// Global variables
var map;
var crosshair;
var coverage;
var coverageI;
var markerI;
var markers=0;

function loadMap() {
  if (google.maps.BrowserIsCompatible()) {
    var imageBase='http://dcdbs.ssec.wisc.edu/inventory/inc/';
    map = new google.maps.Map2(document.getElementById("map"));
    map.setCenter(new google.maps.LatLng(20, 0), 1);

    // Create our crosshair overlay icon
    crosshair = new google.maps.Icon();
    crosshair.image = imageBase + 'crosshair.png';
    crosshair.iconSize = new google.maps.Size(15, 15);
    crosshair.iconAnchor = new google.maps.Point(8, 8);

    // Create our coverage overlay icon
    coverage = new google.maps.Icon();
    coverage.image = imageBase + 'coverage.png';
    coverage.iconSize = new google.maps.Size(235, 425);
    coverage.iconAnchor = new google.maps.Point(118, 213);

    // Listen for map clicks and add crosshair
    google.maps.Event.addListener(map, "click", function(marker, point) {
      if (!markers) {
        markerI=new google.maps.Marker(point,crosshair);
        map.addOverlay(markerI);
        markers=1;
        displayPoint(point.lat(),point.lng());
      }
      else {
        removeMarker();
        displayPoint();
      }
    });
  }
  else { alert('This browser is not compatible with Google Maps'); }
}

function addCoverage(lat,lon) {
  removeCoverage();
  if (String(lat)=='' || String(lon)=='') { return(false); }
  var point = new google.maps.LatLng(lat,-1*lon);
  coverageI=new google.maps.Marker(point,coverage,true);
  map.addOverlay(coverageI);
}
function removeCoverage() {
  if (coverageI==null) return;
  map.removeOverlay(coverageI);
}

function addMarker(lat,lon) {
  removeMarker();
  if (lat=='' || lon=='') { return(false); }
  var point = new google.maps.LatLng(lat,-1*lon);
  markerI=new google.maps.Marker(point,crosshair);
  map.addOverlay(markerI);
  markers=1;
}
function removeMarker() {
  if (markerI==null) return;
  map.removeOverlay(markerI);
  markers=0;
}

function displayPoint(lat,lon) {
  var latElem=document.getElementById('TXT_lat');
  var lonElem=document.getElementById('TXT_lon');
  if (lat==null || lon==null) {
    latElem.value='';
    lonElem.value='';
    return(false);
  }
  var ns='N';
  if (lat<0) { ns='S'; }
  lat=Math.abs(lat.toFixed(2));
  var we='E';
  if (lon<0) { we='W'; }
  lon=Math.abs(lon.toFixed(2));
  latElem.value=lat+' '+ns;
  lonElem.value=lon+' '+we;
}

function checkDisplayPoint() {
  removeMarker();
  var latElem=document.getElementById('TXT_lat');
  var lonElem=document.getElementById('TXT_lon');
  if (latElem.value=='' || lonElem.value=='') { return(false); }
  var point = new google.maps.Point(latElem.value,lonElem.value);
  markerI=new google.maps.Marker(point,crosshair);
  map.addOverlay(markerI);
  markers=1;
}

function clearSubpoint() {
  removeCoverage();
  removeMarker();
  displayPoint();
}