// This shows range rings on the map. Interval is user choice or automatic
// Bill Chadwick Jan 2008

// point is the centre or origin of the rings which are drawn with colour, weight (width in pixels) and opacity (0-1). 
// The interval parameter is either
//  1 - null in which case the interval is automatic depending on zoom level, showing several rings on screen
//  2 - A single number specifying a fixed interval between rings in metres
//  3 - An array of ring spacings in metres 
// MaxRings is used for auto and fixed interval to limit the number of rings drawn, not used with an interval array
// if it is null, rings will be drawn to twice the map's diagonal
// if user labels are wanted, labels should be an array of length maxRings or the length of the interval array 
// if interval is an array, colour can be a matching length array

function BdccRangeRings(point, colour, weight, opacity, interval, maxRings, labels, start_angle, stop_angle, label_dir) {

  this.colour = colour || "#0000FF";
  this.weight = weight || 3;
  this.opacity = opacity || 0.7;
  this.centre = point;
  this.interval = interval;
  this.maxRings = maxRings;
  this.labels = labels;
  if (start_angle == null) 
  {
        start_angle = 0;
  }
  this.start_angle = start_angle;
  if (stop_angle == null)
  {
        stop_angle = 360;
  }
  this.stop_angle = stop_angle;
  this.label_dir = 0;
  if (label_dir != null)
  {
    this.label_dir = label_dir;
  }
}
BdccRangeRings.prototype = new GOverlay();

BdccRangeRings.prototype.initialize = function(map) {

  this.map = map;
  this.circles = new Array();
  this.divs = new Array();//labels

  this.drawFirst = true;
  this.lstnMove = null;
  this.lstnStart = null;
  this.lstnType = null;
      
}

BdccRangeRings.prototype.remove = function() {

    this.unDraw();

    //remove handlers we use to trigger redraw / undraw
    try{
        if(this.lstnMove != null)
            GEvent.removeListener(this.lstnMove);
        if(this.lstnStart != null)
            GEvent.removeListener(this.lstnStart);
        if(this.lstnType != null)
            GEvent.removeListener(this.lstnType);
        }
    catch(ex)
    {
    }

}

BdccRangeRings.prototype.unDraw = function() {

  var div = this.map.getPane(G_MAP_MARKER_SHADOW_PANE);

  try{

    var i = 0;              
    for(i=0; i< this.circles.length; i++)
        this.map.removeOverlay(this.circles[i]);                    
  }
  catch(e){
  }

  try{

    var i = 0;              
      for(i=0; i< this.divs.length; i++)
          div.removeChild(this.divs[i]);                    
  }
  catch(e){
  }
  this.circles = new Array();   
  this.divs = new Array();  

}

BdccRangeRings.prototype.copy = function() {
  return new BdccRangeRings(this.point, this.colour, this.weight, this.opacity, this.interval, this.maxRings, this.labels);
}

//This normally does nothing due to reentrancy problems and problems removing overlays from within an overlay
//Instead we use the moveend event to trigger a redraw, this event occurs after zoom and map type changes
BdccRangeRings.prototype.redraw = function(force) {

    //but draw it the very first time
    if(this.drawFirst)
    {
        this.safeRedraw();

        // We use the moveend event to trigger the redraw
        var rdrw = GEvent.callback(this,this.safeRedraw );
        this.lstnMove = GEvent.addListener(this.map,"moveend",function(){rdrw ();});

        // We use the map type change event to trigger a redraw too
        var rdrw2 = GEvent.callback(this,this.safeRedraw );
        this.lstnType = GEvent.addListener(this.map,"maptypechanged",function(){rdrw2 ();});

        // And undraw during moves - for speed
        var udrw = GEvent.callback(this,this.unDraw );
        this.lstnStart = GEvent.addListener(this.map,"movestart",function(){udrw ();});

        this.drawFirst = false;

    }
}


// Redraw the rings based on the current projection and zoom level
BdccRangeRings.prototype.safeRedraw = function() {

  //clear old
  this.unDraw();

  var bnds = this.map.getBounds();
  var sz = this.map.getSize();
  var pxDiag = Math.sqrt((sz.width*sz.width) + (sz.height*sz.height));
  var diagKm = bnds.getNorthEast().distanceFrom(bnds.getSouthWest()) / 1000.0;
  var pxPerKm = pxDiag/diagKm;
  var d;//km initial/min interval

  if(this.interval == null)
  {
    //auto interval
    
    var width = sz.width / pxPerKm ;
    var height = sz.height / pxPerKm;  
    var ww = Math.max(width,height); 
  
    if(ww < 1.0)
        d = 0.1;
    else if(ww < 2.0)
        d = 0.2;
    else if(ww < 5.0)
        d = 0.5;
    else if(ww < 10.0)
        d = 1.0;
    else if(ww < 20.0)
            d = 2.0;
    else if(ww < 50.0)
            d = 5.0;
    else if(ww < 100.0)
            d = 10.0;
    else if(ww < 200.0)
            d = 20.0;
    else if(ww < 500.0)
            d = 50.0;
    else if(ww < 1000.0)
            d = 100.0;
    else if(ww < 2000.0)
            d = 200.0;
    else if(ww < 5000.0)
            d = 500.0;
    else 
            d = 1000.0;
  }
  else if (this.interval.constructor.toString().indexOf("Array") == -1)
    d = this.interval / 1000.0;// to km  
  else
    d = this.interval;//array of distances      

