel, G_SATELLITE_MAP);
	  midArrows(points);
	  for (var i = 0; i < (numpoints + 1); i++) {
		var text = dates[i] + lc[i];
		var marker = createMarker(points[i],text);
		map.addOverlay(marker);
	  }
	  map.addOverlay(new GPolyline(points));
	});
  }
}
//]]>