  
  if (d.constructor.toString().indexOf("Array") == -1){

      var p = (d >= 10.0) ? 0 : 1;//precision for label distances in km

    if(this.maxRings == null){
        //draw the rings to no more than twice the screen diagonal, auto or fixed interval
        // no custom labels as # rings drawn varies
        for(var r = d; (r < (diagKm * 2)); r += d)
          this.drawCircle (r ,r.toFixed(p) + "km",this.colour);
    }
    else{
        //draw maxRings rings auto or fixed interval
        var r = d;
        for(var i = 0; i<this.maxRings; i++){
            var odd = ((i /2) == Math.round(i /2, 0));
            if (odd)
            {
                this.drawCircle (r ,(this.labels == null)?r.toFixed(p)+ "km":this.labels[i],this.colour); 
            } else {
                this.drawCircle (r ,'',this.colour); 
            }
          r += d;
        }
    }
  }
  else{
    // interval array used
    for(var i = 0; i<d.length; i++){
        var c;
        if (this.colour.constructor.toString().indexOf("Array") == -1)
            c = this.colour;
        else
          c = this.colour[i];
        this.drawCircle (d[i]/1000.0 ,(this.labels == null)?d[i].toFixed(p)+ "km":this.labels[i],c); 
    }

  }

}  

  // get a new GLatLng distanceMeters away on the compass bearing azimuthDegrees
  // from the GLatLng point - accurate to better than 200m in 140km (20m in 14km) in the UK

  BdccRangeRings.prototype.PointAtRangeAndBearing = function (point, distanceMeters, azimuthDegrees) 
        {
             var latr = point.lat() * Math.PI / 180.0;
             var lonr = point.lng() * Math.PI / 180.0;
     
             var coslat = Math.cos(latr); 
             var sinlat = Math.sin(latr); 
             var az = azimuthDegrees* Math.PI / 180.0;
             var cosaz = Math.cos(az); 
             var sinaz = Math.sin(az); 
             var dr = distanceMeters / 6378137.0; // distance in radians using WGS84 Equatorial Radius
             var sind = Math.sin(dr); 
             var cosd = Math.cos(dr);
      
            return new GLatLng(Math.asin((sinlat * cosd) + (coslat * sind * cosaz)) * 180.0 / Math.PI,
            (Math.atan2((sind * sinaz), (coslat * cosd) - (sinlat * sind * cosaz)) + lonr) * 180.0 / Math.PI); 
        }



BdccRangeRings.prototype.drawCircle = function (rKm, label, colour)
{
  if (r < 0)
    return;

  if (r > (6378137.0 * Math.PI * 2))
    return;

  var mapDiv = this.map.getPane(G_MAP_MARKER_SHADOW_PANE);
  var c;
  var b;
  var pts = new Array();
  var r = rKm * 1000.0;

  // use 40 segment polyline to approximate a circle
  var circle_approximation = 36;
  var incr = 360 / circle_approximation;
    incr = 8;
  for(b=this.start_angle; b<=this.stop_angle; b+=incr){

    pts.push(this.PointAtRangeAndBearing(this.centre,r,b));

      // if ((b %45 == 0)&&(b!=360)){
      if (b %this.label_dir == 0) {

        //draw a label every 45 degrees

        var p = this.map.fromLatLngToDivPixel(pts[pts.length-1]);
        var dv = document.createElement("DIV");
        mapDiv.insertBefore(dv,null);
        dv.style.position = "absolute";
        dv.style.border = "none";
        dv.style.color = colour;
        dv.style.fontFamily='Arial';
        dv.style.fontSize='x-small';
        dv.innerHTML = label;
        var dx;
        var dy;

        //offset the labels to be just outside the ring

        if(b==0) {
            dx = -dv.offsetWidth * 0.5;
            dy = -dv.offsetHeight;
        }
        else if(b == 45){
            dx = 3;
            dy = -dv.offsetHeight;
        }
        else if(b == 90){
            dx = 3;
            dy = -dv.offsetHeight * 0.5;
        }
        else if(b == 135){
            dx = 3;
            dy = 3;
        }
        else if(b == 180){
            dx = -dv.offsetWidth * 0.5;
            dy = 3;
        }
        else if(b == 225){
            dx = -dv.offsetWidth -3;
            dy = 3;
        }
        else if(b == 270){
            dx = -dv.offsetWidth -3;
            dy = -dv.offsetHeight * 0.5;
        }
        else if(b == 315){
            dx = -dv.offsetWidth -3;
            dy = -dv.offsetHeight;
        }
            
        dv.style.left = (p.x+dx).toString() + "px";
        dv.style.top = (p.y+dy).toString() + "px";

        this.divs.push(dv);
    }
  }

  var c = new GPolyline(pts,colour,this.weight,this.opacity);
  this.map.addOverlay(c);
  this.circles.push(c);

}